This archive report was first published on 3 July 2020.
July 3, 2020
Clubroot disease is a significant threat to brassica crops, including cabbages, broccoli, and cauliflower. The disease is caused by the soil-borne fungal pathogen Plasmodiophora brassicae.
The fungus infects susceptible crops through their root hairs, causing the roots to swell and deform. This makes it difficult for the plant to absorb water and nutrients efficiently, leading to stunted growth, wilting, and eventual death.
Early symptoms of clubroot disease include the development of galls on the root systems, which can be mistaken for nematode damage. However, nematodes rarely affect brassica crops, making it essential to identify the correct cause of the problem.
Preventing clubroot disease requires a multi-faceted approach. First, ensure you obtain certified seeds that are resistant to the disease. When buying seedlings, acquire them from a reputable producer and inspect them for any signs of the disease before planting.
Keep the farm clean by disinfecting tools and equipment using sodium hypochlorite or hydrogen peroxide. Crop rotation with non-brassicas like onions can also help to reduce the risk of clubroot disease.
For greenhouse production, methods like soil solarisation can be effective in killing the fungus. This involves leaving a clear plastic polythene sheet on the soil surface for four-to-six weeks during the hot season.
Other control measures include controlling the growth of weeds like mustard, which are susceptible to the disease, and raising the soil pH by adding lime. Using clean water for irrigation and considering the soil type, which can affect the development and spread of the disease, are also essential.
