Symptom characteristics and control of peach leaf shrinking disease

Peach leaf shrinkage disease is a common disease in spring, which mainly harms green peach, cherry, apricot, plum and so on.

1. Pathogen: the disease is caused by outer ascomycetes in fungi.

2. Symptoms: it mainly harms leaves, and in serious cases, it can also harm flowers, young fruits and twigs. The plants infected with the disease showed wrinkled ripples after spreading leaves in spring, the leaf tip and edge were rolled back, and the leaf surface was uneven. After that, with the growth of leaves, the leaf color gradually changed from yellowish green to purplish red, the mesophyll thickened and became brittle, and the degree of concavity and convexity increased. In late spring and early summer, a layer of white dust formed on the leaf surface, and soon the diseased leaves blackened, withered and fell off; the young diseased branches were shortened, swollen, grayish green or yellow after infection, the leaves on the diseased branches were clustered, and when they were serious, the branches withered; the diseased fruit developed malformed, the fruit surface cracked, and the fruit hairs fell off, but the surface was smooth.

3. The characteristics of the disease: the pathogen overwintered with ascospores or spores in the crack of bud scales or on the skin. When peach buds germinated in the next spring, the spores produced germ tubes, which penetrated through the epidermis or invaded the tender leaves from stomata. The ascospores and budding spores produced by diseased leaves mature in late spring and early summer and occur seriously from April to May. They are transmitted by the wind, but they are generally no longer infected because of the high temperature, but they are only infected once a year. With the increase of air temperature and stop development, the temperature above 30 ℃ will not cause the disease. It is beneficial to the occurrence of the disease when it is cold and rainy in spring, and it also occurs more frequently along rivers, lakes and lowlands.

4. Prevention and control methods:

① cut off the diseased branches and leaves in late autumn or early spring, remove the diseased body, or remove the diseased leaves before the white powder is formed on the surface of the diseased leaves, so as to reduce the source of the disease.

When ② early spring peach bud expands but leaves are not spread, spray Baomei 4muri 5 degree stone sulfur mixture

Spraying 0.1% copper sulfate solution before ③ leaf spreading can also be effectively prevented.