Control of Peanut Leaf Spot

1. The main symptoms of peanut leaf spot are black spot and brown spot, and the two diseases are mainly harmful to leaves. During the onset of peanut disease, symptoms began to appear in the lower leaves, and then gradually spread to the upper leaves, producing brown spots in the early stage of the disease, and gradually developed into round or irregular disease spots. The spot of brown spot is larger, there is a yellow halo around the spot, while the spot of black spot is smaller, the color is lighter than brown spot, the edge is neat, and there is no obvious halo. The weather is humid or long-term overcast and rainy, disease spots can be combined with each other into irregular spots, leaves scorched, seriously affecting photosynthesis. If it occurs on the petiole, stem or fruit needle, it will produce oval black-brown or brown disease spots, and if it is heavy, the whole stem or fruit needle will blacken and die, resulting in a great decrease in peanut yield.

Second, prevention and control (1) eliminate pathogenic bacteria. Remove the germ remains left in the field in time after peanut harvest, and don't litter or pile up at will. The plots with bacterial residues should be ploughed in time to accelerate the decomposition of bacterial residues and prevent them from infecting peanuts again. (2) selecting disease-resistant varieties. The varieties with more disease resistance are generally varieties with erect growth, thick leaves, dark color, large peanut grains or early maturing varieties, which can be planted in seriously affected plots, such as Jihua 2, Luhua 14 and so on. (3) strengthen cultivation management. It is necessary to sow seeds in time, plant closely in a reasonable way, apply sufficient base fertilizer and topdressing in time so as to promote the robust growth of peanuts and improve disease resistance. (4) Chemical prevention and control. Timely spraying and control in the early stage of the disease can reduce the disease. Better agents: 80% mancozeb 400 times, 70% methyl topiramate 1000-1500 times, 50% carbendazim 1000-1500 times. When spraying, we should pay attention to spray evenly, spray thoroughly, spray once every 7-10 days, even 2-3 times, can basically control the occurrence of the disease.