How to grow dahlias? Efficient cultivation techniques and propagation methods
How to cultivate dahlias? What propagation methods are there for dahlias? In the following article, the editor of Huinong Network brings you dahlia cultivation management and propagation techniques.
1 Dahlia cultivation management
1.1 Land preparation
Dahlias like loose soil. When preparing the land, the plot can be deeply plowed. Before deep plowing, 5000 kg of organic fertilizer per mu and 25 kg of superphosphate should be used as base fertilizer. In addition, diazinon should also be applied to disinfect the soil. The soil should be deeply turned to 20 cm, after which the plot should be prepared into raised beds about 80 cm wide and 20 cm high, with a bed spacing of about 10 cm being most suitable.
1.2 Planting
In mid-May, rooted dahlia seedlings from cuttings can be transplanted onto the raised beds, ensuring a plant spacing of about 75 cm. The depth at which the seedlings enter the soil should be based on the depth of the root system. When covering with soil, be careful to leave a small hole to make watering convenient.
1.3 Watering
After transplanting, dahlias should be watered immediately and thoroughly. Generally, after watering continuously 2 to 3 times, the reserved watering hole should be filled in. The watered seedlings will grow vigorously. After that, the amount of watering should be controlled, mainly to control the height of the dahlias. The period for root establishment and strengthening the seedlings is about 25 days, and water control is mainly determined by the regional rainfall. If sunny weather appears after consecutive cloudy days, dahlia leaves may droop, mainly caused by exposure to the sun. At this time, watering is not needed, because the soil is not lacking moisture.
1.4 Fertilization and weeding
Dahlias like fertilizer. When fertilizer is insufficient, the flower diameter will become smaller, so when fertilizing, sufficient base fertilizer should be applied, with topdressing as a supplement. During the dahlia seedling stage, mainly nitrogen fertilizer is used, while combined with 2 to 3 applications of phosphorus and potassium fertilizer. The flower bud stage of dahlias requires a relatively large amount of fertilizer, so 2 to 3 applications of phosphorus and potassium fertilizer can be made together with watering. At the same time, foliar fertilization can be applied to improve flower quality and color and prolong the flowering period. Dahlias should not be fertilized during the bud coloring stage and the full bloom stage; fertilizing at this time will shorten the flowering period and reduce ornamental value. After the first flowering of dahlias, phosphorus and potassium fertilizer can be applied 1 to 2 times, mainly to promote the development of the flower roots. Weeding of dahlias is mainly done while loosening the soil, in order to preserve soil moisture.
1.5 Support and pruning
Dahlia flowers are relatively large and the stems are hollow, so the plants are prone to lodging. After dahlias produce flower buds, soil can be banked around the roots. For some tall dahlia varieties, supports should also be set up, which can be single stakes or tripod supports. Dahlias have many heads and relatively luxuriant branches and leaves, so they must be treated by removing buds, thinning leaves and disbudding, in order to ensure a graceful plant shape and achieve the best ornamental effect. To promote the growth of dahlias, excess parts at the base and between the leaf axils can be removed in time, in order to increase the supply of nutrients to the main stem of the dahlia. When flower buds appear on the terminal bud of the dahlia, observe promptly and remove 2 to 3 pairs of side buds among them, to ensure lush flowering at the top. In summer, cut off 1 to 2 leaves near the ground, mainly to prevent leaf rot that can lead to pests and diseases. Dahlias like sunlight and a well-ventilated environment, so leaves that block ventilation and light should be cut off in time, increasing leaf photosynthesis while enhancing the flower's frost resistance.
1.6 Pest and disease control
During growth, dahlias are most susceptible to powdery mildew. When powdery mildew is found, remove the diseased leaves in time. During the growing period, Tuzet and similar products can be sprayed for control. In addition, another common disease is flower rot, which mainly occurs during the full bloom stage. Because of high soil moisture and high temperature, it is prone to occur. At this time, Bordeaux mixture and similar products can be sprayed continuously 2 times, which can achieve a very good control effect.
2 Propagation of dahlias
2.1 Storage of tuberous roots
Before the early frost arrives, dahlia varieties should be selected to ensure the purity of the variety. Large flower root tubers generally begin dormancy at 0°C to 8°C. Because dahlias are frost-tolerant but prone to frost damage below 0°C, the rhizomes of dahlias should be harvested before the early frost. The harvesting principle is to cut off the plant about 3 cm above the ground, mainly to avoid damaging the sprouting positions of the rhizome. After the rhizomes are dug out, they should be dried for 1 to 3 days and then stored. The storage site for the flower rhizomes should be disinfected, then the flower rhizomes should be divided into multiple single roots and treated with carbendazim. Place the treated flower rhizomes in a container box, cover the area around the rhizomes with disinfected moist sand, and arrange the rhizomes in 3 layers as the most suitable; if placed too thickly, it will lead to premature sprouting or rot and mold.
2.2 Division propagation
Dahlia division propagation is also called vegetative propagation. Generally, one root tuber can only propagate 8 root tubers. The main method is to take out the stored root tubers, spread them in a single layer in a germination box filled with peat soil, cover them with 2 cm of sand, then water them thoroughly with an 800-fold fungicide-insecticide dual-kill solution, take them out and place them indoors at about 25°C room temperature, leave them for about 15 days to sprout, and then transplant them into flower pots or open ground.
2.3 Cutting propagation
Dahlia cutting propagation mainly follows division propagation to force sprouts. When the young shoots grow to about 4 cm, break the shoots off from the roots. At this time, note that the shoots must carry about 0.01 cm of root tuber from the root part, as this will ensure the survival rate. After the shoots are broken off, bury them properly with suitable soil, then wait for sprouting. Repeating this 3 to 4 times is best. After the seedlings are formed, bury the young seedlings in a substrate mixed with sand, peat soil and perlite, with a seedling spacing of about 4 cm. After the young seedlings are inserted, first water them thoroughly with an 800-fold solution of fungicide-insecticide dual-kill. After that, spray water every day to keep the substrate moist, but there must be no standing water in the substrate, to prevent the seedlings from rotting. Under normal circumstances, in weather of about 20°C, the seedlings can take root in 15 days, and rooted seedlings can be transplanted after 20 days of cultivation. Dahlia cutting propagation technology has a high survival rate. Generally, one root tuber can propagate more than 40 plants, with a high propagation coefficient, and the propagated seedlings have strong disease resistance.
That is all for today's content. Flower farmers who want to grow dahlias can come to Huinong Network to learn more technical knowledge.
Gerbera Gerbera jamesonii Bolus Gerbera illustrated guide: how to grow gerbera / how to propagate gerbera
Gerbera profileGerbera Gerbera jamesonii Bolus
Gerbera cultivation methods and precautions Introduction to gerbera
Gerbera (English name: Gerbera), a perennial herbaceous plant of the Asteraceae family, with fine hairs all over the plant, terminal inflorescences, most leaves basal, pinnately lobed. Plant height 30-45 cm, capitulum solitary, terminal inflorescence, flower colors include red, white, yellow, orange, purple, etc. It rises 20-40 cm above the leaves, flower diameter 10-12 cm, involucre disk-shaped, bell-shaped, ligulate petals 1-2 or multiple whorls in double form, usually flowering in all four seasons, most abundantly in spring and autumn.
It is an important material in modern cut flowers. Gerbera has a relatively large flower diameter (8 cm to 10 cm), and its flowering period is easy to regulate. At present, the cut flower cultivation area is increasing year by year, and its application is becoming more and more widespread. Gerbera can also withstand long-distance transport, and cut flowers last a long time in water; if cultivated properly, each plant can yield 30 cut flowers per year, making it truly an ideal cut flower. Gerbera flowers are large and colorful, and management saves labor. In warm regions it can supply fresh cut flowers year-round. The main types can be divided into modern cut flower types and dwarf cultivation types, with various flower colors such as white, pink, red and yellow.
Morphological characteristics of gerbera
Perennial, hairy herb. Rhizome short, surrounded by remnant leaf stalks, with relatively thick fibrous roots. Leaves basal, rosette-like, leaf blades long elliptic to oblong, 10-14 cm long, 5-6 cm wide, apex shortly acute or slightly obtuse, base gradually narrowed, margin irregularly pinnately lobed or deeply lobed, glabrous above, shortly pubescent below, losing hairs when old; midvein raised on both sides, especially thick and prominent below, lateral veins 5-7 pairs, curved and connected away from the margin, reticulate veins slightly obvious; petiole 7-15 cm long, with thick longitudinal ridges, more or less hairy. Scape solitary, or rarely several clustered, 25-60 cm long, without bracts, hairy, hairs densest at the top, capitulum solitary at the top of the scape, 6-10 cm in diameter when the ligules spread during flowering; involucre bell-shaped, about as long as the bisexual flowers, up to 2 cm in diameter; involucral bracts in 2 layers, outer layer linear or subulate, apex acute, 8-10 mm long, about 1-1.5 mm wide, pubescent on the back, inner layer oblong-lanceolate, apex caudate-acuminate. 10-14 mm long, about 2 mm wide, margin dry membranous, sparsely pubescent on the ridge; receptacle flat, naked, honeycomb-like, 6-8 mm in diameter; outer female flowers in 2 layers, outer corolla ligulate, ligule pale red to purplish red, or white and yellow, oblong, 2.5-3.5 cm long, 2-4 mm wide, apex with 3 teeth, inner 2 lobes filamentous, curled, 4-5 mm long, corolla tube short, about 1/8 the length of the ligule, staminodes filamentous, 3-4 mm long, extending beyond the corolla tube; inner female flowers more slender than bisexual flowers, tubular two-lipped, 6-7 mm long, the two lips equal in length, outer lip with 3 fine teeth or sometimes 2 teeth and 1 lobe, inner lip 2-parted, lobes linear, about 4 mm long, curled, staminodes 4-5, linear or filamentous, hidden within the corolla tube; central bisexual flowers numerous, tubular two-lipped, 8-9 mm long, outer lip large, with 3 teeth, inner lip 2-parted, lobes usually broad, curled; anthers about 4 mm long, with long pointed tails; style branches of female flowers and bisexual flowers both short, apex obtuse, less than 1 mm long. Achene cylindrical, 4-5 mm long, densely covered with white short pubescence. Pappus slightly rough, dirty white when fresh, light brown when dry, 6-7 mm long, united at the base. Flowering period November to April of the following year.
Ecological habits of gerbera
It likes environments with warm winters and cool summers, air circulation and sufficient sunlight. It is not cold-resistant and avoids intense heat. The suitable growth temperature is 20°C-25°C, and the suitable winter temperature is 12°C-15°C. When below 10°C, growth stops. It is a semi-cold-tolerant flower and can endure short periods of 0°C low temperature. In South China it can be cultivated as an open-field perennial flower; in East China it must be covered for overwintering or grown in a greenhouse for cut flower forcing cultivation. It likes fertile, loose, well-drained sandy loam rich in humus, avoids heavy clay soil, and is suitable for slightly acidic soil. It can also grow in neutral and slightly acidic soil, but in alkaline soil, the leaves are prone to deficiency symptoms. The flowering period of gerbera is very easy to regulate; as long as the room temperature is kept above 12°C, the plant can be kept from entering dormancy and continue to grow and bloom. It likes fertile, loose, well-drained sandy loam rich in humus, avoids heavy clay soil, is suitable for slightly acidic soil, is a semi-cold-tolerant flower, and can endure short periods of 0°C low temperature. Gerbera is a light-loving plant, so choose a location with sufficient light for cultivation. Seedlings should not be planted too deeply; the root buds need to be exposed above the soil surface. If light is insufficient, the flower stalks become soft and droop, and cut flower quality is not high.
Economic value of gerbera
Gerbera seedling producers in Yunnan are mainly concentrated in Kunming, about 20 in number, among which more than 10 are relatively large in scale. The annual output of gerbera seedlings is about 20 million plants. Many enterprises or research institutions have collected rich gerbera variety resources and possess strong production technology and experience. The gerbera seedlings they produce are deeply loved by growers inside and outside the province. Kunming has become the center of national gerbera seedling production. After nearly 10 years of development, gerbera, which ranks fifth on the international cut flower sales list, has continuously expanded its planting scale in Yunnan. Its cultivation area is second only to roses, carnations and lilies, making it a major fresh cut flower type in Yunnan.
Market
In March and April, although the upsurge in Yunnan flower sales has receded, it has ushered in the "golden period" for gerbera seedling sales. Gerbera seedlings sold from Kunming to inside and outside Yunnan Province reached more than 2 million plants in April sales. A nationwide gerbera seedling production pattern centered on Kunming has basically taken shape.
Volume declined and prices fell back
It is understood that gerbera seedling producers in Yunnan are mainly concentrated in Kunming, about 20 large and small, among which more than 10 are relatively large in scale. Affected by the relatively high price of gerbera seedlings, although household-based seedling production households have appeared, because the production volume of enterprises has declined, compared with the previous period, the total production of gerbera seedlings has decreased to about 15 million plants. Prices have also fallen back, from 0.8 yuan/plant to 1.0 yuan/plant in the same period, down to 0.6 yuan/plant to 0.8 yuan/plant.
Sales situation is grim
It is reported that growers in Yunnan Province have significantly reduced their demand for gerbera seedlings. In 2005, the planting area was about 5000 mu, an increase of 1000 mu compared with 2004. Calculating at 4500 seedlings planted per mu, the newly added 1000 mu required 4.5 million seedlings. For the remaining 4000 mu, if 1/3 of the gerbera plants needed replacement with new seedlings (generally gerbera growers replace seedlings once every two or three years), then 6 million seedlings were needed, and the province's total seedling demand was 10.5 million plants. If 1/3 to 1/2 of the gerbera plants were replaced with seedlings, then the seedling demand within Yunnan Province was 6 million to 9 million plants. From this it can be seen that the number of seedlings sold outside Yunnan Province could not be less than 6 million plants. But in fact, Yunnan gerbera seedling enterprises did not sell much in markets outside the province. Therefore, gerbera seedlings are in a situation of supply exceeding demand, and the sales situation is grim.
In addition, affected by soil continuous cropping obstacles, the gerbera cut flower market was not very prosperous, causing some flower farmers in Jinning County, Kunming City, which accounts for nearly half of Yunnan's gerbera planting area, to switch the land originally used for gerbera to roses or carnations. Demand for gerbera seedlings within the province shrank. Demand for seedlings in markets outside Yunnan Province is in a growth trend. Surveys show that the gerbera planting area in Jiangsu, Liaoning, Shandong and other provinces is increasing.
Seeking joint development
After nearly 10 years of development, many enterprises or research institutions in Yunnan have already possessed relatively strong production technology and experience, collected rich gerbera variety resources, and the gerbera seedlings they produce have formed a certain brand effect, deeply loved by growers inside and outside the province. However, due to reasons such as relatively large losses in long-distance transport of gerbera, inadequate postharvest handling technology, and declining quality of seedling mother plants, the development of the gerbera cut flower and seedling industry has been affected.
Kunming Tongxin Flower Co., Ltd. has an annual gerbera seedling output of 7 million plants, of which nearly 50% are sold to markets outside the province, and some products are also exported to Vietnam and other neighboring countries. Company general manager Bi Xiaoping said that gerbera tissue culture technology is not difficult, and seedling production by enterprises or research institutions outside Yunnan Province may completely catch up with or even surpass Yunnan. Facing increasingly fierce market competition, for Yunnan gerbera seedlings to gain a firm foothold in the market, they must start from the following 3 points: first, strive to improve seedling quality, extend the hardening period, increase the survival rate of finished seedlings, and at the same time control the propagation coefficient of seedlings to reduce indoor contamination and mold infection of seedlings; second, according to the demand conditions of different regions, select suitable varieties, such as green-centered varieties mainly for outside the province and black-centered varieties mainly within the province; third, take the path of factory-based and specialized production, expand scale effects, implement small profits but quick turnover, and improve market competitiveness.
In early April, led by the Flower Research Institute of the Yunnan Academy of Agricultural Sciences, responsible persons from enterprises such as Kunming Qianhui, Kunming Yuhui, Kunming Tongxin and Kunming Jinkeyi were invited to hold a discussion to jointly discuss matters such as establishing the Yunnan Gerbera Seedling Association. At the same time, they will negotiate with foreign breeders under the name of a "large group" to strive to introduce high-quality mother plants and new varieties at low prices. It is reported that they have already negotiated with the Dutch company Florist and plan to introduce more than 4 million high-quality mother plants from the company, requiring payment of more than 4.8 million yuan in patent fees.
Gerbera Gerbera and daisy difference Gerbera
Scientific name: Gerbera jamesonii
Family: Asteraceae
Origin and distribution: South Africa
Morphological characteristics: with a rosette leaf cluster. Leaves oblong-spatulate, deeply lobed or lyrate-pinnately lobed, with white down on the leaf back. Capitulum. Flower colors range from white to various yellows, oranges, rose reds, reds, etc. If the ambient temperature is suitable, it can bloom all year round.
Growth habits: Likes climate conditions with mild winters and cool summers. Requires well-drained soil rich in humus, deep and fertile, with a pH value of 6-6.5.
Garden use: Barberton daisy is mainly used for cut flowers and potted flowers, and can also be used for flower beds when climate conditions are suitable.
Propagation and cultivation: Potted cultivation, mainly by sowing.
Daisy
Aliases: spring daisy, perennial daisy
Scientific name: Bellis perennis
Family and genus: Asteraceae, Bellis
Habits: A perennial herbaceous plant, often cultivated as an annual or biennial. Likes cool, humid and sunny conditions, relatively cold-tolerant, and can overwinter in open ground where the ground surface is not lower than 3-4°C. It has no strict requirements for soil. Flowering period April-May.
Cultivation: Propagated by sowing or division. The suitable temperature for seed germination is 22-28°C. In North China, sow in August-September, move into raised beds for overwintering in late October, and pot or plant into flower beds in April of the following year. During the growing season, as long as appropriate water and fertilizer are ensured, it can grow well. After flowering, the roots can be divided and planted in pots, placed in a cool place to pass the summer, and moved into a greenhouse or indoors after the autumn cools. With strengthened fertilizer and water management, it can bloom again in winter or the following spring. There are relatively few pests and diseases.
Cultural background, origin and evolution of gerbera
In 1878, Rehman first discovered gerbera in Transvaal, South Africa, and in the same year Bullas sent it to Kew Gardens in England. Lynch in England was the first to carry out hybrid breeding of gerbera. He crossed gerbera with green-leaf gerbera (G. viridifolia Sch.-Bip.) and bred hybrids; afterward, Adenet in France selected and bred varieties for cut flowers; after 1950, new varieties were bred in Europe; in 1980, dwarf potted varieties were also bred, with a flowering period almost continuous throughout the year. Japan also achieved excellent results in breeding double-flowered gerbera. In addition, people have also bred many distant hybrids, using gerbera as the female parent and Coreopsis (Coreopsis basalis Blake.) or marguerite (Argyranthemum frutescens Sch.-Bip.) as the male parent. Their hybrid flower types mostly resemble the male parent.
Gerbera flower color genes are rich in inheritance and highly heterogeneous, and their progeny differ greatly in flower type and flower color. Therefore, excellent hybrid individual plants can be rapidly and massively propagated into clonal lines through tissue culture. As a result, varieties change quickly with fashion trends. Their flower colors are mainly white, red, pink, orange, purple, etc. In addition, interspecific hybridization is easy to combine, so in addition to the above inherent color lines, there are also many intermediate color lines.
Origin of the name Barberton daisy
In the early 20th century, Madagascar, located in southern Africa, was a small country rich in tropical flowers and plants. There was a local girl named Slangyini who, since childhood, loved this kind of wildflower with slightly curved stems and drooping flowers. When she married, she asked for more of them to be arranged in the hall to add to the wedding atmosphere. Relatives and friends from all sides sang and danced, toasting each other frequently. Unexpectedly, the groom, with a very low tolerance for alcohol, became drunk after only three rounds of drinks. He bowed his head and bent his waist, leaning east and west, and the bride had to support him into the bedroom to rest. Seeing this supporting posture and how similar it was to the growth form of that wildflower, many girls said in unison: "Oh, the flower really looks like supporting a husband!" From then on, the name Barberton daisy spread far and wide.
Gerbera is also known as Barberton daisy and is native to southern Africa. Its flowers are large and beautiful, delicate and pleasing to the eye, and it is an important cut flower decorative material. Large red gerbera flowers are used in bridal bouquets. Together with roses, gladioli and carnations, it is listed among the world's best-selling "four major cut flowers."
Cultivation history
The first person to improve gerbera varieties was the Englishman Irwin Lynch, who crossed G. jamesonii with green-leaf gerbera (G. vurufolia). Later, the Frenchman M. Adent continued to improve it and bred a large number of cut flower varieties. In addition, Japan also bred double-flowered varieties with diverse flower types and colors, collectively called hybrid gerbera (Gerbera jamesonii), used for cut flowers and potted flowers.
Feng shui
Gerbera can promote women's romance. The bedroom is probably the most important space for changing a woman. Especially when in love, random thoughts mostly occur in the bedroom. Love feng shui requires confirming the bedroom arrangement. For example, placing a fresh and long-lasting gerbera at the bedside, with a fragrance that is somewhat pleasant and will not easily disappear, can encourage oneself.
Gerbera can promote family harmony. Like sunflowers, gerbera is a flower that represents the sun in everyone's mind, except that the latter is tall and mighty, while the former is elegant and upright. If the sunflower is the blazing sun shining high in summer, then the gerbera is like the warm sun in winter, making people feel cozy. Someone once advocated using gerbera as the flower representing Father's Day, because gerbera is also called sun flower, and the sun can also symbolize fatherly love. The feng shui effect of gerbera, the saying that it can make a family live in harmony and love each other, also arises from this.
For people whose Five Elements belong to fire, gerbera is their lucky flower. In Chinese feng shui, it is believed that the types, properties and placement positions of some plants can affect a person's destiny. Plants also have yin-yang and Five Elements distinctions. Using them appropriately in different directions and environments can produce unexpected regulating effects. In feng shui, plants are considered spiritual and can help people in various aspects to a certain extent. Therefore, plants are often used to regulate the environmental energy field. There are many types of plants and their properties vary greatly, so there are also many particularities when using them. Such plants are called feng shui plants. People whose Five Elements belong to fire should choose red as the main color, because red is the inherent color of fire, or choose green, the inherent color of wood, as the main color, because green wood generates and strengthens red fire. From the perspective of feng shui, this can bring prosperous good fortune to the homeowner and their family. Of course, besides red, gerbera also has many other colors, so gerbera is a lucky star for many people. As the color of gerbera changes, the group of people it blesses is different.
Variety classification of gerbera Variety classification
It can mainly be divided into dwarf potted types and modern cut flower types. Potted types are mainly F1 hybrids, with characteristics such as consistent flowering period, rich color variation, short growth period, uniform habit and strong floriferousness; cut flower varieties have straight flower stalks, and large flower diameter can reach 15 cm, long flowering period, can bloom all year round, long ornamental time, and vase life as long as 7-10 d. Cut flower types can also be divided into single-layer type, semi-double type and double type; according to color, they can be divided into bright red series, pink series, pure yellow series, orange-yellow series, pure white series, etc. Different types of varieties on the market can also be divided into:
1. Narrow-petal type Ligulate petals 4-4.5 mm wide, 50 mm long, arranged in 1-2 whorls; inflorescence diameter 12-13 cm, flower disk small, flower stalk 5-6 mm thick, 50 cm long. Annual yield per plant more than 30 stems.
2. Wide-petal type Ligulate petals 5-7.5 mm wide, 41-48 mm long, about 60 petals, arranged in 1-3 whorls; inflorescence diameter 11-13 cm, flower stalk 6 mm thick, 50-70 cm long. Annual yield per plant more than 20 stems.
3. Large-flowered double type Inflorescence diameter 10-14 cm.
Main domestic varieties
Common varieties include the red "Passion", the yellow "Sun Dance", the white "Bianca", etc. Miniature small flowers include "Ballroom" (white), "Ballet" (orange), "Sudan" (yellow), "Conga" (red), etc.
Serial number Variety Flower diameter cm Number of ligulate flower layers Ligulate flower color Tubular flower color
1 Cathy 10-12 Many Pink Green
2 Chateau 10-12 2-3 Dark purple Dark purple
3 Diablo 10 Many Purplish red Black purple
4 Golden Gate 10-12 Many Deep yellow Black purple
5 Jolly Disc 12-14 3-4 White Pink purple
6 Lorraine 10-12 Many Deep yellow Green
7 Magnum 10-12 Many Deep pink Black purple
8 North Star 8-9 3-4 Red Green
9 Oprah 10-12 Many Yellow Green
10 Optima 10-12 Many Orange-red Black purple
11 Ramona 10 3-many Red with golden edge Green
12 sangria 11-13 Many Purplish red Black purple
13 Savannah 10-12 3-4 Purplish red Black purple
14 Shirley 10-12 4 Deep pink Black purple
15 Sunset 10-12 Many Orange-red Black purple
16 Twiggy 10-12 Many Blue-purple Yellow-green
17 Venus 10-12 Many Cream yellow Deep pink
18 Willy 7 Many Deep pink Purplish red
Main species in the same genus
There are about 80 species in this genus, mainly distributed in Africa; 20 species are produced in China, the vast majority concentrated in the southwest region, with no ornamental applications seen. Commonly cultivated for ornamental purposes are also:
1. Orange-yellow gerbera (G. aurantiaca Sch.-Bip.) Flowers orange-yellow or dark red, back yellow or brown
2. Green-leaf gerbera (G. viridifolia Sch.-Bip.) Leaves entire, smooth; flowers relatively small, white, back yellow
Distribution area of gerbera
Native to South Africa, with a few distributed in Asia. Commercial production now also occurs in Taiwan, China and Guangdong. With the progress of domestic greenhouse technology and the introduction of new foreign greenhouse technologies, it is cultivated in South China, East China and Central China.
Garden use of gerbera
Its flowers are large, flower stems upright, flower colors brilliant, long-lasting in water, high cut flower rate, vase life up to 15-20 days, and cultivation saves labor and time. It is one of the world's famous top ten cut flowers. It can also be used to arrange flower beds and flower borders, or grown in greenhouses as potted plants for decorative display in halls, meeting rooms, etc.
Potted gerbera is often used to decorate doorways and halls, and its cut flowers are used in vases and flower arrangements, adorning desks, display windows and living rooms. With pink gerbera as the main flower, paired with Dendrobium, gypsophila and orchid leaves, the tone is elegant and the interest is strong. If red gerbera is used as the main flower, paired with sword fern, palm bamboo leaves, dried branches and dyed walnuts for wall-hanging decoration, it can produce a relatively strong decorative effect. It is commonly cultivated in gardens across China, mostly as potted plants.
Propagation methods of gerbera Propagation is by sowing or division.
Because gerbera is a cross-pollinated plant and self-incompatible, its seed progeny will inevitably vary. The variation types generally show thinner and softer flower stalks, smaller flower shape, and greatly reduced cut flower value. Therefore, gerbera must be propagated asexually. Division propagation is usually used, but each plant can only be divided into 5-6 new plants each year. To accelerate propagation, cuttings and tissue culture can also be used.
Propagation methods
Tissue culture is the main method for propagating gerbera. Gerbera tissue culture commonly uses the receptacle as explant. Use flower buds about 2 cm in diameter, disinfect and wash them, leaving only the receptacle, cut it into 2-4 pieces, and place them on the medium. The medium formula is MS plus BA 1.0 mg/L, plus indoleacetic acid (IAA) 0.5 mg/L. At 22°C with 16 h of light per day, callus gradually forms, and after 1-2 months shoots form from the callus. Transfer the material that has differentiated shoots to the subculture medium, which is MS plus BA 0.1/L, plus indoleacetic acid 0.1 mg/L. When the leaves of the test-tube plantlets reach 2 cm in length, transfer them to the rooting medium. When transferring the plantlets, remove the callus at the base of the test-tube plantlets. The rooting medium formula is 1/2 MS plus naphthaleneacetic acid (NAA) 0.1 mg/l.
After gerbera explants induce shoots, after 4-5 months of test-tube proliferation, thousands upon thousands of test-tube plants can be produced. The most suitable field transplanting period for gerbera is April. Seedlings transplanted at this time can produce flowers in large quantities in August. Therefore, callus differentiation into shoots should be completed before mid-October; the 1st test-tube proliferation is from mid-October to mid-November, then once every month thereafter, ending the 4th proliferation in mid-February of the following year, followed by 2 weeks of test-tube plantlet rooting; after rooting, transplant to the seedling bed, maintain for 1 month, and then move to the field in early April.
Gerbera mostly uses tissue culture for rapid propagation, or division propagation, with each mother plant able to be divided into 5-6 small plants; seed propagation is used for dwarf potted varieties or breeding; single buds or short lateral buds occurring at the neck base can be cut and used for cuttings. Its response to photoperiod is not sensitive, and day length has no effect on flower number and flower quality. It requires loose, fertile, well-drained sandy loam rich in humus, with deep soil layers and slightly acidic.
Artificial culture soil cultivation of gerbera can significantly increase yield and quality. Mix 5 parts humus, 2 parts perlite and 3 parts peat to make culture soil for planting, but the production cost of this method is relatively high. Field planting can be carried out by selecting loam with a deep soil layer of at least 25 cm that is suitable for gerbera growth for planting. Before planting, sufficient base fertilizer should be applied: 5 tons of livestock manure per mu, 600 kg of chicken manure, 100 kg of superphosphate, 300 kg of plant ash, and the organic fertilizer must be fully decomposed. The fertilizer should be thoroughly mixed with the soil of the planting bed and plowed, made into a form of one ridge and one furrow, with ridge width 40 cm and furrow width 30 cm. Plants are planted on the ridge in double rows in staggered arrangement. Plant spacing 25 cm. Care should be taken to expose the rhizome part slightly above the soil to prevent root rot. Afterward, irrigate in the furrow.
However, because of its fast propagation speed, it has been listed as an invasive alien species in Guangdong, China. If you want to transplant it outdoors, consider it carefully, otherwise once the flower seeds open, it will cause unnecessary trouble.
Division propagation
Because old plants flower poorly, division is usually done once every 3 years. The method is to dig up the old plant and divide it, with each new plant carrying 4-5 leaves, and plant them separately. The disadvantage of this method is that propagation speed is slow.
Cutting propagation
Dig up selected robust mother plants, remove the soil from the roots and remove the leaves, and cut off the growing points. Keep the rhizome part and plant it in a planting box for cultivation. Place the planting box under conditions of 22-24°C and 75%-80% relative air humidity. Afterward, the rhizome part will successively grow axillary buds and adventitious buds, forming cuttings for propagation. Cut off the shoots after they have 4-5 leaves, insert them in soil or other substrate, and cover the surface with 1-2 cm of perlite. Keep the temperature at about 25°C and relative humidity at 75%-90%. After 3-4 weeks they can root, and rooted cuttings can be transplanted.
Cultivation Techniques for Gerbera: Key Cultivation Points
The optimum temperature for the growing period of Gerbera is 20-25 °C. Below 10 °C or above 30 °C, growth stops and the plant enters a semi-dormant state. If year-round flowering is desired, the temperature must be maintained above 12-15 °C in winter and not exceed 26 °C in summer. Therefore, in the southern Fujian area it can overwinter in the open field, but to obtain high-yield, high-quality cut flowers, it is best to have insulation equipment such as plastic greenhouses; in summer, shade nets can be installed or water sprayed to lower the temperature, ensuring a year-round supply of cut flowers.
(1) Soil must be sterilized. Gerbera is not very demanding about soil; loose, breathable, sandy soil rich in humus is ideal. Because the pathogens of various diseases harmful to Gerbera can survive in the soil, and soil also contains underground pests and earthworms that damage the root system, soil sterilization must be carried out before planting.
(2) Land preparation and fertilization. Because Gerbera is afraid of waterlogging, high-ridge cultivation is generally used. The ridges usually run north-south, with a ridge height of about 30 cm, a ridge width of 1 m, and a furrow width of 40-50 cm. Along with land preparation, apply an appropriate amount of base fertilizer, applying 200 kg of barnyard manure per 100 m.
(3) Planting. Planting is best done on cloudy days or in the evening of sunny days. Apart from the high-temperature period from July to September in summer, planting can be done at any other time. When planting, it must be planted shallowly, with the root crown exposed above the soil surface, and watered thoroughly. Newly planted plants should be shaded with shade nets.
(4) Pay attention to seedling-stage management. According to the weather conditions at the time of planting, carry out insulation or cooling management, controlling the temperature at 20-25 °C so that the plants quickly resume growth. After the seedlings have recovered, apply 1:10 human manure and urine once every two weeks, ensuring that each plant has 8-10 healthy leaves before entering the flowering period. When watering and fertilizing, be careful not to let water get into the center of the leaf rosette, otherwise the flower buds are prone to rot.
(5) Fertilizer and water management. Gerbera is drought-tolerant but not moisture-tolerant, and waterlogging must be strictly avoided. During the seedling stage, the soil should be kept appropriately moist to promote root development. During the growing period, the amount of watering can be determined by how dry or moist the soil is: do not water until it is dry, and when watering, water thoroughly. In winter, water as little as possible; the soil is better kept slightly dry. In summer, the weather is hot and water evaporates quickly, the plants enter a semi-dormant state, flower production drops noticeably, and plant vigor weakens; at this time pests and diseases are very likely to occur. This can be combined with topdressing to promote the roots' absorption of nutrients. In summer, it is necessary to loosen the soil in time, clear the roots to prevent disease, control water and fertilizer, and provide shade and rain protection.
(6) Leaf stripping and bud thinning. Gerbera can flower year-round within the range of 5-30 °C, so it has a high fertilizer demand throughout the growing period. Before flower bud differentiation, increase the application of organic fertilizer and nitrogen fertilizer to promote full plant growth, mainly using monopotassium phosphate and urea, plus an appropriate amount of liquid organic fertilizer, applied as a topdressing once a week. When the plant enters the period of simultaneous vegetative and reproductive growth, the proportion of phosphorus and potassium fertilizer should be increased, generally once a week, while adding an appropriate amount of organic fertilizer. Before the two flowering peaks from April to June and in September and November, foliar spraying of KH2PO4 should be carried out as appropriate to meet the needs of reproductive growth.
(7) Humidity and light. Gerbera is relatively cold-tolerant, and its growth is not sensitive to light, but it likes sufficient sunlight. When cultivated in a greenhouse, adding 2-3 layers of plastic film in winter allows it to overwinter safely. Before the first frost arrives in late October, cover with one layer of plastic film; around November, small tunnels should be built over each ridge for insulation. From June to September, 50% shade nets can be used to lower the temperature.
(8) Removal of withered leaves. The leaves clustered at the base of Gerbera easily turn yellow and age, and should be removed in time. This not only benefits the sprouting of new leaves and new flower buds, but also helps ventilation and light penetration, preventing the lower young flower buds from failing to receive sunlight and hormones and becoming "hidden buds." In addition, excessively numerous flower buds or deformed flowers should also be removed in time to ensure that the retained flower stems have sufficient nutrients and to improve the quality of cut flowers. Generally, a one-year-old single plant has 15-20 healthy leaves at the peak flowering stage and can produce 5-6 flowers per month; a two- or three-year-old single plant can retain 20-25 leaves and can produce 7-8 flowers per month.
(9) Harvesting and preservation. When the outermost two layers of ligulate flowers of the Gerbera flower head are perpendicular to the flower stem and show the color unique to the variety, it can be picked. The best time is in the morning and evening when temperatures are low, as it is easy to pick then without damaging the plant. The method is to hold the lower half of the flower stem with your hand and shake it side to side, and it can be harvested. Remove flowers with disease spots, insect spots, or deformities, cover the flowers with No. 12-15 funnel-shaped plastic bags, then grade them by variety and length, tie them in bunches of 20 with rubber bands, and they are ready for sale. If not sold immediately, they should be placed upright in a bucket or other container with clean water for water preservation, with the water depth preferably covering 5-10 cm of the base of the flower stem.
Cultivation Protocol: Soil Preparation
1. Soil tillage and base fertilizer: Before planting, deep-plow once (30-40 cm). Apply chemical fertilizer and barnyard manure (apply 2000 kg of thoroughly decomposed barnyard manure, 5 m3 of humus soil, 65 kg of superphosphate, and 50 kg of compound fertilizer per mu) to the soil, then deep-plow again (15-25 cm).
2. Bed preparation: Dig a drainage ditch 70-100 cm deep nearby (depending on the water table level), and form high ridges 45 cm high, with a ridge width of 1.0 m and a ditch width of 40 cm.
3. Soil sterilization: Use formaldehyde sterilization and chemical agents such as Weibomu (tentative), taking 40% industrial formaldehyde sterilization as an example: dilute to a concentration of 1%, spray evenly on the soil, and immediately cover well with plastic film for sealed fumigation. After 2-3 days, remove the film, air-dry the soil for two weeks, then rinse with water, and only after another two weeks can planting be carried out. Different sterilizing agents should be determined according to the instructions and trials. Soil used for the first planting does not need sterilization.
Seedling Selection
Select seedlings 11-15 cm tall with 4-5 true leaves for planting. Standards for high-quality seedlings: robust seedlings, glossy green leaves, well-developed root systems with many fibrous roots that are white in color, and leaves free of disease spots, insect bite gaps, and mechanical damage.
Planting
Planting time: Planting can be done year-round, but from the perspective of production and sales, April to June is ideal.
Planting method: Plant 3 rows per ridge, with the middle row staggered against the side rows, plant spacing 30 cm, 9-10 plants per sq m, and more than 1100 plants can be planted per greenhouse.
Planting method: 2-3 days before planting, water the soil thoroughly; carry out planting on cloudy days or in the morning and evening of sunny days; when planting, make a deep hole and plant shallowly, with the root crown exposed 1-1.5 cm above the soil surface; otherwise, the plant is prone to fungal infection. If the plant is planted too shallowly, the plant is easily loosened or pulled out when harvesting flowers; after planting, water thoroughly in time.
Cultivation Management
1. Management during the seedling stage: After planting, shade with 70% shade nets for 7-10 days, and gradually increase light after the seedlings have survived; regulate day and night temperatures by opening and closing the side film and top film, maintaining a daytime temperature of 22-25 °C and a nighttime temperature of 20-22 °C for 1 month; during this period, use sprinkler irrigation, preferably watering in the morning. Make a small hole beside the plant to indicate soil moisture. The soil should not be too dry or too wet; the watering frequency is once every 5 days, but this is not fixed and should be determined specifically according to soil structure, weather conditions, etc.; inspect plant by plant every day, promptly remove diseased plants, and fill in with robust young seedlings.
2. Management during the mature seedling stage: About 1 month after planting, Gerbera enters a period of vigorous growth, and appropriate shading is needed when light is too strong; adjust the temperature to 14-16 °C at night and 18-25 °C during the day as the minimum temperature; apply 0.1% compound fertilizer (N:P:K = 15:15:15) once every week, and spray 0.1% monopotassium phosphate as a foliar fertilizer once every 2 weeks; spray broad-spectrum fungicides, such as 800-**** times dilution of thiophanate-methyl, 2-3 times to prevent disease.
3. Management during the flowering period: About 3-4 months later, the plant enters the flowering period. Apply compound fertilizer with N:P:K = 12:12:17 once every week. Use foliar spraying of micro-fertilizers, generally once every 25 days, each time alternately spraying 0.1-0.2% Ca(NO3)2.4H2O, 0.1-0.2% chelated iron plus 0.1-0.2% borax plus 5-10 ppm sodium molybdate; use drip irrigation for watering, with the principle of "do not water until dry, and when watering, water thoroughly," and never water from the leaf rosette. Keep the relative humidity in the greenhouse at 80%-85%; weed in time, remove diseased and withered leaves, pull out diseased plants and disinfect the soil in the planting holes with quicklime; during the summer flowering period, pay attention to shading and ventilation for cooling; during the winter flowering period, pay attention to insulation and heating, especially preventing too large a temperature difference between day and night to reduce the production of deformed flowers.
The cultivation techniques are briefly introduced as follows: I. Growing Environment
Gerbera is native to South Africa and adapts to a mild climate. It is heat-tolerant and slightly cold-tolerant, and likes an environment that is warm in winter, cool in summer, well-ventilated, and sunny. The optimum growth temperature is 20C-25C during the day and about 16C at night. The optimum flowering temperature is not lower than 15C, and it can flower year-round in a growing environment where the daytime temperature does not exceed 26C. The optimum temperature during the winter dormant period is 12C-15C, and growth stops below 7C. It is not sensitive to photoperiod, and the length of natural daylight has no effect on flower number or flower quality. Gerbera requires loose, fertile, well-drained, humus-rich, deep, slightly acidic sandy loam.
II. Propagation
Gerbera is mostly rapidly propagated by tissue culture, and can also be propagated by division, with each mother plant divisible into 5-6 small plants; seed propagation is used for dwarf potted varieties or breeding; single buds or short lateral buds occurring at the base of the crown can be cut and used for cuttings.
III. Planting
Cultivating Gerbera with artificial culture soil can significantly increase yield and quality. Please refer to the formula: 5 parts humus; 2 parts perlite; 3 parts peat, mixed as culture soil for planting, but the production cost of this method is relatively high. Field planting can also be carried out, and loam soil suitable for Gerbera growth with a deep soil layer of at least 25 cm or more should be selected for planting. Before planting, sufficient base fertilizer should be applied; generally, 5 tons of livestock manure, 600 kg of chicken manure, 100 kg of superphosphate, and 300 kg of plant ash are applied per mu, and the organic fertilizer must be fully decomposed. All fertilizers must be thoroughly mixed with the soil of the planting bed and plowed in, forming a pattern of one ridge and one ditch, with a ridge width of 40 cm and a ditch width of 30 cm. Plants are planted on the ridges in double rows in a staggered manner. Plant spacing is 25 cm. When planting, care should be taken to expose the root crown part slightly above the soil to prevent root crown rot. After planting, irrigate in the ditch.
IV. Management After Planting
1. Temperature
Use cultivation facilities to meet as much as possible the temperature requirements of Gerbera during the seedling stage, growing period, and flowering period, so as to facilitate normal growth and flowering. Outside southern China, it cannot overwinter in the open field and requires greenhouse cultivation; outside the Yangtze River Basin, it can be cultivated in an unheated greenhouse. In summer, shade nets need to be covered on top of the greenhouse, and the plastic films on both sides of the greenhouse should be opened to lower the temperature. In winter, when the outdoor nighttime temperature approaches 0C, seal the plastic film tightly, and additional plastic film must be added inside the greenhouse. On clear, warm days, open the film at the south end of the greenhouse around noon for ventilation for about one hour.
2. Light
Gerbera is a light-loving flower and needs full light in winter, but in summer appropriate shading should be given and ventilation strengthened to lower the temperature and prevent high temperatures from causing dormancy.
3. Irrigation
After planting, the seedling stage should be kept appropriately moist and the seedlings should be hardened to promote root development and rapid establishment. During vigorous growth, an adequate water supply should be maintained, watering once every 3-4 days in summer and about once every half month in winter. When watering during the flowering period, be careful not to let water touch the center of the leaf rosette, to prevent flower bud rot. In open-field cultivation, pay attention to preventing waterlogging. In addition, fertilization can be combined with irrigation.
4. Topdressing
Gerbera is a fertilizer-loving perennial herbaceous flower with a high fertilizer demand. The ratio of nitrogen, phosphorus, and potassium applied is 15:18:25. When topdressing, special attention should be paid to supplementing potassium fertilizer. Generally, apply 2.5 kg of potassium nitrate, 1.2 kg of ammonium nitrate or ammonium phosphate per mu, once every 5-6 days in spring and autumn, and once every 10 days in winter and summer. If high temperatures or abnormally low temperatures cause the plant to enter a semi-dormant state, stop fertilizing.
5. Removal of Withered Leaves
The lower leaves of the basal leaf rosette of Gerbera easily turn yellow and age, and should be removed in time. This is beneficial both for the sprouting of new leaves and new flower buds and for ventilation, enhancing plant vigor.
6. Pest and Disease Control
The main diseases of Gerbera include leaf spot, powdery mildew, and viral disease. For leaf spot, spray 800-**** times dilution of 70% thiophanate-methyl wettable powder or 500 times dilution of 50% carbendazim wettable powder. For powdery mildew, use 1500 times dilution of 70% thiophanate-methyl or 1000-1200 times dilution of 75% triadimefon wettable powder for control, once every 7-10 days, spraying two to three times consecutively. For viral disease control, strict seedling entry checks should be enforced, and aphids should be controlled in time to reduce virus transmission vectors; diseased plants found should be removed and destroyed in time. The main insect pests of Gerbera include tarsonemid mites, cotton bollworm, oriental tobacco budworm, beet armyworm, and aphids. For tarsonemid mites, 1000 times dilution of 40% dicofol can be used for control.
Harvesting
Harvest when the pollen of the outer ring of flowers begins to shed. At harvest, the plant is required to be growing vigorously, with upright scapes and open flowers. The quality of cut flowers greatly affects their vase life. Never cut flower stems when the plant is wilting or when the flowers are half-closed at night. After harvesting, grade, preserve, package, and market them.
Most of the specialized production bases for Gerbera seedlings in China are concentrated in the Yunnan region, and a large number of emerging specialized flower seedling producers, represented by the Yunnan Luxin Flower Seedling Base, are booming.
Disease Control of Gerbera: 1. Bacterial Diseases of Gerbera
Gerbera spot disease is a bacterial disease caused by Pseudomonas cichorii. The bacterial cells are single, straight or slightly curved, rod-shaped, motile, with multiple flagella; Gram-negative, aerobic, respiratory metabolism, chemoorganotrophic. This pathogen mainly infects various cruciferous plants such as chicory, lettuce, pea, melon, and Chinese cabbage, and can also harm tomato, clover, etc. The pathogen mainly overwinters in diseased field soil and diseased plant residues and spreads by rain, farming operations, insect carrying, and other means.
2 Gerbera Viral Diseases
2.1 Gerbera Spotted Wilt
After being affected, Gerbera shows symptoms such as discoloration, necrosis, and dwarfing, with deformed flowers. This disease occurs on Gerbera cultivated in Italy, France, Spain, and Japan. The pathogen is Tomato spotted wilt virus (TSWV). The virus particles are spherical, 85 nm in diameter, with a lipid envelope; the inactivation temperature is 40-46 °C, the survival period in vitro is less than 5 h, and the dilution endpoint is 10-3. It is transmitted by mechanical inoculation, and the insect vector thrips transmits it in a persistent manner. This disease has a wide host range and is an important pathogen of many crops such as tobacco, tomato, and potato.
2.2 Gerbera Mosaic Disease
Diseased plants show leaf chlorosis, deformed leaves, and formation of patches; growth weakens, the number of cut flowers drops sharply, and as the disease progresses, the diseased plant dies. It can infect other crops such as common tobacco and Nicotiana glutinosa, producing mosaic symptoms, and infecting zucchini causes chlorotic yellow spots and mosaic symptoms. The pathogen is Cucumber mosaic virus (CMV). The virus particles are spherical, 30 nm in diameter, with three types of particles that are similar in morphology. It is transmitted by mechanical inoculation, and aphids transmit it in a non-persistent manner. The inactivation temperature is 70 °C, the survival period in vitro is 4 days, and the dilution endpoint is 10-3. This disease has a wide host range, and the main modes of transmission are sap and aphids.
2.3 Gerbera Mottle Disease
Chlorotic ringspots appear on the leaves, and some chlorotic spots appear as oak-leaf patterns, with individual tissues near the spots necrotic. When the disease is severe, the leaves become smaller, shrunken, and brittle; in some varieties, the petals become broken-colored, the flowers become smaller (deformed), the flower color is not vivid, and the plant becomes stunted. The pathogen is Tobacco mosaic virus (TMV). The particles are straight rod-shaped, 300 nm x 18 nm, and the inactivation temperature is 90-95 °C. This disease has a wide host range and can be transmitted by mechanical inoculation, contact between plants, contaminated soil, farm tools, etc., and can also be transmitted by sap, soil, nematodes, and seeds.
3 Gerbera Fungal Diseases
3.1 Gerbera Powdery Mildew
This disease mainly harms leaves. In the early stage of the disease, white mold spots appear on the leaves, which gradually expand into round or long oval yellow-white lesions. The lesions are covered with a white coating, and in severe cases the entire leaf is covered with white powder; later the powder layer turns gray-white, and the leaves scorch and wither. The pathogen is (Oidium sp.). The mycelium is white, superficial, and penetrates host epidermal cells with haustoria to absorb nutrients. Conidiophores are erect, unbranched, and produce conidial spores in a holoblastic manner. Conidia are oblong, single-celled, colorless, produced in chains, and mature sequentially from top to bottom. This disease is more likely to occur when the temperature is high, the relative humidity is 80%-90%, and ventilation in the greenhouse is poor.
3.2 Gerbera Leaf Spot
There are mainly two types of Gerbera leaf spot: (1) Phyllosticta leaf spot. Small purple-brown to tea-brown spots first appear on the leaves, gradually expanding into round or nearly round lesions with dark brown edges; later, black small dots form on the lesions. The pathogen is Phyllosticta chrysanthemi. The pycnidia are spherical, immersed, unilocular, with an ostiole. Conidiogenous cells are cylindrical, colorless, smooth, and produce spores in a holoblastic manner; conidia are elliptical, single-celled, colorless, with a flat base. It grows very quickly on artificial medium, with abundant aerial mycelium, relatively sparse pycnidia formation, and membranous pycnidial walls. The pathogen overwinters as mycelium and pycnidia in diseased fallen leaves. Old leaves are more severely affected than young leaves. (2) Cercospora leaf spot. Small purple-brown spots first appear on infected leaves, gradually expanding into round or nearly round lesions, with a dark gray center, slightly raised brown line markings at the edge, and a purple-brown outer periphery; dark green mold spots are produced on both the front and back sides of the leaves. The pathogen is Cercospora chrysanthemi. The mycelium is mostly immersed, often with a stroma; conidiophores are thick, mycelial type, olive-brown or brown, lighter in color at the top, unbranched or occasionally branched, clustered on stromatic tissue; conidia are whip-shaped, straight or slightly curved, colorless, with 3-12 septa. Conidiogenous cells are mostly polyblastic, with sympodial extension, cylindrical, with obvious conidial scars. Conidia are solitary, with a scar at the base, having multiple septa, and a smooth surface. This disease mostly overwinters on diseased residues and diseased leaves, and generally occurs severely in environments that are damp and shaded with insufficient light, heavy clay soil, and poor drainage.
3.3 Gerbera Gray Mold
Water-soaked round or irregular lesions appear on the stem near the ground of diseased plants, later turning gray-brown to brown; the diseased part becomes soft and rotted, and the surface is densely covered with a gray mold layer. When seedlings are infected, the stems and leaves near the ground rot in a brown water-soaked manner, with gray mold produced on the surface, and later small flat sclerotia form in clusters. The pathogen is Botrytis cinerea, belonging to Deuteromycotina, genus Botrytis. Conidiophores are straight or bent, 960-1200 μm x 16-22 μm, clustered in several, brown, smooth, with 1-2 branches at the top. The ends of the branches often swell noticeably, forming colorless or pale flask-shaped conidiogenous cells; conidia are short elliptical, 12-18 μm x 9-13 μm. The pathogen overwinters as conidia and sclerotia in infected tissues, and disease is likely to occur when humidity is high.
3.4 Gerbera Sclerotinia Rot
This disease starts from the stem base and causes the stem to rot. In the early stage of the disease, the diseased part shows water-soaked soft rot, brown, gradually spreading to the stem and petiole. Later, black mouse-dropping-like sclerotia can be seen both inside and outside the stem. The typical symptom of this disease is rapid soft rot at the diseased part, densely covered with white flocculent matter, or black mouse-dropping-like sclerotia; each sclerotium can produce 1-9 apothecia. This disease is caused by the fungus Sclerotinia sclerotiorum Fuck. Apothecia are produced on sclerotia, disc-shaped, with long stalks. Asci are arranged in parallel, with persistent paraphyses among the asci. Asci are club-shaped or elliptical, colorless; ascospores are single-celled, elliptical, arranged in a single row. The pathogen has a very wide host range. The pathogen overwinters as sclerotia in diseased residues and soil, and produces ascospores the following year to infect and cause damage. Fields whose previous crop was cruciferous crops are severely affected. The disease is severe in the rainy season. This disease spreads through contact between diseased plants and healthy plants and through the growth and spread of mycelium in the soil.
3.5 Gerbera Root Rot
This disease is one of the most important diseases of Gerbera, with a wide occurrence area and great damage. The plant is affected throughout the entire growth period, and is most severely affected during the flowering period. The pathogen infects from the stem base at the ground; the affected part becomes soft, water-soaked, and light black; the plant leaves suddenly wilt and turn purplish red. When the diseased plant is pulled out, the diseased part at the stem base breaks easily, and white mold spots can grow on the surface when moist. This disease is mainly caused by Phytophthora cryptogea. Phytophthora cryptogea belongs to the kingdom Chromista, phylum Oomycota, order Peronosporales, family Pythiaceae, genus Phytophthora. Its vegetative body is aseptate, multinucleate mycelium, with hyphal swellings produced, and asexual reproduction produces zoosporangia. Sporangia are pear-shaped or elliptical, without papillae, large, with an average size of 46 μm x 27 μm, and a wide host range. It is heterothallic; sexual reproduction produces oogonia, oospores, and antheridia. Oogonia are spherical and contain a spherical thick-walled oospore; antheridia are single-celled, colorless and transparent, and amphigynous. The pathogen overwinters on residues or in soil, and the overwintering pathogen is the main primary infection source of this disease. Sudden alternation of dry and wet soil or frequent intertillage and loosening of the soil causes many wounds on the plant roots; the pathogen invades through the wounds and spreads from irrigation water or rainwater when conditions are suitable, causing severe outbreaks of the disease. Fields with poor drainage and continuous cropping are severely affected. 3.6 Gerbera Fusarium Wilt
The symptoms of this disease are similar to Gerbera root rot, and it occurs throughout the entire growth period of Gerbera. The root system of diseased plants is dark brown, the cortex of diseased roots peels off, there are few fibrous roots, and the plant is easy to pull up. When the disease develops slowly, the leaves of the diseased plant turn purplish red or dark brown and gradually wither; when the disease is severe, the plant dies in a green-wilt state. This disease occurs in Italy, Australia, and China, among other countries. Because Gerbera is basically cultivated under protected conditions, this disease can occur throughout the year, and April to August each year is the period when it occurs more severely. The pathogen overwinters in soil or diseased plant residues. Contaminated soil and affected plants are the main sources of infection of this disease. High-temperature and high-humidity weather and heavy clay soil both promote the proliferation and spread of the pathogen. This disease is mainly caused by Fusarium oxysporum. On artificial medium it produces dense mycelium, loose cotton-like; conidiophores are colorless, and conidiogenous cells produce spores in an enteroblastic phialidic manner, producing two types of spores. Microconidia are oval to elliptical, 5-12 μm x 2.5-3.5 μm; macroconidia are 27-46 μm x 3-4.5 μm, spindle-shaped to sickle-shaped, with a hooked apex and a small pedicel at the base, with 3-5 septa, most commonly 3 septa. Chlamydospores are usually formed in large numbers, intercalary or terminal, solitary, occasionally in chains, with smooth or rough walls.
In addition, Gerbera diseases also include downy mildew (caused by Bremia lactucae), white rust (caused by A. tragopogonis), and ring spot mosaic disease (caused by TBRV), etc.
4 Pest: Whitefly
Key control techniques: Thoroughly remove weeds, insert yellow sticky boards for continuous monitoring, and once pests are found, take measures in time. Choose the right pesticide and use it correctly: Whiteflies easily develop resistance to pesticides, so pesticides must be rotated. Pesticides with better effects include beta-cypermethrin, abamectin, imidacloprid, etc. Choose dawn for spraying, keep the greenhouse sealed for 4-5 hours after spraying, and spray once more the next morning. Keep the greenhouse ventilated and low in humidity; remove diseased leaves in time; when the disease occurs, spray 1500 times dilution of 70% thiophanate-methyl, or use 20% Junke smoke for fumigation control, once every 7 days, for 2-3 consecutive treatments. In addition, use sulfur fumigation for control, placing 20-30 g of sulfur powder in each fumigator each time; after lowering the curtain at 17:00 each day, keep the greenhouse sealed and energize and heat for 2 hours, replace the sulfur powder once every 6 days, and continue fumigation for 15 days. During the outbreak period of powdery mildew, fumigate 8-10 h each day, and powdery mildew can be eliminated in about 10 days.
Thrips
Key control techniques: Cut off insect-infested flowers in time, thereby reducing the source of insects in the greenhouse (room). Fumigating pesticides in the greenhouse is the best control method. Use 300-400 ml of 80% dichlorvos for fumigation for 1 hour, or spray 1500-2000 times dilution of 5% imidacloprid and then close the greenhouse for 8-10 hours. Fumigation can be carried out at around 10 a.m. or 5 p.m. when the temperature is slightly higher, to achieve good efficacy.
Cabbage Caterpillar
Key control techniques: For larvae, spray 2000-2500 times dilution of 10% Chuchujin for control; for older larvae, beta-cypermethrin at 1000 times dilution can be used for control, once every 7 days, for 3 consecutive treatments.
Note: The above pesticides were determined after testing according to the reference formula provided by the Resources and Environment Institute.
Phytophthora Blight
Key control techniques: Soil under continuous cropping must be sterilized with Weibomu and formaldehyde, etc.; see the instructions for usage and dosage; plant shallowly, with the root crown exposed 1 cm above the surface; prevent the soil from being too wet. If soil taken from below 10 cm of topsoil cannot be formed into a ball after being placed in the palm and squeezed hard, then it can be watered; in the early stage of the disease, when part of the leaves turn red and begin to wilt, drench the roots with 400 times dilution of 58% phosethyl-Al and mancozeb, then after 7 days drench the roots with 500 times dilution of 64% oxadixyl and folpet powder. Apply the pesticide in the morning and evening when temperatures are low, stop applying when the temperature is above 28 degrees, apply once every 7 days, for 3 consecutive treatments.
Spot Disease
Key control techniques: Remove diseased leaves promptly when found and destroy them in a centralized manner; in the early stage of the disease, spray 300 times dilution of 2.5% myclobutanil emulsifiable concentrate or 800-**** times dilution of 70% thiophanate-methyl wettable powder, once every 7 days, spraying 2-3 times consecutively.
Gray Mold
Key control techniques: Controlling humidity is the key to controlling gray mold. Thin out densely planted and overly crowded leaves; increase ventilation and air permeability, keeping air humidity at 75-85%; water from below the plant canopy; to prevent water vapor from condensing on the flowers, on clear mornings after 10 a.m., gradually open the side greenhouse film to avoid a sharp rise in temperature inside the greenhouse; in the early stage of the disease, spray 1500 times dilution of 70% thiophanate-methyl on the leaves, and combine with smoke agents for control.
5 Physiological Diseases
1. Symptoms: Dark green spots appear on young leaves. In severe cases, the young leaves and growing points die first, while old leaves can still remain normal.
Solution: Judging from the symptoms, it may be caused by calcium deficiency. Spray 0.15% Ca(NO3)2.4H2O on the leaves, once every 25 days.
2. Symptoms: "Mosaic" appears in the mesophyll of old leaves, and an inverted "V"-shaped green part forms at the base of the leaf, whose top can also extend to near the leaf tip. The leaves become brittle, curved, and even red; new leaves grow few and small, petioles are slender, veins of young leaves protrude, inflorescence formation is inhibited, flower stalks are thin, and flowers become smaller. Spray 0.2% magnesium fertilizer twice. Solution: Judging from the symptoms, it may be caused by magnesium deficiency.
3. Symptoms: Leaves turn pale yellow, even almost white; the veins remain green at first, but eventually change color as well.
Solution: Judging from the symptoms, it may be caused by iron deficiency. Spray 0.02% chelated iron, once every 25 days.
4. Symptoms: Small leaves curl, thicken, and become brittle. Growing points die, flower buds abort, or deformed sterile inflorescences are produced.
Solution: Judging from the symptoms, it may be caused by boron deficiency. Spray 0.05% borax, once every 25 days.
5. Symptoms: Spots and "mosaic" appear on young leaves; one side of the leaf develops normally, while the other side is abnormal, and the leaf curves sideways.
Solution: Judging from the symptoms, it may be caused by zinc deficiency.
7 Quality Defects
1. Flower stalk breakage: Transverse cracks appear on the flower stalk, and in severe cases the flower stalk breaks, with the crack appearing like a cut.
Solution: Spray 1-2‰ calcium nitrate once a week.
2. Leaf edge scorch: Sudden scorching appears at the leaf tip or the tips of the lobes.
Solution: Caused by too high a fertilizer concentration. Immediately spray clean water to dilute it or wash off the fertilizer solution adhering to the leaves; extend the fertilization interval and reduce the fertilization concentration, and it will recover naturally after a period of time.
Prevention First, Integrated Control
Disease Control
The diseases of Gerbera include leaf spot, powdery mildew, and viral disease. For leaf spot, spray 800-**** times dilution of 70% thiophanate-methyl wettable powder or 500 times dilution of 50% carbendazim wettable powder. For powdery mildew, use 1500 times dilution of 70% thiophanate-methyl or 1000-1200 times dilution of 75% triadimefon wettable powder for control, once every 7-10 days, spraying two to three times consecutively. For viral disease control, strict seedling entry checks should be enforced, aphids should be controlled in time to reduce virus transmission vectors, and diseased plants should be removed and destroyed in time. The main insect pests of Gerbera include tarsonemid mites, cotton bollworm, oriental tobacco budworm, beet armyworm, and aphids. For tarsonemid mites, 1000 times dilution of 40% dicofol can be used for control. Other pests can be controlled with 2.5% deltamethrin or 1000-1500 times dilution of 40% omethoate, once every eight to nine days; spraying has an adverse effect on flower color and should not be used during the flowering period.
Spot Disease
When Gerbera is cultivated in protected facilities year after year, the warm, humid environment with poor air movement easily leads to the occurrence of pests and diseases. Among them, one of the most common diseases is Gerbera spot disease, a disease caused by fungi.
Symptoms: Small purple-brown spots are produced on the leaves, gradually expanding into large spots with concentric rings (2 mm to 5 mm in diameter). Later the flower center rots, with sparse gray-brown dust-like fungal filaments on it.
Disease pattern: Generally, the lower leaves are affected first. Excessive application of nitrogen fertilizer easily triggers the disease. Heavy clay soil and poor drainage are also important conditions that induce the disease.
Control Methods
1. Soil treatment: Chloropicrin fumigation can be used to effectively kill the pathogen and reduce the accumulation of inoculum from the substrate.
2. Regulate temperature and humidity: The optimum temperature for Gerbera growth is 20 °C to 25 °C, kept above 10 °C at night. Under conditions of low temperature and low humidity, the disease is less likely to occur.
3. Spray fungicides once every 7 to 10 days, such as 500 times dilution of 75% chlorothalonil, 500 times dilution of 50% captan, and 1000 times dilution of 70% thiophanate-methyl, with obvious control effects.
Phytophthora Disease Control
Gerbera Phytophthora disease, also known as rhizome rot, is seriously harmful once it occurs, often causing the death of the entire plant, or even the death of the entire greenhouse, bringing serious economic losses to growers. After several years of cultivation experience, the author has summarized some effective measures and now introduces them to everyone.
1. Disease pattern: Phytophthora overwinters as chlamydospores and oospores in diseased residues or soil. Resting spores can survive for a long time when there is no host. The pathogen is spread by water flow, soil, and diseased plants.
2. Symptoms: It first infects the rhizome part of the plant. The leaves of affected plants first turn yellow, then gray-brown, and finally wither and die; the rhizome part turns black and rots.
3. Control: (1) Select healthy, disease-free plants for cultivation.
2. Sterilize the soil of the nursery before planting. This pathogen mainly spreads through soil, so the nursery must be carefully sterilized before planting. The main sterilization methods are: (1) Chemical sterilization: The chemicals can be a mixture of dexon and quintozene (3:1), at a dosage of 4-6 g/m2. During sterilization, spray the chemicals on the soil surface, mix the soil evenly, seal with plastic film, seal and fumigate the greenhouse for 30 hours, then remove the covering, ventilate and exchange air, stir the topsoil again, and plant after 15 days. (2) Steam sterilization: Release steam into the soil through pipes. This method has relatively high investment costs, but the effect is good.
3. The planting depth of Gerbera should follow the principle of shallow planting, requiring the root crown to be exposed about 1.5 cm above the soil surface, with slight lodging as the standard (gently straighten it after 3 days). Because it has contractile roots, the root crown of the plant will be buried deeply in the soil, making it convenient for the pathogen to infect. To better facilitate the growth and development of seedlings, a planting method using local substrate can be adopted, that is, first dig a round planting hole about 10 cm in diameter at the planting point, then fill it with sun-sterilized river sand or a perlite + vermiculite (1:1) substrate, plant the seedling on the substrate, and water thoroughly.
4. When diseased plants are found, if it is the early stage of the disease, drench the rhizosphere with captan 0.1 g/1 + 1% copper sulfate; if it is already the late stage of the disease, the diseased plant should be burned immediately, and the surrounding plants and soil should be treated with the above chemicals.
Whitefly Damage and Control
Whitefly belongs to Homoptera, Aleyrodidae, and can be divided into greenhouse whitefly and silverleaf whitefly. It is an important pest of greenhouse horticultural crops in Europe and America. In the 1980s it became a major pest in northern China, and has now spread throughout the country. In the Kunming area, varying degrees of infestation have appeared on greenhouse crops such as cucumber, Gerbera, rose, and poinsettia. Among the farmers surveyed in the author's Gerbera production area, 100% had whitefly infestation. Many farmers consider whitefly to be the most difficult pest to manage and the most harmful pest on Gerbera. The author takes this opportunity to call on relevant departments to attach importance to this.
(1) Damage characteristics of whitefly: The Kunming area is warm in winter and cool in summer, which is very favorable for the reproduction and overwintering of whitefly. Under greenhouse conditions, whitefly does not stop reproducing throughout the year. Each female produces 100-200 eggs, so killing eggs is very important in control, but the vast majority of pesticides only kill adults and do not harm eggs and pupae. Therefore, whitefly resistance to pesticides has become a common problem; a pesticide may work very well in one place but may work poorly in another. According to foreign research, to eliminate a relatively severe infestation, it is necessary to spray pesticide at least once every 3-4 days, for 10-12 consecutive sprays. The eggs, older nymphs, and puparia of whitefly have strong resistance to temperature and pesticides. Once various stages of the pest occur together on a crop, control becomes very difficult. It can be seen that whitefly is more difficult to control than ordinary pests and is more likely to resurge and cause repeated cycles of damage.
The population density of whitefly has the characteristic of rising exponentially. In the early stage of whitefly infection, it occurs only in small patches, and on the surface the plant does not show obvious symptoms of damage, so it is often overlooked. However, the harm of whitefly in transmitting viruses, weakening plant vigor, and seriously affecting shipment quality is already developing. Once it spreads, it may cause years of cyclical damage in the greenhouse and be difficult to completely eliminate. Therefore, in daily flower production management and the process of introducing seedlings, importance must be attached to the inspection and control of whitefly, and once it occurs, measures must be taken in time.
(2) Inspection for whiteflies. Whiteflies have four forms: egg, nymph, puparium (false pupa), and adult. Adults lay eggs on the underside of leaves; the eggs are 0.2-0.25 mm long, difficult to see with the naked eye, and require a magnifying glass or microscope to observe; they are mostly distributed on young leaves. Nymphs and puparia usually remain fixed on the middle and lower layers of older leaves and are easy to find. Adults like to attach to the undersides of young and mature leaves. Both adults and nymphs secrete honeydew, which accumulates on the leaves and causes sooty mold. If a black, ash-like sooty mold caused by fungal infection is found on the leaves, it indicates that the infestation has already lasted a relatively long time and is fairly serious. The colors whiteflies like most are lemon yellow and orange yellow, so yellow sticky boards can be hung or set up to monitor them.
Among greenhouse flower crops, those that attract whiteflies most and suffer severe damage are: Gerbera (Gerbera jamesonii), Alstroemeria, Primula, Salvia splendens, Dahlia, Pelargonium, Senecio cruentus (cineraria), Gloxinia, Fuchsia, Hibiscus, Clematis, Abutilon, Solanaceae plants, Aquilegia, and Rhododendron. Those damaged more lightly are: Chrysanthemum, Poinsettia, Calceolaria, Calla lily, Rose, Lily, and Marigold. Those not damaged are: Cyclamen, Carnation, Freesia, Tulip, Narcissus, Hyacinth, Orchidaceae plants, Lilac, Palmae plants, and most succulents.
Sometimes flower crops and vegetable crops are rotated and planted in contiguous blocks, so it is necessary to know the vegetable crops that whiteflies damage severely, such as cucumber, tomato, lettuce, green bean, celery, muskmelon, pumpkin, and garlic. Greenhouses and the weeds inside and around greenhouses are breeding grounds for whiteflies; the weeds it likes are chickweed (Stellaria media), wood sorrel, nettle, dandelion, and so on.
(3) Control of whiteflies
1. Give priority to prevention and cultivate insect-free seedlings. Seedlings, crop residues, and weeds carrying insects are important pathways for the spread of whiteflies, so before planting a new crop, weeds and the previous crop must be thoroughly removed, and the ground left empty for a period. When introducing seedlings and potted flowers, carefully check whether there are nymphs or eggs and whether many leaves are missing. Once a greenhouse is infested with whiteflies, the entry and exit of its crops must be handled very carefully to prevent all greenhouses from becoming infested. Yellow sticky boards should be placed in the greenhouse for monitoring at any time. Fields should be inspected regularly to check growth conditions and whether pests and diseases are occurring. Hanging white or silvery-white plastic strips at the doorway of the greenhouse can repel invading adults.
2. Choose pesticides well and use them correctly. Whiteflies easily develop resistance to pesticides, so it is necessary to know more about the available types of pesticides in order to select them. For pesticides to which they originally have no resistance, pest resistance will only develop in the second generation. Therefore, for pesticides with good trial results, they can be used continuously for at least one generation or more until resistance is found. Attention should be paid to correct pesticide application methods, and it is not advisable to change pesticides frequently. The table below lists pesticides with relatively good results that have been tried domestically and abroad, for reference.
Category English name Chinese name or trade name Precautions
Organophosphate acephate has a fumigant effect
chlorpyrifos chlorpyrifos
etrimfos etrimfos
Carbamate methomyl methomyl, Lannate has a certain ovicidal effect
Pyrethroid sumicidin fenvalerate
Propoxur+methoxychlor propoxur + methoxychlor
Cypermethrin cypermethrin
Alphamethrin alpha-cypermethrin
fluralinate cyfluthrin
Acaricide mitac amitraz, has a fumigant effect
Chitin synthesis inhibitor pesticide buprofezin
Other Tempo endosulfan
abamectin abamectin, spray concentration 1000 times
Diazinon diazinon
imidacloprid imidacloprid
3. Application of the high-temperature sealed method. In the process of controlling whitefly infestation, conventional spraying methods have the problems of low efficacy, rapid decline in efficacy, and easy development of pesticide resistance. Whiteflies attach to the undersides of leaves and suck the leaf sap, easily forming dead angles that pesticides cannot contact, especially when plants are growing luxuriantly. When disturbed, whiteflies can fly several meters away, thereby avoiding contact with the spray solution; therefore, even if pesticides to which no resistance has developed are used, their efficacy is limited. The growth, development, and reproduction of whiteflies are greatly related to temperature. The developmental threshold temperature for eggs is 7.2°C, and the optimum temperature for survival is 20-28°C. Above 30°C, egg and larval mortality is high, adult lifespan is shortened, fewer eggs are laid, and reproduction may even stop. Whiteflies are poikilothermic animals, so above 30°C their respiratory frequency rises greatly, making it easy for them to take in more pesticide.
In the practice of whitefly control, the author adopted high-temperature sealing, combining the advantages of fumigation and spraying, targeting the weak points of the pest and making full use of solar energy and the greenhouse effect, and achieved remarkable control results. The method is to mix a pesticide with a fumigant effect together with a pesticide with an ovicidal effect (such as chlorpyrifos + methomyl), add an appropriate amount of washing powder as a surfactant, and spray between 3:30 and 5:30 in the afternoon. Before spraying, or while spraying, close the vents of the greenhouse or plastic tunnel to create sealed conditions, and maintain the air temperature between 30-35°C for more than one hour. In summer, draw the shade net and delay the spraying time to prevent the temperature inside the tunnel from rising excessively. In the absence of sealed conditions, spraying during the high-temperature period in the afternoon is also more effective than spraying in the morning. When the temperature is high, the greenhouse or tunnel can easily rise above 30°C even without being sealed; at this time, it is better to spray in the morning when the temperature is lower, keep the tunnel sealed for 1-2 hours, and use a shade net to cool it if necessary, so there will be no concern about excessive humidity causing disease.
4. Other methods. Very effective methods for controlling whiteflies also include fumigation, smoke fumigation, and mist methods, which are introduced in other books. Biological control is a more scientific method and should be vigorously popularized and applied.
Mosaic disease
1. Symptoms. Leaves appear mosaic-like, and sometimes markings also appear on petals. The pathogens include cucumber mosaic virus (CMV) and tobacco mosaic virus (TMV).
2. Control methods. (1) Remove weeds in the flower nursery and its surroundings at any time, and promptly use insecticides to control aphids. (2) Use 10% trisodium phosphate to disinfect cutting tools such as flower shears.
Root rot
1. Symptoms. The symptoms of this disease are similar to those of wilt, but the diseased part has no pink spore masses. The stem and roots show water-soaked soft rot and turn black. The rotting phenomenon is obvious. The pathogen is Phytophthora cryptogea Pethy-br et Laff., belonging to Mastigomycotina; sporangia are obpyriform, and oospores are yellow and spherical. It is both parasitic and saprophytic, with an optimum growth temperature of 25°C.
2. Control methods. (1) Select and breed disease-resistant varieties. (2) Before planting in a flower bed where this disease occurred the previous year, first mix the soil with 1000-1500 times diluted dexon solution for sterilization. (3) When diseased plants are found, pull them out and burn them at any time to prevent the spread of the pathogen. The diseased soil must also be dug out and replaced with new soil.
Greenhouse pests and diseases
1. Phytophthora disease first infects the root crown. The leaves of affected plants turn yellow, then grayish brown, and finally die; the root crown turns black and rots.
Control methods:
① Choose healthy, disease-free plants for cultivation.
② This pathogen mainly spreads through soil, so the nursery ground must be carefully disinfected before planting. The pesticide can be dexon plus quintozene (3:1), at a dosage of 4-6 grams per square meter. When disinfecting, spray the pesticide on the soil surface, mix it evenly with the topsoil, seal it with plastic film, and at the same time seal the greenhouse for fumigation for 30 hours, then remove the covering, ventilate, and stir the topsoil again; planting can be done after 15 days. Steam can also be released into the soil through pipes; this method has relatively high investment costs but gives better results.
③ When planting, the root crown should be exposed about 1.5 cm above the soil surface, with slight lodging as the standard. Because it has contractile roots, the plant's root crown will become deeply buried in the soil, making infection by the pathogen easier. To benefit the growth and development of seedlings, a cultivation method using local substrate can be adopted, that is, first dig a round planting hole about 15 cm in diameter at the planting point, then fill it with sun-sterilized river sand or a perlite + vermiculite (1:1) substrate, then plant the seedling on the substrate, water thoroughly, firm the roots, and thereafter enter normal daily management; this can achieve immediate results.
④ When diseased plants are found, in the early stage captan 0.1 g/L + 1% copper sulfate can be used to drench the roots; in the late stage of the disease, the diseased plants should immediately be pulled out and burned, and the surrounding plants and soil should be treated with the above pesticides.
2. Virus-infected diseased leaves have indistinct yellow-green spots, and new leaves become narrow. During high-temperature periods the markings are not obvious. Growth is weakened, the number of cut flowers drops sharply, and if it continues to develop, the diseased plant will die.
Control methods:
① Remove diseased plants.
② Thoroughly eliminate aphids, the vectors that transmit the virus.
③ When cultivated in greenhouses with poor ventilation, scale insects often occur and should be removed promptly.
3. For whiteflies, imidacloprid, dichlorvos, phoxim, and methamidophos all have relatively good control effects. However, if a single product is used, resistance is easily developed, so it is best to use mixed pesticides or alternate multiple pesticides, and avoid using the same pesticide continuously many times. For those that have developed resistance, organophosphate pesticides can be mixed with methomyl water plus pyrethroid pesticides.
4. Leafminer flies have peak damage periods from April to May and October to November, and can be killed by mixing abamectin, avermectin, abadin, or bisultap with fenvalerate.
Causes of root rot
Gerbera color: in midsummer, especially under drought and water shortage, petal color becomes dark and dull; while flowers blooming during the suitable-temperature period of September to October or March to June of the following year are brightly colored. This shows that Gerbera is relatively sensitive to temperature and light intensity. In summer, the soil should be kept moist and not allowed to dry out, a shade net with 50% light transmittance should be used for covering, and water should be sprayed on the leaves to increase air humidity and lower temperature.
In winter, adequate warmth should be provided and the plants should not be frozen; the nighttime temperature should not be lower than 10°C, and the daytime temperature should not be lower than 15°C. These are all very beneficial for improving the brightness of Gerbera. In addition, mites are a major enemy in Gerbera cultivation; once damaged, not only is the brightness lost, but the shape of the petals also becomes incomplete.
Therefore, ensuring that the plants are not harmed by mites throughout the entire growth period is a particularly important link in guaranteeing the brilliant color of Gerbera.
The cause of root rot in Gerbera is mostly root rot disease occurring in the roots, and once it occurs it is difficult to cure completely. The external conditions that produce root rot are excessively high soil moisture around the roots, long-term water accumulation in the root zone, or prolonged rainfall in open fields, which can cause the death of Gerbera plants.
Potted cultivation techniques for Gerbera: potted production
In the daily production process of potted Gerbera, the following points need attention.
1. The production greenhouse should be equipped with ventilation, shading, and heating facilities. If conditions permit, it should also be equipped with benches, ground fabric, or an irrigation system. The greenhouse must be airtight to prevent insects from entering.
2. The temperature in the greenhouse should be controlled between 15°C and 25°C, with the maximum not higher than 30°C and the minimum not lower than 13°C. Generally, the average daily production temperature is 18°C to 19°C, and ventilation should be provided once it exceeds 19°C. At the same time, the night temperature should not be too high, otherwise it will affect normal flower bud differentiation; the ideal night temperature should be between 15°C and 18°C.
3. Use a medium with good air permeability and drainage, preferably a substrate mixed with peat and perlite. A pH of 5.5 to 6.0 and an EC of 0.7 to 1.0 are favorable for the absorption of trace elements.
4. Potted Gerbera is very sensitive to water, so the correct watering time must be guaranteed. Water in the morning or evening, and keep the plants relatively dry at nightfall. When the plants begin to grow roots, water must be applied from below, and bottom infiltration can be used; during high-temperature periods, water can be applied from above the plants, but care must be taken to prevent fungal mold starting from the center of the plant.
5. Gerbera relatively prefers fertilizer. In summer, the ratio of nitrogen to potassium when fertilizing is 2:1, and in winter it is 1.5:1. The pH of the fertilizer should be 5.5 to 6.0.
6. The most suitable day length for Gerbera during growth is 11 hours to 13 hours, so artificial supplemental lighting can be used during low-light periods. Generally, the requirement for artificial supplemental lighting is 3500 to 4000 lux per square meter. It should be noted that supplemental lighting should be carried out 4 weeks after the plants are potted.
7. From potting to flowering, Gerbera requires 8 to 9 weeks if produced in summer, and 11 to 12 weeks if produced in winter. The pot size is 10 cm to 15 cm. About 30 pots can be produced per square meter in the greenhouse, but note that after the plants grow to a certain size they should be spread out in time.
Gerbera - postharvest handling
Harvesting: For single-petaled varieties, the flowers can be harvested after 2-3 whorls of stamens mature; double-petaled varieties should be harvested when more mature, as flowers harvested too early will have a shorter vase life. After harvesting, they must be immediately placed in water, and the water must be very clean. Before putting the fresh flowers into water, the bottom 2-5 cm of hairy, lignified flower stalk must be cut off so that the stalk can absorb water. Vase life is one of the most important components of the commercial value of cut flowers. Postharvest handling is very important for the vase life of Gerbera; Gerbera cut flowers that have not undergone postharvest handling will ultimately be difficult to satisfy consumers after entering the market, which in turn will reduce Gerbera consumption. The methods introduced below can extend the vase life of Gerbera.
Harvesting cut flowers
Gerbera flowers can only be harvested when one or two whorls of stamens have released pollen; harvesting too early will shorten vase life. This is because when harvested too early, the energy stored in the outer ray flowers is not enough to complete their development. When harvesting, the entire flower stalk should be picked rather than cut, because the part left after cutting will rot and infect the sensitive roots, and will also inhibit the sprouting of new flower buds. After harvesting, trim the flowers, then cut off 2-4 cm from the bottom of the stalk; cut at an angle to avoid crushing the xylem vessels. The bottom of the stalk is composed of very narrow xylem vessels, which hinder water transport; after cutting them off, the flower absorbs water more easily, which is very important for avoiding cracking and bending at the flower neck. In addition, during harvesting, air may be drawn into the vessels and prevent the flower from absorbing water; cutting off part of the stalk also removes the air bubbles in the vessels.
Postharvest pretreatment
After the cut flowers are harvested, immediately immerse the stalks in a bucket and transport them to a cool place. The water and bucket used must be very clean and must be washed and disinfected before each use to prevent bacteria from multiplying, because bacteria will clog the vessels and prevent the flowers from absorbing water. During pretreatment, the pH of the water should be adjusted to 3.5-4.0 with chloride (bleaching powder). Too high a pH will create ideal living conditions for bacteria. Bleaching powder can both lower the pH of the water and sterilize, and the calcium chloride in it can also help extend the life of cut flowers. Studies show that the appropriate amount of bleaching powder added is 50-100 mg/l, and the treatment time must not exceed 4 hours. Too long a treatment time will damage the stalks, shown as brown markings on the stalks or bleaching of color. For longer treatments, the concentration of bleaching powder should be reduced, with a maximum of 25 mg/l and a minimum of 3 mg/l. Below 3 mg/l, bleaching powder should be replenished. The treatment site must not be exposed to sunlight, otherwise the useful components of the bleaching powder will decompose and become ineffective.
Preservative solution treatment
After pretreatment is completed, immerse the stalks in preservative solution for 6-24 hours. During treatment, immersing more of the stalk in water helps the flower absorb water, and a length of 10-15 cm is ideal; too high an ambient temperature will cause the flower to lose too much water through transpiration, so 10-15°C is ideal. Loss of water will cause Gerbera flowers to age, so drying and wind must be avoided throughout the entire postharvest handling process. It is best to raise the relative humidity of the environment to 70%. In addition, during preservative solution treatment, care must be taken to prevent the cut flowers from being harmed by ethylene; ethylene is an aging hormone that will shorten the vase life of Gerbera. The exhaust gas emitted by truck engines contains ethylene, so during loading, the truck engine should be turned off. The preservative solution for Gerbera consists of the following components: sucrose, 3 g/l; citric acid, 150 mg/l; dipotassium hydrogen phosphate containing seven molecules of water of crystallization (K2HPO4·7H2O), 75 mg/l. Sucrose provides energy for Gerbera to continue opening during the process and also promotes water absorption by the flowers. Citric acid lowers the pH of the preservative solution, thereby preventing bacterial growth.
[Fresh-keeping management] Cut flowers can be stored in an environment with a relative humidity of 90%-95% and a temperature of 2-5°C. During storage and transport, Gerbera can tolerate relatively long dry storage. However, after opening the box, they must be inserted into water as soon as possible; commercially available preservative solutions can also be used to extend vase life.
[Grading] Harvested flower material should be graded on the premise that it has the typical characteristics of the variety, is free of damage and contamination, and has good visual effect: the length of first-grade cut flowers is about 60 cm; the length of second-grade cut flowers is about 55 cm; the length of third-grade cut flowers is about 50 cm. The difference in length among cut flowers of the same grade should not exceed ±2 cm from the standard.
Packaging and transport
During transport, lower the ambient temperature to 6-9°C, which slows down the life activities of the flowers and preserves energy for use when they reach consumers. Reusing cardboard boxes for packaging is more economical, but they can become places where bacteria multiply. Therefore, cardboard boxes should not be reused too frequently. In short, cleanliness and hygiene must be maintained throughout the entire postharvest handling process in order to effectively extend the vase life of Gerbera. After Gerbera arrives at its destination, the bottom of the stalk will become dry; use a clean knife to cut off a little of the stalk at an angle, then immerse it in clean preservative solution. If there is no preservative solution, a low-concentration bleaching powder solution can also be used.
Gerbera - daily management: humidity management
It likes relatively high air humidity; if the air humidity is too low, individual flowers will wither faster. It is also afraid of rain, and the leaves need to be kept dry at night. The optimum relative air humidity
is 65-75%. It likes a warm climate and dislikes intense heat; when the summer temperature is higher than 34°C, growth is obviously poor. It is not tolerant of frost and cold; when the winter temperature is below 4°C, it enters dormancy or dies. The most suitable growth temperature is 15-25°C. It is generally sown in autumn and winter to avoid high summer temperatures.
Light management
In spring, summer, and autumn, it needs to be maintained under shaded conditions. When the temperature is relatively high (daytime temperature above 25°C), if it is placed in direct sunlight for maintenance, the leaves will obviously become smaller, the internodes of the branches will shorten, the lower leaves will turn yellow and fall off, and growth will be very slow or it will enter a semi-dormant state. In winter, because the temperature is not very high, it should be given direct sunlight to facilitate photosynthesis and the formation of flower buds, flowering, and fruiting. After the flowering period, keep it indoors for a period (10-15 days), then move it outdoors to a place with shade (and warmth) for a period (about one month), and alternate this way, which helps the plant accumulate nutrients and continue flowering.
Fertilizer and water management
Like other herbaceous flowers, it has relatively high fertilizer and water requirements, but the fertilization (and watering) principle of "light fertilizer applied frequently, small amounts but many times, complete nutrition" should be followed, and after fertilizing, the leaves and flowers should be kept dry at night: Spring and autumn: These two seasons are its peak growth periods. Fertilizer and water management follows the cycle of "Huabao"-"Huabao"-clear water-"Huabao"-"Huabao"-clear water (at the very least, "Huabao" must be guaranteed twice a week). The interval period is about: 1-4 days for outdoor maintenance; the interval is shorter on sunny days or during high-temperature periods, and longer or no watering on rainy days or during low-temperature periods; 2-6 days for indoor maintenance; the interval is shorter on sunny days or during high-temperature periods, and longer or no watering on rainy days or during low-temperature periods. Summer: During the high-temperature period in summer, it often enters a dormant state and has low fertilizer and water requirements, and may even need fertilizer and water control. Fertilizer and water management follows the cycle of "Huabao"-clear water-clear water-"Huabao"-clear water-clear water. The interval period is about: 3-5 days for outdoor maintenance; the interval is shorter on sunny days or during high-temperature periods, and longer or no watering on rainy days or during low-temperature periods; 4-7 days for indoor maintenance; the interval is shorter on sunny days or during high-temperature periods, and longer or no watering on rainy days or during low-temperature periods. Watering should be scheduled as much as possible in the morning when the temperature is lower, and the leaves should be kept dry at night.
The plants should also be sprayed frequently. Winter: During the winter dormant period, the main task is to control fertilizer and water. Fertilizer and water management follows the cycle of "Huabao"-clear water-clear water-"Huabao"-clear water-clear water. The interval period is about 7-10 days; the interval is shorter on sunny days or during high-temperature periods, and longer or no watering on rainy days or during low-temperature periods. Watering should be scheduled as much as possible at noon on sunny days when the temperature is relatively high.
Maintenance points: temperature
Cultivation facilities should meet the temperature requirements of Gerbera during the seedling stage, growth stage, and flowering stage, to facilitate normal growth and flowering. Except in South China, it cannot overwinter in open fields and must be cultivated in greenhouses; outside the Yangtze River basin, it can be cultivated in unheated plastic tunnels. In summer, a shade net needs to be covered on top of the tunnel, and the plastic film on both sides of the tunnel should be opened to lower the temperature. In winter, when the outdoor night temperature approaches 0°C, the plastic film should be lowered, and additional plastic film must be covered inside the tunnel. On clear and warm days, open the film at the south end of the tunnel for ventilation for about one hour.
Light
A light-loving flower; it needs full light in winter, and in summer appropriate shading should be provided, ventilation strengthened, and temperature lowered to prevent high temperatures from causing dormancy.
Irrigation
After planting, the seedling stage should maintain appropriate moisture and exercise the seedlings to promote root development and rapid establishment. During the vigorous growth period, sufficient water should be maintained, watering once every 3-4 days, and once every half month in winter. When watering during the flowering period, care should be taken not to let water touch the center of the leaf rosette, to prevent flower bud rot. During cultivation, attention should be paid to preventing waterlogging. Fertilization can be combined with watering.
Topdressing
Gerbera is a fertilizer-loving perennial herbaceous flower with high fertilizer demand. The ratio of nitrogen, phosphorus, and potassium in fertilization is 15:18:25. Special attention should be paid to supplementing potassium fertilizer. Apply 2.5 kg of potassium nitrate per mu, and 1.2 kg of ammonium nitrate or ammonium phosphate, once every 5-6 days, and once every 10 days. If high temperature or relatively low temperature causes the plant to enter a semi-dormant state, then stop fertilizing.
Remove residual leaves
The lower leaves of the basal leaf rosette easily turn yellow and age. Removing them in time is beneficial for the sprouting of new leaves and new flower buds, helps ventilation, and strengthens plant growth.
Selection of Gerbera fresh cut flowers: selection
The junction between the flower stem and the flower head of Gerbera is relatively thin and soft, while the flower head is large and heavy, so it easily bends down from the neck. Therefore, when selecting, one must choose those with short, thick flower stems, so that the neck can be stronger in supporting the flower head.
Only a small section at the bottom of the Gerbera flower stem is solid; the stem above is hollow. However, Gerbera mainly relies on this solid part to absorb water, so if the solid bottom has been cut off, do not choose it! After buying it and taking it home, put it into water as quickly as possible, and try not to cut off the solid stem section at the bottom.
Arranging
The "neck" of Gerbera is thin, and the flower head easily droops, causing it to decline. Therefore, every possible means should be used to fix the neck, such as wrapping it with soft wire for reinforcement, then covering it with green tape to conceal it.
Gerbera petals decline from the outside inward; therefore, when the outer petals are not good, they can be directly pulled off, and the remaining flower center part is also quite ornamental. Because Gerbera petals are very easily damaged and leave scars, they must be handled with care.
The water level only needs to reach one third of the length of the flower stem, because the stem is soft and easily rots, so the water level should not be too high.
Fresh-keeping methods
Gerbera bought back from the flower market does not need its roots cut, especially the hard knot at the base of the root should not be cut off; just put it directly in water. Put in less water, just enough to immerse its hard bottom. The flower bucket should be relatively tall, preferably reaching the flower head part. Gerbera whose roots have been cut easily rots at the stem, and rots especially quickly.
If newly received stock shows dehydration, first put it directly into water. If it has not recovered after a few hours, then slightly cut the base into a slanted opening and put it into water.
If there is no dehydration, then it is a normal bending-stem phenomenon. Actually, it is also very simple to straighten its flower head: just take it out and lay it flat, or wrap it in paper and leave it for one or two hours before putting it into water.
The flower language of Gerbera
The flower language of Gerbera symbolizes mystery, mutual respect and mutual love, perseverance, and fearlessness of hardship. It likes to pursue a rich life. Single-petaled varieties represent warmth, while double-petaled varieties represent commendable passion. In the Shanghai area, people like to use Gerbera to make bouquets to decorate the bridal chamber during wedding celebrations. Using its homophonic meaning, it takes the meaning that the newlyweds respect and love each other and that the wife supports her husband in achieving his career. The Gerbera flower shape is radial and is often used as the main body in flower arrangements, often configured with Nephrolepis (Boston fern) and Asparagus setaceus.
The flower language of Gerbera is -- eternal happiness. Its most commonly used flower language in China: elegant. noble. reclusive.
Gerbera pictures
What are the methods for controlling flower pests?
With the improvement of people's living standards, the construction of green homes is increasingly favored by people, and flower planting is becoming more and more widespread. But home flower growing often has pest problems. These pests not only affect the healthy growth of flowers and trees, but also hinder ornamentation. How to prevent and control pests and diseases is a question often discussed by friends who love growing flowers.
Generally speaking, the environmental conditions suitable for the growth and survival of home-cultivated flowers also create conditions for the occurrence and spread of many pests and diseases. The sooner or later pests and diseases occur first depends on temperature, and the severity of pest and disease damage, in addition to being affected by temperature, mainly depends on humidity. To prevent and control pests and diseases, the principle of "prevention first" should be grasped, management should be strengthened, and attention should be paid to maintenance work such as ventilation, light transmission, watering, and fertilizing. Make flowers and trees grow vigorously and enhance their own ability to resist pests and diseases. Once pest or disease damage is found, measures should be taken early, achieving "early treatment, treatment while minor, and complete treatment" to prevent spread. When necessary, use pesticide control to inhibit and kill pests and diseases, eliminate the threat of pests and diseases, and ensure the healthy growth of flowers.
Common pests of household flowers include: aphids, red spider mites, mosquitoes and flies (fungus gnats), thrips, scale insects, whiteflies, etc.; diseases include anthracnose, brown spot, soft rot, root rot (black stem disease), powdery mildew, etc.
The methods for controlling flower pests mainly include two methods: manual killing and chemical killing.
1. Manual killing
For pests that are relatively large and few in number, such as scarab beetles, scale insects, and larvae of Lepidoptera, once found, capture and kill them promptly.
2. Chemical killing
That is, using the toxicity of chemicals to kill pests. According to the different mouthparts of pests, spray different types of chemicals. For pests with chewing mouthparts, such as scarab beetles and larvae of Lepidoptera, stomach-poison pesticides can be sprayed to kill them. For pests with piercing-sucking mouthparts, such as aphids, scale insects, and whiteflies, systemic pesticides can be sprayed to kill them.
For soil pests, such as scarab larvae, white grubs, wireworms, and nematodes, contact-poison pesticides can be sprayed into the soil.
Next, let us briefly introduce the control methods for several of the most common pests:
Common pests and harmful small animals and their control
1. Aphids
Damage characteristics: Aphids are a kind of small green-yellow insect that harms almost all flowers and trees. Between spring and summer, they often gather densely on new shoots or flower buds of rose, pomegranate, oleander, chrysanthemum, etc., using their mouthparts to suck sap, causing young leaves to curl and shrink. In severe cases, they not only affect growth and flowering, but also cause plant leaves to curl, wither, and produce galls, and transmit viral diseases. When aphids suck sap, they excrete a sticky liquid called honeydew that sticks to the leaf surface, attracting ants and easily causing sooty mold. Aphids can produce 20-30 generations a year, and eggs can overwinter.
Flowers damaged: The host range is broad, mainly damaging rose, pomegranate, oleander, chrysanthemum, carnation, chrysanthemum, cyclamen, hibiscus, redbud, poinsettia, cineraria, and other flowers.
Control methods: When a small amount occurs, they can be squeezed with something, then rinsed clean with water; tobacco water (50 times dilution) or soapy water can also be used to smear continuously several times. For pesticide control, 25% derris extract 800-1000 times dilution, 40% omethoate 2000 times dilution, 3% natural pyrethrum 1000 times dilution, and deltamethrin 2000-3000 times dilution can be sprayed, all of which can kill aphids very well, with relatively ideal results.
Two, Red Spider Mite
Damage symptoms: Red spider mites are small and red, and very difficult to see with the naked eye. They often gather in groups on the undersides of the leaves of flowering plants, using their piercing-sucking mouthparts to suck sap and damage the plant, causing small yellow-white spots on the leaves, which then turn grayish-white, until the leaves wither and scorch or drop off. They can produce more than 10 generations a year, and often breed in high-temperature, low-humidity environments. Plants damaged: They are widely distributed and have a varied diet; almost all ornamental plants, such as herbaceous and woody plants, cut flowers and potted flowers, may be harmed by them. They commonly damage rhododendrons, Chinese roses, scarlet sage, crabapple, as well as Chinese juniper, kumquat, bitter orange, cactus, dragon juniper and so on, among which rhododendrons and Chinese juniper suffer the most serious damage. They usually occur more often in high-temperature, dry environments (such as indoors near a sunny window) and reproduce quickly.
Control methods: Remove weeds from pots and eliminate overwintering eggs. When the infestation is light, remove the severely infected leaves and rinse the leaves with water; improve ventilation conditions and lower the temperature; frequently spray more water around the plants to increase air humidity. For chemical control, acaricides can be used, such as diafenthiuron, abamectin, pyridaben, fenpropathrin, amitraz, dicofol or omethoate 100-fold solution, sprayed alternately on the leaves in the early stage of red spider mite occurrence, once every week, for 2-3 consecutive sprays.
Three, Fungus Gnats (Sciarid Flies)
Damage symptoms: The main food of the larvae is saprophytic fungi that are plant pathogens, and the larvae's feeding results in plant pathogens being able to infect through the root system. Fungus gnat larvae feeding on flower roots reduces the ability of flowering plants to absorb water and nutrients, causing the plants to grow slowly and stunted. In addition, the feeding of fungus gnats can also cause Pythium rot, Phytophthora blight and black root rot in flowers.
Plants damaged: Commonly seen in potted flower cultivation or herbaceous flower seedling raising, such as poinsettia, cyclamen and pansy.
Control methods: For chemical control, use agents such as Citation, imidacloprid and abamectin, applied by root drenching to control fungus gnat larvae.
Four, Thrips
Damage symptoms: Thrips are black or brown; common species include flower thrips, tobacco thrips, yellow thrips and western flower thrips. The period of serious damage is spring and summer. Thrips often rasp and suck sap on the undersides of tender leaves and on flower organs, causing the damaged leaves to curl, with yellow rasping spots appearing on the leaf tissue, and the damaged leaves turning yellow, becoming brittle and dropping off. Sometimes grayish-white or brown spots appear on the petals, or loss of color and discoloration occur, affecting flowering quality.
Plants damaged: Anthurium, cyclamen, rose, carnation, lisianthus and many other flowers.
Control methods: Because they can develop resistance to many insecticides, integrated physical, chemical and biological control methods are used in production. For chemical control, use agents such as imidacloprid, lufenuron, imidacloprid + lambda-cyhalothrin, abamectin and spinosad, sprayed alternately on the leaves every 5 to 7 days.
Five, Scale Insects
Damage symptoms: There are many species, mainly mealybugs, red wax scale, cottony cushion scale, brown soft scale and so on. It is one of the common pests of indoor foliage plants, and is especially likely to occur on woody foliage plants and coniferous plants. It mainly gathers and parasitizes on the young stems and leaves of plants, inserting its piercing-sucking mouthparts into plant tissues to suck sap. The wounds are highly susceptible to disease infection and can induce sooty mold. It has very strong reproductive capacity, and under suitable environmental conditions it reproduces for many generations a year, so in warmer regions it can cause damage throughout the year.
Control methods: When the infestation is light, manual control is usually used, that is, brushing off the insects with a brush and then rinsing clean with water. Chemical control is best carried out at the peak hatching stage of the nymphs, before the waxy scale covering has formed on the insect body, as this makes it easier to kill the insects and improves the control effect. Agents that can be selected include isocarbophos 1000-fold solution, 20% fenvalerate 1500-2000-fold solution, 40% omethoate 800-1000-fold solution, etc., sprayed 2-3 times every week. If the infestation is relatively serious, a combination of manual and chemical control methods should be used, that is, first brush off the medium, then spray with the above agents, for a more ideal effect.
Six, Whiteflies
Damage symptoms: They are widely distributed and harm many kinds of flowers; they occur frequently on indoor foliage plants in greenhouses or plastic tunnels, and are especially likely to occur in dry environments. The insects are small and white; the mouthparts of adults and larvae are inserted from the underside of the leaves to suck sap, causing the leaves to wither and yellow. The wounds are highly susceptible to brown rot, and in severe cases lead to plant death. At the same time, they excrete honeydew on the leaves, triggering sooty mold.
Control methods: 2.5% deltamethrin, 20% fenvalerate 1500-2000-fold solution and other pyrethroid pesticides can be sprayed to control nymphs, adults and eggs, generally once a week, for 3-4 consecutive times.
Seven, Nematodes and White Grubs and Other Subterranean Pests
Damage symptoms: These pests mainly bite and feed on plant roots and tender stems underground, or damage root bulbs, causing roots and stems to rot and the plant to die.
Control methods: Use steam or chemicals to sterilize the soil and eliminate sources of nematodes and the like; mix food with trichlorfon and scatter it beside the seedlings or bury it beside the seedlings for trapping and killing; drench the plants with 90% trichlorfon 1000-fold solution; manual capture and killing.
Eight, Snails
Damage symptoms: They are small terrestrial mollusks, mostly living in year-round damp and shaded environments. They like shade and moisture, and fear dryness and strong light. They often damage the leaves, tender stems and roots of perennial herbaceous foliage plants, causing the branches and leaves of the plant to become incomplete, affecting plant growth and ornamentation, or causing the plant to die.
Control methods: Food mixed with trichlorfon can be scattered in the places where they frequently move to trap and kill them; trichlorfon or deltamethrin 1500-2000-fold solution can also be sprayed around the plants; 8% metaldehyde granular formulation can be scattered on the soil surface around the roots to kill snails. In addition, pay attention to indoor cleanliness and hygiene, and promptly remove dead branches and fallen leaves to reduce their living space.
Here we introduce the general methods for preventing and controlling flower pests and diseases:
1. Maintaining the environmental hygiene of the flower cultivation site can reduce damage.
2. Protect the plants; do not let the skin break or be damaged, and guard against pathogen invasion.
3. Pre-disinfection of the growing medium can kill pathogens and pests.
4. Strengthen daily management, keep water and fertilizer appropriate, air circulation good, temperature suitable and light moderate, so that the plants grow robustly and the breeding and spread of pests and diseases are controlled.
5. For flowers overwintering outdoors, after leaf fall spray or apply lime sulfur mixture; in early spring and before flower buds sprout, spray 1-3 times with Bordeaux mixture to prevent pests and diseases. For damping-off disease, sown seedlings near the soil surface first show scald-like symptoms, then soften and fall over and die. Scattering plant ash on the surface of the pot soil or drenching with amobam solution can sterilize and protect the seedlings. For rust disease in carnations and Rosaceae flowers, orange-red or yellow spots appear on the leaf surface in the early stage, and later the undersides of the leaves are covered with yellow powder, and the leaves scorch. For anthracnose in ornamental-fruited flowers, brown spots appear on the fruit skin before the fruit ripens, gradually expanding, and the fruit hardens after ripening; after the flowers fade, spray 1-3 times with lime sulfur mixture or carbendazim. For powdery mildew in Rosaceae and Asteraceae flowers, white powder appears on both sides of the leaves; reduce humidity, spray amobam or carbendazim solution, and spray Bordeaux mixture to prevent it. For downy mildew in herbaceous flowers, white spots with indistinct outlines appear on the leaf surface in the early stage, and later they are covered with fine white hairs; spraying 1-3 times with Bordeaux mixture can prevent it. For soft rot in herbaceous flowers, water-soaked spots appear on the leaf surface, petioles and flower stems, and later they wilt and droop; spray Bordeaux mixture. For brown streak disease in orchidaceous flowers, brown sunken spots appear on the leaf surface and the leaves dry and scorch; pay attention to shading and increasing air humidity, and use equal-amount Bordeaux mixture. For black rust disease in Asteraceae flowers, yellow-green spots appear on the leaf surface in the early stage, and after rupturing they release yellow powder, finally becoming black patches; strengthen drainage, provide sufficient sunlight and strengthen ventilation, and spray Bordeaux mixture. For sooty mold in perennial evergreen flowers, dark brown sooty smudge appears on the leaf surface, later gradually expanding to form a black sooty mold layer; spray Bordeaux mixture, or use 5% alcohol to wipe off the sooty smudge.
Next, let us introduce several commonly used methods for preventing and controlling flower pests and diseases.
One, Tobacco has stomach poison, contact-killing and fumigant effects; because of its strong penetration, it can paralyze and poison pests' nerves and kill them. The method is to soak tobacco leaf stems or leftover cigarette butts (with the filter removed) in 50-60 times their volume of water for a day and night, then filter and spray; it can control aphids, cotton red spider mites and newly hatched scale insects.
2. Essential balm: Dilute essential balm 600-800-fold to control aphids, scale insects and moth and butterfly larvae; 400-600-fold essential balm can control cotton red spider mites.
3. Mosquito coils: Hang a lit mosquito coil on the flower plant, seal it with plastic film and fumigate for about 10 minutes to kill whitefly-type pests.
4. Soapy water: Take ordinary soapy water, or use leftover soap scraps or thin slices dissolved in hot water, add water at a ratio of 1:60, and after cooling, spray; it can control aphids and cotton red spider mites. If cigarette butts (with the ash removed) are soaked in the soapy water, in addition to improving control of aphids and red spider...
Washing powder solution: Take 2 grams of washing powder, add 500 grams of water and stir into a solution, add one drop of clear oil and spray on the insects on the plants; it can kill aphids, scale insects, cotton red spider mites, green stinging moths, white butterflies, whiteflies and so on. Flowers with tuberous roots (such as peony and dahlia) or with bulbs (such as lily and Lycoris) as well as fleshy root systems are susceptible to nematodes; a 1000-fold diluted washing powder solution can also be poured around the roots of the plants.
Soap solution: Take soap and hot boiled water and dissolve them at a ratio of 1:50, then spray; because soap can block the pests' respiratory organs and kill them, it is effective against aphids and scale insects. Tobacco solution: Tobacco contains nicotine, which has a strong contact-killing effect on aphids, cotton red spider mites, ants and so on, and also has fumigant and stomach poison effects. Take 20 grams of tobacco powder or cut tobacco, add 500 grams of water and soak for 24 hours, then filter; add 500 grams of 2% soapy water to the filtrate and spray on the leaf surfaces with pests; the filtrate can also be sprayed directly without soapy water onto the pot soil and around the bottom of the pot to kill pests in the soil.
Garlic solution for treating powdery mildew and black spot disease of Chinese roses: Take 30 grams of garlic cloves, mash them, add 500 grams of water, stir well and filter; take the filtrate and spray on the leaf surface, once a day, for 3-4 consecutive sprays. A writing brush or toothbrush can also be used to apply the garlic solution directly onto the surface, and mashing garlic and scattering it in the pot soil can also kill earthworms, ants and nematodes.
Scallion solution: Take 50 grams of scallion, mash into a paste, add 50 grams of water and soak for 12 hours, then filter and spray with the filtrate, several times a day, for 3-4 consecutive days; it can treat aphids and other soft-bodied pests as well as powdery mildew.
Fresh ginger solution Take fresh ginger, mash into a paste, add 20 times its volume of water and soak for 12 hours, then filter and spray with the filtrate; it can prevent and control leaf spot disease, sooty mold, rot disease, black spot disease and so on, and can also control aphids, cotton red spider mites and leaf miners.
Sichuan pepper solution: Put 50 grams of Sichuan pepper and 500 grams of water in a pot and heat to a boil, boiling down to 250 grams of medicinal liquid; when using, add 6-7 times water and spray to control whiteflies, aphids and scale insects.
Citrus peel solution Take 50 grams of citrus peel, add 500 grams of water and soak for 24 hours; after filtering, take the filtrate and spray on the leaf surface to control aphids, cotton red spider mites and leaf miners, and pour it into the soil to control nematodes. Alternatively, take 1 part citrus seeds, add 5 parts clear water and soak for 4-5 days, then soak flower seeds in this liquid for 10 minutes; it can control many kinds of pests.
Bitter gourd leaf solution Take 100-200 grams of bitter gourd leaves, add water and mash, add an equal amount of lime and stir evenly, then pour around the roots of plant seedlings to control cutworms.
Tomato leaf solution Mash 50 grams of fresh tomato leaves, add 150 grams of water and soak for 6 hours, then filter and spray with the filtrate to control aphids, cotton red spider mites and so on; it can also drive away flies.
Chili solution: Take 50 grams of chili, add 10 times water and boil for 20 minutes, then filter and spray with the filtrate; it can control pests such as aphids, cotton red spider mites and stink bugs, and when poured into the soil it can control cutworms.
Castor bean leaf powder: Dry castor bean leaves and stems in the sun, then grind them into powder and apply into the soil to control white grubs.
Oleander solution: Chop 50 grams of oleander branches and leaves, add 100 grams of clear water and boil for 20-30 minutes, remove the residue and take the clear liquid and spray to control aphids and whiteflies, and pour it into the soil to control nematodes. But note that oleander is highly toxic, so be careful to prevent people and livestock from eating it by mistake.
Rice vinegar solution: Rice vinegar contains abundant organic acids, which have a good inhibitory effect on pathogens. Spray a 150-200-fold diluted rice vinegar solution on the leaf surface, once every 7 days or so, for 3-4 consecutive sprays; it can prevent and control powdery mildew, black spot disease, downy mildew and so on.
Baking soda solution: Take 5 grams of baking soda, also known as sodium bicarbonate, first dissolve it with a small amount of alcohol, then add about 1000 grams of water to make a 0.5% concentration solution and spray the plants; it can prevent and control powdery mildew.
Mosquito coils: After lighting a mosquito coil, hang it on a plant with pests and cover the plant and flower pot with a plastic bag; after 1 hour the pests are killed. Essential balm: Essential balm diluted 400-500-fold with water can kill aphids. Mothballs: After crushing mothballs and placing them in the pot soil, they can control subterranean pests.
Potassium permanganate, commonly known as gray manganese oxygen: Potassium permanganate solution can prevent and control flower powdery mildew. In the initial period of onset, spray a 0.1%-0.2% solution once every 7 days or so, for 2-3 consecutive sprays, and the effect can reach more than 92%. Note: do not touch the solid potassium permanganate directly with your hands.
Common insecticides, common fungicides
Common insecticides. One, Trichlorfon is a highly effective, low-toxicity organophosphorus preparation; it has a strong stomach poison effect on pests and also a contact-killing effect, and kills quickly. In the field its effective period is 4-5 days. Commonly use the original solution at 1000-1500-fold dilution for spraying to control pests such as rose sawfly, great bagworm, Atractomorpha sinensis, cotton leaf roller, inchworm, leafhopper and cutworm. Trichlorfon must not be mixed with alkaline agents.
2. Dichlorvos is a highly effective, low-toxicity organophosphorus preparation with strong contact-killing, fumigant and stomach poison effects. It has a broad insecticidal range, acts quickly, has a short effective period and low residual toxicity. Commonly use 50% emulsifiable concentrate at 1000-fold dilution or 80% emulsifiable concentrate at 1500-fold dilution for spraying to control pests such as whiteflies, spider mites, green plant bugs, aphids, scale insects and pomegranate noctuid moths. Note that it must not be mixed with alkaline agents. Dichlorvos emulsifiable concentrate volatilizes easily, so the bottle cap must be tightened after taking the medicine; at high concentrations it is likely to cause phytotoxicity to cherry blossoms and plum blossoms.
3. Omethoate has contact-killing, systemic and stomach poison effects and can control many pests with piercing-sucking and chewing mouthparts. Its acute oral toxicity to humans and livestock is relatively high. Commonly use 40% emulsifiable concentrate at 1000-1500-fold dilution for spraying to control pests such as scale insects, aphids, whiteflies, cinnabar spider mites, green plant bugs, thrips, leafhoppers and citrus leaf miners. It must not be mixed with alkaline agents.
4. Dimethoate is a highly effective, low-toxicity broad-spectrum organophosphorus pesticide with contact-killing, systemic and stomach poison effects. Generally use 40% emulsifiable concentrate at 1000-1500-fold dilution or 60% wettable powder at 3000-5000-fold dilution for spraying to control pests such as aphids, cotton red spider mites, leafhoppers, leaf miners and whiteflies. It can also be used by adding 20-40 grams of water to 1 gram of the medicine and then mixing with 400-500 grams of seed to control subterranean pests such as mole crickets. Plum blossoms and cherry blossoms are sensitive to dimethoate and should be used with caution. It must not be mixed with alkaline agents.
Five, Malathion has contact-killing, stomach poison and fumigant effects, with high efficacy and a broad insecticidal range; the residual effective period is generally about one week, and its toxicity to humans and livestock is low, making it relatively safe. Commonly use 50% emulsifiable concentrate at 1000-2000-fold dilution for spraying to control pests such as aphids, cotton red spider mites, leafhoppers, thrips, scale insects and scarab beetles. Malathion has relatively poor stability, its effective period is not very long, and it must not be mixed with alkaline or strongly acidic pesticides.
6. Monocrotophos has a strong contact-killing effect and also systemic and stomach poison effects. It has a broad insecticidal range and an effective period of about one week, and its toxicity to humans and livestock is relatively high. Commonly use 50% emulsifiable concentrate at 2000-4000-fold dilution for spraying to control pests such as aphids, cotton red spider mites, leafhoppers, thrips and green plant bugs. It must not be mixed with alkaline pesticides.
7. Fenitrothion is a broad-spectrum insecticide with contact-killing and stomach poison effects, or it kills boring pests; its efficacy generally lasts 3-4 days. Generally use 50% emulsifiable concentrate at 1000-2000-fold dilution to control pests such as aphids, stinging moths, leafhoppers, fruit borers, scale insects, thrips and spider mites. A 2% powder can also be used for dusting; the usual application rate is 1-3 grams per square meter. It is likely to cause phytotoxicity to cruciferous plants. It must not be mixed with alkaline pesticides.
8. Deltamethrin has strong contact-killing and stomach poison effects, and its effective period can last as long as several months; it is relatively toxic to the skin. Commonly use 2.5% emulsifiable concentrate at 3000-8000-fold dilution for spraying to control stinging moths, green moths, cotton leaf rollers, cutworms, thrips, leafhoppers and so on.
Nine, Tetradifon is an acaricide containing organochlorine; it has a strong contact-killing effect, has effects of killing young mites and eggs, and can disrupt the physiological functions of adult mites so that they cannot reproduce. Its residual effective period can reach about 1 month. Commonly use 20% wettable powder at 800-****-fold dilution or 50% wettable powder at 1500-2000-fold dilution for spraying to control mite pests.
10. Dicofol has a very strong contact-killing effect and acts quickly; it is effective against mite eggs, larvae, nymphs and adults. Its residual effective period is 10-20 days. Commonly use 20% emulsifiable concentrate at 600-1000-fold dilution or 40% emulsifiable concentrate at 1000-1500-fold dilution for spraying to control various mites. It must not be mixed with alkaline pesticides.
11. Carbofuran is a broad-spectrum insecticide with low residual toxicity; it has systemic action and a certain contact-killing effect, and can control insects with chewing and piercing-sucking mouthparts as well as nematodes. Commonly use 3%, 5%, 10% and 5% granules and 75% wettable powder; it can control pests such as nematodes, scale insects, mites, leafhoppers, striped stem borers, stinging moths, aphids and thrips. It must not be mixed with alkaline pesticides.
12. Rosin mixture is a dark brown liquid boiled from rosin and caustic soda; it is strongly alkaline and has a contact-killing effect. It is often sprayed at 8-12-fold dilution during the winter dormant period or at 10-18-fold dilution during the growing season to control pests such as scale insects, whiteflies and cotton red spider mites. It must not be mixed with alkaline-sensitive pesticides or calcium-containing pesticides.
13. Metolcarb has contact-killing, systemic and fumigant effects and acts quickly; its efficacy generally lasts only 2-3 days. Commonly use 25% wettable powder at 200-400-fold dilution or 20% emulsifiable concentrate at 1000-1500-fold dilution for spraying to control pests such as leafhoppers, aphids, whiteflies and scale insects. It must not be mixed with alkaline pesticides.
Common fungicides
One, Bordeaux mixture is a good protective fungicide, prepared from copper sulfate, quicklime and water. According to the difference in the amounts of copper sulfate and quicklime used, it can be divided into several types such as the equal-amount formula 1:1, the half-amount formula 1:0.5, the multi-amount formula 1:3 and the double-amount formula 1:2. When preparing, first use half of the water to dissolve the copper sulfate and quicklime separately, then pour the copper sulfate into the quicklime solution and stir evenly with a stick. The prepared Bordeaux mixture is a sky-blue colloidal suspension, alkaline, with strong adhesion, and can form a thin film on the plant surface; its effective period can be maintained for about half a month. Bordeaux mixture does not store well and must be prepared and used immediately; it must not be mixed with alkaline-sensitive pesticides. It can prevent and control many diseases such as black spot disease, rust disease, downy mildew and gray leaf spot.
Two, Lime sulfur mixture is also a protective fungicide, made by boiling quicklime, sulfur powder and water in a ratio of 1:2:10. The stock solution is a dark reddish-brown transparent liquid with a rotten egg smell, and is alkaline. When preparing, first boil the water in a pot, pour in 1 part quicklime, and after the lime has dissolved, add 2 parts sulfur powder that has first been mixed into a paste with a small amount of water, stirring while adding. After adding, boil over high heat for about 1 hour, and when the medicinal liquid turns reddish-brown, stop the fire; after cooling, filter out the sediment, and this is the lime sulfur mixture stock solution. Its Baume degree is generally 20-24. The stock solution must be diluted before use; for dormant-season spraying, Baume 3-5 degrees can be used, while during the growing period only a diluted liquid of Baume 0.3-0.5 degrees can be used. It can prevent and control many diseases such as powdery mildew, rust disease, downy mildew, shot hole disease and leaf spot disease, and can also control pests such as whiteflies, spider mites and scale insects.
Three, Chlorothalonil has protective and therapeutic effects, a broad fungicidal range and a long residual effective period; it is irritating to the skin and mucous membranes. Commonly use 75% chlorothalonil wettable powder at 600-1000-fold dilution for spraying to prevent