Scientific Name

Clavibacter michiganensis subspecies michiganensis

Overall Plant Symptoms

Systemic wilt of entire plant; canker sometimes not apparent.

Leaf Symptoms

Downward turning of lower, oldest leaves first, uniform leaf burning.

Stem Symptoms

Stems show internal creamy-white to yellow or brownish tinge especially at joints in the growing areas of the plant, crack open.

Root and Fruit Symptoms

Roots: similar to stem. Fruit: small individual dots with distinctive halo.

Disease Source

Contaminated seed, transplants or equipment.

Source Peristence

Reintroduced annually. Poor soil persistence in California.

Favoring Conditions

Warm, 75^o, humid conditions. Secondary spread by transplant handling, cultivation, sprinkler irrigation and vine training.

Critical Crop Time

Early season seedling and transplant infections most devastating.

Controls/Management

Non-host crop rotation very effective. Avoid field work during wet conditions to reduce spread between plants.

Additional Notes

Increasing incidence.