How to prevent and cure the disease of leek

Leek blight is a fungal disease, caused by tobacco Phytophthora infection. Once the disease occurs, the disease occurs rapidly, spreads quickly, and the whole field is destroyed in a short time, resulting in losses.

Leek blight

The disease can occur in the whole plant of leek, especially in pseudostem and bulb. The disease began to appear dark green watery spot, the spot expanded rapidly, the disease part lost water, constricted, thinned, the leaf yellowed, withered and drooped, resulting in soft rot and leaf sheath shedding. When the humidity is high, the disease grows into a white sparse mildew layer. When the bulb occurs, the stem disk first appears watery, and then becomes light brown and dark brown, and decays quickly. Root disease, brown rot, reduced root hair, leek stopped growing and withered.

The blight of leek is caused by re-infection caused by sporangia spread by wind and rain, irrigation water and dripping water in greenhouse film. The suitable temperature for the disease is 2532 ℃, and the relative humidity is more than 90%. The disease is serious in leek with water droplets in the greenhouse film. During the root cultivation period in the open field, the disease is serious in case of heavy rain or heavy rainfall.

Prevention and control methods:

1. Agricultural prevention and control. When building a shed, the drip-free film should have strong pulling force and good light transmittance. In the open field root maintenance period, after the precipitation, timely discharge of stagnant water, ventilation and dampness. The application of nitrogen fertilizer should not be excessive, and the planting density of leeks should not be too high, so as to avoid delicate leeks and poor disease resistance. When watering, a small amount of water should be watered carefully to prevent flooding. It is necessary to ventilate and reduce humidity in time.

two。 Chemical control. In the early stage of the disease, spray in time, the agent can choose 25% metalaxyl wettable powder 750 times liquid, or 58% metalaxyl manganese zinc wettable powder 500 times liquid, or 64% poisonous alum wettable powder 400 times liquid, or 77% can kill 500 times liquid, or 80% Dasheng wettable powder 600 times liquid, or 72.2% Prike water agent 800 times 1000 times liquid, or 90% plague wettable powder 700 times liquid. Spray every 7 days for 2 times in a row. The leek root can also be irrigated with copper sulfate 500 × 1000 times and metalaxyl wettable powder 1000 times.