Open-field Propagation and Pest and Disease Control Cultivation Techniques for Southern Iris

Irises grown in open fields form a sea of flowers, and every passerby lingers over them. Below, the editor will share with you the propagation and pest and disease control cultivation techniques for southern iris. Those who love flowers and plants can take a look.

1 Propagation

Iris is commonly propagated by division. Divide once every 2 to 4 years, in spring after flowering. When separating the rhizomes, keep 2 to 3 buds on each rhizome piece; this is the best time for division. 2 Cultivation and Handling. When planting, deeply plow the soil and apply a small amount of inorganic fertilizer. During the seedling stage, iris should be managed with watering, fertilizing, and intertillage weeding; after planting out, management becomes more complicated.

2.1 Land Preparation

First plow the soil, break up the clods, and remove stones, tiles, residual roots, broken branches, and all other weeds. If the soil is too poor or unsuitable, replace the soil to a depth of 40 to 50 cm. After plowing, apply decomposed inorganic fertilizer, then rake level.

2.2 Transplanting

Transplanting includes two steps: lifting the seedlings and planting them. The purpose is to plant the flower seedlings at the planned planting center. Because transplanting expands the nutrient area for the flowers, it can enhance the ornamental effect.

2.2.1 Lifting Seedlings

According to the editor's understanding, iris is generally planted bare-root, so bare-root seedlings can be lifted. It is best to lift seedlings when the plants are 10 to 15 cm tall. If the plants are taller than 15 cm, part can be properly cut back, keeping about 15 cm. This ensures survival and growth after planting. When lifting bare-root seedlings, use a shovel to lift the flower seedlings together with a block of soil, then gently shake off the soil attached to the roots. Be careful not to break the fine roots or injure the roots, and transport them promptly to the planting site for planting out.

2.2.2 Planting

Before planting, dig the planting holes according to the rules, with a plant and row spacing of 20 to 30 cm. When planting, make sure the root system is in close contact with the soil, and the planting depth should be the same as the original height of the flower seedlings. Be careful not to crush the soil ball. Only in this way can the survival of transplanted seedlings be ensured.

2.3 Management

2.3.1 Watering

Watering after planting out is key to survival. After transplanting, flowers must be watered thoroughly twice in succession: the first time after planting, and the second time after 3 d. Each time it must be watered thoroughly, and soil should be earthed up promptly. At each watering, water enough and thoroughly according to conditions. However, waterlogging must be avoided, otherwise the roots rot easily; in mild cases the branches and leaves wither, growth is poor, and ornamental value is affected; in severe cases the plant dies. The timing of watering changes with the weather. Generally, in hot summer, watering should be arranged at night or in the evening. If it is cloudy, watering can be done at any time. Before freezing in late October, water thoroughly for winter.

2.3.2 Fertilizing

To ensure the growth and development of iris and achieve its ornamental value, nutrients must be supplemented through fertilization. The timing of fertilization depends on the purpose of application and the type of fertilizer. Moreover, throughout the entire planting process, regular topdressing is needed. Before fertilizing, loosen the soil first to help the roots absorb nutrients, then water thoroughly in time. Only in this way can it absorb enough nutrients.

2.3.3 Intertillage and Weeding

Intertillage and weeding is an important measure in field management.

(1) Intertillage. The purpose is to loosen the soil, increase water evaporation, raise soil temperature, increase air circulation in the soil, promote the decomposition of nutrients in the soil, create excellent conditions for flower root growth and the absorption of water and nutrients, and also remove some weeds. During intertillage, the soil should be neither too dry nor too wet. During the seedling stage of flowers or shortly after transplanting, intertillage should be carried out in time. The depth of intertillage depends on the different growth stages. It should be shallow during the seedling stage, and shallow near the plants to avoid damaging the roots; between plants and rows it can be appropriately deeper, generally 3 to 5 cm.

(2) Weeding. Weeding should be carried out as early as possible when weeds first appear. At this time the weed roots are shallow and easy to remove, and the principle of removing them while small and completely should be maintained. For perennial weeds, all underground parts must be dug out, and especially care should be taken to remove them completely before they flower and set seed. When weeding, the soil should not be too dry or too wet, and the flower plants should not be disturbed. Loosening the soil and weeding begins in April and is carried out multiple times until the end of October.

2.3.4 Pest and Disease Control

Iris has relatively few pests and diseases. The common disease is leaf spot, and the main pests are white grubs, red spiders, and aphids.

(1) Leaf spot. When plants are damaged by leaf spot, nearly round to oval grayish-brown lesions appear on the leaves. To control iris leaf spot, generally use 69% dimethomorph wettable powder and 75% chlorothalonil wettable powder, mix them at a 1:1 ratio, then dilute 1,500 times to prepare the spray solution. Spray once every 10 to 15 d, for 3 to 4 sprays, and a relatively good effect can be obtained.

(2) White grubs. White grubs are a pest commonly occurring in iris flowers in field production. They mainly lurk in the soil and gnaw the iris roots, causing plant death. When they occur, use 200 g of 90% trichlorfon powder per 667 sq m, mix it into 10 kg of soil to make poisonous soil, and scatter it in the field. Prepare the poisonous soil according to the size of the affected area.

(3) Red spiders. Red spiders like to suck sap on the undersides of leaves. The damaged leaves turn yellow and show many small white spots, and soon wither and yellow. When they are causing damage, spray with 1,000 to 1,500 times dilution of 40% dimethoate emulsion, or 2,000 times dilution of 40% dicofol emulsion.

(4) Aphids. Mainly green peach aphids, cotton aphids, and others. Between spring and summer, they often cover new shoots or flower buds and suck sap, causing tender leaves to curl and shrink. In severe cases, they not only affect growth and flowering, but also make the plants flourish excessively. Spray with 3,000 times dilution of 40% dimethoate emulsion, or 1,000 times dilution of 25% phosmet emulsion.

3 Spring Management the Following Year

In spring the following year, when the ambient temperature reaches the temperature at which iris can grow normally, that is, between 5 and 20°C, spring management can begin.

3.1 Pruning Old Leaves

The first task in spring is to remove old leaves in time. This can clear away hiding places for insect eggs and bacteria, and also promotes the growth of new iris leaves and a rapid return to green. When removing old leaves, use an iron rake to gather the old leaves and take them out of the garden, then burn them.

3.2 Fertilizing

After removing old leaves, apply 1 more topdressing of chemical fertilizer to ensure the nutrient supply for iris. Generally apply 20 to 30 kg of urea evenly per 667 sq m, and water promptly after fertilizing to prevent fertilizer burn.

3.3 Watering

After removing old leaves, water promptly so that the soil reaches a suitable humidity for iris growth and promotes rapid growth of the iris plants.

Iris can be grown not only in open fields but also in pots. Its flower shape is unique and has very high ornamental value. The above are the propagation and pest and disease control cultivation techniques for southern iris. Everyone, do not miss them.

How to Cultivate Dutch Iris: Dutch Iris Propagation Methods

Dutch Iris is an autumn-planted bulbous flower, with original species native to Spain and Morocco. It is generally planted in mid-to-late October. The rooting and sprouting period is late October to late November, the bolting period is mid-to-late February the following year, the beginning flowering period is early March, the final flowering period is early April, and the bulb maturity period is early May. In autumn, plant the bulbs into the soil. Choose sandy loam with good drainage and rich in organic matter or compost, and cover with soil twice the thickness of the bulb. Topdressing should be mainly nitrogen fertilizer. The flowers and leaves are delicate and beautiful, and can be used as cut flowers for ornamental purposes.

Morphological Characteristics of Dutch Iris

Stems and Leaves
Dutch Iris is a bulbous flower. The leaves are lanceolate, folded in half, with a sheath-like base, entire margins, obvious midribs, smooth, green, and glossy. At maturity there are 8 to 11 leaves;

Flowers
Dutch Iris has double flower stems, with terminal flowers, bearing 1 to 2 flowers. The flower stem is 50.0 to 75.0 cm long and 0.75 to 1.10 cm thick; the flower is butterfly-shaped and radially symmetrical, with a flower diameter of 11.0 to 16.0 cm; there are 3 falls, heart-shaped, yellow, with a violin-shaped claw, the central part has a spoon-shaped orange-yellow stripe, and the petal edges bend downward, 7.0 to 11.5 cm long and 3.0 to 5.0 cm wide; there are 3 standards, long oval, slanted upright, white with a slight light purple tint, 6.0 to 11.0 cm long and 2.0 to 3.0 cm wide; the underground corm is oval and covered with a brown skin; each mother corm can form 1 oval central corm and 4 to 7 daughter corms after flowering, with an average propagation coefficient of 5.54; mature flowering commercial corms have a circumference of 8 to 12 cm, and a few can reach 14 cm. The plant height is about 60-80 cm, with underground bulbs. The plant is similar to gladiolus, with single leaves clustered, leaf shape long lanceolate, apex pointed and fine, base sheath-like, 6 to 7 leaves growing out, and a single flower stem emerging. The flower shape is graceful, with three petals, as a single terminal inflorescence. Flower colors include gold, white, blue, and deep purple.

Ecological Habits of Dutch Iris

Dutch Iris is a planted bulb. It has strong cold resistance and drought resistance, and prefers slightly acidic soil with good drainage and moderate moisture. Its suitable growth temperature range is relatively wide; it flowers easily at about 20-25°C, and when encountering high temperatures above 25°C the flower buds wither and die; it can tolerate a low temperature of 0°C, but when encountering -2 to -3°C the flower buds are damaged and die. The flower buds are not differentiated in the bulb; rather, after the bulb is planted, they differentiate in winter when the plant extends to 2 to 3 cm, and then bolt and flower after spring begins. Daughter corms are attached at the base of the mother corm. In June, as the aboveground part withers and dies, the bulb temporarily enters dormancy.

Cultivation Techniques for Dutch Iris

Bulb Treatment
The dormancy of Dutch Iris bulbs is relatively shallow, and it is commonly broken with high temperature, low temperature, or smoke. High-temperature treatment is treatment at 30°C for 2-3 weeks; low-temperature treatment is most effective at 8 to 10°C for 7 to 9 weeks, and dry cold storage is mostly used. Smoke treatment is currently the most practical method. During treatment, first prepare a room that can be sealed or temporarily enclosed with plastic sheeting. Then put the iris bulbs in. If rice husks are used as fuel, the amount needed is 3 liters per sq m. Burn them indoors for smoke, and seal the entrance. Do this once a day for 3 consecutive days. During the treatment period, the bulbs do not need to be specially spread out.

Planting Out
Bulbous Dutch Iris is generally planted out in mid-September. Apply base fertilizer two weeks before planting out. For continuous cropping plots, methyl bromide should also be used for soil disinfection to prevent diseases such as southern blight. Prepare the planting bed, with a bed width of 1.0 to 1.2 m. The planting spacing is about 9 cm x 9 cm or 10 cm x 8 cm. When planting out, if the bud tips or roots have already extended, be careful not to damage them. The planting depth is based on leaving about 5 cm from the neck of the bulb to the soil surface.

Cut Flower Production
Choose slightly acidic sandy loam with good drainage, and avoid continuous cropping; choose healthy, pest-free bulbs with a circumference of 8.0 cm or more for cut flower production, and daughter bulbs with a circumference of 4.5 to 6.0 cm as the stock for cultivating flowering commercial bulbs. Disinfect before planting; open-field planting is generally in mid-to-late October. When the temperature is above 0°C, open-field planting can be done, and the suitable growth temperature is 18 to 23°C; the flower bud differentiation temperature is 8 to 15°C, with the optimum temperature being 13°C. Above 25°C or below -2°C, flower bud development is inhibited and the buds easily wither and die; strengthen water and fertilizer management, and pay attention to pest and disease control. Throughout the growing period, keep the soil fully moist. Fertilization should be mainly base fertilizer, with 2 to 3 topdressings. After cutting the flowers, apply one nutritional fertilizer to favor bulb growth; when the tips of the flower buds begin to color is the suitable cutting time. After cutting the flowers, keep 2 to 3 leaves on the plant to favor new bulb growth; when the aboveground part turns yellow and withered, choose a sunny day to dig out the bulbs, dry them, grade them, and store them.

Management and Maintenance

Temperature
Temperature is the most important factor affecting the growth of Dutch Iris. The optimum temperature for Dutch Iris is 13 to 18°C. The maximum should not exceed 25°C, and the minimum temperature is 5 to 8°C. When encountering a low temperature of -2°C to -3°C, the flower buds are prone to freezing damage and withering. In the early growth stage, maintain the room temperature at 8 to 12°C. As the flower stems gradually emerge, gradually raise it to room temperature. When the temperature exceeds 20°C, cut flower quality declines. Temperature can be lowered through measures such as ventilation and shading to meet its flowering needs.

Light
Light is also an important factor affecting the quality of iris cut flowers. With a long light period, the plants grow robustly, the inflorescences are full, and the flower colors are vivid; with a short light period, the inflorescences are thin, and blind flowers may even occur. When light is strong and the temperature is above 25°C, shade appropriately and strengthen ventilation at the same time, which can effectively control the decline in cut flower quality; in greenhouses with high temperatures and weak light transmission, lack of light is the main cause of flower withering. When light is insufficient, supplemental lighting is needed.

Fertilizer and Water Management
Keep the soil moist throughout the entire growing period, which helps promote root growth. The suitable soil moisture is when it forms a ball in the hand without dripping. If humidity is insufficient, plants are often shorter and flowers wither easily. Watering is best done in the morning, which can effectively relieve the air humidity in the greenhouse and also help the plants remain dry, reducing the chance of pathogen infection. The ideal air humidity is 75% to 80%. During forcing cultivation, taking measures of heating and ventilation can effectively reduce air humidity and avoid humidity dropping too quickly, which would cause leaves to wither and lead to a decline in cut flower quality. To improve cut flower quality, spray 0.5% urea or ferrous sulfate once every 7 d during the growing period, and spray 0.2% monopotassium phosphate once before budding.

Propagation Methods of Dutch Iris

Bulb Propagation
After the mother bulb is planted and flowers, its nutrients are almost exhausted, and it gradually becomes hollow, shriveled, and dry, while producing a small number of new bulbs. Many daughter bulbs then form around the new bulbs. Daughter bulbs planted for 1 to 2 years can develop into flowering bulbs.

Seed Propagation
Seeds can be sown after maturity. To make them germinate earlier, soak them in water for 24 h, then refrigerate for 10 d, and sow them in a cold frame. They can germinate in autumn. Seedlings take 2 to 3 years to flower, so this method is rarely used in production.

Tissue Culture Propagation
After disinfecting young inflorescences, inoculate them on induction medium of MS+BA5mg/L+NAA0.1mg/L at 22+-2 and 1,500 to 3,000 lx. After 20 days, a small amount of light green callus forms at the nodes of the receptacle. The callus successively differentiates white embryoids. When the differentiated flower shoots grow to 2 cm, separate them and inoculate them on 1/2ms+iba0.7mg/l+s3% rooting medium. After 1 month they root.

Temperature, humidity, light, and moisture are important factors affecting iris growth. In production, the suitable growth temperature for iris is 16°C to 18°C, and the humidity is 75% to 80%.

Because there are many iris varieties with different growth characteristics and cultivation cycles, during forcing cultivation, suitable management measures should be determined according to the variety's own characteristics to achieve the ideal cultivation effect.

Tissue culture is an effective method to accelerate the breeding of new varieties. It is recommended to promote tissue culture methods when propagating new varieties.

Uses and Purposes of Dutch Iris

Cut Flower Material

Dutch Iris flowers are large and beautiful, with various flower colors and forms, like irises and like cockroaches, and are an important flower material for flower arranging in Europe and America. At present, Dutch Iris has become a new member of cut flower cultivation in China.

Dutch Iris (Iris xiphium Var.) is a variety of Spanish Iris, widely distributed in the temperate Northern Hemisphere. It has rich flower colors, unusual flower shapes, and large and beautiful flowers. It is widely used in landscaping spots and courtyard greening, and is also a world-famous fresh cut flower material.

After reading the above introduction on how to cultivate Dutch Iris, do you have a better understanding of Dutch Iris cultivation? If you want to know more about Dutch Iris, please continue to follow.

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