Epiphyseal root parts of the leek plants can be disease, especially pseudostems and bulbs the most serious disease. On the pathogenesis of the leaves, dark green water-spotted lesions began to appear, and the lesions spread rapidly. The diseased part shrank and became thinner, the leaves became yellow, withering, and soft rot and sheath shedding occurred. When the humidity is high, the disease minister sparse the white mold layer. When the bulbs were onset, the stems and pans first appeared water stains, which turned into light brown and dark brown, and decay soon. Root disease, brown rot, root hair reduction, plant growth and death.
The disease is caused by wind and rain, irrigation water, and shed film dripping water, causing reinfection. The optimum temperature for pathogenic disease is 25～32°C, and the relative humidity is above 90%. During the cultivation of roots in open fields, the leeks have a severe onset when there is heavy rain or rainfall.
Control methods
1. Agricultural control. When building a shed, use a drip-free membrane with good light transmission. During the cultivation of the roots in the open season, water should be drained in time after rainfall, and the air should be scattered and wet. Fertilizer should be careful not to excessively apply nitrogen fertilizer, and the planting density should not be too large, so as to avoid the delicate leek plants and poor disease resistance. When watering, it is necessary to pour small water and prevent flooding. Ventilate and dampen in time.
2. Chemical control. Early onset of the disease should be sprayed in a timely manner. The agent can be used with 25% metalaxyl WP 750 times, or 58% metalaxyl MnZn WP 500 times, or 64% WP WP 400 times, or 77% can kill WP 500 times, or 80% WP WP 600 times, or 72.2% Proclex 800 to 1000 times, or 90% EVID WP 700 times. Once every 7 days, spray 2 or 3 times. Can also be used 500 ~ 1000 times copper sulfate, 25% metalaxyl wettable powder 1000 times Irrigation root.
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