Symptoms: The disease mainly damages the leaves and can also invade the tubers. At the time of initial onset, some sporadic brown spots were found on the leaves, and the lesions gradually expanded and irregularly shaped, with concentric rings on top. There is a narrow fading halo around the lesion. When the disease is severe, the leaves of the plant gradually dry off from the bottom up, and only a few leaves at the top remain green.
Transmission route and onset rule: The disease is caused by the infection of the genus Alternaria subgenus Alternaria genus. The pathogens overwinter with the diseased tissues in the soil, and they can also overwinter on the lesions of the potato block. Conidia can survive for a long time, spread by wind and rain, and undergo repeated infections during host growth. The high temperature is beneficial to the infection of the early blight bacteria; the old leaves of the lower part of the plants that are degraded and debilitated are susceptible to disease; the land of the infertile and lacking fertilizers is heavy.
Control methods 1. Seed selection: Select early-maturing disease-resistant varieties, appropriate early harvest. 2. Selection of land: Choose to plant in fertile soils and high land areas. 3. Fertilization: Increase organic fertilizers, increase phosphorus and potassium fertilizers, and increase plant disease resistance. 4. Chemical control: At the beginning of the disease, use 75% chlorothalonil WP/600 times for every 667 square meters, 64% antitoxic WP for 500 times, or 77% for WP 500 times. Liquid spray, spray once every 7 to 10 days, continuous spray 2 to 3 times.
The level of IgM antibody begins to rise after 1 week after the initial infection, while the IgG appears later than IgM (usually in 14 days after infection) and can last for 6 months or even several years, which meansthat the IgG serves as an indicator of previous infection. Suspected patients that are infected by 2019-nCoV can be rapidly identified by simultaneous monitoring of IgM and IgG. During the outbreak period of2003-SARS and the 2016-Zika, IgM / IgG antibody detection was used as one of the recommendeddiagnostic methods.
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