Prevention and control of sunflower downy mildew

(1) to establish disease-free farming. It is strictly forbidden to introduce species from disease areas and do everything possible to protect disease-free areas. (2) rotation with Gramineae crops for 3-5 years. (3) selecting resistant varieties such as Liaokui 2, Fenkuiza 2, Kang3A × Hui6, CM592 and so on. (4) if downy mildew is suspected, the endocarp and seed coat of sunflower should be tested to determine the carrying rate. The seriously affected areas were mixed with 25% metalaxyl with 0.5% seed weight. (5) sowing at the right time should not be too late, the density is appropriate, and should not be too dense. Diseased plants found in the field should be pulled out and sprayed or irrigated in time to prevent the disease from spreading. (6) after seedling or adult disease, spray 58% metalaxyl manganese zinc wettable powder 1000 times or 64% alum M8 wettable powder, 25% metalaxyl wettable powder 1000 times, 40% Ruidui wettable powder 600800 times, 72% DuPont Kru or 72% frost urea manganese zinc or 72% frost urea manganese zinc or 72% Shuangba wettable powder Areas that have developed resistance to the above-mentioned fungicides can be changed to 69% ampere ·manganese-zinc wettable powder 900-1000 times.