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How to effectively prevent and control cotton angular leaf spot

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Cotton angular leaf spot is a bacterial disease. Cotton can be affected from the cotyledon stage to the mature plant stage. After infection, dark green small spots first appear on the underside of the leaves, and later the spots gradually expand, restricted by the leaf veins to form polygonal oil-soaked lesions. When the bacterial fluid is moist, it is a yellowish-brown sticky substance, and after drying it becomes a white scab-like substance. In severe cases, it can cause the leaves to dry up and fall off. If diseased leaves are held up to the light, the lesion areas look like oiled paper. The causes are, first, continuous cropping on the same land, with the disease developing from bacteria carried by diseased residues in the soil; second, poor light, high humidity and high temperature, with damaged cotton branches and leaves, which favors

Cotton angular leaf spot is a bacterial disease. Cotton can be affected from the cotyledon stage to the mature plant stage. After infection, dark green small spots first appear on the underside of the leaves, and later the spots gradually expand, restricted by the leaf veins to form polygonal oil-soaked lesions. When the bacterial fluid is moist, it is a yellowish-brown sticky substance, and after drying it becomes a white scab-like substance. In severe cases, it can cause the leaves to dry up and fall off. If diseased leaves are held up to the light, the lesion areas look like oiled paper.

The causes are, first, continuous cropping on the same land, with the disease developing from bacteria carried by diseased residues in the soil; second, poor light, high humidity and high temperature, with damaged cotton branches and leaves, which favors infection by the pathogen.

Prevention and control: Clean the cotton field: promptly carry the pruned branches, old leaves and diseased residues from the cotton field out of the field and burn them in a centralized way or bury them deeply. Balanced fertilization: in particular, do not apply too much nitrogen fertilizer. Reasonable drainage and irrigation: when dry, do not irrigate by flooding; after rain, promptly drain off accumulated water and cultivate the soil to reduce moisture. Chemical control: in the early stage of the disease, spray with 65% zineb wettable powder at 600 times dilution, or use 72% agricultural streptomycin soluble powder (10 million international units) per mu plus 50 kg of water for spraying, or spray with 50% carbendazim or 70% thiophanate-methyl at 1000 times dilution, spraying once every 7-10 days, for 2-3 consecutive sprays.

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