[Distribution damage] commonly occurs in peach production areas in China, especially in coastal areas along the lake, poor drainage, high salinity orchards and rainy years are more serious. In addition to peaches, nectarines, but also harm Lee, apricot, plum, cherry and so on.
[Pathogens and Symptoms] The pathogen of Xanthomonas pruni (Smith) Dowson. is a bacterium of the genus Xanthomonas. The cells are short-barreled, 0.4-1.7 micron (0.2-0.8) micrometers in size, with two ends rounded and one to six flagella at one end. Non-acid-resistant, aerobic, Gram-negative bacteria.
The disease mainly damages the leaves and also invades shoots and fruits. At the beginning of the onset of the leaves, yellow-white to white round spots, 0.5 to 1 mm in diameter. Then gradually expanded into a light brown to purple brown round, polygonal or irregular lesions, the outer edge of a green halo, usually about 2 mm. After the spot dry off, forming perforation. Severe disease can also lead to early defoliation; shoots appear more than lesions near the shoots. Lesions centered on the lenticels, initially dark green, water-stained, gradually turning brown to dark purple, with depressions in the middle, often with dendritic secretions on the edges. The epidermis of the lesions in the center of the late lesions began to crack; when the young fruit began to appear light brown round spots, after the color becomes darker, slightly concave, secrete yellow mucilage when wet, and form irregular cracks when dry.
[Influence] The pathogenic bacteria overwintered in the diseased tissue, and the temperature in the spring of the following year rose. The latent bacteria began to move and released a large number of bacteria, spread by wind and rain, dew drops, fog beads, and insects. The stoma of the leaves, the buds of the shoots, and the lenticels of the fruit invade. The disease is severe under frequent rainfall, foggy and warm and humid weather, and the disease is light with dry and rainy conditions. Poor vigor, poor drainage, and poor ventilation in Taoyuan are serious. When the pests are serious, such as spider mites, they are invaded by wounds and the disease is severe.
[control methods]
(1) Strengthen Taoyuan comprehensive management, enhance tree vigor, and improve disease resistance. Avoid grounds in high or low groundwater levels. When soils are heavy and there is a lot of rain, use water in Taitian and change the soil. , improve the ventilation and light transmission conditions; pruning in winter and summer, timely cutting disease branches, cleaning litter, concentrated burned or buried.
(2) Control of the buds before the bud spread Bami 5 degree lime sulfur or 1:1:100 Bordeaux mixture to kill the overwintering germs; spread the leaves to the onset before the onset of 65% zein zinc wettable powder 500' Double liquid, or zinc sulfate lime solution (0.5 kg of zinc sulfate, 2 kg of slaked lime, 120 kg of water) 1 to 2 times, or 10% of agricultural streptomycin WP 500 to 1000 times, can also spray wave 0.3 degree lime sulfur agent.
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