clubroot

Symptoms

Stunted plants wilting on hot afternoons despite adequate moisture, swollen distorted root systems with club-like galls, plant pulls out easily revealing massive root deformation.

Plants affected

• cabbage / broccoli / cauliflower / Brussels sprouts
• turnip
• rocket (arugula)
• radish

Easily confused with

• brassica black rot

  How to tell them apart: Xanthomonas campestris pv. campestris (black rot) shows V-shaped yellow-to-brown lesions opening from the leaf margin inward, with the leaf veins inside and around the lesion turning black; cut the petiole or stem and the vascular ring is darkened. The plant may still stand reasonably upright, often with one-sided or patchy leaf damage. Plasmodiophora brassicae (clubroot) instead causes a whole-plant flag-wilt that recovers overnight and worsens in midday heat, with uniform dull-yellow leaves and stunting but NO marginal V-lesions and NO blackened veins. The decisive check is to pull the plant: clubroot roots carry swollen, spindle- or finger-shaped white-to-brown galls, whereas black-rot roots are normal. Clubroot is favoured by acidic, wet, warm soils.

• white blister rust (white rust of brassicas)

  How to tell them apart: Albugo candida (white rust) and Plasmodiophora brassicae (clubroot) both swell and distort Brassica rapa tissue, but they attack opposite ends of the plant. Albugo is aerial and foliar: look for chalky-white, blister-like pustules on the undersides of leaves, and 'staghead' deformity where the flower stalk and seed-pod cluster turn into a thickened, twisted, hypertrophied above-ground mass. Plasmodiophora is strictly below-ground: pull the plant and you see smooth, swollen, club- or spindle-shaped galls on the roots, while the leaves above merely wilt, yellow and stunt with no white pustules. If the swollen 'club' is on roots underground it is clubroot; if it is on the shoot, flowers or leaves with white blisters it is white rust.

Common questions

How do I recognise clubroot on cabbage / broccoli / cauliflower / Brussels sprouts?

Stunted plants wilting on hot afternoons despite adequate moisture, swollen distorted root systems with club-like galls, plant pulls out easily revealing massive root deformation.

Do I have to report clubroot?

No. clubroot is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is clubroot treated?

Mainly with biological and cultural measures — removing affected material, changing the conditions that favour it, and treating with agents approved in your country. The exact steps and their timing depend on the plant, the season and where you live: Dr. Phyto works them out in a free diagnosis.