How to identify and control gray mold in cabbage?

Cabbage (Brassica oleracea L.) is an annual or biennial herbaceous plant of the genus Brassica in the family Brassicaceae, and is one of the important vegetables in China. Except for Chinese kale, which originated in China, all the varieties of cabbage originated along the coast from the Mediterranean to the North Sea. As early as 4000-4500 years ago, the ancient Romans and ancient Greeks already cultivated it.

The growing environment of cabbage

Cabbage prefers mild, humid conditions and sufficient sunlight. It is relatively cold-tolerant and also has the ability to adapt to high temperatures. The suitable temperature for growth is 15-20°C. If the fleshy stem enlargement stage encounters high temperatures above 30°C, the flesh is prone to becoming fibrous. It is not very strict about soil selection, but it is suitable for planting in clay loam or sandy loam rich in humus. Cabbage seedlings must pass through vernalization at 0-10°C, and then bolt, flower, and set fruit under long-day conditions and suitable temperatures.

The distribution range of cabbage

It originated in European and American countries, and is mainly distributed in the colder regions of northeast, northwest, and north China as well as in south China and other places.

Identification and control of cabbage gray mold

Gray mold (Botrytis cinerea Pers.) occurs mostly in protected cultivation of cabbage, and the incidence tends to worsen.

Field identification of cabbage gray mold:

It usually first develops on leaves closer to the ground. At first, the diseased part is water-soaked; when humidity is high, the diseased part rapidly expands, becoming brown or pale reddish brown, causing rot, and gray mold-like growth appears on the diseased part. When the stem base is affected, the diseased part turns brown and rots. Gray mold-like growth appears, developing from bottom to top, the outer leaves wither, and it spreads to the entire head, leading to rot. In the later stage of the disease, the diseased part sometimes produces nearly round black small sclerotia.

Causes of cabbage gray mold:

The pathogen overwinters on the ground with diseased plant residues. It spreads via wind and rain, and infects through wounds or weakened parts of the plant to cause disease. The pathogen prefers warm, humid conditions and weak light; when the temperature is around 20°C and the relative humidity is above 90%, the disease is prone to occur. With extensive management and weak plant growth, the disease worsens.

Key points for controlling cabbage gray mold:

① Use purple light film and close the shed early to heat the field.

② Carry out good fertilizer and water management to strengthen seedlings and prevent disease.

③ Properly control irrigation and strengthen ventilation to remove moisture.

④ Keep the shed film clean and increase light as much as possible.

⑤ Promptly pull out diseased plants and bury them deeply. After harvest, thoroughly remove diseased plant residues and deeply plow the soil.

⑥ For chemical control, use 50% Sumilex 2000-fold solution, or 50% procymidone 1500-fold solution, or 50% vinclozolin 1000-fold solution, or 40% meibingwei 600-fold solution, or 68% Beideli 800-fold solution, or 30% kemeling 800-fold solution. When the protected facility is closed, 10% Sumilex smoke agent can be used at 3.75 kg per hectare for fumigation, or 10% miekefen dust can be sprayed at 15 kg per hectare.