Common diseases and pests of chives and their control methods

Common diseases and prevention methods

Downy Mildew

The disease can occur at any stage from seedling to harvest, with mature plants being more severely affected. It mainly harms the leaves, spreading from the base to the upper leaves.

In the early stage of the disease, light yellow, nearly circular to polygonal spots form on the leaf surface, which are easily complicated by angular spot disease. When the air is humid, a frosty mildew layer forms on the back of the leaves, which can sometimes spread to the leaf surface.

In the later stage, the spots wither and become yellow-brown in color. In severe cases, all the outer leaves turn yellow and die, similar to Verticillium wilt.

Prevention and control methods: When the disease is mild, spray HILOT Kaishuang at a dilution of 400-600 times, once every 5-7 days; when the disease is severe, spray HILOT Kaishuang at a dilution of 100-300 times, once every 3 days. The specific number of applications depends on the disease.

Botrytis cinerea

The seedlings infected with gray mold are light in color, and the leaves and petioles are grayish white and water-soaked. The tissues soften and rot, and gray mold grows on the surface when the humidity is high.

Young stems often initially develop irregular water-soaked spots at the base of the petiole, which quickly become soft and rotten, and then shrink or break. Finally, the diseased seedlings rot, wither and die.

Prevention and control methods: Use 50% isoprodinil diluted 1000-1500 times for spraying, once every 5 days; using it twice in a row can effectively control the disease and make the symptoms disappear.

Common Pests and Control Methods

Onion Maggots

Onion maggots are a general term for the larvae of several pests in the family Muscidae. Onion maggots like plants with pungent smells such as onions, ginger, and garlic. They feed on their tender roots or stems. They usually cause damage in spring and autumn. The root maggots that damage onions are mainly onion flies.

Prevention and control methods: Use 200 times the concentration of 5% high-efficiency cyanamide to irrigate the roots; or use 100 times the concentration of dichlorodiphenyltrichloroethane to irrigate the roots, both are very effective.

Leafminer

The eggs of the leaf miner are white, oval, and 0.9 mm × 0.3 mm in size. The mature larvae are about 7.5 mm long, wrinkled, and dark yellow in color. The pupa is about 5 mm long and oval in shape. It is light yellowish brown at first, then turns reddish brown, and becomes dark brown before emerging.

Prevention and control methods: Understand the peak period of adult insects and spray pesticides in time to prevent adult insects from laying eggs. Adults mainly lay eggs on the back of leaves, so the pesticide should be sprayed on the back of the leaves. Or spray pesticides to control the larvae when the damage just occurs. Spray 2 to 3 times in a row to control the larvae. The pesticide can be 1000 times diluted 40% Dimethoate Emulsifiable Concentrate.