Clubroot - Brassicas

Pathogen

Fungus

Hosts

Field brassica crops, all cultivated brassicas, oilseed rape as well as cruciferous weeds such as shepherds purse and charlock.

Symptoms

Patches within the crop wilt, exhibit stunted growth and have swollen, misshapen roots which decay by rotting.

Development

Resting spores of the fungus can survive in the soil for up to 20 years and infect cruciferous crops and weeds through the root hairs. The fungus then stimulates root cell multiplication and produces spores which reinfest the soil during root decay.

Favourable Factors

Cool, wet weather.

Importance

Clubroot is a serious and destructive disease of all brassica crops and oilseed rape. Affects all cultivated brassicas as well as cruciferous weeds such as shepherd`s purse and charlock. Resistant horticultural varieties are available to commonly occurring races of clubroot but in the presence of inoculum plants will still produce small restricted galls. There are reports of more aggressive races of clubroot from both Europe and the UK.

Control

• Select resistant cultivars
• Long rotation of 6-8 years between susceptible crops including oilseed rape
• Improve drainage and apply lime as necessary
• There is no satisfactory chemical treatment, but effective cruciferous weed control may reduce disease incidence
• It is possible to have the soil tested to determine the presence or absence of clubroot in the soil. The test can take up to 6 weeks before results are available so tests should be planned well in advance.