Control of powdery mildew of growing wheat

In recent years, with the improvement of fertilizer and water conditions in wheat fields and the increase of population density in high-yield fields, the incidence of wheat powdery mildew increased year by year. After the wheat was parasitized by powdery mildew pathogen, the plant respiration increased, the transpiration intensity increased, and the photosynthetic efficiency decreased, which seriously affected the normal growth and development of wheat, the early withering of wheat leaves, the decrease of spike rate, the decrease of 1000-grain weight and the decrease of yield. According to the investigation, wheat is damaged by powdery mildew, and the yield of serious fields can be reduced by 20% to 30%.

Symptoms: wheat powdery mildew mainly occurs in leaves and can also occur in leaf sheaths, stems and ears of plants. Generally speaking, the disease spot on the front of the leaf is more than that on the back of the leaf, and the disease in the lower leaf is more serious than that in the upper leaf. The white powdery mildew layer on the surface of the disease part first appeared white filamentous mildew spot, which gradually expanded and combined with each other, showing a long oval large mildew spot, which could cover most or even all of the leaves in severe cases, and the thickness of the mildew layer could reach about 2 mm. And gradually showed powder. In the later stage, the mildew layer gradually changed from white to gray, and the upper black particles. The leaves turn yellow in the early stage, curl and die, and seriously diseased plants are often dwarfed and unable to heading.

The occurrence and development of wheat powdery mildew is closely related to meteorological conditions, variety resistance and cultivation management level. When the temperature is 15: 20 ℃ and the field air relative humidity is more than 70%, the disease develops rapidly. When the fog is heavy and the temperature rises, the disease is serious, and the high humidity in the field is beneficial to the infection. Excessive application of fertilizer and water, excessive growth of wheat, excessive population density, airtight, high humidity in the field, young plants, low disease resistance, but also prone to powdery mildew.

Prevention and control methods:

1. Selection of disease-resistant varieties is an effective method.

two。 Eliminate primary infection sources, such as autogenous wheat seedlings or Gramineae weeds on the edge of the field as far as possible before sowing.

3. Reasonable fertilization and close planting, balanced application of nitrogen, phosphorus and potassium fertilizer, appropriate increase of phosphorus and potassium fertilizer, density should not be too high, pay attention to ventilation and light transmittance in the field.

4. Chemical control.

The obvious effect of stopping the spread of the disease can be obtained by using pesticide control, and the frequency and time of pesticide application can be determined according to the time and time of the disease, the severity of the disease and the type of medicine. Generally, from jointing stage to booting stage to full heading stage, the medicine is sprayed every 7-10 days, and a total of 2-3 times can be sprayed to get good results. The types of drugs are carbendazim, topiramate, triazolol and so on.