How to prevent and cure the white blight of green onions?

Onion white blight is a fungal disease. The pathogen mainly overwinters in the soil with chlamydospores. When the conditions are suitable in the next spring, sporangia are produced. It is transmitted by irrigation water or wind and rain. The newly produced zoospores on the disease spot and the ground are transmitted by raindrops. The seedling stage and adult plant stage can all be affected. The harmful parts are onion leaves. Let's take a look at how to prevent and control onion white blight.

White onion disease symptoms

The white blight of scallion can occur in seedling stage and adult plant stage. There are dark green spots in leaf sheath and leaf body of seedling stage and adult plant infected, and then gradually expand to large greenish-white spots of 5~10 cm. The center of the spots is white to gray, and the spots extend to the leaf tips and gradually dry and droop. In the early stage of disease, the disease is mostly at the same height, which is different from blight and gray mold.

Condition of white blight of Chinese onion

The pathogen overwinters mainly as chlamydospores in soil. When the conditions are suitable in the next spring, sporangia are produced and transmitted by irrigation water or wind and rain. The zoospores newly produced on the disease spot and on the ground are transmitted by raindrop sputtering. Generally, it starts from May to June. With the arrival of rainy season, the disease is aggravated. It is easy to occur in rainy weather in summer. The drainage is not timely after rainstorm. The disease is serious due to accumulated water, excessive nitrogen fertilizer or excessive plant growth.

How to prevent and control white onion blight?

1. Choose high foot white, chicken leg onion, Wuyeqi, Bikeqi onion, Zhangqiu Wutong and other resistant varieties.

2. Onion and garlic vegetables should not be planted in the affected area within 2~3 years. After harvest, attention should be paid to removing the sick and disabled bodies, and they should be buried deeply or burned.

3. Adopt high ridge or ridging cultivation, cultivate soil in time, and try to avoid contact between onion seedlings and water.

4. Compost made by enzyme bacteria should be applied, and less available nitrogen should be added to enhance plant disease resistance.

5. At the early stage of disease, spray 30% Lvdebao suspension agent 400~500 times solution or 77% Kexide wettable particle powder 500 times solution, 60% succinic acid·ethyl phosphorus aluminum wettable powder 500 times solution, 72% Kexu wettable powder or 72% cymoxanil manganese zinc wettable powder, 72% Kexu wettable powder 800 times solution, once every 10 days or so, control once or twice. When resistance to the above fungicides occurs, 69% Anke Mangzinc wettable powder or 1000 times water dispersible granules can be used instead.