What are the main diseases of onions? How to prevent and cure it?

Onion is widely cultivated in China, and it is one of the main vegetables in China. So what are the diseases of onions in planting? How to prevent and cure it?

Although onions are widely planted, they are mainly concentrated in Fujian, Shandong, Gansu, Inner Mongolia, Xinjiang and other places in China. Onions contain prostaglandin A, which can reduce peripheral vascular resistance and blood viscosity. It can be used to lower blood pressure, refresh the brain, relieve stress and prevent colds. Onion can also scavenge oxygen free radicals in the body, enhance metabolic capacity, and effectively prevent aging factors. It is a health food suitable for the middle-aged and elderly.

Since onions have so many benefits, what diseases are there in onion cultivation and how to prevent them? Let's learn about onions.

1. Downy mildew

The disease can occur in all stages of onion growth from seedling to harvest, and the damage of adult plant is more serious. The disease generally occurs on the leaves and develops slowly from the leaf base to the leaf. When the air humidity is too high, the frost-like mildew layer visible to the naked eye will appear on the back of the leaves, and when it is serious, the outer leaves will all wither and yellow and die, which is very similar to Verticillium wilt. After the discovery of this disease, on the one hand, dehumidification, excessive air humidity is only one of the causes of the disease, and then 75% chlorothalonil wettable powder 600 times solution can be used for prevention and control.

two。 Purple spot disease

Purple spot disease occurs when more concentrated with the leaves, and then slowly expand, the onset time is more concentrated in the rainy season, so we must do a good job of drainage. At the beginning of the disease, there will be some lavender spots on the top of the leaves, with the spread of purple as the core, brown withered around, and finally the whole plant withered and died. More than 2% antimycin 30ppm agents can be used for prevention and treatment, and the leaf tip should be sprayed emphatically, about an hour before nightfall.

3. Grey mold disease

This kind of disease mainly harms the fruit, and the green fruit suffers seriously. In the early stage of the disease, the residual stigma or petals were first infected, and then extended to the fruit, resulting in a gray-white pericarp with a thick gray mildew layer, showing water rot. When the disease is serious, the leaves begin to get sick, and the main symptom is that they start from the leaf tip and expand inward in the shape of "V" along the leaf veins to form grayish-brown edges with dark and light lines, and the disease keys have a clear boundary. After the disease is stable, the serious disease can be removed directly to avoid infection, and the mild disease can be prevented and treated with 1.5% Zhiyanling emulsion 1000 times.

4. Anthrax

The disease also occurs mainly in leaves. In the early stage of the disease, small round and oval reddish-brown spots will appear on the leaves, and in the later stage, when the disease is serious, it will expand to show dark brown spots, the center will be grayish brown to gray-white, while the edge is purple-brown or dark green, and sometimes there is yellow halo on the edge. finally, the disease spot turns dark brown, and produces small black spots arranged in a wheel. In the process of treatment, to carry out disinfection in the seedbed and shed, the seedbed is generally mixed with pentachloronitrobenzene and carbendazim according to 1:1 proportion to make cushion soil and cover seed, and the greenhouse disinfection had better be fumigated overnight with sulfur powder.

After reading this article, do you know the diseases and control methods in the process of onion growth?