Key points of control techniques for common diseases and insect pests of rhododendron

1. The main diseases of rhododendron are root rot, brown spot, black spot, leaf blight, iron deficiency chlorosis and so on.

The main results are as follows: (1) after the rhododendron suffered from root arm disease, the growth was weak, the leaves wilted and withered, and the brown fields appeared on the surface of the roots, which were seriously soft rot, gradually rotted and peeled, and the xylem blackened. The disease is most likely to occur in an environment with high temperature and high humidity.

Prevention and control methods: strictly disinfect Pei 10 soil before turning the basin, and keep the soil loose and moist, make it have good permeability and avoid stagnant water. If the plant is found to be sick, the diseased plant and basin soil should be dealt with in time. During treatment, the diseased plant can be eluted with 0.1% potassium permanganate aqueous solution or 2% ferrous sulfate, then rinsed with clean water and put on the basin again. The basin soil can be cured by spraying basin soil with a solution of 70% topzine wettable powder and 1000 times water.

(2) Brown spot is a major disease of rhododendron. At the beginning of the disease, small brown spots appeared on the leaf surface, which gradually developed into irregular spots, and many black or grayish brown spots were produced on the disease spots, which made the damaged leaves yellow and fall off, affecting the flowering of the current year and the development of flower buds in the coming year. This disease often occurs during the rainy season when the humidity is high.

Control methods: at ordinary times, we should pay attention to make the plant ventilated and transparent, do not make the humidity too high, and increase the application of organic fertilizer and nitrogen, phosphorus and potassium mixed fertilizer to enhance the plant resistance to infection and growth. If diseased leaves are found, they should be removed in time and burned centrally. At the initial stage of the disease, 0.5% Bordeaux solution or 0.4 Baume stone sulfur agent was sprayed, and 4% flour was added to increase the adhesion. Leaf spot and black spot can also be treated with the same method.

(3) Iron deficiency chlorosis often occurs in areas where the soil is alkaline, when the disease is mild, only the plant is late green; in severe cases, the leaf tissue can all turn yellow and the edge of the leaf becomes scorched. When the disease occurs, it is most obvious in the leaves of the top tip of the plant, which is generally caused by internal iron deficiency.

Control method: change the property of iron deficiency in soil and reduce soil alkalinity. Apply more organic fertilizer to transform clayey soil. 0.2%-0.3% ferrous sulfate liquid can be directly sprayed on iron-deficient plants. You can also poke several holes about 15 cm deep in the soil around the plant with chopsticks and slowly inject them with liquid ferrous sulfate solution at 1:30 to fill the holes to increase soil acidity and reduce alkalinity.

The incidence and environmental conditions of rhododendron black spot are similar to those of brown spot, and similar methods can be used for prevention and control.

2. The common pests of azaleas are red spiders, military insects, aphids, short-bearded snails and so on. Red spiders are small in size, but they do serious harm to azaleas. Cuckoos raised in high-rise buildings are most prone to this kind of pest.

Prevention and control methods: manual hunting and killing. Medicine can be used to kill insects with 5 degrees of stone sulfur mixture, or you can use walnut leaves, Yangzhu peach leaves, green poles and other parts to soak out the juice, dilute it with water and sprinkle it with ll, and it is also a good way to spray and kill with 1000 dichlorvos solution.

(1) the adult body of the military worm is small and flat, about 4 mm long and black. It is the most harmful pest to the evergreen rhododendron. It often sucks leaf sap at the back of the leaf, and yellow and white spots appear on the leaf surface of the victim, causing the leaf to fall off, causing the tree to weaken and affect its growth and flowering. This insect is easy to occur in rhododendrons in greenhouses.

Prevention and treatment: mainly with drug spray. It can be sprayed with 1000 times of 90% trichlorfon or 1500 times of 40% omethoate EC or 1000-1500 times of fenitrothion emulsion.

(2) aphids mainly harm the young branches and leaves of rhododendron, light ones can make the leaves lose green, heavy ones can make the leaves curl, become hard and brittle, can not absorb nutrients and affect flowering.

Control methods: usually pay special attention to the overwintering aphids, after wintering, you can spray a 5-degree stone sulfur mixture on the plant to eliminate overwintering eggs, shovel off weeds near flowers and eliminate insect sources. In the aphid danger period, 40% dimethoate or omethoate plus 1200 times water solution for continuous spraying, 3-4 times can be effective.

(3) Scutellaria is one of the important pests of rhododendron, which often sucks juice near the main vein on the back of the leaf, which forms many oil-stained fields on the back of the leaf, and finally causes the leaf to fall off. The insect is Obovate, about 0.3 mm long, flattened, red, dark red, wood red, irregular black spots on the back and irregular black patches on the side. This insect is most common when it is hot and dry in summer, and then decreases when the rainfall is long.

Prevention and control methods: spraying Baume 0.5 degree stone sulfur mixture once in mid-late October and early spring March respectively, the effect of spraying 25% insecticidal bloating agent 500 times is also good.

Key points of prevention and control of seedling diseases and insect pests in summer

The summer temperature is high, the humidity is high, especially the thunderstorm weather after the plum rain season, the seedling disease and insect damage is the most serious. It is especially important for those plots with high density, poor ventilation and high groundwater level, so this period is the key season for pest control. The following are recommended ways to control common diseases and insect pests:

I. Diseases

1. Rose, rhododendron powdery mildew, black spot, once occurred, the plant will be short, not luxuriant, branch development deformity, can not bloom, or abnormal flowers, serious leaf shrinkage and withering, affecting plant growth, resulting in the death of the whole plant.

two。 Camellia leaf spot and anthracnose are common diseases, which occur everywhere from time to time, sometimes very serious, and the diseased plants affect the ornamental value and cause economic losses.

3. Magnolia red spot disease, leaf spot disease, when the disease is serious, more than half of the leaves or the whole leaf withered and blackened, affecting plant growth.

Commonly used medicament: 70% topiramate 600,800 times, 50% carbendazim 500,600 times, 15% trimethoprim 2000-2500 times, 62.25% Xiansheng 400,600 times spray control effect is better.

II. Insect pests

1. The normal harm of scale insects are yellow poplar, cherry blossoms, camellias, oleander, Luohansong and so on. Scale insects are the most common pests in flowers. Normal clustering in branches, leaves, adults, nymphs special mouthparts to absorb juice, causing branches and leaves to wither, or even the whole plant to die, and can induce coal disease, causing great harm.

Control agents: 20% scale killer 1000-1500 times, 80% EC 800 times, dragon sword 1000-1500 times, scale treasure 1500-2000 times spray requirements during the egg incubation period, spray requirements uniform, thoughtful. If the wax shell has been formed, the spray will not be effective.

two。 Red spider is a kind of mite, which normally harms sweet-scented osmanthus, cypress, rhododendron, begonia, citrus and so on.

Control agents: 20% amitraz 1000-1500 times, 73% propargite EC 2000-3000 times Longjian 1000-1200 times, the alternate use of these agents have a certain effect.

A detailed introduction to the incidence characteristics and control methods of rhododendron leaf blight

Rhododendron, a common herbaceous flower, is often used in family courtyard and garden decoration, attracting many flower lovers to breed. The cultivation method of rhododendron is relatively simple. We all know that the common disease of rhododendron is leaf blight. So, do you know how to prevent and cure it? Today, the editor will give you a detailed introduction of the relevant knowledge, let's learn from the editor.

Rhododendron leaf blight is a fungal disease. The pathogen lives on the plant disease residue and spreads through watering, insects and human activities. It can occur all the year round in the indoor environment. High temperature, dryness and poor ventilation are easy to cause the disease. The disease is serious after plant growth is weak or is affected by insect pests.

The leaf blight of rhododendron mainly harms the leaves, which mostly occurs at the leaf tip. In the initial stage, the disease spot is faded green macula, and spreads inward from the edge, showing an irregular shape, the disease spot is yellowish brown in the later stage, and the diseased leaves dry up in severe cases.

The main points of prevention and control are three: 1. Remove the fallen leaves in time and burn them centrally. two。 Strengthen maintenance and often spray water to the leaf surface or the surrounding space to improve the small environment. Increase the application of phosphorus and potassium fertilizer to enhance plant growth potential. 3. At the initial stage of the disease, 500-800 times liquid carbendazim or topazine fungicides were sprayed. If there are pests, you can spray 1000-1500 times the liquid of nicotine to control.

That's all I know about azaleas today. I hope it will be helpful for flower friends to read this article. If you want to know more about azaleas, please continue to pay attention to the succulent flower beds and we will provide you with more related knowledge!