Detailed Explanation of Azalea Cutting Methods, Step-by-Step Propagation Guide
Azalea cutting methods: Azaleas are mostly propagated by cuttings. Azalea cuttings can be taken anytime from April to August. The ideal medium is mud and sand from mountain gullies, though river sand can also be used as a substitute. After sifting, sterilize with 1% potassium permanganate, then place into clay pots for later use. Break off by hand a semi-lignified new shoot of the current year, remove the lower leaves and this becomes the cutting. Do not cut it with scissors, otherwise the result will be less satisfactory.
Note that if the base of the broken-off shoot is horseshoe-shaped with excess bark attached, trim it off. When inserting the cutting, first make holes in the medium with a wooden stick of suitable thickness, with a spacing of 2-4 cm between plants, then insert the cutting about halfway, and water with a fine-spouted watering can so that the cutting makes close contact with the medium.
Cover the clay pot with plastic film and place it in a cool, ventilated spot. Avoid direct sunlight at all costs, lest the cuttings wither and die. The frequency of misting depends on the weather. Roots will form in about 1 month. After rooting, gradually extend the sunlight exposure time, but avoid harsh sun. After about 3 months, they can be divided into separate pots. With this method, the survival rate of cuttings can reach 100%. That concludes the introduction to azalea cutting methods.
How to Grow Azaleas
The azalea is one of China's top ten famous flowers. Among all ornamental flowering trees and shrubs, the one that can be said to have both beautiful flowers and foliage, suitable for both ground planting and container growing, and with the widest range of uses, is the azalea.
Azaleas have always been a flower that everyone loves. Surely many people have grown azaleas, but many may not be very clear on how to grow them. Today I will introduce the relevant tips and methods for growing azaleas, hoping to help everyone when growing azaleas.
Below is an introduction on how to grow azaleas well
How to grow azaleas well? First, you need to understand the conditions required for their growth and development. Azaleas have "six likes" and "six dislikes."
① Likes coolness, dislikes extreme heat
② Likes partial shade, dislikes scorching sun
③ Likes moisture, dislikes dryness
④ Likes acidic soil, dislikes alkaline soil
⑤ Likes light soil, dislikes heavy clay soil
⑥ Likes good drainage, dislikes waterlogging.
After being moved outdoors in spring, when the sunlight is relatively soft, azaleas should be properly shaded around midday.
After summer arrives, place azaleas in a ventilated, cool spot. In the heat of summer, shade them with reed curtains, bamboo blinds or shade netting, and open the curtains before 8 AM and after 5-6 PM. Because azaleas are semi-shade-loving flowering plants, tender leaves are easily scorched under harsh sun. If kept in direct strong light for a long time in summer, branches and leaves will turn yellow and wither, growth will be stunted, and in severe cases the entire plant will die.
In autumn, as sunlight intensity gradually softens, azaleas can be given more sun before 9 AM and after 5 PM. In late autumn, place them in a sunny spot to promote flower bud differentiation. Azaleas are not cold-tolerant. Between the Cold Dew and Frost's Descent solar terms, they should be moved indoors to a sunny location. In the early period after moving indoors, pay attention to opening windows and doors for ventilation. If kept in a shaded spot for a long time, they are prone to bud drop.
Azalea Growing: How to Grow Azaleas
How to grow azaleas, and how to cultivate beautiful azaleas.
Introduction to Azaleas
One of China's top ten famous flowers. Among all ornamental flowering trees and shrubs, it can be said to have both beautiful flowers and foliage, suitable for both ground planting and container growing, and is the most widely used. Bai Juyi praised it: "Idly plucking two branches to hold in hand, on close look they seem not of this world; among flowers this one is Xi Shi, while hibiscus and peony are both plain." In the natural distribution of azaleas worldwide, no region can rival China in the number of species and the vast quantity of azaleas. China is the world's treasure house of azalea resources! Today, Jiangxi, Anhui and Guizhou have the azalea as their provincial flower, and as many as seven or eight cities have designated it as their city flower.
1. It is one of China's top ten famous flowers. The azalea can be said to have beautiful flowers, beautiful leaves and wide uses. As one of the most famous flowers in the world today, it is a small shrub in the Ericaceae family, with both evergreen and deciduous types. Azaleas are distributed across temperate regions of the Northern Hemisphere. Of the more than 900 varieties worldwide, China has nearly 600 species. Therefore, the azalea has been nominated by some enthusiasts as one of China's candidate national flowers. The colorful azalea evokes people's passionate and beautiful feelings about life, and it also symbolizes the prosperity and strength of the nation and the happy life of the people. This is the true meaning of our people's love for the azalea. Thus, the azalea has become the city flower of many cities in our country and the national flower of many countries. It is very beautiful, with tubular flowers in various colors including deep red, light red, rose, purple and white. When azaleas bloom in spring, the mountains are brilliantly colored, like rosy clouds encircling the forest, truly deserving the title "Xi Shi among flowers."
2. It has many classifications. The vast majority of varieties are low-growing with a natural form; a few varieties are tall and majestic with graceful branches and leaves. Low-growing varieties are much-branched with fine, dense twigs, and young branches are hairy, brown or dark brown. Flowers are solitary or in racemes, with corollas bell-shaped, tubular or broadly funnel-shaped, usually five-lobed. Flower colors are numerous and vary by variety, including pale purple and gold-speckled; some even have two colors, and some flowers are fragrant. Capsules turn dark brown when mature, and seeds are dark yellow and very small. Based on flowering period, they can mainly be divided into four major categories: spring azaleas, summer azaleas, spring-summer azaleas and Western azaleas.
3. Its living environment. Azaleas like a semi-shaded environment and dislike direct scorching sun exposure; they like a cool and humid climate and fear hot, dry weather; they like acidic soil and water and dislike alkalinity; they like loose, humus-rich light loam and fear poorly drained clay soil; they like dilute fertilizer water and dislike strong fertilizer water. They have certain light requirements but are not tolerant of harsh sun. In summer and autumn, there should be deciduous trees or a shade canopy to block the scorching sun, and the ground should be frequently sprayed with water. Azaleas generally send out new shoots in spring and autumn, mainly in spring. The most suitable growing temperature is 15-20°C. When the temperature exceeds 30°C or falls below 5°C, growth stalls. At the same time, they are tolerant of pruning; latent buds sprout very easily once stimulated, which can be used to control tree shape and rejuvenate the plant.
What kind of potting soil is suitable for azaleas?
The choice of soil is crucial to the growth and development of azaleas. There are many formulas for azalea potting soil, varying by cultivar, but the following conditions must be met: loose, well-drained, well-aerated, acidic soil, rich in humus, with sufficient base fertilizer. Usually azaleas only grow vigorously in acidic loam; if in alkaline soil, they will soon turn yellow, weaken and die. Azaleas are regarded as an indicator plant for acidic soil. Leaf mold is generally acidic, and pine needle humus is the best, making it a relatively ideal potting soil for growing azaleas. It can be dug from beneath pine and cypress forests in mountainous areas, or taken from soil beneath areas with many pine and cypress trees in courtyards. Before use, add an appropriate amount of sulfur powder and alum to increase acidity. Soil with high humus content is most suitable for azalea growth. Abundant humus can timely replenish nutrients in the soil, improve soil structure, and help the soil retain water, retain fertilizer, aerate, absorb heat and insulate. It can also reduce the harm of toxic substances in the soil and promote the azalea's root system to spread in all directions.
The new product black mountain mud from Tongguan Mountain in Yixing, Jiangsu and Fenghua, Zhejiang is most suitable for azalea growth and development, and is widely used in various places. Potting soil can also be made at home. Take 2 parts of weathered mountain topsoil, 1 part fallen leaves, and 1 part dry herbivore manure, pile and mix for 1 year, sift out impurities, and it is ready to use. Alternatively, use 3 parts mountain surface soil, 3 parts horse manure, 3 parts fallen leaves and weeds, and 1 part human feces and urine, layered and composted, and after 1-2 years sifted for use. The prepared potting soil should be stored indoors to prevent reduced fertility from sun and rain.
What should be noted when potting and repotting azaleas?
Azalea cuttings should be potted once they survive. Clay pots with good breathability are best, purple sand pots second, and glazed and porcelain pots the worst. When potting, pay attention to choosing the right pot size, and never use a large pot for a small seedling. If the pot is too large, the potting soil will not dry for a long time, aeration will be poor, and the roots will not easily reach the pot wall, affecting seedling development. Generally, cuttings can be placed in clay pots about 10 cm in diameter, and after one year repotted into pots about 15 cm. When potting, pay attention to making a drainage layer: first cover the drainage hole with a tile piece, then add 1/3 coarse soil particles, and slightly add fine soil. Then place the azalea seedling in, holding the seedling upright with one hand while filling soil into the pot with the other. Note that the soil can only be filled to 2 cm below the pot rim, not too full, to allow for future watering. Finally, press firmly around the pot and shake the pot to level the surface. After planting, water thoroughly once with a watering can. Note that when watering, you must water until water seeps out of the bottom of the pot. If watering is not thorough and only the surface layer is moistened but not the inner layer, the potted flower will dry out and die.
There are two situations in which azaleas need repotting. First, when the seedling has grown and the root system fills the potting soil, requiring an expanded range for root extension. Usually check whether roots are growing out of the drainage hole at the bottom of the pot; if so, repotting is needed, moving the plant from a small pot to a large pot. Second, after a potted plant has grown for 2-3 years, the nutrients in the potting soil are nearly depleted. To replenish nutrients and improve the soil, the potting soil should be replaced.
Azalea repotting is generally done after flowering, or before bud formation in autumn. When repotting, remove some of the old soil, and note to use sharp scissors to trim away old roots. Old roots are those that grow poorly and have turned black and shriveled. But note: when repotting seedlings, do not trim roots. When repotting mature plants, note that the roots should be kept with a soil ball. After potting, also note that the first watering should be thorough, and for the next few days let it be on the dry side. If too wet, the cut root ends will rot. Generally, normal watering should only resume after new roots have grown. If repotting in autumn, it is best done in October. Although azaleas like coolness, after repotting, attention should be paid to keeping them warm through winter. If there is no greenhouse, build a small shed in a south-facing, sunny, ventilated spot and cover with plastic film to overwinter safely. For azalea repotting, generally small seedlings are repotted once a year, and large azaleas are repotted once every 2-3 years.
How to water azaleas?
Watering azaleas is a very important task. Because the azalea's root system is relatively fine and weak, it fears waterlogging and is not drought-tolerant. Too dry or too wet is harmful to plant growth, so special attention must be paid to controlling water volume. If water is lacking during the leaf-expansion period, the azalea's leaves will turn yellow and curl, and if the drought is severe, they will wither and die. If water is lacking during flowering, the petals will soften and shrivel, the flowers will droop, the color will be dull, and the flowers may even wither and die. Therefore, watering must be done as appropriate based on sunny or rainy weather, dry or humid air, and the moisture content of the potting soil.
Watering time should be in the morning and evening, especially in the hot summer when watering at noon is even less advisable. This is because cold water stimulating the roots will harm the plant. The principle of watering is: do not water if not dry, water thoroughly when watering, and strictly avoid half-watering. Spring and autumn are the growth, flowering and bud-forming periods for azaleas, so water supply should be appropriately increased, but during the flowering period do not water too much, as too much water will make the flowers fade early. Generally, in spring and autumn, water once every 2-3 days. In summer, new branches sprout and growth is vigorous, consuming more water. Combined with high temperatures and dry air, water thoroughly 1-2 times daily. If it has not rained for several days and the air is dry, also spray clean water on the leaves with a fine-holed watering can, and spray the ground around the pot as well to increase air humidity. During the plum rain season or in rainy conditions, stop watering and promptly drain accumulated water from the pot. After autumn begins, although temperatures drop, the air is dry and evaporation is still high, so water frequently to keep the potting soil moist. During flower bud differentiation, appropriately control water volume to promote flower bud formation. After October, when pots are moved indoors, reduce watering as appropriate; with less water content in the branches and stems, plant tissues develop more fully, which can increase cold resistance. At this time, keeping the potting soil slightly moist is sufficient.
How should water quality be treated when watering azaleas?
When watering azaleas, pay special attention to water quality. It is best to use natural rainwater, because natural rainwater contains no bleach powder or other chemicals and impurities. Next best is river water and pond water, and then tap water. Tap water is softened water that has undergone purification treatment, containing chemicals such as bleach powder, liquid chlorine and alum. If used long-term, the alkalinity in the potting soil will gradually increase, which is not conducive to azalea growth. Therefore, water quality must be treated before use. The treatment method is to acidify it. For water that is neutral or slightly alkaline, prepare it into acidic water. The usual method is to acidify the water with ferrous sulfate (green vitriol) and edible vinegar. If the water is on the alkaline side, ferrous sulfate and edible vinegar can be used together, with the specific amounts prepared according to the measured pH values of the water, ferrous sulfate and vinegar. A simple method is to water long-term with an aqueous solution containing 0.1%-0.5% ferrous sulfate, or sprinkle a little ferrous sulfate on the pot surface every 10-15 days. Alternatively, water once every 10-15 days with an aqueous solution containing 0.5%-1% edible vinegar. Watering can also use tap water or well water after standing/aging treatment. Letting water stand can reduce the harm of harmful ions in tap water; it can also raise the water temperature of well water, eliminating the temperature difference between the water and the potting soil, which benefits root absorption. When using tap water, also add 0.15% ferrous sulfate. If watering can be alternated with decomposed fertilizer liquid water, it is even more beneficial. This is because regular use of these two types of water can keep the potting soil at a certain acidity and also supply certain nutrients, suitable for the needs of azalea growth.
How should azaleas be fertilized?
The azalea is a flower that does not need heavy fertilizer. If too much or too concentrated fertilizer is applied, it will instead be harmful to its growth. But this is not to say no fertilizer should be applied. To make it bloom abundantly and with large flowers, it still needs timely and appropriate fertilization. Therefore, flower-growing experts have summarized fertilization in 8 words of experience: "Apply dry fertilizer sparingly, apply liquid fertilizer diluted." This is very appropriate and worth referencing for flower growers. Under normal circumstances, 1-2 year old seedlings need no fertilization, because the fertility contained in the humus soil is already enough to supply the seedling's growth and development needs. For 2-3 year old small plants, from late spring or early summer, apply dilute cake fertilizer water or dilute alum fertilizer water once every 10-15 days. For plants over 4 years old, apply about 20 grams of dry cake fertilizer each in spring and autumn every year. In mid-June, apply a quick-acting phosphorus and potassium fertilizer once to promote flower bud differentiation. After June, fertilization can be stopped. After the flowers fade, which is exactly when new branches are growing, apply a liquid fertilizer of slightly higher concentration once, but never too concentrated, and never apply raw fertilizer, otherwise the root system will be damaged. Excessive fertilization in summer will cause old leaves to drop and new leaves to turn yellow. It is particularly worth noting that for home-grown azaleas, the most common problem is not a lack of fertilizer in the plant, but damage caused by excessive fertilization. If leaf yellowing and withering occur due to excess fertilizer, immediately stop fertilizing, dig out the dry fertilizer, and water more to flush out the accumulated fertilizer in the soil. After watering, move to a ventilated spot for care; some need to be rinsed twice. In this way, after half a year they can gradually return to normal growth.
If no abnormalities appear in summer, after the Start of Autumn the azalea will begin its second period of vigorous growth. During this short period, apply 1-2 times a dilute solution of phosphorus fertilizer such as superphosphate to supply the plant's growth and bud formation needs. After each fertilization, water with clean water 2 days later, and loosen the potting soil once to fully aerate it. After winter begins, as the weather gradually turns cold and the plant stops growing, fertilization should also stop immediately. If fertilization is not stopped and the plant sprouts tender leaves, it will instead make it difficult for the azalea to overwinter. Never be careless about this.
How to prune and shape azaleas?
Azaleas have strong sprouting and regeneration ability. Every 1-2 years after the flowers fade, they should be moved to a pot slightly larger than before, with fresh potting soil. Experienced flower growers often combine repotting with pruning and shaping, intentionally pruning an attractive tree form. When pruning, remove overly dense branches, crossing branches, weak branches, drooping branches, leggy branches and diseased or pest-infested branches. This is not only for the beauty of the tree form, but also to improve ventilation and light penetration, conserve nutrients, and encourage the main branches to become strong, so that new shoots sprout as quickly as possible and the next year's flowering achieves the goal of more flowers, larger flowers and brighter colors.
After azaleas bloom, the spent flowers often remain for a long time, which consumes considerable nutrients. To avoid wasting nutrients in vain, promptly remove the spent flowers so nutrients can supply the needs of new shoot growth. In addition, the shorter summer azaleas grow many lateral branches. Every spring, many small branches sprout from the base of the stems. To concentrate nutrients for the main branches and flowers, allowing them to grow faster and larger, these small branches should also be pruned promptly. If there are too many flower buds, besides keeping 1 per branch, the remaining flower buds should also be removed. Exactly which tree shape to prune into can be decided according to your own preference. There are umbrella shape, round shape, semicircular shape, pagoda shape, square shape, etc. You can choose freely, then deliberately prune accordingly.
How do azaleas propagate by cuttings?
Azaleas can be propagated by five methods: cuttings, grafting, layering, division and sowing. Among these, the cutting method is the most common and produces the largest number of propagules; layering produces seedlings fastest; grafting is the most complicated, and is only used for varieties that are difficult to root from cuttings; sowing is mainly used for breeding cultivars.
For propagation by cuttings, a new shallow clay pot with a 20 cm diameter is best, because it has good breathability and roots easily. A potting soil mix of 20% humus garden soil, 40% horse manure crumbs and 40% river sand can be used as the medium. The best times for cuttings are spring (May) and autumn (October), when the temperature is between 20-25°C, most suitable for cuttings. When taking cuttings, select a robust semi-lignified shoot of the current year as the cutting, use very sharp scissors or a knife, cut 6-10 cm with a node, with a smooth, neat cut. Remove the lower leaves and keep only 3-4 small leaves at the tip. Buy 1 ampoule of vitamin B12 injection, open it, dip the cutting in the liquid, take it out and let it dry briefly, then it is ready for insertion. Before insertion, use a watering can the previous day to moisten the potting soil in the pot, but do not spray too much; by the next day it will be just moist, most suitable for cuttings. The insertion depth is 3-4 cm. When inserting, first use chopsticks to poke a hole in the soil, then insert the cutting, press the soil firm with your hand so the potting soil makes full contact with the cutting, then water thoroughly once. After insertion, it is best to cover the pot with a plastic bag, tie the bag opening with a string, open it when watering is needed, and tie it again after watering. The pot with cuttings should be placed where there is no direct sunlight. The potting soil of the cuttings should be misted every day for 10 days; except on rainy days, mist once on cloudy days, and twice when the air is dry, but the amount of misting each day should not be too much. After 10 days, still frequently check to keep the soil moist. Within 4-5 weeks, keep them shaded, and only after sprouting can they gradually receive some sunlight. Generally, rooting takes about 2 months. After that, only shade for 2-3 hours at midday, and the rest of the time let them receive light, so they can manufacture nutrients on their own through photosynthesis.
How do azaleas propagate by layering?
Azalea layering is also one of the commonly used propagation methods, generally using air layering. Azalea layering is often done in April-May. The specific procedure is: first, on the mother plant of a potted azalea, select a robust 2-3 year old branch. About 10-12 cm from the branch tip, use a sharp knife to cut a ring of bark about 1 cm wide around the branch, gently strip the phloem sieve tubes clean, cutting off the channel by which leaves send organic matter downward, so that it accumulates and accelerates cell division to form a tumor-like protrusion and sprout root buds. Then loosely wrap a rectangular piece of plastic film around it twice, tie it tightly with fine string 2-3 cm below the ring cut, leave the upper end of the plastic film open in a trumpet-bag shape, then fill in moist soil and a little moss, and tie the upper opening of the bag tightly. Move the pot to a place not reached by direct sunlight for routine care. When watering, spray water on the leaves and let the water run down along the branch and slowly seep into the bag, keeping the soil in the bag always moist, to help the wound on the branch heal and sprout new roots as early as possible. After about 3-4 months, when the roots have grown to 2-3 cm long, the branch can be cut off from the mother plant and planted into new potting soil.
How do azaleas propagate by sowing?
Sowing is sexual reproduction. Because the seed-setting rate from natural crossing is very low, artificial pollination is generally required to increase the seed-setting rate of azaleas and obtain more seeds. The main method is: when azaleas are in full bloom, select a robust mother plant with good growth and beautiful flower color, move it to a greenhouse, and on each pot keep 3-4 flowers that are large and early-blooming. Remove the stamens and new buds near the flowers to concentrate nutrients. When mucus appears on the stigma, use a new brush to dip the pollen from the father plant and apply it several times. One week after pollination, move the pot outdoors and strengthen water and fertilizer management. After about 5-6 months of growth and development, by November-December the fruit can be seen gradually turning from green to brown, and the seeds are ripe. Then harvest them, let them dry in the shade, winnow clean, and place in a cool, ventilated spot.
Azalea seeds are very small and should not be stored for long, otherwise the germination rate will be low. If they are evergreen azalea seeds, sow them immediately after harvest in pots in a greenhouse; if they are deciduous azalea seeds, they can be kept until next spring for sowing.
Shallow clay pots are suitable for sowing. For the sowing soil, dig loose topsoil with moss from the surface of a shady hillside, pick out stones, and it is best to spray once with a dilution of 40% formalin plus 100 times water for disinfection, then let it dry. It can also be steamed for 15-25 minutes for disinfection, then sun-dried until half dry and set aside. Before sowing, first moisten the shallow pot, place a layer of about 2 cm of charcoal crumbs on the bottom, then spread a layer of 5-6 cm of sterilized soil, scrape level, press lightly, then evenly distribute the seeds on top, press gently. Do not water with a watering can; it is best to use the bottom-watering method of soaking the pot. Cover with a piece of glass and move to a greenhouse. When the surface of the potting soil is dry, spray some water in mist form, but do not spray too much; just keep the potting soil moist regularly.
After sowing, germination generally occurs in 5-6 weeks. When the seedlings have 2-3 true leaves, gently pick them out with a small bamboo piece and transplant them into separate pots. Do not plant too densely; keep them sparse. After planting, shade with reed mats, etc. Do not let direct sunlight hit them, and do not let rain fall on them. When the seedlings are tender, do not fertilize. Wait until the second year when the seedlings reach nearly 10 cm tall, then begin applying dilute fertilizer. Generally, from late spring to early autumn of the second year, they can be transplanted individually. By the third year, when the seedlings reach 20 cm tall, if grown well, a few plants may produce flowers.
What common diseases do azaleas have? How to prevent and control them?
The main diseases of azaleas include root rot, brown spot, black spot, leaf blight and iron-deficiency chlorosis.
After azaleas contract root rot, growth weakens, leaves wilt and wither, the root surface shows water-soaked brown patches, and in severe cases soft rot occurs, gradually rotting and peeling, with the xylem turning black. This disease is most likely to occur in environments with high temperature and high humidity.
The prevention and control method is to strictly disinfect the potting soil before repotting, and keep the soil loose, moist and well-aerated, avoiding water accumulation. If a plant is found to be diseased, promptly deal with the diseased plant and potting soil. For treatment, wash the diseased plant with a 0.1% potassium permanganate aqueous solution or 2% ferrous sulfate, then rinse with clean water and repot. Spraying the potting soil with a solution of 70% thiophanate wettable powder plus 1000 times water can cure it.
Brown spot is a major disease of azaleas. When the disease first appears, small brown spots appear on the leaf surface, gradually developing into irregular large spots. Many small black or grayish-brown dots form on the lesions, causing affected leaves to turn yellow and drop, affecting the current year's flowering and the development of next year's flower buds. This disease often occurs during the plum rain season when humidity is high.
The treatment method is to usually ensure the plant has ventilation and light, not let humidity get too high, and increase organic fertilizer and mixed nitrogen-phosphorus-potassium fertilizer to strengthen the plant's resistance to infection and growth ability. If diseased leaves are found, promptly remove them and burn them in a centralized manner. In the early stage of the disease, spray 0.5% Bordeaux mixture or 0.4 Baume degree lime-sulfur mixture, and add 4% flour to increase adhesion. Leaf spot and black spot can also be treated with the same method.
Iron-deficiency chlorosis often occurs in areas where the soil is on the alkaline side. In mild cases, only delayed greening of the plant appears; in severe cases, leaf tissue can turn entirely yellow, and leaf edges wither and scorch. When the disease occurs, it is most obvious on the leaves at the top of the plant, and is generally caused by internal iron deficiency.
The prevention and control method is to change the iron-deficient nature of the soil and reduce soil alkalinity. Increase organic fertilizer to improve clay soil. For iron-deficient plants, directly spray 0.2%-0.3% ferrous sulfate solution. Alternatively, use chopsticks to poke several holes about 15 cm deep in the soil around the plant, and slowly inject a 1:30 ferrous sulfate aqueous solution, filling the holes, to increase soil acidity and reduce alkalinity.
The onset situation and environmental conditions of azalea black spot are similar to brown spot, and similar methods can be used for prevention and control.
What common pests do azaleas have? How to prevent and control them?
Common pests of azaleas include: red spider mite, lace bug, aphid and short-bearded mite. Red spider mites are tiny in body size but cause serious harm to azaleas. Azaleas grown on upper floors of high-rise buildings are most prone to this type of pest.
The prevention and control method is manual capture and killing. For chemical pest control, spray 5 Baume degree lime-sulfur mixture, or use equal parts of walnut leaves, oleander leaves and sweet wormwood, crush and soak to extract the juice, dilute with water and spray. Spraying with 1000 times water-diluted dichlorvos solution is also a good method.
The adult lace bug is small and flat, about 4 mm long, black, and is one of the most serious pests harming evergreen azaleas. It often pierces and sucks leaf sap from behind the leaves. At the damaged spots, yellow-white spots appear on the upper leaf surface, causing leaves to drop, weakening the tree's vigor, and affecting growth and flowering. Azaleas in greenhouses are extremely prone to this pest.
The prevention and control method is mainly chemical spraying. Spray 90% trichlorfon original powder at 1000 times dilution, or 40% omethoate emulsifiable concentrate at 1500 times dilution, or 50% fenitrothion emulsion at 1000-1500 times dilution for prevention and control.
Aphids mainly harm azalea young branches and leaves. In mild cases, leaves lose their green color; in severe cases, leaves curl, harden and become brittle, cannot absorb nutrients, and flowering is affected.
The prevention and control method is to pay special attention to aphids during the overwintering period. After winter begins, spray 5 Baume degree lime-sulfur mixture once on the plants to eliminate overwintering eggs, and clear weeds near the flowers to eliminate the source of pests. During the aphid damage period, use 40% dimethoate or omethoate plus 1200 times water to make a solution and spray continuously; 3-4 times is effective.
The short-bearded mite is one of the important pests of azaleas. It often sucks sap near the main vein on the underside of leaves, causing many oil-stain-like patches on the leaf underside, and finally causing leaves to drop. This pest is obovate, about 0.3 mm long, flat-bodied, with body colors of red, dark red and wood red, irregular black spots on the back and irregular black patches on the sides. This pest is most common in summer when the weather is hot and dry, and decreases immediately when rainfall is abundant.
The prevention and control method is to spray 0.5 Baume degree lime-sulfur mixture once in mid-to-late October and once in early spring March, or spray 25% mite-killing water agent at 500 times dilution, which also works well.