What is the value of azaleas? Propagation and pest control techniques of rhododendron in western countries

What is the value of western azaleas? Western rhododendrons are rhododendrons, which are bred by repeated hybridization between Holland and Belgium with rhododendrons, azaleas and white rhododendrons. The flower is colorful and diverse, buds bloom many times a year, flowers in four seasons, has three major values of ornamental, ecological and medicinal, so it has received extensive attention from all walks of life, and its application field has been continuously expanded.

1. Value and characteristics of rhododendrons

1 Azalea ornamental, ecological and medicinal value

(1) The ornamental value of western azaleas: Western azaleas have many colors and are very beautiful, so they are more common in courtyards, alleys and landscaping projects. Among them, the "Baili Western Azalea" scenic spot is more famous and has become a famous tourist attraction.

(2) Ecological value of western azalea: western azalea flowers can not only effectively absorb O3 and SO2 components in the air, but also effectively purify the air, which plays an important role in improving the environment to a certain extent. At the same time, azalea is also an important indicator of acidic soil, which can play an important role in improving ecological environment on the basis of maintaining water conservation.

(3) Medicinal value of western rhododendron: The root part of western rhododendron can be used as medicine, which is mostly used to treat cough and phlegm, mainly quercetin, which has very important cough and asthma effect.

2. Cultivation techniques of western rhododendron

2.1 Propagation Technique of Rhododendron

Sowing propagation, cuttage propagation, grafting propagation and layering propagation are common propagation methods of western rhododendron, which should be determined according to the actual varieties of western rhododendron in the propagation process. (1) Seed reproduction: Common is evergreen western rhododendron. (2) Cutting propagation: The more common is deciduous western rhododendron. (3) Branch splitting propagation: some rare varieties that are difficult to survive. Cuttage propagation: conventional western rhododendron has higher propagation coefficient and higher survival rate.

2.2 Cultivation Techniques of Western Rhododendron

The cultivation of western rhododendron should control the basic pH value of the culture soil between 4.5 and 6. In addition, the fertilization process should be paid attention to and controlled during the cultivation process, and the fertilization management should be carried out orderly according to the standardized process. During the cultivation period, attention should be paid to soil nutrients to ensure that the soil is loose and the overall ventilation and water permeability are good. If the soil fertility is insufficient, fertilizer should be applied to meet the needs of western rhododendrons. In the process of cultivation, balance and high efficiency of fertilization should be maintained fundamentally. When fertilizer is applied, fertilizer must be fully fermented and concentrated water control operation should be carried out before retting fertilizer.

2.3 Flowering management techniques of rhododendron

(1) Lighting conditions: Western rhododendrons like light, so it is necessary to ensure good lighting conditions.

(2) Temperature condition: The best temperature is 12℃, but the best temperature is 20℃ for cuttings.

(3) humidity conditions: humidity should be controlled between 70%~90%, watering every 2~ 3 days in spring and autumn, and watering every morning and evening in summer.

3. Pest Control of Western Rhododendron

3.1 Disease control of rhododendron

(1) Rhizoctonia solani: disinfect the soil with formalin before reproduction; irrigate with 500 times solution made of thiophanate methyl with concentration of 70% or chlorothalonil with concentration of 70%.

(2) Black spot disease: timely remove the diseased leaves in winter and strengthen daily management; in the early stage of black spot disease, 1∶1∶100 Bordeaux mixture should be used for disinfection treatment, or 70% methyl thiophanate should be used to make 1000 times solution for irrigation control.

3.2 Pest control of azalea

Common pest problems are red spiders and army bugs.

(1) Red spider: use the method of removing diseased leaves and burning them intensively, and spray dicofol at a concentration of 40%.

(2) Military-matched insects: In July and August, spraying with a solution of 0.0067%~0.01% prepared from 50% zinc and phosphorus.

Western rhododendron cultivation method Western rhododendron is relatively difficult to raise in the hands of novices, because the climate is different everywhere, especially in the north, when bought very good, not long to raise and deciduous, bud drop, as long as more understanding of the habits of Western rhododendron to raise Western rhododendron is not so difficult. First, the growth habits of western azaleas like warm, humid, cool air, ventilation and semi-overcast environment. The soil is acidic, fertile, loose, rich in organic matter and well drained. Avoid direct sunlight in summer, should shade, often spray water, maintain air humidity. The soil is good with loose, fertile and well-drained acid sandy loam. Pot soil is a mixture of moldy soil, culture soil and coarse sand, pH 5~5.5 is appropriate. Second, common problems in the process of Western rhododendron cultivation 1, after flowering plants easy to die to solve the key: air humidity should be moderate. Western rhododendrons have strict requirements for air humidity. Western rhododendron cultivated in greenhouse, as long as the greenhouse ground does not accumulate water, under normal circumstances, its air humidity can be completely suitable for rhododendron growth. It should be pointed out that in an air-conditioned room, the air humidity is far less than the physiological needs of azaleas. Therefore, there will be yellow leaves, flowers after most of the plant die-off phenomenon. This is the crux of the difficulty in cultivating western rhododendrons. This problem can be solved by spraying water on the leaves of rhododendrons daily to increase the humidity of the air around the plants. 2. The key to solving the unbalanced growth on both sides of the plant: daily watering and fertilization should be uniform. Because the culture soil of western rhododendron must be loose and breathable substrate, most of the soil used in actual cultivation is pine leaf soil, which has strong water permeability. Water will seep directly during watering, and some nutrients will also be lost with water. And we are often accustomed to watering from the side that is convenient to operate, and the cultivated soil is always in a dry side, wet side, and lean side. Over time, it will cause one side of the capillary root system of the plant to develop and one side to atrophy, thus making the appearance of the plant show unbalanced growth on both sides. Therefore, when watering and fertilizing Western Rhododendron, we must start from the four sides of the flowerpot and operate evenly. 3, sporadic flowering plants, flowering inconsistent solution key: timely concentration of the head. From the operator's point of view, flowers can win the maximum profit only when they bloom at the peak of flower use such as holidays. Therefore, it is very important for western rhododendron to concentrate and open on time. Topping is an important means to adjust flowering period. Experience has proved that it should be carried out in late July to early August when western rhododendron reaches full flowering period during Spring Festival. In the process of heading, each branch end of the plant must be thoroughly removed to ensure that the whole plant type is neat. In the cultivation of Western rhododendron in the whole process, this step is extremely critical, can not be ignored. 4, the plant appears "small leaf disease" solution key: control mites. Western rhododendron itself has strong resistance, but in the case of improper operation, there are also diseases and insect pests. In addition to common brown spot disease and iron deficiency, there is also a common symptom. It usually occurs first in the new shoots of plants. The leaves are clustered, do not stretch and the leaves are yellowish. The symptoms of small leaf disease are very similar to those of fruit trees, so it is used to calling it "small leaf disease" of rhododendron. Most flower farmers also naturally think that the "small leaf disease" of western rhododendron is also a physiological disease caused by zinc deficiency, and all kinds of methods have been used to supplement zinc to rhododendron plants, but the effect is not good. In fact, this disease is caused by mites. We remove the diseased plants when they are brought into the greenhouse or purchased. At the budding stage, we can spray 1 to 3 Baume's sulfur mixture or dry them with 40% omethoate 5 to 10 times. Once the disease occurs, select 20% dicofol EC 500 to 600 times solution can achieve very ideal results. Common diseases and pests of rhododendron and their control Rhododendron (scientific name: Rhododendron simsii Planch.): Also known as azalea, pomegranate, evergreen or flat evergreen shrubs. According to legend, ancient cuckoo, day and night whining and hemoptysis, dyed flowers all over the mountain, hence the name. Azalea flowers in general spring, each cluster of flowers 2-6, corolla funnel shape, red, reddish, apricot, snow green, white and so on, luxuriant and gorgeous color. It is a typical indicator plant of acid soil in central and southwestern China. It grows under sparse thickets or pine forests at altitudes of 500-1200 (-2500) m.

Common diseases and insect pests of Rhododendron and their control rhododendron black spot Rhododendron black spot disease is also called brown spot disease, which is a common multiple leaf spot disease of Rhododendron. After the disease leaves form black spots, gradually dry off until the plant dies. The disease mainly damages the leaves of Rhododendron, which are infected by Cercospora rhododendron. Several brown spots appear at the beginning of the disease. With the continuous expansion of the spots, the disease spots connect with each other and produce gray brown mold filaments. The affected leaves start from the petiole and turn brown yellow early. When serious, it affects the growth and development of Rhododendron and its ornamental value. Pathogens overwinter on leaves or diseased plants, and spores spread with the wind. The reoccurrence period of this disease is usually in high temperature and wet season, and there are also diseases in greenhouse in winter. Generally, the disease is more serious in weaker plants, seedlings, lower leaves, plants with poor ventilation conditions and western cuckoo (compared with hairy cuckoo). According to the disease law, the following control measures can be taken: (1)Strengthen cultivation management, cuckoo cultivation pot soil should choose rotten leaf soil, watering pH value should be between 4.5 and 6.5, watering substrate should be dry and wet, often irrigate some decomposed thin organic liquid fertilizer, in order to promote plant health, leaf hypertrophy to improve resistance, cuckoo pot should be placed in ventilated place, summer to shade, moisture prevention, ponding prevention. The diseased leaves should be removed and burned in time, and attention should be paid to the selection of disease-resistant varieties, while strengthening the quarantine of plant diseases and insect pests. (2)Chemical control: spray 800 times of 70% thiophanate wettable powder or 300 times of 50% carbendazim solution after flowering. In addition, it can be sprayed regularly for prevention, and protective fungicides and fungicides can be used for mixed application. For example, good results can be obtained by alternating application of Polyamine plus M Dasheng 45 and Kexide, or continuous spraying twice a week with 1:1:150 Bordeaux mixture; spraying 1:1:100 Bordeaux mixture once every 10 days in rainy season, continuously spraying 3 to 4 times. rhododendron chlorosis Rhododendron chlorosis is a non-infectious disease and a common disease in Rhododendron cultivation. After the occurrence of plant disease, the leaves become thin, chlorotic, pale leaf color, so also known as chlorosis, new leaves lack green obviously, when the new shoot leaf color becomes light, mesophyll turns yellow, vein is still green, then generally diagnosed as iron deficiency symptoms, this phenomenon occurs in alkaline soil and the use of alkaline irrigated flowers. After the leaves appear symptoms, photosynthesis can not be carried out normally, which will affect the growth and development of plants and ornamental value in mild cases, and lead to plant death in severe cases. Control measures: to strengthen cultivation management, can be combined with irrigation, irrigation ferrous sulfate solution, foliar spray 0.5% ferrous sulfate solution, you can gradually restore the green leaves of plants. rhododendron spider The female adult is about 0.3 mm long, dark red, nearly elliptical, with a raised back and four pairs of dark red feet; the male adult is 0.25 mm long, wedge shaped, flat red. It occurs many generations a year. Adults overwinter at the root of the plant, mainly near the main vein on the back of the leaf near the petiole. It is cultivated quickly in high temperature, little rain and dry weather from June to July. When the damage is serious, the injured leaves are scorched and fallen off. Prevention and control methods: artificial control, regular inspection after April, found that individual leaves have red spiders, can be timely burned pest leaves. Natural enemies such as ladybugs, green flies, thrips, etc. can be artificially released under conditions for biological control. If more leaves are found to have red spiders, chemical control can be carried out, such as spraying 40% dicofol 800 to 1000 times solution, adults, nymph, larvae and eggs have strong lethality, as long as the spraying effect is good. Dictyocoris rhodoides Azalea net bug, also known as azalea army with insects, small smelly sister. Adult body length of about 3.5 mm, black-brown, wings covered with reticulate wings slightly rectangular, static; wings on the black-brown stripes constitute "X" shape. The nymph resembles an adult, but the insect body is tender and wingless, about 2 mm long, the egg is 0.6 mm long, oval, milky white, produced in the midvein and larger veins, pale green at the beginning of production, and then becomes pale yellow. The adults overwintered in the bark and crevices of the ground in the middle and late October, and began to move from April to May of the next year, feeding on the back of the leaves. The damage was most serious from July to August. The adults and nymph liked to gather near the main veins on the back of the leaves, sting and sucking the sap of the leaves. Their secretions formed large yellow-brown rust spots. When serious, the leaves were pale, causing early drop, affecting the growth and flowering of Rhododendron. Control methods: (1) After winter, remove the fallen leaves and weeds near the flowers and trees, bury them deeply or burn them, and eliminate the overwintering adults. (2)For pesticide control, 80% dichlorvos emulsifiable solution or 50% bolong emulsion 1000 times solution is sprayed once every 7 to 10 days and continuously sprayed for 2 to 3 times after overwintering adults appear and the first generation nymph occurs in May. Can also be used 3% furan Dan buried about 5 grams per pot, the effect is also very good. Azalea earthworm, slug harm root mainly. Sometimes slugs also harm leaves, cultivation medium used to high temperature disinfection, kill eggs, found pests, available furan Dan, iron Mieke basin application control.