Seasonal development
and life cycle—Clubroot
Clubroot infects all of the cole crops, as well as many weeds in the mustard family. The fungus persists
in soil for many years. Infection is favored by acid soils with adequate moisture, but infections can
occur above pH 7.0. In the presence of host plant roots, spores germinate and release swimming spores,
called zoospores. These zoospores infect and colonize root hairs. Later, a second type of zoospore appears
that can infect the main roots. Infection and colonization by this second zoospore causes the galling
and clubbing of roots. Additional spores are formed inside the galled roots and are released into the
soil when roots decay. The fungus is dispersed by the movement of infected plants, especially transplants,
and the movement of soil.
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Plants
infected with clubroot are stunted
Infected
plants show root clubbing
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