Common diseases of peanuts include stem rot, root rot, leaf spot, and rust.
1. Stem rot. The cotyledon cotyledons are dark brown, dry and rotted, and the petiole extending along the petiole to the base of the stem into a yellow-brown water-soaked lesion, and finally dark brown rot, late onset, first water-soaked lesions at the base of the stem or the main branch, It is dark brown after yellowish brown, and the ground is wilted and dead.
Control methods: stem rot is mainly based on seed-borne bacteria, and continuous cropping is serious. Therefore, reasonable rotation should be carried out. Before seed storage, it should be fully dried. Before sowing, it should be dried and selected, without mildew and poor quality seeds. Seed disinfection, 50% carbendazim 0.2% seed dressing; when the disease rate reaches 5%, use 50% carbendazim or 70% methyl thiophanate 800 times spray stalk unit.
2, root rot. The base of the stem is water-immersed, yellow-brown, the plant is short, the leaves are dry from the bottom to the top, the main side roots become brown and rot, and only the main root of the brown dry shrinkage is left in the later stage.
Control method: rational rotation, strict selection and sun-breeding, seed dressing with 0.2% seed germination of 50% carbendazim. When the disease rate reaches 5% at the beginning of the disease, it is sprayed with carbendazim 800 times liquid.
3, leaf spot disease (mainly including brown spot, black spot) brown spot disease lesions round, dark brown, large, yellow halo on the outer edge of the lesion, gray mold in the later stage; black spot disease The spot is round, dark brown, and there is no yellow halo around the lesion, and the lesion is smaller than brown spot.
Control method: rational rotation; use resistant varieties. The hot and rainy July and August are the key periods for the prevention and control of leaf spot disease. When the diseased leaf rate reaches 10% at the beginning of the disease, it can spray 50% carbendazim 800 times liquid or 70% mancozeb 800 times, every 15 days. Spray once, a total of 2 to 3 times.
4, flower rust disease. The bottom leaves begin to occur first, the leaves produce yellow erythema, small shape, surrounded by a very narrow yellow halo, the surface of the epidermis splits to emit rust-colored powder, in severe cases the leaves are yellow, dry and fall off.
Control method: In the initial stage of the disease, 75% chlorothalonil 600 times solution or 20% powder rust 500 times liquid spray.
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