Crown Gall

Crown gall appears as rough, irregular galls at the base of the plant, at the soil line, or occasionally on roots and aerial branches. Young galls are pale, soft, and almost wart-like; as they age, they become dark and woody with a bumpy, cauliflower-like texture. In some cases, they're smooth enough that you might mistake them for callus tissue from grafting or pruning. Infected plants often show stunted growth, poor foliage color, and reduced flowering. On stone and pome fruits, roses, and blueberries in Western Washington, crown gall can develop slowly, sometimes taking over a year for visible symptoms after initial infection.

Crown gall is caused by a bacterium that enters plants through wounds, whether from pruning, mechanical injury, or natural root emergence. Once inside, the bacterium transfers DNA that transforms normal cells into tumor cells that proliferate uncontrollably. There is no cure; management depends on prevention and sanitation. Purchase only disease-free nursery stock and inspect plants before planting; discard any showing gall symptoms. Avoid wounding plants, especially during planting. Sterilize pruning tools frequently when working around infected plants, as contaminated shears spread bacteria to cut surfaces. Do not plant susceptible crops in previously infested soil for 2-3 years, and do not allow tools or equipment to track infested soil into clean areas. Choose resistant rootstocks when available, particularly for roses.