A Detailed Guide to the Latest Control Measures for Downy Mildew of Chinese Kale

Downy mildew of Chinese kale is a major disease in Chinese kale production. It is widely distributed and commonly occurs; symptoms generally affect up to 20% of the crop, and in severe cases the entire greenhouse is affected, causing total crop loss. It can also harm other cruciferous crops, so how should downy mildew of Chinese kale be controlled? Let's take a look together.

1. Symptoms

This disease occurs at every growth stage of Chinese kale, and is more severe at the seedling stage. It mainly infects the leaves. When it occurs at the seedling stage, white downy mold appears on the underside of the leaves, and the seedlings turn yellow and die. When it occurs in mature plants, the lesions on the upper surface of the leaves are initially pale green to yellowish white, then gradually turn light brown and become irregular necrotic spots; on the underside of the leaves, small gray-brown dots first appear, and when humidity is high they become water-soaked, or gradually expand into irregular gray-brown to gray-white sunken spots. The pathogen sometimes also invades the stem, and during storage it can also invade the leaf head, producing irregular yellow necrotic spots, and the leaves dry up and fall off.

2. Occurrence Pattern

The pathogen has no obvious overwintering period. It mainly overwinters as mycelium on diseased plant debris or other hosts during winter, or hides on other cruciferous vegetables, and can also overwinter in the soil in spore form. After temperatures rise the following year, it germinates and infects, and after disease develops it produces spores that cause reinfection. In addition, seeds can also carry the pathogen, infecting seedlings after sowing. After infection, the pathogen produces large numbers of sporangia, which spread in the field by wind and rain and airflow, causing the pathogen to expand and spread.

3. Agricultural Methods

① Choose disease-resistant varieties

Choose disease-resistant varieties according to local conditions, such as Zhonghua Chinese kale and Lvbao Chinese kale, which have relatively strong resistance to downy mildew.

② Choose suitable plots

Before planting, it is best to choose plots with deep soil, high and well-drained terrain, convenient irrigation and drainage, and rich in organic matter, and practice a 2-3 year rotation with cruciferous crops, preferably paddy-upland rotation, which can effectively reduce disease occurrence.

③ Seed treatment

Use seed from disease-free plants and disinfect the seeds. Before sowing, treat the seeds with thiram or chlorothalonil seed dressing, which can provide excellent sterilization.

④ Clean the field in time

After harvest, clean the field in time, remove diseased leaves and diseased plant debris from the field, and at the same time plow the soil deeply to reduce the source of inoculum in the field. This is even more important for seed-production fields.

4. Chemical Control

Do a good job of disease forecasting. At the early stage of disease or when central diseased plants appear, spray immediately to control it. Available agents include chlorothalonil, yishuangling, anilazine, zineb, fosetyl-aluminum, sandofan, and others. Use the above agents alternately, spraying evenly and thoroughly. Do not use pesticides within 15 days before harvest. In protected cultivation, chlorothalonil smoke agents can be used; when smoking, doors and windows must be closed.

  The above is an introduction to the control measures for downy mildew of Chinese kale. We hope it can help you. To learn more related knowledge, please follow us.