Home Garden Disease Controls
The Pennsylvania State University
Cooperative Extension

Root Crops: Beet, Carrot, Parsnip, Radish, Rutabaga, Turnip

How important are diseases on root crops in gardens?
Diseases are a problem occasionally on these crops.

What diseases can affect root crops?
Listed below are several diseases that most frequently occur on root crops. Symptoms are described briefly. Colored pictures of disease symptoms can be seen in the publication Identifying Diseases of Vegetables.

Cercospora Leaf Spot of Beets
These spots usually are brown or gray with a purple border. THey usually develop late in the season. Most beets are resistant.

Control: Follow a 2-3 year rotation. Remove refuse from the garden as soon as beets are harvested. If necessary, fungicides can help when applied as labeled.

Leaf Spot and Root Canker of Parsnips
Spots develop on leaves and dead canker areas develop at the top of parsnip roots. Disease is promoted by wet conditions.

Control: Practice at least a 2-year rotation. Provide good drainage of soil. Lime soil to ph 7. Ridge soil over shoulders of the roots.

Leaf Spot of Carrots
Lower leaves become spotted and may die.

Control: Grow carrots in a sunny location. Avoid growing carrots in the same area during successive years. When a leaf spot problem is anticipated, labeled fungicides can be helpful if started when symptoms first appear. Remove carrot tops from the garden at harvest; the tops can be composted.

Root Knot Nematodes
Nematodes are microscopic worms that live in soil. The root knot nematode causes small swellings to develop on the side of the main root and on fine roots.

Control: Rotate crops in the garden. Avoid planting susceptible crops during successive years. Susceptible crops include carrots, parsnips, tomatoes, lettuce, and cucurbits. Sweet corn is seldom affected and is a good crop for affected areas.

Clubroot of Turnip
Roots become swollen and distorted and leaves may wilt.

Control: Avoid areas where turnip and cabbage related plants were grown within 7 years. If clubroot has been a problem during past years, apply hydrated lime (1 lb for 30 square feet) in the spring before preparing the seedbed. Remove plants including roots as soon as harvest is completed. Do not compost roots that have clubroot symptoms; discard them.

Note: Where trade names are used, no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.
Information provided is intended for consideration by the user, but is not intended to be a recommendation. Production decisions should be based on consideration of many types of information (scientific, experiential, economic, legal, etc.) available to the user.

Back to Vegetable Pathology Home