Cherry blossom brown spot perforation

[distribution] Cherry blossom brown spot perforation is an important disease in cherry blossom leaves, which occurs in cherry blossom planting areas in China.

[symptoms] it mainly harms the growing leaves and the twigs. The susceptible leaves initially appeared needle-shaped purple-brown dots, and soon expanded into a round to near-circular spot, 1mm to 4mm, middle brown, slightly concentric rims, edges purple or reddish brown, gray-brown velvet dots appeared on the disease spot; in the later stage, there were detachment around the disease spot, brown mildew on both sides of the disease leaf, dry and shedding in the middle of the disease spot, forming round holes, forming perforation spots, and irregular perforation when several disease spots overlapped. The disease spots can be connected to each other, and when there are many disease spots on the leaves, the leaves will fall off early.

[pathogen] the pathogen was fungus, Cercosporacircumscissa, conidiophores crowded into bundles, conidia whipped to stick-shaped, olive-colored, straight or slightly curved, with 1-7 septum.

[incidence regularity] the pathogen still harms many kinds of woody flowers, such as peach, plum, apricot, plum and so on. The pathogen overwinters in diseased branches and fallen leaves. Ascospores mature in spring and spread by wind and rain when the temperature is suitable in the following year. Generally speaking, the disease starts from the lower leaves in June, and the peak is from August to September. The disease is serious when there is a lot of wind and rain, and only a few leaves remain on the plant in late September. Where poor ventilation, dense plants, weak tree potential and other conditions are conducive to the serious occurrence of diseases. The summer drought, the tree potential is weak, the incidence is also high.

[prevention and control methods]

(1) Pesticide control: spraying 65% Dysen zinc 500 times solution or Baume 3-5 degree stone sulfur mixture or 100-200 times Bordeaux solution before and after leaf spreading (especially for seedlings). Or spray Baume 2-3 degree stone sulfur mixture or 1% Bordeaux solution before germination to disinfect the tree. Spray 1.02kg / Shengshi sulfur mixture before leaf spreading, and spray 50% carbendazim 800x solution, or 1500 times methyl topiramate, or other fungicides after leaf development. For bacterial perforation, zinc sulfate lime solution (500g of zinc sulfate, 2000 grams of hydrated lime, 120kg of water) can be sprayed after leaf expansion.

(2) spraying 1500 times of 50% benzoate wettable powder or 65% of Dysen zinc or 1000 times of carbendazim during the onset period has good control effect.

(3) strengthen cultivation management, create good ventilation and light transmission conditions, apply more phosphorus and potassium fertilizer, and enhance disease resistance. Do not plant cherry blossoms in the tuyere area and water them in time during drought.

(4) clean the courtyard, remove the diseased leaves and burn them in autumn, combined with pruning and pruning to reduce the source of infection in the coming year.