How do wild mustard plants help spread clubroot disease to cabbage?

Wild mustard plants contribute to the spread of clubroot because they belong to the same family as cabbage, the Brassicaceae.

Clubroot is caused by the soil-borne pathogen Plasmodiophora brassicae, which infects a wide range of susceptible plants within this family, including mustard, shepherd’s purse, and winter cress. Because these weeds are susceptible hosts, they can harbor the pathogen in the soil even when a primary crop like cabbage is not present. The pathogen can survive in infested soil for 10 years or more, and its spread is facilitated by the movement of contaminated soil on tools, equipment, or through surface-drainage water.1

By acting as a reservoir for the pathogen, wild mustard plants allow the disease to persist in an area, making it difficult to eradicate and increasing the risk of infection for subsequent cabbage crops planted in the same soil.1