Wheat powdery mildew is a kind of epidemic disease, which is affected by weather conditions. Especially when the temperature of wheat is late at the late growth stage, the temperature is too low, which will prolong the epidemic phase of powdery mildew and aggravate the disease. The group is too big, and the wheat field with excessive nitrogen fertilizer application, especially the large-scale planting of susceptible varieties, is very susceptible to epidemics. The continuous continuous rainy weather in recent days poses a potential threat to the epidemic of wheat powdery mildew. Therefore, we must organize inspections and timely prevention and control to control the occurrence of powdery mildew. 1. Symptoms are mainly caused by damage to the leaves. When the disease is severe, it can also damage the leaf sheath, stem and ear. From seedlings to adulthood can occur. In the middle and late stages of wheat, heavier, filamentous white moldy spots grow in the early stage of the lesions, and the surface layer of the mold layer gradually thickens and becomes villous. The color gradually changes from white to gray, which is the pathogenic conidiophore stems and points. Spores. Scattered black dots later. Second, the incidence conditions 1. Climatic conditions. Wheat powdery mildew can be affected from autumn to adult growth in wheat, and the epidemic period is from May to June. In general, more rainy days, higher humidity, and lack of light are the major habitat conditions for severe powdery mildew. 2. Cultivation management. The incidence of early sowing of wheat in the early sowing field was heavy; the population was too large and the disease was heavier than the group's reasonable field; irrational fertilization would aggravate the occurrence of diseases, and the high fertilizer and water, especially the partial application of nitrogen fertilizer fields, would cause serious diseases. A large amount of nitrogenous fertilizer was applied to the late growth stage of wheat and the incidence was also severe. Third, control methods 1. Agricultural control. According to variety and fertility, sowing should be reasonably arranged at the time of sowing, postponing sowing time, controlling groups should not be too large, increasing phosphorus and potash fertilizers, rational fertilizing and watering, and strengthening field management to promote strong wheat growth. 2. Chemical control. When the diseased leaf rate reaches 15%, 50 ml of 20% triadimefon EC or 15% of triadimefon can be used per mu, and 40 to 50 kg of water can be sprayed on the middle and lower parts of wheat.
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