Peanut leaf spot disease is mainly brown spot, black spot, and net spot. 1, brown spot, leaves after the victim, the primary round or nearly round yellow-brown small spots, lesions gradually expanded, diameter of about 10-14mm tip, leaf margin lesions irregular shape, darker than black spot, The leaves are brown or dark brown with a brown or brownish brown on the back. There was a clear yellow halo around the initial lesion and the back was not obvious. When wet, the surface of the lesion produces a brownish brown layer, which is the conidiophore and conidia of the pathogen. 2, melasma, the early onset of symptoms is not easy to distinguish with the brown spot, but the difference is significant later. After the leaves were damaged, the size of the primary brown needle lesion gradually expanded to a round lesion with a diameter of about 1-5 mm. The lesion gradually changed from light brown to dark brown, and the color of the lesion was similar to the back of the leaf. There are no obvious yellowish halos around the lesions on the front of the leaves. There are many black dots on the back of the lesions, which are arranged in a concentric ring pattern, namely the conidia of the pathogen. In wet conditions, a layer of gray-brown mildew can be produced on the lesions, namely the conidiophore and conidia of the pathogen. Occasionally dozens of lesions are produced on a leaf, and sometimes several lesions synthesize irregular large lesions. Lesions on stem and petiole are oval, dark brown 3, net spot disease, mainly in the middle of peanut growth, damage the leaves. The symptom type is affected by the climatic conditions, especially the relative humidity. When the relative humidity is lower than 80%, the lesions are brown network type. At the beginning of the disease, a starburst-like black spot appears on the front of the leaves, and then expands into the edge mesh. Irregular and fuzzy dark brown lesions, about 2-4mm in diameter, lesions do not penetrate the leaves, only damage epithelial cells, causing necrosis, does not damage the palisade tissue; lesions are stains when the relative humidity exceeds 90% Type, large spots, about 7-15mm, nearly round, dark brown, lesions edge clearer, penetrate the leaves, but the leaves on the back of the lesion is smaller, the necrosis can form black dots, that is, conidia. Control methods 1. Shandong, the resistant variety, was selected as the most resistant to “Oil Oil 92â€, and the medium-maturing variety was the most resistant to “Flower 39â€. All localities should choose disease-resistant varieties according to local conditions. 2. Crop rotation The host plant of the pathogen is relatively single and only infects peanuts. In areas with severe disease, crop rotation may occur, especially crops such as corn and sweet potatoes, which can effectively control the occurrence of this disease. 3, strengthen the cultivation and management of timely sowing, rational close planting, Shizu base fertilizer, especially the application of organic fertilizer, can promote the robust growth of peanuts, improve resistance to disease. 4. Chemical control In the early stage of the disease, when the diseased plant rate is 20%, spraying and controlling in time can reduce the disease, generally increasing the yield by 15-20%. Available Bordeaux mixture 1:2:150-200, 70% mancozeb 400 times, 70% thiophanate-methyl wettable powder 1000 times, 50% carbendazim 1000 times wettable powder, 75% 100% Bacterial liquid wettable powder 600-800 times liquid, etc., generally spray once every 10-15 days, even spray 2-3 times. If the weather is dry and the disease ceases to develop, the spraying interval may be extended appropriately. Since the leaf surface of the peanut is smooth, the adhesive can be properly added when spraying, and the control effect will be better. Monensin Granular,Monensin Growth Promoter,Monensin Antibiotics,Monensin Feed Additives Shandong Shengli Bioengineering Co., Ltd , https://www.shenglipharm.com
Peanut leaf spot symptoms and prevention