Plants infected by this disease appear sickly and wilt in sunny weather. They are backward and often die before reaching maturity. If diseasedare examined, there will be various degrees of swelling and distortion, as well as evil-smelling decomposing tissue.
Clubattacks brassicas generally, especially cauliflowers, and thrives on acid, badly-drained land. It also attacks alyssum, wallflowers and stocks. On neutral or limy soils it is rarely troublesome. Once the fungus secures a footing, the soil may be contaminated for many years. There is no outright cure. When the disease has occurred the previous year give generous applications of lime before planting susceptible crops — say 14 lbs. per 30 sq. yd. This prevents the trouble spreading where it has secured a hold and also helps to prevent the infection of clean land — but it does not actually kill the fungus and it is a year or more before the real effects of liming are evident. Wherever possible try to starve the fungus to death by avoiding susceptible crops for up to 7 years. This may well be impracticable but it is possible to grow a fair brassica crop by the use of calomel dust, mercurous chloride or corrosive sublimate (this material is highly ). Keep down weeds like shepherd’s purse and charlock which are host plants for the fungus.
Examine all purchased brassicavery carefully and burn any with solid swellings on the roots. Where the disease occurs on older plants, again burn immediately. Club can be spread by implements and even by boots, when walking from infected to clean land. Do not confuse club root damage with injury by the cabbage and turnip gall weevil. Swellings on the roots of brassicas attacked by this weevil are hollow and odourless, whereas with club root the swellings are solid and distinctly odorous!
Plants attacked by the weevil may be weakened but long-term effects are not serious and an application of complete fertiliser may be given to stimulate vigorous growth.