Clubroot Disease of Brassica species

Chinese broccoli, Brassica oleraceae var alboglabra was diagnosed in the UD Plant Diagnostic Clinic  this week with clubroot, a disease caused by an oomycete fungus- like pathogen. Plasmodiophora can be found persisting in the soil and may be moved along with transplants. I have never seen this disease in the field. It affects all Brassica species, and the resting spores can remain in soil for 10 years or more. The swellings are the result of hyperplasia and hypertrophy. The plasmodia are in the plant cells in the swellings. Swimming zoospores can result in spread in wet soils. It is not a USDA regulated pathogen, but can be very problematic in agricultural soils where cabbage, broccoli, or kale is grown.

5/25/17 NFG