Cavity Spot

Lesions on CarrotLesions on Carrot
Black Lesion on Carrot Black Lesion on Carrot 

HOSTS

  • Carrots
  • Parsnips

DESCRIPTION

Cavity spot is caused by fungal diseases Pythium sulcatum and Pythium violae. Cavity spot is most commonly seen in carrots, but can occasionally be seen in other root crops, such as parsnips. 

BIOLOGY

Both P. sulcatum and P. violae do best in cool, wet weather. They overwinter as spores in the soil. As the weather warms, they will use travel through water to find infect new hosts.  

Lesions will start very small and grow over time. Mature carrots will have the largest lesions, which can act as an entrance for secondary infections. 

SYMPTOMS

  • Oval-shaped lesions on the taproot

GENERAL MANAGEMENT

  • Rotate with non-susceptible crops every three years 
  • Avoid overhead irrigation, instead try drip irrigation to maintain even soil moisture.
  • Harvest carrots soon after maturity.  


 

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.