How to Manage Pests

Cavity spot—Pythium violae

Cavity spot is a problem on carrots and is characterized by elliptical to irregularly shaped depressed lesions oriented across the mature carrot tap roots. Individual lesions are usually less than 0.5 inch in diameter, but can be much larger, especially on processing varieties. Infections can occur anywhere along the tap root, but lesions tend to be more abundant on the upper third of the root. Lesions begin as pinpoint, sunken spots and generally enlarge as roots mature.

Identification

Symptoms of cavity spot on roots may sometimes be confused with symptoms of flea beetle feeding. Both are characterized by irregularly shaped lesions on the roots. However, flea beetle damage can be confirmed by looking at the leaves. Flea beetles also feed on the undersides of leaves, leaving small pits or irregularly shaped holes.

Solutions

The fungus that causes cavity spot is favored by low soil temperatures. Practice 3-year crop rotations with nonhosts of the disease such as tomato, watermelon, corn, and potato. Do not overirrigate. Harvest carrots soon after they mature because older carrots are more susceptible to infection. All carrot varieties are susceptible.

Cavity spot on carrots