In recent years, with the improvement of fertilizer and water conditions in wheat fields and the increase in population density of high-yield fields, the incidence of wheat powdery mildew has increased year by year. After parasitic wheat with powdery mildew, the respiration of plants increased, the transpiration intensity increased, and the photosynthetic efficiency decreased, which seriously affected the normal growth and development of wheat. The early leaves of wheat, the tillering and ear-forming rate decreased, and the 1000-grain weight decreased, resulting in reduced yield. According to the China Pesticide Network , wheat is endangered by powdery mildew, and serious fields can reduce production by 20% to 30%.
Symptoms of wheat powdery mildew: mainly occur on leaves, and can also occur in plant sheaths, stems and ears. Generally, the frontal lesions of the leaves are more than the back of the leaves, and the lower leaves are heavier than the upper leaves. The surface of the diseased part is covered with white powdery mildew. The diseased part first appears white filamentous mildew, gradually enlarges and combines with each other, and has a long oval-shaped moldy spot. In severe cases, it can cover most or even all of the leaves. The layer thickness can be up to 2 mm and gradually powdery. In the later stage, the mold layer gradually changed from white to gray, and the black particles were produced. The leaves turn yellow in the early stage, and the curls die. The seriously diseased plants are often dwarfed and unable to head.
The occurrence and development of wheat powdery mildew is closely related to meteorological conditions, variety resistance and cultivation management level. When the temperature is between 15 and 20 ° C and the relative humidity of the field is above 70%, the disease develops rapidly. When the fog is heavy and the temperature rises, the disease is serious, and the humidity in the field is conducive to infection. Excessive application of fertilizer and water, excessive growth of wheat, excessive population density, dense air, high humidity in the field, young plants, low disease resistance, and powdery mildew are also prone to occur.
Control method:
1. Selection of resistant varieties is an effective method.
2. Eliminate the source of initial infection, such as killing the self-produced wheat seedlings or the grass-side weeds before planting.
3. Rational fertilization and close planting, nitrogen, phosphorus and potassium fertilizers should be applied in a balanced manner, and appropriate increase of phosphorus and potassium fertilizer should be carried out. The density should not be too large, pay attention to the ventilation and light transmission in the field.
4. Pesticide control.
The use of pesticide control can receive obvious effects of stopping the spread of the disease. The frequency and time of application can be determined according to the onset of the disease, the severity of the disease and the type of the drug. Generally, the medicine is started from the jointing stage to the booting to the heading, and it is sprayed every 7~10 days. A total of 2~3 times can be used to receive good results. The types of drugs include carbendazim, thiophanate, retort, and triazol.
This article is published by the China Pesticide Network , please indicate the source.
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