What Is Wrong With My Chinese Cabbage?

Are there any dark spots on leaves that turn brown to gray, lesions may be round or angular and may possess a purple-black margin?

Do the leaves have any small circular or irregularly shaped dry spots that are gray to straw in color?

Do the leaves have pale areas on upper surfaces and "downy" patches underneath?

Are the leaves covered with white powder?

Are the seedlings dying and the stems are girdled or rotted at the soil line?

Are the roots enlarged and clublike, plants are stunted with yellowish leaves that wilt during the day?

Are there any irregularly shaped dull yellow areas along leaf margins that expand to leaf midrib and create a characteristic "V-shaped" lesion?

Are there any irregular, necrotic gray lesions on leaves, and white-gray lesions on stems?

Are there any water-soaked, brown lesions on the leaves, the center of leaves is breaking down?

These symptoms indicate Alternaria leaf spot. Warm, wet conditions favor this fungal disease. Spray infected plants with copper and/or sulfur to prevent further disease development.

These symptoms indicate a fungal disease - Anthracnose. Keep plants dry when watering to prevent spread. Spray plants with copper when the first fruit develops if you have had problems in the past.

Pale areas on upper surfaces of the leaves and "downy" patches underneath are caused by Downy mildew. This fungus spreads quickly during cool, wet nights and warm, humid days. Leaves will wilt and die. Remove and destroy all affected plant parts and encourage good air circulation around plants by thining them. Water plants early in the morning to make sure they dry before nightfall.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from below to keep foliage dry. Any affected leaves should be cut off and removed.

If your seedlings are falling over and the stems are girdled or rotted at the soil line, the most likely cause is a damping-off disease. Remove and destroy all infected plants. To prevent damping-off let the soil surface dry between waterings, thin seedlings to avoid overcrowding, and do not add nitrogen fertilizers until plants have developed leaves.

Enlarged and clublike roots are most likely caused by fungal disease - Club root. Remove and destroy any infected plants. Applying lime to the soil can reduce fungus sporulation.

These symptoms indicate a bacterial disease - Black rot. Prevent this disease by providing well-drained soil and by using a 2-year rotation. Plant resistant varieties. Control cruciferous weed species which may act as a reservoir for bacteria. Plant pathogen-free seed.

Sclerotinia stem rot (white mold) is a fungal disease that causes these symptoms. Wet weather conditions favor this disease. The disease is usually introduced to non-infected areas by infected seeds. Plant only certified seed. If the disease is known to present rotate crops with non-hosts such as cereals.

Bacterial soft rot is caused by a bacterium that is common in most soils, particularly if the area is frequently planted with susceptible crops. Remove and destroy infected plants. Avoid planting in poorly draining soil. Rotate crops with corn, small grains, or grasses where possible. Treat soil with an insecticide before planting to reduce damage caused by grubs and larvae which promotes bacterial soft rot.

Round or irregularly shaped gray necrotic lesions on leaves with dark margins indicate a fungal disease - Blackleg. Other symptoms include stem with sunken areas that enlarge over time. Dead leaves will stay attached to the plant. Spray plants, especially the stems, with copper at the first sign of disease.