How to prevent and control late blight in peace lilies
[Symptoms] It mainly affects stems and leaves. The disease first appears near the ground, with water-soaked round spots that turn brown as they expand, and grayish-white mold, namely the pathogen's sporangiophores and sporangia, grows on the stems and leaves. When humidity is high, diseased leaves and stems rot rapidly. When stems are infected, the affected parts first appear water-soaked, and after expansion the entire section softens and becomes wet rot.
[Symptoms] It mainly affects stems and leaves. The disease first appears near the ground, with water-soaked round spots that turn brown as they expand, and grayish-white mold, namely the pathogen's sporangiophores and sporangia, grows on the stems and leaves. When humidity is high, diseased leaves and stems rot rapidly. When stems are infected, the affected parts first appear water-soaked, and after expansion the entire section softens and becomes wet rot, and the stems and leaves above the diseased parts wilt and die. When leaves are infected, the spots are yellowish-brown, and under high humidity a white mold layer develops and they rot. The rhizome base becomes water-soaked and wet-rotted.
[Disease pattern] The pathogen overwinters in seeds or as mycelium and oospores with diseased residues in the soil, and spreads through wind, rain and irrigation water. The pathogen infects seedlings and causes damping-off. It is prone to occur when there is much rain and high humidity. The optimum temperature for pathogen development is 27-31°C, with a maximum of 36°C and a minimum of 10°C. The disease is severe during overcast and rainy weather or high humidity, or in heavy clay soil and low-lying areas.
[Control methods]
1. Prune promptly, remove diseased leaves, apply more phosphorus and potassium fertilizer, etc., and apply sufficient high-quality fully decomposed organic fertilizer.
2. At the early stage of the disease, spray 75% chlorothalonil wettable powder at 500-600 times dilution, or 40% fosetyl-aluminum (phosethyl-Al) wettable powder at 200 times dilution, or 70% fosetyl-Al·mancozeb wettable powder at 500 times dilution, or 58% metalaxyl·mancozeb at 400-500 times dilution, or 72.2% propamocarb aqueous solution at 700-800 times dilution, or 64% oxadixyl·mancozeb wettable powder at 500 times dilution.
What pests and diseases affect peace lilies? How to prevent and control them?
(1) Diseases. Common diseases include bacterial leaf spot, brown spot and late blight, and root rot and stem rot also occur.
Bacterial leaf spot has two infection modes. The first infection type begins on the leaves and is called leaf infection. Leaf infection usually begins at the leaf margins and the lower parts of the leaves where there are more stomata. In the early stage, water-soaked spots can be seen on the back of the leaves; in the later stage, brown spots appear at the leaf margins, with a yellow halo at the edges. The second infection type begins on the stems and spreads rapidly throughout the entire plant through the vascular system, and is called systemic infection (or vascular infection).
Systemic infection can be detected by yellowing leaves, and in the early stage of bacterial infection the new leaves are dull in color. In a relatively short time, this type of infection can cause peduncles and leaves to fall from the plant, the growing point to rot rapidly, and bacterial ooze to exude. Systemic infection is beyond saving.
Brown spot mainly affects the leaves of the plant. The disease usually starts from the basal leaves, initially producing small light green water-soaked round spots, which gradually become brown or black over time. As the spots gradually expand, the affected leaves also wither and finally scorch and die.
Late blight symptoms appear first on the parts near the ground, and the rhizome base, stems and leaves can all be affected. Water-soaked spots first appear and turn brown after expansion. Under high humidity, the spots expand rapidly, the diseased parts soften and become wet rot, and a sparse white mold layer grows. When the rhizome base is infected, the plant topples;
when the stem is infected, it bends and breaks after wet rot, and the stems and leaves above the diseased part wilt or die; on the leaves, it often expands into large yellowish-brown spots, seriously affecting the ornamental effect.
For the control of bacterial leaf spot and brown spot, at the early stage of the disease, agents such as 75% chlorothalonil, 50% mancozeb and 50% captan can be sprayed. The concentration is generally 800-1,000 times aqueous solution, sprayed once every 7 days for 2-3 consecutive times; or 50% Shujunwang at 1,000 times dilution, sprayed continuously 3-4 times every 7-10 days, which has a very good control effect.
For late blight, the following can be adopted: ① Crop rotation or planting with disease-free soil. ② Choose a well-drained place for planting or placing flower pots. Avoid overly dense plant clumps and ensure good ventilation and light transmission. ③ Promptly pull out diseased plants and burn them. Disinfect the soil before planting, and drench with 95% Lüheng No. 1 premium product at 3,000 times dilution. ④ According to the weather forecast, before heavy rain arrives or as early as possible after rain, spray 58% metalaxyl·mancozeb wettable powder at 600 times dilution or 61% fosetyl-Al·mancozeb wettable powder at 400-500 times dilution, or Shuangmeiyijing wettable powder at 600 times dilution, about once every 10 days, and carry out 2-3 treatments depending on the weather and the occurrence of late blight.
(2) Pests. The common pests are mainly scale insects and red spider mites.
Scale insects are one of the most common pests of flowers, often gathering in groups on branches, leaves and fruits. The mouthparts of adults and nymphs are inserted into the leaf and branch tissues of flowers to suck sap, causing withering and deformation of branches and leaves, and inducing sooty mold, causing great damage. Scale insects have strong reproductive capacity and can produce multiple generations a year. After crawling for a short time, they form a scale and become fixed in life, which is a major characteristic of scale insects. Scale insects have strong resistance to pesticides, and ordinary pesticides can hardly penetrate them, making control relatively difficult. Therefore, control should be carried out at the appropriate time. Control methods: when scale insects are found on individual leaves or branches, they can be gently brushed off with a soft brush or wiped clean with a cotton ball or loofah stem; when scale insects occur over a large area, pesticide control should be used, mainly focusing on spraying during the egg hatching period, because at this time the scale has not yet formed or thickened, and the insects can be killed by the pesticide. The pesticides can be 40% omethoate, 50% malathion, or 80% dichlorvos emulsifiable concentrate at 800-1,000 times dilution, sprayed once every 7-10 days for 2-3 consecutive times, which can effectively prevent the damage of scale insects.
In the process of flower cultivation, red spider mite is a common pest. This pest damages plants by piercing its mouthparts into flower leaves to suck sap, destroying the chlorophyll of the flowers, causing the leaves to show grayish-yellow spots or patches, and the leaves become withered and yellow, or even fall off. Control methods: to prevent red spider mite damage, observe the flowers carefully in normal times, and when abnormal leaf color is found, carefully check the underside of the leaves. When individual leaves are affected, the infested leaves can be removed; when more leaves are affected, pesticides should be sprayed as early as possible for control. Commonly used pesticides include propargite, dicofol, dimethoate, Huachongjing, and fenvalerate. For home flower growing, a flower sprayer can be kept on hand. Add 4 drops of Huachongjing to 400 ml of water (equivalent to 2,000 times dilution), or add 8 drops of dicofol or dimethoate (equivalent to 1,000 times dilution), shake well after adding the pesticide, and spray immediately. Spraying should be uniform and thorough, and special attention should be paid to spraying the underside of the leaves well.
Cultivation methods and precautions for peace lilies
White crane taro, also known as white palm and peace lily spathe taro, has an air-purifying effect and can filter benzene, trichloroethylene and formaldehyde from the air, and its purification rate for ozone in particular is especially high. Its leaves have a very high transpiration rate and can increase air humidity, making it a very good indoor foliage and flowering plant. White crane taro is more shade-tolerant than ordinary indoor plants, and can bloom in an environment with a little light and warmth. Its flowers are also excellent decorative materials for flower baskets and flower arrangements.Peace lilies are 30-40 cm tall and bloom in spring and summer. The spathe is large and prominent, rising above the leaves, white or slightly green, and the spadix is creamy yellow. They like a warm, humid, semi-shaded environment, avoid direct sunlight, and fear cold. They avoid heavy clay soil and prefer sandy loam rich in humus. The optimum growth temperature for white crane taro is 22°C-28°C. During cultivation, 24°C-30°C is suitable from March to September, and 18°C-21°C from September to March of the following year. The winter temperature must not be lower than 14°C. When the temperature is lower than 10°C, plant growth is inhibited and the leaves are prone to cold damage. During storage and transportation of potted white crane taro, the temperature should be controlled at 13°C-16°C and the relative humidity at 80%-90%, and it can tolerate a dark environment for 30 days.
Key points for potting peace lilies
Light and temperature
Peace lilies are relatively shade-tolerant. As long as there is about 60% scattered light, their growth needs can be met, so they can be grown year-round indoors in a place with bright scattered light. In summer, 60%-70% of sunlight can be shaded. Avoid direct strong light, otherwise the leaves will turn yellow, and in severe cases sunscald will occur. However, long-term overly dim light will cause the plant to grow weakly and make it difficult to bloom. The suitable light intensity is 500 lux. During potting, the minimum nighttime temperature in winter should be 14°C-16°C, and the daytime temperature should be around 25°C.
Water
Peace lilies have relatively large leaves and are quite sensitive to humidity. During potting, the potting soil should be kept moist frequently during the growing period, but excessive watering should be avoided, otherwise root rot and plant yellowing are likely to occur. In summer and dry seasons, water should frequently be sprayed onto the leaf surface with a fine-nozzle sprayer, and water should also be sprinkled on the ground around the plant to keep the air humid. When air humidity is low, new leaves will become smaller and yellow, and in severe cases wither, turn yellow and fall off. In winter, watering should be controlled, and it is appropriate for the potting soil to be slightly moist.
Fertilization
Potting requires loose soil with good drainage and aeration. Generally, leaf mold soil and peat soil mixed with a small amount of perlite can be used as the substrate, with a small amount of superphosphate and a small amount of bone meal or cake meal added as base fertilizer. During the peak growing season, apply a dilute compound fertilizer or decomposed cake fertilizer water once every 1-2 weeks, or apply "Huiyou" 20-20-20 general-purpose fertilizer, which not only ensures robust plant growth but also enables continuous blooming. When the winter temperature is low in the north, fertilization should be stopped.
Repotting
Peace lilies have strong tillering ability. When repotting each year, pay attention to trimming the roots and cutting off withered leaves. Overly dense plants should be divided and then potted. Generally, before a large number of new shoots sprout in early spring each year, they should be repotted once. When repotting, remove part of the old soil, trim the root system, add new culture soil and plant in a pot one size larger to promote root development.
Propagation methods for peace lilies
Division propagation
It is best to carry this out in May-June. Take the whole plant out of the pot, cut the rhizome apart from the base of the clump, ensuring each clump has at least 3-4 leaves, and after separate planting place in half shade to recover. Vigorously growing plants can be divided about once every two years, generally in spring together with repotting or after autumn. Before new shoots emerge in early spring, take the whole plant out of the pot, remove the old soil, divide the rhizome at the base of the clump into several clumps, each containing more than 3 stems and buds, and replant in new culture soil. Keep as many roots as possible to help the new plants quickly produce new leaves and ensure a full plant shape.
Seed propagation
After blooming, white crane taro can produce seeds through artificial pollination in a greenhouse. After the seeds mature, they can be sown immediately after collection. The sowing temperature should be around 25°C, and they germinate 10-15 days after sowing. At low temperatures the seeds are prone to rot, affecting emergence.
Pest and disease control
Common bacterial leaf spot, brown spot and anthracnose damage the leaves, and can be sprayed with 50% carbendazim wettable powder at 500 times dilution. When root rot and stem rot occur, in addition to paying attention to ventilation and reducing humidity, use 75% chlorothalonil wettable powder at 800 times dilution for control. For scale insects and red spider mites, use 50% malathion emulsifiable concentrate at 1,500 times dilution for spraying control. If mites are harmful and the leaves show adverse symptoms such as wilting, reduced luster and yellow withering, special acaricides can be sprayed for control, such as dicofol, hexythiazox and pyridaben.
★Potted cultivation methods for peace lilies
White crane taro, also known as white palm, peace lily and spathe taro, is a perennial evergreen herbaceous flower of the genus Spathiphyllum in the Araceae family. White crane taro has an air-purifying effect. It can filter benzene, trichloroethylene and formaldehyde from the air. At the same time, it also has certain health benefits, can increase air humidity, prevent nasal mucosa dryness, and reduce the probability of people getting sick. It is a very good indoor foliage and flowering plant. It is more shade-tolerant than ordinary indoor plants and can bloom in an environment with a little light and warmth. White crane taro has emerald green leaves and pure white spathes, very fresh and elegant. Potted plants decorating the living room or study are very unique, and their flowers are also excellent materials for flower baskets and flower arrangements.
White crane taro is 30 cm-40 cm tall, with no stem or a very short stem. The leaves are oblong or nearly lanceolate, with obvious midribs and petioles, dark green. It blooms in spring and summer. The spathe is large and prominent, rising above the leaves, white or slightly green, and the spadix is creamy yellow. It is very beautiful when in bloom, and even when not blooming it is an excellent indoor potted foliage plant.
White crane taro likes a warm, humid and semi-shaded environment, and direct sunlight must be avoided. It fears cold. It avoids heavy clay soil and is suitable for sandy loam rich in humus. The optimum growth temperature for white crane taro is 22°C-28°C. The winter temperature should not be lower than 14°C. When the temperature is lower than 10°C, plant growth is inhibited and the leaves are prone to cold damage.
Key points for potting
White crane taro is relatively shade-tolerant. As long as there is about 60% scattered light, its growth needs can be met, so it can be grown year-round indoors in a place with bright scattered light. In summer, 60%-70% of sunlight can be shaded. Avoid direct strong light, otherwise the leaves will turn yellow, and in severe cases sunscald will occur. However, long-term overly dim light will cause the plant to grow weakly and make it difficult to bloom. The suitable light intensity is 500 lux. During potting, the minimum nighttime temperature in winter should be 14°C-16°C, and the daytime temperature should be around 25°C. Long-term low temperature easily causes leaf drop or scorched yellow conditions.
White crane taro has relatively large leaves and is quite sensitive to humidity. During potting, the potting soil should be kept moist frequently during the growing period, but excessive watering should be avoided. Long-term wet potting soil can easily cause root rot and plant yellowing. In summer and dry seasons, water should frequently be sprayed onto the leaf surface with a fine-nozzle sprayer, and water should also be sprinkled on the ground around the plant to keep the air humid, which is beneficial to leaf growth. When the climate is dry and air humidity is low, new leaves will become smaller and yellow, and in severe cases wither, turn yellow and fall off. In winter, watering should be controlled, and it is appropriate for the potting soil to be slightly moist.
Potting requires loose soil with good drainage and aeration. Heavy clay soil must not be used. Generally, leaf mold soil and peat soil mixed with a small amount of perlite can be used as the substrate, with a small amount of superphosphate added, and additionally a small amount of bone meal or cake meal as base fertilizer. During the peak growing season, apply a dilute compound fertilizer or decomposed cake fertilizer water once every 1-2 weeks, or use 20-20-20 general-purpose fertilizer, which is beneficial both for robust plant growth and for continuous blooming. When the winter temperature is low in the north, fertilization should be stopped.
White crane taro has strong tillering ability. When repotting each year, pay attention to trimming the roots and cutting off withered leaves. Overly dense plants should be divided and then potted. Generally, before a large number of new shoots sprout in early spring each year, they should be repotted once. When repotting, remove part of the old soil, trim the root system, add new culture soil and plant in a pot one size larger to promote root development and plant growth.
Propagation methods
Division propagation. Vigorously growing plants can be divided about once every 2 years, generally in spring together with repotting or after autumn. Before new shoots emerge in early spring, take the whole plant out of the pot, remove the old soil, divide the rhizome at the base of the clump into several clumps, each containing more than 3 stems and buds, and replant in new culture soil. Keep as many roots as possible to help the new plants quickly produce new leaves and ensure a full plant shape.
Seed propagation. After the seeds mature, they can be sown immediately after collection. The sowing temperature should be around 25°C, and they germinate in 10-15 days. At low temperatures the seeds are prone to rot.
★Care methods for peace lilies
Likes sun, not cold-tolerant, relatively likes water, relatively likes fertilizer
[January] For potted white crane taro, place it on a sunny windowsill or balcony, keep the room temperature at 15°C-18°C, and it can bloom as usual. Water immediately when the potting soil is slightly dry, once every ten days, to keep the soil moist. Never allow the indoor temperature to fluctuate or allow low-temperature dampness, which can cause brown spots and mold spots on the edges of the spathe.
[February] For flowering white crane taro plants, keep the placement unchanged and the room temperature at 15°C-18°C, and they continue to send up flower stems from the leaf clump and bloom. If the room temperature is around 10°C, they can survive the winter safely, but it is difficult for them to send up flower stems and continue blooming. Keep the potting soil moist. If the indoor air is dry, spray water on the ground or the pot surface to increase air humidity. Flowering plants should be kept away from air conditioning vents and radiators to prevent the spathe from withering prematurely.
[March] The daily management of flowering white crane taro plants is the same as last month. Flowering plants should be kept away from air conditioning vents or radiators to prevent the spathe from wilting prematurely. When in bloom, use a brush for artificial pollination to increase the seed-setting rate.
[April] As the temperature rises, white crane taro blooms gradually more. Water 2-3 times a week to keep the potting soil slightly moist. Fertilize once a month, but nitrogen fertilizer must not be excessive. Otherwise, it will affect blooming. Prevent the damage of root rot and stem rot.
[May] It enters the full blooming period. Potted flowering plants are still placed on a sunny windowsill or balcony, with the room temperature kept at 18°C-20°C, watered 3 times a week, and fertilized once a month. For seed propagation, use indoor pot sowing, with peat soil as the sowing soil, cover with shallow soil after sowing, and the suitable germination temperature is 23°C-27°C. They germinate 10-15 days after sowing. If the room temperature is too low, the seeds are prone to damp rot.
[June] Blooming gradually decreases. Repot together with division. Take the whole plant out of the pot, remove the old soil, cut off overly long fibrous roots, and cut the rhizome apart from the base of the clump, ensuring each clump has 3-4 buds. Use a mixed soil of garden soil, leaf mold soil and river sand for the potting soil, and after potting place in half shade for care.
[July] Continue division and repotting, with the method the same as last month. After the divided seedlings recover and grow, keep the potting soil slightly moist. When there is direct sunlight, shade appropriately, and apply thin fertilizer once a month. Prevent the damage of scale insects.
[August] In the high-temperature season, in addition to keeping the potting soil moist, spray more water on the leaf surface to maintain relatively high air humidity, which is very beneficial to leaf growth. Shade during strong light, but long-term insufficient light makes it difficult to form flower buds and it will not bloom.
[September] The temperature gradually becomes cooler, and the plant continues to send up flower stems from the leaf clump and bloom. Water 2-3 times a week to keep the potting soil slightly moist. Fertilize once a month. Prevent the damage of leaf spot and brown spot.
[October] At a room temperature of 15°C-18°C, the plant continues to bloom. Water 2-3 times a week, gradually control the amount of watering, and stop fertilizing to avoid overly rapid plant growth and weakened cold resistance.
[November] For potted plants, place them on a sunny windowsill or balcony, keep the room temperature at 15°C-18°C, water once every ten days, and keep the potting soil slightly moist.
[December] For potted plants, keep the placement unchanged, keep the room temperature at 15°C-18°C, water once every ten days, cut off the yellow leaves and dead leaves on the outer part of the plant, and gently wipe dust off the leaves with a slightly damp soft cloth to keep the leaves clean and shiny.
★How to grow peace lilies well in northern households
White crane taro, also known as white palm and Spathiphyllum floribundum, is a foliage plant of the genus Spathiphyllum in the Araceae family. It is an excellent small- and medium-sized indoor potted flower newly introduced to China in recent years. It also has a very popular name -- peace lily.
White crane taro is native to tropical America, so in the process of cultivation in northern households, attention should be paid to creating a high-temperature and high-humidity environment for it. White crane taro has a large leaf transpiration rate, and air humidity needs to be kept above 60%. In the room, a water basin can be placed under the flower pot, or an electric humidifier can be placed near the plant, so that the area around the leaves is filled with water vapor; water can also be sprayed directly around the plant and on the leaf surface. In hot summer, generally more than 4 sprays are needed each day. The potting soil should be kept moist frequently, but there should be no standing water. White crane taro is a flower that likes high temperatures. The minimum nighttime temperature in winter should be kept at 14-16°C, and around 25°C during the day is best. Long-term low temperature and dampness can easily cause root rot and yellowing of the aboveground parts. (Authors: Miao Jinsu, Sun Fengshan)
★Cultivation management and disease control of peace lilies
1. Ecological habits
White crane taro, also known as white palm, spathe taro and peace lily, is a perennial evergreen herbaceous foliage plant of the genus Spathiphyllum in the Araceae family. It is native to the tropical rainforests of Colombia and is relatively adapted to a warm, humid and semi-shaded environment. The optimum growth temperature is 20°C-28°C, and the overwintering temperature is 10°C. It is a high-temperature-loving plant and has strict soil requirements. Heavy clay soil must not be used; generally use loose, breathable and well-drained soil.
2. Propagation methods
Division propagation is mostly used, and seed propagation can also be used. White crane taro plants tiller quickly. Generally, vigorously growing plants can be divided after two years, and when dividing, make sure each clump contains more than 3 buds. For seed propagation, the seeds should be sown immediately after collection.
3. Cultivation management
White crane taro plants tiller relatively quickly, so they have a relatively large demand for fertilizer and water, and timely supply should be noted, while maintaining the humidity of the surrounding environment. During the growing season, 60%-70% shade is needed, but the light must not be too dim. In particular, long-term low light will affect plant growth and make it difficult to bloom. At the same time, note that it must not remain in a low-temperature, humid environment for a long time, so as to avoid root rot and yellowing leaves. When potting, add an appropriate amount of farmyard manure as base fertilizer. When the plants grow too densely, moderate pruning can be carried out.
4. Disease control
White crane taro (white palm, spathe taro) late blight
Symptoms. The parts near the ground are affected first, and the rhizome base, stems and leaves can all be affected. Water-soaked spots first appear and turn brown after expansion. Under high humidity, the spots expand rapidly, the diseased parts soften and become wet rot, and a sparse white mold layer grows. When the rhizome base is infected, the plant topples; when the stem is infected, it bends and breaks after wet rot, and the stems and leaves above the diseased part wilt or die; on the leaves, it often expands into large yellowish-brown spots, seriously affecting the ornamental effect.
Transmission routes and disease conditions. It overwinters in the soil as oospores. Under warm and high-humidity conditions, it spreads to plants through splashing rain and irrigation water, and causes disease after germination. The disease is severe in rainy conditions, dense planting and poorly drained planting sites.
Control methods. ① Crop rotation or planting with disease-free soil. ② Choose a well-drained place for planting or placing flower pots. Avoid overly dense plant clumps and ensure good ventilation and light transmission. ③ Promptly pull out diseased plants and burn them. Disinfect the soil before planting, and drench with 95% Lüheng No. 1 premium product at 3,000 times dilution. ④ According to the weather forecast, before heavy rain arrives or as early as possible after rain, spray 58% metalaxyl·mancozeb wettable powder at 600 times dilution or 61% fosetyl-Al·mancozeb wettable powder at 400-500 times dilution, or Shuangmeiyijing wettable powder at 600 times dilution, about once every 10 days, and carry out 2-3 treatments depending on the weather and the occurrence of late blight.
White crane taro bacterial leaf rot
Symptoms. It mainly affects leaves. Brown rot spots form at the leaf margins and continuously expand inward, and yellow halos appear between the diseased and healthy parts.
Transmission routes and disease conditions. The pathogenic bacteria overwinter in the soil with diseased residues. When conditions are suitable the following year, they spread through irrigation water or rain splashes, and the bacteria invade through wounds. The disease is prone to occur when there are many consecutive rainy days, when moisture remains for a long time, or when the potting soil has long-term standing water.
Control methods. ① Horticultural control. Choose a high, dry and well-ventilated flower nursery to cultivate white crane taro, drain promptly after rain, and strictly prevent moisture retention. In greenhouses, ventilate and dehumidify timely and appropriately. ② Chemical control. When the rainy season arrives, promptly spray 72% agricultural streptomycin soluble powder or Xinzhiromycin at 4,000 times dilution, 53.8% Kocide 2000 dry suspension at 1,000 times dilution, 47% Kasumin wettable powder at 700 times dilution, or 12% Lülütong emulsifiable concentrate at 600 times dilution, about once every 10 days, for 2-3 treatments. (Hebei Agricultural Science and Technology, author: Feng Li)
★Potted care and management of peace lilies
White palm, also known as white crane taro, silver spathe taro and peace lily, etc., English names whiteflag and peace-lily, is a perennial evergreen herbaceous plant of the genus Spathiphyllum in the Araceae family of the monocotyledon class.
White palm is native to tropical regions of the Americas such as Colombia. It was introduced from its place of origin to Europe in 1874, began to be used for potted ornamental purposes in the early 20th century, and by the 1980s it was already very popular in Europe. China began introducing and cultivating it in the late 1980s, and there was small-scale production. Because white palm is a type of flower suitable for indoor potting that can be enjoyed for its flowers when blooming and its leaves in all four seasons, to date, flower production bases in southern provinces, regions and major cities across the country have successively mass-propagated seedlings through tissue culture. Market sales and prices have always been promising, and the price is relatively high. Therefore, it is quite favored by merchants and flower growers. Due to sufficient supply, it has gradually entered thousands of households.
The cultivated varieties that have been introduced into China now include: Green Giant white palm, Perfume white palm, Divine Lamp white palm and Mauna Loa spathe white palm, etc.
1. Botanical characteristics
White palm has a short rhizome and a plant height of 30-50 cm, mostly in clump form. The leaves are leathery, oblong-elliptical, tapering at both ends, dark green, glossy, with obvious veins and long petioles that are sheath-like at the base; the flower stalk is upright and rises above the leaf clump, and the spathe is oblong-lanceolate and upright; the spadix is oval and spoon-shaped, persistent, white as a snow lotus, closely resembling clasped hands; the flowers are small and densely arranged, white, slightly fragrant, and bisexual; the berries are red. The flowering period is May-August.
2. Biological characteristics
White palm likes a warm, humid, semi-shaded environment and is not cold-tolerant; it avoids direct sunlight and exposure. It is suitable for planting in sandy loam rich in humus that is loose, breathable and well-drained, and avoids heavy clay.
3. Propagation
Division
When the plants in the pot are too densely clustered, during repotting in April-June, take the whole plant out of the pot, remove the old soil and diseased and weak roots, pull the rhizome apart from the base of the clump, keep 3-4 leaves per clump, and replant in new culture soil, taking care not to damage the roots. Place in half shade to recover, so as to promote the production of new leaves and ensure a full plant shape.
Artificial pollination
Indoor potted white palm can set seed after artificial pollination following blooming. For artificial pollination, it is advisable to pollinate twice, at 9-10 o'clock and 15-16 o'clock.
From pollination to seed maturity takes 10-12 months. During the seed growth and development stage, pay attention to ventilation and water and fertilizer management to promote full seed setting.
Sowing
After the seeds mature, sow immediately after collection. Before sowing, remove the peel and pulp, soak the seeds in warm water at 40°C for 10 hours, then sow on loose, well-drained river sand, then cover with a thin layer of soil, and after spraying or soaking the pot, cover the pot mouth with plastic film to keep the culture soil at more than 80% humidity. Place indoors at 20-25°C, and they sprout 15-25 days after sowing. If the room temperature is too low during this period, it will cause the seeds to rot or affect emergence.
Tissue culture
Induction of callus
Rinse the young leaves of white palm clean with tap water, disinfect with 70% alcohol for 1 minute, disinfect with 1% mercuric chloride for 10 minutes, then rinse 5 times with sterile water, and inoculate on MS+24D 0.2 mg/L+
BA 1.0 mg/L culture medium and culture for about 15 days to form callus.
Embryoid differentiation
Transfer the callus to MS+BA 1.0 mg/L+NAA 0.1-0.1 mg/L culture medium for subculture.
Rooting culture
Transfer the rootless seedlings obtained from subculture to 1/2 MS+NAA 0.5 mg/L culture medium for rooting culture.
Other
The pH of the culture medium is 5.8, and 3% sucrose and 5% agar need to be added in all cases; the sucrose in 1/2 MS is halved. The culture temperature is 24-28°C, the light intensity is 1,500-2,000 lx, and the photoperiod is 10-12 hours.
Tissue culture proliferates rapidly and the plants are uniform, and it is the method currently used in production. After emergence, when 1-2 true leaves have grown, they can be divided and transplanted into pots. After a period of planting, spray dilute manure fertilizer to make the seedlings grow robustly. Seedlings from sowing need to be cultivated for 3-4 years before they can bloom, but after 2-3 years, they can be used for indoor potted ornamental display.
4. Cultivation management
4.1 Light
White palm is shade-tolerant. About 60% scattered light can meet its growth needs. Therefore, it can be placed year-round indoors in a place with bright scattered light. In summer, the light level is 50%, and in winter it can be increased to 70%, but direct strong light should be avoided. In addition to avoiding direct strong light at noon, it should receive more sunlight in the morning and evening.
It is suitable for potting indoors on south- or north-facing balconies or windowsills; otherwise, yellow leaves or scorched leaves will occur, and in severe cases sunscald will appear. If placed in too dim a place for a long time, it will also cause poor plant growth and make it difficult to bloom. It can grow at a light intensity of 200 lx and can bloom at a light intensity of 500 lx. Therefore, although it is shade-tolerant, 500 lx is preferable.
In order to keep the plant posture graceful and symmetrical, rotate the flower pot once every period of time so that light is received evenly and the plant is prevented from growing toward the light source.
4.2 Temperature
The optimum growth temperature for white palm is 22-28°C. From March to September it is 24-30°C, and from September to March of the following year it is 18-22°C. In winter, the room temperature should be kept above 14-15°C; below 10-15°C, the leaf tips dry up and plant growth is inhibited.
4.3 Water
White palm is quite sensitive to humidity. During potting, the potting soil should be kept moist frequently during the growing period, but excessive watering and standing water should be avoided, otherwise root rot or plant yellowing is likely to occur. In summer and when the potting soil is dry, use a fine-hole sprayer to spray water on the leaf surface to keep the potting soil moist; a plastic flower
tray with water can be placed under the pot to increase air humidity; the greater the air humidity, the more vigorous the growth and blooming; it is sufficient to keep humidity above 50%; when air humidity is low, new leaves are small and yellow, and in severe cases wither, turn yellow and fall off. In winter, control watering, and it is appropriate for the potting soil to be moist.
4.4 Fertilization
For potted plants, a water-retentive and fertilizer-retentive potting soil is best. A substrate can be mixed from leaf mold, garden soil and perlite, with a small amount of superphosphate, bone meal and decomposed poultry or livestock manure added as a base fertilizer, plus extra potassium fertilizer such as plant ash to support growth, so that the leaves stand upright and stay green, and the plant does not lodge. During the peak growing season, apply a dilute compound fertilizer or decomposed cake fertilizer water once every 15 days to promote robust plants and glossy leaf color; you can also apply Huifriend 20-20-20 general fertilizer, which both keeps the plants robust and promotes continuous flowering; or spray the leaves with a 0.2% potassium dihydrogen phosphate solution to make the leaves broad and glossy. However, never apply raw fertilizer or an excessive amount of fertilizer; if the fertilizer strength is too high, it easily causes fertilizer damage such as yellowing leaves and root rot.
4.5 Repotting
The plant has strong tillering ability, so repot it in early spring each year before a large number of new shoots sprout. When repotting, trim the root system, cut off residual roots and diseased roots, remove withered leaves and leaves affected by pests or diseases, and divide overly dense clumps, then pot them up. Before potting, remove part of the old soil and add new soil. Because the plant has relatively large leaves and a well-developed root system, a suitably deep pot should be chosen so that the thick roots can spread out and grow inside the pot, favoring root development, deep roots and lush leaves, and a pot full of flowers.
4.6 Soilless culture
The culture substrate is made by mixing vermiculite or perlite with river sand at 1: 1. The nutrient solution pH is 6, and it is applied once every 5 days.
4.7 Hydroponic management
For a medium-sized, robustly growing peace lily (Spathiphyllum), the planting cup is wrapped with a solid substrate or sponge. Use 1/5 to 1/3 strength Garden Test formula for the nutrient solution, with pH 4.7 to 5.8. During the growing period, renew the nutrient solution once every 15 days. In summer, place it in a suitably shaded spot for care, avoiding direct sunlight, with diffused light being preferable. However, if it is kept in shade for a long time, flower buds are not easily formed. In winter, the room temperature should be kept above 15°C; below 10°C, the leaves fall off or turn scorched yellow. Spray water on the leaves frequently, and keep the air humidity above 50%.
5. Pest and disease control
5.1 Diseases
5.1.1 Viral disease Caused by taro mosaic virus.
Control: Do not introduce virus-carrying seedlings, and strengthen quarantine; use tissue culture for propagation as much as possible, so vegetative propagation can be carried out only after confirming that the mother plant is virus-free; when disease occurs, promptly remove and burn diseased plants; for spray control, use 2% formaldehyde (formalin) and 2% sodium hydroxide aqueous solution, or a solution of 164 g anhydrous trisodium phosphate or 377 g crystalline trisodium phosphate plus 1 l water.
5.1.2 Root rot Caused by Cylindrocladium spathiphylli.
Control: Promptly cut off diseased leaves, apply Bordeaux mixture to the wounds, and remove severely diseased plants; you can also pull out affected plants, soak them in 1% potassium permanganate solution for 5 minutes, rinse them, place them in sunlight for 15 minutes, and plant them after drying; in the early stage of disease, use 30% Ludebao suspension concentrate at 400 times, or
14% copper ammonia complex aqueous solution at 400 times, 0.5% Bordeaux mixture, 200 mg/l agricultural streptomycin or methyl multi-sulfur phosphorus, 75% chlorothalonil wettable powder at 800—1000 times, 50% Benlate powder or thiophanate-methyl at 500—1000 times for spray control, or drench the base of diseased plants with 50% benomyl at 800 times or 50% captan.
5.1.3 Phytophthora blight Caused by Phytophthora parasitica, also called Phytophthora rot.
Control: Remove diseased leaves, apply more phosphorus and potassium fertilizer, and apply sufficient high-quality, fully decomposed organic fertilizer; in the early stage of disease, use 75% chlorothalonil wettable powder at 800—1000 times, or 50% folpet wettable powder at 700 times, 50% Tuzet wettable powder at 500 times, 40% triethyl phosphonate
aluminum (phosethyl-Al) wettable powder at 200 times, 70% phosethyl-Al · mancozeb wettable powder at 500 times, 58% metalaxyl · mancozeb (zinc manganese metalaxyl) at 400 to 500 times, 72.2% Previcur aqueous solution at 700 to 800 times, 64% Sandofan wettable powder at 400 to 500 times, 50% Benlate wettable powder at 1000 to 1500 times, 80% zinc manganese nabam wettable powder at 400 times for spray control; do not use only one pesticide, but alternate several pesticides.
5.1.4 Leaf rot Caused by Erwinia and Erwinia carotovora.
Control: Grow strong seedlings, transplant at the proper time, and plant at a reasonable density; do not water excessively, and drain promptly in the rainy season; before and after rain, use 72% agricultural streptomycin sulfate soluble powder at 4000 times, or Xinzhimeisu at 4000 times, or 50% copper sulfate wettable powder at 500 times for spray control.
5.1.5 Anthracnose Caused by Colletotrichum.
Control: Spray a mixture of 50% thiophanate-methyl wettable powder at 800 times plus 75% chlorothalonil wettable powder at 800 times; or spray a mixture of 50% carbendazim wettable powder at 800 times plus 75% chlorothalonil wettable powder at 800 times; you can also use 80% Daconil wettable
powder at 500 times, or 65% zineb at 800 times, 60% Fangmeibao, 50% carbendazim at 1000 times, benomyl at 800 times, etc. for control, spraying once about every 10 days, for 2 to 3 consecutive sprays.
5.1.6 Leaf spot disease Caused by Acremonium, also called leaf spot.
Control: Pay attention to ventilation; when disease occurs, first remove diseased leaves and burn them in a centralized manner to reduce the initial infection source; use 75% chlorothalonil wettable powder at 500 times, or 40% multi-sulfur suspension concentrate at 500 to 600 times, 50% mixed sulfur suspension concentrate at 500 times, 65% zineb wettable powder at 500 to 700
times for spraying or soaking; you can also spray 1% Bordeaux mixture, or 70% thiophanate-methyl at 1000 times, or 50% benomyl at 1000 to 1500 times, spraying once about every 10 days, for 1 to 2 consecutive sprays.
5.1.7 Brown spot disease Caused by fungi.
Control: Improve ventilation and light transmission conditions; when disease occurs, promptly cut off and burn diseased leaves to prevent spread; according to the condition, spray thiophanate-methyl, carbendazim at 1000 times, or 60% zineb wettable powder at 800 to 1000 times for control.
5.1.8 Chlorosis
Control: Take corresponding measures according to soil test results; when the pH reaches 6.5 to 6.7, lime must not be used and physiologically acidic fertilizer should be used instead; if hydroponics is used, add
ferric citrate solution to the nutrient solution at a concentration of 3 to 4 mg/kg, adding once every 7 days for 2 to 3 consecutive additions; you can also use a 50 mg/kg chelated iron (edta-fe) aqueous solution at 100 ml per plant applied to the soil; you can also spray the leaves with 0.2% ferrous sulfate aqueous solution.
Applying appropriately more organic fertilizer can dissolve insoluble iron in the soil, making it easier for the plant to absorb and use; when disease occurs, apply alum fertilizer water or spray 0.2% ferrous sulfate solution once every 7 days for 3 to 4 consecutive sprays; for potted plants, choose slightly acidic loam.
5.2 Pests
5.2.1 Scale insects
Control: When only a few occur, gently brush them off with a soft brush or remove the insects by hand, then rinse clean with water; if the nymphs have recently hatched and have not yet formed a waxy shell, use 40% dimethoate or omethoate emulsifiable concentrate at 1000 times, or 2.5% deltamethrin emulsifiable concentrate at 2000 to 2500 times for spray control, spraying once every 7 to 10 days for 1 to 3 consecutive sprays. Scale insects easily develop resistance to pesticides, so master the use concentration of pesticides well and alternate pesticides.
5.2.2 Red spider mite
Control: Keep ventilation good, maintain environmental humidity above 40%, and frequently spraying water on the leaves can control the reproduction of red spider mites; when only a few occur, remove severely infected leaves and rinse the leaves with water; chemical control: carry it out during the adult and nymph stages, using 20% trichlorfon acaricide emulsifiable concentrate at 1000 times, or 40% omethoate emulsifiable concentrate at 1000 times, or 20% tetracypermethrin emulsifiable concentrate at 4000 times for spray control, spraying once every 5 to 7 days for 2 to 3 consecutive sprays; alternating pesticides gives good results.
For home cultivation, you can spray with 600 times derris extract plus about 1% laundry detergent solution, or spray with Imidacloprid at 20000 times, or Actara at 10000 times, or Wute at 3000 to 5000 times.
5.2.3 Aphids
Control: When only a few occur, crush them with an object, then rinse clean with water, and finally apply 50 times tobacco water or soapy water continuously several times; in March to April when the eggs hatch, use 40% omethoate emulsifiable concentrate at 1000 times, or 50% fenitrothion emulsifiable concentrate at 1000 times, or 20% fenvalerate emulsifiable concentrate at 2000 to 3000 times for spray control, spraying once every 7 to 10 days for 3 to 4 consecutive sprays. (Special Economic Animals and Plants, authors: Zhou Shurong, Bao Xiufang, Guo Wenchang, Niu Shiliang, Liu Jiahe)