For field crop spraying, the factors that affect the field disease prevention effect of fungicides are no more than three aspects: pesticides, environment, and crops. However, the application technology of fungicides is more demanding than that of pesticides and herbicides, especially It is necessary to fully understand the law of occurrence and development of diseases, because the occurrence and development of diseases are not as clear as insects and weeds.
Pay attention to two points when spraying pesticides on field crops: First, the type and concentration of pesticides. The choice of the type of medicine depends on the type of disease, so the correct type of disease diagnosis must be made before the right medicine can be prescribed. For example, rice blast disease can choose rice blasting, rice blasting, tricyclazole, etc., wheat powdery mildew, rust disease should choose triadimenol, triadimefon, etc., peanut leaf spot disease should choose thiophanate methyl and so on. However, it should also be noted that if the same disease occurs on different crops, sometimes the same agent cannot be used. For example, Bordeaux mixture can prevent and control downy mildew, but it is easy to cause phytotoxicity to cabbage, so it is not suitable to control cabbage downy mildew. After the choice of the type of medicament, the appropriate application concentration should be selected according to the type and growth period of the crop, the type and dosage form of the fungicide, and environmental conditions.