Club root is caused by a soil borne organism (Plasmodiophora brassicae) that infects a number of Brassica species. The first sign of clubroot is a wilting of plants and as the symptoms progress plants often fail to develop a crop. Symptoms include galls along roots, soft rot and stunted root growth.

It is important to test soil for the presence of club root as the organism produces zoospores that remain in the soil for many years that can infect future crops.

Club root can be found and stay in contaminated soil for a significant period of time. This soil bait test with a molecular component can determine presence of active club root in the soil.