Black rot is a bacterial disease in cabbage that causes up to 100 per cent yield losses in infected crops.
The disease has no chemical control but farmers can manage it by crop rotation, disposal of affected residues, and planting of resistant cabbage varieties such as the Green Challenger, Riana, and Pruktor.
Black rot is spread through irrigation (splashing of water), infected plants, wind, farm machinery, seeds, and soil. The disease can survive in crop residues buried under the ground for up to two years.
The disease attacks cabbages at any stage of growth. Farmers can spot signs of the disease through the presence of yellow v-shaped or u-shaped areas extending inwards from the margins of the leaf.
As the disease progress, the yellow areas turn brown and the leaf dies. One plant can produce enough infectious materials to destroy a whole field. Early removal of infected plants and foliage from the fields can assist in reducing black rot damage.
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At planting, ensure that you plant only healthy seedlings and crop rotation practiced every three years.
To fasten the decomposition of crop residues, chop them up before incorporating in the soil. Workers should wash their hands and disinfect their tools using jik after working in infested fields.