How to prevent downy mildew from growing edamame beans

Introduction of downy mildew of edamame bean

[symptom characteristics] mainly harms the leaves. Yellow-white to yellow irregular spots appeared on the leaf surface, and gray loose mold layer symptoms (cyst peduncle and sporangium) appeared on the back of the leaves, and the leaves dried up and fell off in severe cases.

[pathogen and pathogenic characteristics] the pathogen is Peronosporaman-schurica (Naum.) Syd.exGaum. The pathogen overwinters as oospores on diseased remains or seeds. When the conditions were suitable in the following year, the oospore germinated and produced sporangia, which released zoospores, which were spread by Rain Water sputtering and invaded from the embryonic stem to form systematic infection. After the disease, new sporangia formed on the diseased leaves, germinated and released zoospores, and spread with the help of wind and rain. In the growing season, re-infection occurred many times and the disease spread. The disease is easy to spread when the temperature is usually 20-24 ℃ and the weather is rainy and humid. The difference of disease resistance among varieties is unknown. Among the nearly 50 edamame bean varieties introduced in China in recent years, some varieties with strong disease resistance, such as Lu Qingdou 1 (87-5, Shandong), May and June pulls out (Zhejiang local species), Edou 4 and 5 (Hubei), Wuxiang edou (August and September, Zhejiang), Iwate green edamame bean (Riyin), Zhoudou 30 (Hubei and Hubei) are also resistant to downy mildew, it remains to be further observed.

Prevention and control of downy mildew of edamame bean:

The main results are as follows: (1) selecting improved varieties with disease resistance and high yield according to local conditions.

(2) seed disinfection before sowing (seed treated with 35% metalaxyl of 0.3% seed weight or 72% Kloe wettable powder, or 69% Anke manganese zinc wettable powder).

(3) reasonable close planting, good management of fertilizer and water, improvement of inter-plant permeability and enhancement of plant resistance.

(4) timely spraying to prevent and control the disease. When the plant is close to being closed, starting at the latest time of disease, spray 25% metalaxyl wettable powder 600-700 times, or 40% ethyl phosphorus aluminum 200 times, or 72% Kelu wettable powder 600-800 times, or 69% Anke manganese zinc wettable powder 600-800 times, or 64% poisonous alum wettable powder 600 times, 1-2 times or more, spray alternately, spray evenly.