Control methods of wheat powdery mildew

Wheat powdery mildew is a worldwide disease, which is distributed in major wheat-producing countries. It is common in the coastal areas of Shandong, Sichuan, Guizhou and Yunnan, and is becoming more and more serious in Northeast, North and Northwest wheat regions in recent years. It can damage the aboveground organs of wheat plants, but mainly leaves and leaf sheaths, and glumes and awn can also be damaged when the disease is serious. Let's take a look at the prevention and control methods of wheat powdery mildew.

Harmful symptoms

Wheat powdery mildew can damage the aboveground organs of wheat plants, but mainly leaves and leaf sheaths, and glumes and awn can also be damaged when the disease is serious. At the beginning of the disease, a white mildew spot of 1mm to 2mm appeared on the leaf surface, and then gradually expanded into a nearly round to oval white mildew spot, with a layer of white powder on the surface of the mildew spot, which flew away immediately in case of external force or vibration. These powdery substances are the mycelium and conidia of the bacteria. In the later stage, the mildew layer of the disease became grayish white to light brown, and there were small black spots the size of needles, that is, the closed capsule of the pathogen.

Disease condition

The pathogen of spring disease in winter wheat area is mainly from the local, spring wheat area, not only from the local bacterial source, but also from the adjacent areas with early onset. The occurrence of the appropriate temperature is 15-20 ℃, the onset is slow below 10 ℃, and the relative humidity is more than 70% may cause the epidemic of the disease. In less rainy areas, the disease is serious if there is more rain in that year. In rainy areas, if there is too much rain, the disease slows down, and the surface conidia are washed away by continuous rainfall. Excessive nitrogen application results in greedy green plants and serious disease. Improper management, lack of water and fertilizer, dry land, weak plant growth, low disease resistance, also prone to the disease, in addition to high density and serious disease.

Prevention and cure method

1. Planting disease-resistant varieties can be selected according to local conditions. For example, Beijing winter wheat is now mainly planted in Jing411, and Jingdong 8, Jingdong 6 and Zhongmai 9 are planted in high-fertilizer wheat fields. Drought-resistant and barren-tolerant varieties such as Jing437, Jinghe 1 and Lunkang 6 are planted with poor medium fertilizer and irrigation conditions, and Jing411, Jingdong 8 and Jingshuang 18 can be selected for rice stubble wheat and late sowing wheat fields.

2. It is recommended to apply compost or mature organic fertilizer retted by enzyme bacteria, adopt formula fertilization technology, properly increase phosphorus and potassium fertilizer, and reasonably close planting according to variety characteristics and soil fertility. Timely drainage after rain in the southern wheat area to prevent moisture retention. The northern wheat area was watered at the right time to enhance the disease resistance of the host.

3. In the over-summer area of authigenic wheat seedlings, winter wheat should be cleared before autumn sowing, which can greatly reduce the bacterial source of autumn seedlings. Seed weight 0.03% (active ingredient) 25% triadimefon (triadimefon) wettable powder is used to mix seeds, or 15% triadimefon wettable powder 20g / 25g mixed with 667m2 wheat seed to control powdery mildew, smut, stripe rust and so on.

4. In areas where there are few resistant wheat varieties or large variation of pathogen races and rapid loss of resistance, when the disease index of wheat powdery mildew reaches 1 or the rate of diseased leaves reaches more than 10%, 20% triadimefon EC 1000 times or 40% Fuxing EC 8000 times can also be sprayed according to the field conditions. Insecticides can also be mixed to achieve one-time use in the critical period, and to treat major diseases and insect pests such as wheat powdery mildew and rust.

5. In the middle and later stage of wheat growth, when stripe rust, powdery mildew and ear aphid mixed, 7g / mu was used to add pirimicarb 3G plus 150g potassium dihydrogen phosphate. Stripe rust, powdery mildew, trematodes, armyworm mixed areas or fields, 7 grams of active ingredients per mu plus 2000 times of omethoate plus 150grams of potassium dihydrogen phosphate. In the mixed area of scab, powdery mildew and aphid, 40 grams of carbendazim, 7 grams of trimethoprim, 3 grams of aldicarb and 150 grams of potassium dihydrogen phosphate were used per mu.