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How to Effectively Prevent and Control Cherry Blossom Brown Spot Shot Hole Disease

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I. Symptoms: Shot hole disease can be divided into fungal and bacterial types. Cherry blossom brown spot shot hole disease is caused by fungi. It mainly damages leaves and also infects new shoots. It usually starts from the lower part of the canopy and gradually spreads upward. In the early stage of the disease, needle-tip-sized purplish-brown small spots are scattered on the upper side of the leaves, later expanding into round or nearly round lesions 3-5 mm in diameter. The edges of the brown spots are purplish-brown, and grayish-brown mold spots appear on the lesions in the later stage. An abscission layer forms at the edge of the spot, and the lesion dries up and falls off, forming shot holes. II. Disease Pattern: The pathogen of cherry blossom brown spot shot hole disease overwinters in diseased leaves or shoot parts

I. Symptoms: Shot hole disease can be divided into fungal and bacterial types. Cherry blossom brown spot shot hole disease is caused by fungi. It mainly damages leaves and also infects new shoots. It usually starts from the lower part of the canopy and gradually spreads upward. In the early stage of the disease, needle-tip-sized purplish-brown small spots are scattered on the upper side of the leaves, later expanding into round or nearly round lesions 3-5 mm in diameter. The edges of the brown spots are purplish-brown, and grayish-brown mold spots appear on the lesions in the later stage. An abscission layer forms at the edge of the spot, and the lesion dries up and falls off, forming shot holes.

II. Disease Pattern

The pathogen of cherry blossom brown spot shot hole disease overwinters in diseased leaves or shoot parts, and produces spores the following year that spread by wind and rain and invade through stomata. The disease begins in June each year, and is severe from August to September. It is severe in years with heavy wind and rain, and is prone to occur in summer drought and when tree vigor is weak.

III. Control Methods

① Collect diseased branches and leaves in autumn and burn them to reduce sources of infection.

② Strengthen management measures, apply more organic fertilizer and phosphorus and potassium fertilizers, and promptly prevent drought and waterlogging, so as to enhance tree vigor and improve resistance.

③ Before and after leaf expansion (especially for seedlings), spray Bijunsha at 1000-1500 times dilution, or 65% zineb at 500 times dilution, or lime sulfur mixture at 3-5 degrees Baume, or Bordeaux mixture at 1:1:100-200 times dilution for prevention. After the disease occurs, Penkejun at 2000-3000 times dilution can be used to promptly control the spread of the disease. Amistar, kresoxim-methyl, and others can also be used.

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