How to prevent and control bacterial shot hole disease and brown spot shot hole disease on cherry blossom leaves?

How to prevent and control bacterial shot hole disease and brown spot shot hole disease on cherry blossom leaves? Small shot holes often appear on cherry blossom leaves, and in severe cases they cause the leaves to turn yellow or even drop. This is caused by bacterial shot hole disease and brown spot shot hole disease of cherry blossoms.

(1) Bacterial shot hole disease of cherry blossoms: It mainly harms cherry blossom leaves. In the early stage of the diseased leaves, light brown water-soaked small spots appear, which gradually form nearly round brown or purplish-brown lesions surrounded by light yellow halos. In the later stage, the lesions dry up and fall off, forming shot holes. The pathogen of bacterial shot hole disease of cherry blossoms is a species of bacterium in the genus Xanthomonas. The pathogen mainly overwinters in diseased buds and lesions on twigs. In the second spring, it spreads by wind, rain and insects, and invades through stomata, lenticels, bud scars, etc. The disease begins in April to May, and the peak incidence period is from June to August. Rainy and cloudy days easily lead to an epidemic of this disease.

(2) Brown spot shot hole disease of cherry blossoms: This disease initially harms old leaves, then develops upward. In the early stage, the diseased leaves produce purplish-brown small spots, which later expand into concentric lesions about 3 mm in diameter. The center of the lesion is white or brown, and the edge is purplish-brown. In the later stage, the lesions fall off to form shot holes. The pathogen of brown spot shot hole disease of cherry blossoms is a fungus in the genus Mycosphaerella, which mainly overwinters as mycelium in diseased leaves. The pathogen spreads by wind and rain. It generally begins to cause disease in June, with the peak period in August. The disease is severe when there is a lot of wind and rain.

(3) Control methods: To control these two diseases, dead branches and fallen leaves should be removed and burned in time. For chemical control, before cherry blossom buds sprout, spray 3-5 degrees Beaume lime sulfur mixture or 1:1:120 Bordeaux mixture. After leaf expansion, spray 80% zineb wettable powder 600 times dilution, once every 7-10 days, for 3 consecutive sprays.