Clubroot

About

Clubroot swells and deforms the roots of cabbage-family crops, starving the plant of water. Its spores can survive in soil for up to 20 years, so keeping it out of your garden is far easier than getting rid of it.

Also called clubroot, club root

How to recognize it

Symptoms

Plants are stunted and wilt on warm afternoons even with only slight dryness, and leaves may yellow. Pulled up, roots are swollen into thick clubs or spindles, which later rot and turn black.

Worse when

Acidic soil (pH below about 6.5) and wet, poorly drained soil.

How it spreads

Spores move on infected transplants, soil on tools and boots, unheated compost and wind-blown soil, and survive up to 20 years; many weeds can carry it without symptoms.

When

Through the growing season; symptoms show most on warm afternoons.

What to do, gentlest first

Prevention works best; most sprays only protect healthy leaves and can't cure infected ones. Always read and follow the product label.

1. Start with clean transplants Prevent

   Grow your own or buy transplants raised in clean soil, and use only compost heated to at least 148°F.

2. Raise soil pH with lime Prevent

   Keep soil pH at 6.8 or higher (WSU) and maintain calcium and magnesium; get a soil test first.

3. Long rotation and drainage Prevent

   Leave cabbage-family crops out of infested beds for 5 to 7 years or more, remove mustard-family weeds, and do not plant in soggy soil. Resistant varieties exist for some crops.

4. Remove infected roots and clean tools By hand

   Dig out infected plants with their roots and do not compost them in regular piles. Clean tools with a 1:9 bleach and water solution.

5. No home fungicides Conventional spray

   WSU notes no fungicides are labeled for home use against clubroot.

Plants it affects

Arugula, Bok choy, Broccoli, Broccoli raab (rapini), Brussels sprouts, Cabbage, Cauliflower, Collards, Kale, Kohlrabi, Mustard greens, Napa cabbage, Radish, Rutabaga, Turnip