High humidity at wheat seedlings is favorable for downy mildew

October 13, 2022

Downy mildew is an occasional disease on wheat caused by fungal infection, also known as yellowing and atrophy. Wheat is infected at the seedling stage, the seedlings are dwarfed, and the leaves are light green or have slight stripes. After returning to the joints, the symptoms of the disease are more obvious, the leaf color becomes lighter, and a yellowish-white stripe pattern appears. The leaves become thicker and wrinkled and twisted. The diseased plant is dwarfed, and the heading or ear can not be normally arched beside the flag leaf sheath and bent into a deformed faucet. ear. The stems of diseased plants are thicker than healthy plants and have a thick layer of white frost-like wax on the surface. The diseased leaves are left to moisturize for 14 to 48 hours at 25°C. The surface can grow sparsely frosted.
The pathogenic bacteria used oospores as the disease body to go through the summer or winter in the soil. When the humidity is high, the zoospores produced by the oospore germination spread along with water and invade the growing point from the bud scale or epiblast to infect the system. The germs prefer a warm and humid environment. Appropriate temperature after wheat sowing, high rainfall and high humidity, or flooding in wheat fields are conducive to disease. Low-lying land masses are heavy. Flooding before flooding in winter, long time in the field, can easily lead to downy mildew. Late sowing of wheat, low tillering rate before winter, weak seedlings, poor disease resistance, easy to disease. In some wheat fields, there are pre-warm corn stalks covering the field and moisture retention, which is also conducive to the occurrence of downy mildew.
Wheat downy mildew is mainly spread in soil, mainly in the seedling stage, and prevention and control should focus on comprehensive measures focusing on fertilizer and water management. In the seedling stage of wheat sowing irrigation can not be flooded for a long time, drowning or rapid irrigation speed row, the amount of watering on the end of the day is appropriate to avoid the accumulation of water in the field, if the cold, the temperature is too low, cloudy should not be watered temporarily . Improve soil preparation and sowing quality, remove field weeds, increase soil drainage and ventilation, and promote the growth of wheat seedlings. Combined use of formula fertilization technology, comprehensively balanced soil nutrients, appropriate sowing, cultivating strong seedlings, increase plant resistance to cold and disease resistance, and reduce the chance of pathogen infestation. After emergence of downy mildew strains in the wheat fields, if necessary, it can be used for sprays of arsenic manganese zinc, propamocarb hydrochloride, frost urea manganese zinc and other drugs.

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