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 quite small, as sunken pinpoints that grow larger as the root grows. Lesions are usually less than 1/2 inch across, but they can get much larger. These lesions are usually seen on the top one-third of the carrot, near where lateral roots emerge.

---

Cavity spot on carrot (UCANR)

Cavity spot on peeled carrots (Lindsey du Toit, WSU)

Cavity spot on carrots (UCANR)

---

This fungal disease is caused by Pythium sulcatum and P. violae spores found in the soil. These spores become active in cool, wet weather. The same time your carrots are growing. Cavity spots occurs most often when soil temperatures are near 58°F. In addition to carrots, cavity spot occurs on alfalfa, beets, blackeyed peas, celery, cucumber, wheat, and several weeds.


Controlling cavity spot

Harvesting carrots as soon as they are mature will reduce the chance of them becoming infected. 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!