Control methods of Apple powdery mildew

Apple powdery mildew occurs commonly in apple producing areas in China. In addition to harming apples, it also harms pears, sand fruits, begonias, penang seeds and mountain stators. It is harmful to the seedlings of mountain stators, small apple seeds, begonias and apple varieties such as Japanese brocade, Zhu, Hongyu and Guoguang. Let's take a look at the control methods of apple powdery mildew together.

occurrence conditions of

When winter buds germinate in spring, conidia produced by overwintering hyphae are infected by air flow. April to September is the occurrence period of powdery mildew, April to May is the peak occurrence period when the temperature is lower. From June to August, the disease occurred slowly or stagnated, and the second peak occurred in September when the autumn shoots germinated. Warm and dry spring, rainy and cool summer, sunny autumn are beneficial to the occurrence and epidemic of powdery mildew, continuous rain will inhibit the occurrence of powdery mildew. The orchard with high planting density, closed crown, poor ventilation and light transmission, partial application of nitrogen fertilizer and weak branches has serious disease. When pruning branches do not head, long put, retain carbon overwintering disease bud, disease heavy.

hazard symptom

1. Young shoots: the growth of young shoots is inhibited, the internodes are shortened, the leaves attached to them become narrow or not open, become hard and brittle, the leaf edges are rolled up, the initial surface is covered with white powder, and the later stage gradually becomes brown, and the serious whole shoots die.

2. Leaves: sparse white powder appears at the beginning of the back of the leaf, the new leaf is slightly purple, wrinkled and deformed, the white powder layer gradually spreads to the front and back sides of the leaf in the later stage, the color of the front side of the leaf is uneven, the white powdery spots appear on the back of the leaf, the diseased leaves become narrow and long, and the edges are wavy and wrinkled or the leaves are uneven. When the disease is serious, the leaves gradually turn brown from the tip or edge of the leaves, and finally the whole leaves dry and fall off.

3. Flowers: Apple flower organ is damaged, calyx depression or peduncle depression produces white pink spots, sepals and pedicels become deformed, petals are narrow and light green. The female and stamen of the victim flower lose their function, cannot pollinate and set fruit, and finally dry up and die.

4. Young fruit: Apple young fruit is mostly damaged near the calyx, white powder spots are produced at the calyx depression, the diseased part hardens, the white powder falls off after the fruit grows up, forming network rust spots, and the hardened tissue forms cracks or cracks in the later stage.

control methods

1, winter shear to thoroughly cut off the disease tips, spring and summer careful inspection, found that the disease tips cut off in time, into plastic bags sealed, take out the orchard to focus on burning or deep burial. Reasonable close planting, improve ventilation and light transmission conditions, reduce the incidence of disease. At the same time, appropriate control of nitrogen fertilizer application, attention to nitrogen, phosphorus, potassium coordination, increase phosphorus, potassium fertilizer,

2. Apple trees must be cleaned before germination, such as stone sulfur mixture, Guoguang cyprodinamine, methyl thiophanate-methyl, etc. spray 15% Guoguang Triadimefon 1000~1500 times solution or Guoguang Baixiu 1000 ~1500 time solution for that first time after apple flower dew red stage and flower drop.

3. Spraying 5 times of medulo-sulfur mixture before budding and 1 time of medulo-sulfur mixture at budding stage, spraying 25% triadimefon WP or 20% triadimefon EC 2000 times solution and 12.5% terprozole 2000 times solution at the early stage of disease in spring, once every 10~20 days, totally 3~4 times.

4. Spray "Fruit and Fruit Zhuangdiling" once before apple flowering, young fruit stage and fruit expansion stage respectively to improve fruit expansion vitality and nutrition matching function by thickening fruit tree nutrient transport vessels and increasing nutrient delivery, so as to achieve the goal of flower protection, fruit protection, strong fruit and more fruit setting.

5. Spray 3000~5000 times solution of 15% triadimefon wettable powder or 1500~2000 times solution of 15% triazole wettable powder. If powdery mildew occurs seriously and the diseased shoot rate reaches 15%, 15% triadimefon can be sprayed at 1000~1500 times night or 70% thiophanate-methyl at 1000 times liquid.