Cavity Spot

Cavity spot is not your worst prison nightmare. Instead, it is a fungal disease of carrots.

Cavity spot appears as depressed lesions on mature carrot taproots. These lessons can be elliptical or irregular in shape. They start out as sunken pinpoints that grow larger as the root grows. Lesions are usually less than 1/2 inch across but can get bigger. These lesions are commonly seen on the top one-third of the carrot, near where lateral roots emerge.

This fungal disease is caused by Pythium sulcatum and P. violae spores found in the soil. These spores become active in cool, wet weather, which happens to be when your carrots are growing. Cavity spots occur most often when soil temperatures are near 58°F.

In addition to carrots, cavity spot occurs on alfalfa, beets, black-eyed peas, celery, cucumber, wheat, and several weeds.

Controlling cavity spot

Harvesting carrots as soon as they are mature will reduce the likelihood of infection. And avoid over-watering. Too much moisture in the soil encourages several different fungal growths. A three-year crop rotation is the best way to prevent this disease or to interrupt the disease triangle in your garden.

So, protect your carrot crop with good cultural practices and just the right amount of irrigation.