Symptoms and control of early defoliation disease of pomegranate

Early defoliation includes a variety of diseases, which can be divided into brown spot, round spot and ring spot, among which brown spot is the most serious. When the disease is serious, it causes a large number of fallen leaves in the early stage, premature senescence of tree potential, less flower buds and lower measurement.

1. Symptoms

Mainly damage the leaves. In the initial stage, it occurs in the lower part of the crown and on the inner leaves. The disease spot of brown spot is brown spot at first, and then develops into needle-shaped, concentric wheel-shaped or mixed disease spot, and the small black particles on the disease spot is the spore disk of the pathogen; the disease spot of round spot is round or nearly round at first, brown or gray spot; the leaf of wheel pattern disease spot is brown or dark brown and has obvious wheel pattern, which mostly occurs at the edge of the leaf, and a few occurs in the middle of the leaf. When the air is moist, black mildew often appears on the back of the leaves.

2. Pathogenic bacteria

The above three kinds of leaf spot disease all belong to semi-known fungi. The pathogen overwinters on fallen leaves with mycelium or spore disk, and forms spores in spring to spread by wind and rain. The leaves in the lower part of the crown were first infected, and then re-infected many times. If there is more rain and humidity, the disease is quite serious; if Rain Water is less, the disease seldom occurs.

3. prevention and control measures

First, remove the fallen leaves in the garden in autumn and winter and burn them or bury them deeply in order to reduce the pathogen of overwintering.

Second, during the growth period, spray 2-3 times as much as 1-100 Bordeaux solution, or 50% acetaminophen wettable powder 600x, or 50% methyl topiramate wettable fen 1000-fold, or 65% Dysen zinc wettable fen 500800x. The first medicine should be taken before the wheat harvest. When spraying, you should pay attention to spray evenly and carefully, do not miss the spray. The back and surface of the leaf should be sprayed.

Third, strengthen comprehensive management, reasonable pruning, improve ventilation and light transmission conditions in the canopy, and reduce the occurrence conditions and opportunities of bacteria.