Wheat downy mildew is a fungal disease. It occurred in 2004 and 2005 in some cities and counties in south central Hebei Province. It has become an emerging disease that affects the safe production of wheat in our province. Generally, the rate of field disease is about 15-30%. The rate of serious diseased plants is as high as more than 80%. The three types of wheat fields with weak soils and weak growth are particularly serious and pose a great threat to the high quality and high yield of wheat. I. Symptoms of the disease Wheat downy mildew is also called yellowing and atrophy. It is infected at the seedling stage, and the diseased seedlings are dwarfed. The leaves are light green or have a slight stripe mosaic. After returning to jointing, the diseased leaves became lighter, and the yellowish-white stripe pattern was present. The leaves became thicker and wrinkled and twisted. The diseased plants were dwarfed, and the headings or spikes couldn't be arched beside the flag leaf sheaths and bent into the deformed leading spikes. The 1000-grain weight of diseased strains at various levels fell by an average of 75.2%. Second, the cause of the disease 1, the appropriate temperature and flood conditions conducive to disease. Crop seedling stage is the main infection period of wheat downy mildew. After wheat sowing, the wheat field before budding was flooded for more than 24 hours. In March of the following year, it was cold and cold. The low temperature is conducive to the disease, and the low-lying land is susceptible to disease. Due to improvement of water pouring conditions in recent years, the area of ​​water pouring is large, especially flood irrigation, large amount of irrigation water, long flooding time, and most of the surface is covered by corn stalks returning to the field, moisture retention, extremely conducive to disease The epidemic occurred. 2. The sowing date is late, the tillering rate is low before winter and the seedlings are weak. The vast majority of farmland in central and southern Hebei Province is a cropping system for "wheat-maize" rotation. Due to more rainy days in late September and late September 2005, the temperature was low and the maize harvest was late, and the rush was not timely. As a result, some plots were planted late, the tillering rate was low before winter, the seedlings were weak, and the resistance was low. Disease occurs. 3. Reapply nitrogen and phosphate fertilizers, and the soil generally lacks potassium. Due to the emphasis on the application of nitrogen and phosphate fertilizers for many years, little or no potassium fertilizer was applied, so that most plots lacked potassium, resulting in poor stress resistance and low resistance during the fertility period of wheat, which was beneficial to disease occurrence. Third, control methods 1, agricultural measures prevention. It should be based on agricultural measures. In the seedling stage of wheat sowing, we must do the irrigation without flooding, and use drowning or quick-irrigation speeding. It is advisable to control the amount of water to be soaked on the day so as to avoid accumulation of water in the field. If there is cold current, the temperature is too low, and the sky should be cloudy. Be careful not to water it temporarily. Improve the quality of soil preparation and sowing, pay attention to the removal of weeds in the field to increase the drainage and ventilation of the soil and promote the rapid growth of wheat plants. Combined use of formula fertilization technology, a comprehensive balance of soil nutrients, appropriate sowing, cultivating strong seedlings, increase plant resistance to cold and disease resistance, reduce the chance of pathogen infestation. 2, chemical control. Before sowing, 50 kg of wheat seeds can be soaked with 25% metalaxyl WP, 100-150 g of water and 3 kg of water. If necessary, spraying 0.1% copper sulphate solution or 58% metalaxyl MnZn WP 600 times solution and 72.2% Propomethacin 600x solution in the initial stage of disease can effectively control the downy mildew of wheat.
Pu Glove,Work Glove,Safety Glove
Fenghua Jade Motor Co., Ltd. , http://www.xwgloves.com