(1) Incidence pattern: Grape downy mildew is a disease caused by fungi. The pathogenic bacteria live in the soil in diseased tissue, buds, or with diseased leaves. When conditions are appropriate in the following year, winds and rain will spread to the leaves of the host, which will invade from the stomata and lenticels, and can be repeatedly infected. Dew rain is the primary condition for invading bacteria. Therefore, the occurrence and prevalence of diseases are easily caused in environments with low temperatures, heavy rain, or heavy fog. Plants too dense or shed too low, poor ventilation and light transmission, partial application of nitrogen fertilizer, declining tree vigor, etc. are also conducive to differences in disease resistance varieties, the general grape system in the Americas is more resistant to disease, the European system grapes are susceptible to disease. (2) Control measures: 1 Strengthen orchard management. In the late autumn, the diseased leaves, diseased fruits, and diseased shoots are removed, burned or buried deeply to reduce the source of bacteria. During the growth period, timely drainage and irrigation should be conducted, and reasonable pruning should be carried out. Phosphorus and potassium fertilizers should be applied to increase the disease resistance of plants and reduce the chance of pathogen infestation. 2 spray protection. In the early stage of disease-causing varieties in the garden, spray 1:10:200 times Bordeaux fluid or 40% EB aluminum wettable powder 300 times, spray once every half month or so, and spray 2 to 4 times. It is also possible to use 25% of Rhizoctonia WP or 65% of zein zinc wettable powder 500 times of liquid, 65% of thiram zinc wettable powder 500 times.
Guofu Technology Group Co., Ltd , https://www.guofufarm.com