Clubroot
Disease · Commonly affects: Cabbage, Broccoli, Cauliflower, Brussels sprouts, Kale, Turnip
Clubroot is a soilborne disease of cabbage-family plants caused by the microorganism Plasmodiophora brassicae, which attacks the roots and starves the plant. It matters to home gardeners because its resting spores can persist in the soil for a decade or more, making a contaminated bed unreliable for brassicas for many years.
How to identify it
The clearest sign is below ground: infected roots swell into distorted, club-shaped or spindle-shaped galls instead of forming a normal fibrous root system. Above ground you will notice stunted growth, yellowing lower leaves, and plants that wilt in the afternoon heat but often perk back up overnight. Because the wilting mimics simple drought stress, gardeners usually confirm clubroot only after lifting a struggling plant and inspecting the swollen roots.
Damage
The root galls disrupt the plant's ability to take up water and nutrients, leading to stunting, poor head formation, and reduced yields. Severely infected seedlings and young plants may collapse and die, while older plants survive but remain weak and unproductive.
Prevention
Rotate brassicas out of any affected bed for at least seven years, since the pathogen favors returning to the same soil. The disease thrives in acidic, wet ground, so improving drainage and liming the soil to raise the pH toward neutral or slightly alkaline strongly discourages infection. Start with certified disease-free transplants, plant clubroot-resistant varieties where they are offered, space plants for good air movement, and pull out cabbage-family weeds such as wild mustard and shepherd's purse that can quietly host the organism.
How to manage it
There is no cure for an infected plant, so promptly dig up affected plants along with their entire root system and dispose of them in the trash rather than the compost pile, where spores would survive. Prevent spread by cleaning soil off tools, boots, and tires, and by never moving soil or transplants from an infected area into clean beds. Water at the base and avoid keeping the soil waterlogged, since standing moisture helps the spores move and infect new roots.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.