The symptoms are also called melasma. It mainly damages leaves, petioles, stems and flower shafts. The leaf spot is present on both sides of the leaf, with a round or near-circular shape and a size of 0.5-8mm. The lesion expands and fuses into a large irregular patch. Petiole, stem, and flower axis infected with linear or oval lesions, dark brown to dark brown, sometimes with a yellowish water-stained halo.
The pathogen Cercosporidium state of Mycosphaerlla berkeleyi WAJinkins called the Physalospora phase of the shell of the groundnut. Synonyms Cladosporium personatatum, Cercospora personata, etc. The fruiting body was born on both sides of the leaf, mostly on the back of the leaf. The pedestal was born under the epidermis, nearly spherical or elongated, brown to black, 75-197μm wide. The conidiophore stems are very densely clustered, ranging from dark brown to black smoke, uniform in color, with regular width, upright or slightly curved, with 1-3 knees, no branching, smooth, obvious scarring, thick and thick. Prominent, 1.8-3.1 μm wide, located at the vertices, with 0-1 diaphragms, size 16-59.64.4-7.9 (μm). Conidia dark blue, terete, club-shaped, erect or slightly curved, obtuse top, base inverted
The cone is truncated and the basal umbilicus is distinct, with a width of 1.9-3.1 μm, with 1-8 septa, more often than 5, not constricted, and size 18.1-695.2-8.8 (μm). In addition to harming peanuts, it also harms legumes.
Transmission routes and pathogenic conditions The pathogens may overwinter on the sick or sick body with their seats or mycelial masses, but they may also live through the ascendum in diseased tissues, but this is not the main source of primary infection. In appropriate conditions, the conidia are transmitted by wind and rain, and the spores fall on the leaves of the peanuts. When they encounter suitable temperature and water droplets, they germinate and produce germ tubes, penetrate the epidermis directly into the tissues, and produce branch-type suction devices to obtain nutrients. The temperature limit for the growth of bacteria is 10-37°C, and the optimum temperature is 25-28°C. It is rainy in autumn, humid in climate and heavy in disease. Infertile soil, continuous cropping field easy to disease. Aging organs are heavy; the bottom leaves are heavier than the upper leaves. Luhua No. 3, Haihua No. 1, and small creeping species are susceptible to disease.
Control methods (1) Selection of resistant varieties such as Zhanyou No. 1, Nonghua No. 26, Zhonghua No. 2, Yanyu 101, P12, Shanhua No. 2000, Luhua No. 6, No. 9, No. 11, No. 13 and No. 14 No. 23, Yueyou No. 3, Langjiang No. 3, large stems, a nest of monkeys, etc. (2) Promote the use of compost or fermented organic fertilizer made from fermented bacteria. The use of formula fertilization technology, increase phosphorus and potassium fertilizers, improve resistance to disease. (3) Rotate 2-3 years with other crops. (4) Strengthen field management. (5) Spray 70% thiophanate-methyl (thiophanate-methyl) WP in the early onset of the year 1000 solution or 50% Benzoate (Benzoxacrine) WP 1500x, 50% carbendazim wettability Powder 900-1000 times liquid, 70% chlorothalonil wettable powder 600-800 times liquid, 40% chlorothalonil suspension (Shuntianxing No. 1) 600 times liquid (Beijing Shunyi County Pesticide Factory), 80% spray grams Wettable powder 600 times liquid, 70% mancozeb WP wettable powder 400-500 times, agricultural resistance 120 water 200 times, 50% colloidal sulfur 200 times, 1:2:200 times Bordeaux mixture, spray When adding the drug, 0.2% detergent should be added as a spreading agent. The interval should be 15-20 days and it should be protected 2-3 times.
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