Lagerstroemia indica leaves turn yellow from old leaves and then fall off. What is the reason?

Powdery mildew is a worldwide disease with a wide range of hosts, and Lagerstroemia indica is its 1 important target. Powdery mildew of Lagerstroemia indica is common in the provinces and cities where Lagerstroemia indica is planted in China. After the onset of Lagerstroemia indica, the leaves often turn yellow and fall off, which directly affects the tree potential and ornamental effect.

Prevention and control methods:

1. Gardening has a strong ability to control the germination of Lagerstroemia indica. Therefore, for plants with serious diseases, all the branches of the year can be cut off in winter and burned centrally, thus completely eliminating the source of the disease. If Lagerstroemia indica planted at home is found to be infected with powdery mildew, the diseased leaves should be removed in time and the potted flowers should be placed in a ventilated and light-transmitting place. In field cultivation, it is necessary to control planting density, strengthen daily management, pay attention to increasing the application of phosphorus and potassium fertilizer, control the application amount of nitrogen fertilizer, and improve the disease resistance of plants; At the same time, we should also pay attention to the selection of disease-resistant varieties. When1.3,2 is used to control serious diseases, Pomei 3 ~ 4 lime-sulfur mixture can be sprayed before germination in spring; When the disease occurs in the growing season, it can be prevented by spraying 500 times 80% zineb wettable powder, 1000 times 70% thiophanate-methyl, 1500 times 20% triadimefon emulsifiable concentrate or 800 times 50% carbendazim wettable powder.