How to prevent and treat common diseases of crape myrtle
A little plant knowledge, introducing the related introduction of crape myrtle clinic, how to prevent and treat common diseases of crape myrtle, please see the detailed introduction below.
Crape myrtle is also a type of landscaping tree that is easily affected by diseases and pests. The following is a specific introduction to the occurrence patterns and control methods of the main diseases and pests of crape myrtle.
Powdery Mildew
Powdery mildew is a worldwide disease with a wide range of hosts, and crape myrtle is one of its important targets. Powdery mildew is common in provinces and cities where crape myrtle is planted in China, and after the disease occurs, it often causes the leaves to turn yellow and fall off, directly affecting the tree's vigor and ornamental effect.
Control
Horticultural control: Crape myrtle has a strong tendency to sprout, so for severely affected plants, all annual branches can be cut and burned in winter to completely remove the disease source. If family potted crape myrtle is found to be infected with powdery mildew, affected leaves should be removed promptly and the pot should be placed in a well-ventilated and lighted area. Field cultivation should control planting density and strengthen daily management, pay attention to applying phosphorus and potassium fertilizers, control the application of nitrogen fertilizers to improve plant disease resistance; also pay attention to choosing disease-resistant varieties.
Chemical control: When the disease is severe, a 3-4° Bordeaux mixture can be sprayed before spring sprouting; during the growing season, 80% wettable powder of zinc omethasone 500 times, or 70% wettable powder of thiophanate-methyl 1000 times, or 20% wettable emulsion of triadimefon 1500 times, or 50% wettable powder of carbendazim 800 times can be sprayed for control.
Brown Spot Disease
Brown spot disease is also a widespread disease in landscape plants and often occurs during the growing season of crape myrtle. Severe brown spot disease can lead to a large number of yellowed and fallen leaves, affecting both the ornamental value and flowering.
Control
Horticultural control: Detect and remove diseased branches and leaves early, and burn or bury them to reduce the source of pathogens. Strengthen cultivation management, pruning, and ensure good ventilation and light penetration. It is best to change the soil for potted plants every year.
Chemical control: In the early stage of the disease, 50% wettable powder of carbendazim 500 times, or 65% wettable powder of zinc omethasone 1000 times, or 75% wettable powder of chlorothalonil 800 times can be sprayed for control.
Sooty Mold Disease
Sooty mold disease, also known as sooty blight, is common in various landscape plants across China. It affects crape myrtle mainly after it is attacked by crape myrtle scale and long spotted aphid, using their excreted sticky liquid as a nutrient source, causing the mass reproduction of sooty mold bacteria. After the disease occurs, the leaves of the affected plants are covered with a black mold layer, which not only affects the ornamental value of crape myrtle but also affects the photosynthesis of the leaves, leading to weak growth and early defoliation.
Control
Horticultural control: ① Through thinning and pruning measures, ensure proper ventilation and light penetration; ② Control aphids, scales, and whiteflies in time, as their secretions are the basis for the existence of the sooty mold pathogen.
Chemical control: The commonly used fungicides are Bordeaux mixture, 3° in winter, and 0.3° in summer and autumn. Sulfophosphide and Litsea cubeba leaf juice can also be used for control.
Yellow刺蛾
The yellow刺蛾, of medium size, with caterpillars known as bristly caterpillars or "yang lazi," is one of the main polyphagous leaf-eating pests of landscape flowers.
Control
Horticultural control: In winter, combine pruning to remove overwintering cocoons from branches, thereby destroying or reducing the source of pests.
Physical control: For family potted crape myrtle, after defoliation, manually remove overwintering cocoons to completely eliminate the pest source. In field production, black lights can be set up during the adult emergence period to attract and kill adults.
Chemical control: It is best to apply chemicals before the larvae spread, and spray 80% dichlorvos emulsion 1000 times, or 50% phoxim emulsion 1000 times, or 2.5% bromide emulsion 4000 times for control.
Crape myrtle can also be affected by green刺蛾 or brown刺蛾, but they all belong to the刺蛾 family. In addition to slight differences in appearance, they have great similarities in terms of living habits and occurrence patterns, and can be treated together with yellow刺蛾.
The above is a detailed introduction on how to prevent and treat common diseases of crape myrtle, have you understood it?