Clubroot

Plasmodiophora brassicae is a soil-borne obligate parasite responsible for the severe plant disease known as clubroot. This pathogen infects the roots of host plants, causing them to develop distinctive club-like swellings and galls that disrupt the plant's ability to uptake water and essential nutrients.

The primary hosts of this pathogen are members of the Brassicaceae (cruciferous) family. This includes all forms of cabbage, broccoli, cauliflower, Brussels sprouts, kale, radishes, turnips, and oilseed rape. Several wild mustard species also serve as alternative hosts for the disease.

The characteristic symptoms begin underground with the formation of white, fleshy galls on the root system. Above ground, affected plants exhibit stunted growth, yellowing foliage, and a tendency to wilt during warm periods, despite adequate soil moisture. As the galls decay, the root system fails, often leading to total crop collapse.

The pathogen thrives in cool, moist, and acidic soil conditions. Spores can persist in the soil for several years, making the disease difficult to eradicate once established. Spread typically occurs through the movement of contaminated soil on machinery, equipment, tools, footwear, and the use of infected seedlings.

Effective management requires an integrated approach.

• Implement long-term crop rotation (5–7 years).
• Apply lime to raise soil pH to 7.0 or higher.
• Improve soil drainage to prevent waterlogging.
• Use certified disease-free transplants.
• Select resistant cultivars where available.