How to prevent and control peanut bacterial wilt? Detailed explanation of prevention and control methods

1. Symptoms. Peanut bacterial wilt mostly begins to develop around flowering, but the disease is most severe during the peak flowering and pegging stage, and the condition eases somewhat after pod formation. The most notable feature of its symptoms is: the aboveground leaves of diseased plants wilt rapidly, the vascular bundles in the underground roots turn brown, and when the root crown is cut lengthwise, in moist conditions a cloudy bacterial ooze can be squeezed from the cut. If the diseased root crown section is suspended and immersed in clear water, a smoky cloudy liquid can be seen gushing from the cut, which is a reliable basis for confirming this disease. Usually the chlorophyll of the wilted leaves has not yet been destroyed, and although the leaves lack gloss, they still remain green, hence the name bacterial wilt.

2. Disease occurrence pattern. The pathogenic bacteria of bacterial wilt mainly overwinter in the soil, and can also overwinter in diseased residues and soil mixed with organic fertilizer. Diseased soil and diseased fertilizer are the main primary infection sources for the disease the following year. The pathogen spreads through soil, rainwater, irrigation water, and agricultural activities, and invades through wounds or natural openings in the host roots and stems. The occurrence and epidemic of the disease are closely related to factors such as weather, soil, cropping system, plant growth stage, and variety resistance. High temperature and heavy rain, especially alternating clear and rainy weather, or long drought followed by sudden rain, or drastic changes in soil temperature and moisture, are most likely to induce this disease; shallow soil layers, coarse sandy soil with poor water and fertilizer retention, or yellow clay soil with poor permeability are all favorable to disease development; continuous cropping fields have more severe disease than rotated fields; excessive or one-sided application of nitrogen fertilizer makes the disease more likely; trailing-type varieties are more resistant than erect-type and pearl bean-type varieties; southern-type varieties are more resistant than northern-type varieties. Disease incidence from around flowering to pod formation accounts for more than 70% of the total incidence during the whole growth period. 

3. Prevention and control measures (1) Reasonable crop rotation. It is best to implement paddy-upland rotation, or at least dryland rotation with sugarcane, sweet potato, etc. The rotation period depends on the severity of the disease. (2) Select resistant varieties. Varieties such as Xiekangqing No. 10, No. 11, Tianfu No. 11, Yuhua No. 14, Yuanza 9102, Yueyou 589, 320, Guiyou No. 28, Quanhua 3121, and Taishan Pearl Bean can be selected according to local conditions. (3) Strengthen cultivation management. Deep plow and sun the soil or introduce water to soak the field (the longer the better); improve drainage and irrigation systems to enhance the field's ability to prevent waterlogging and resist drought, prevent cross-irrigation, appropriately increase lime application to adjust soil acidity; promptly remove central diseased plants, pay attention to field sanitation; use formula fertilization, avoid one-sided nitrogen application, and do not apply soil mixed with organic fertilizer containing diseased residues. (4) Use spot treatment by spraying liquid medicine to block the disease center. For the disease center, you can try 20% oxolinic acid 1000-fold solution, or potassium permanganate 600-fold solution, or copper-ammonia solution 600-fold solution, continuously spraying the diseased holes and adjacent healthy plants 2-3 times or more, which has a certain effect on blocking the disease center and controlling the spread of the disease.