Cabbage Integrated Pest Management : An Ecological Guide.

Major Diseases of Cabbage· Practices such as dipping or spraying transplants with water after digging may spread black rotdisease and should be avoided.· Use other irrigation methods than overhead irrigation and/or irrigate in the morning when the leavesof the plants will dry quickly. The bacteria can easily spread with splashing water and soil particles.· Avoid planting downstream from infected fields. The bacteria may spread with the water runningdown from the infected field.· Control cruciferous weeds: they may be a source of infection.Once an infection is present in the field:· When symptoms of black rot appear in the nursery: do not transplant seedlings with symptoms.When many seedlings already show symptoms, it would be advisable not to use any of theseedlings because probably all of them (also the ones that look healthy now) will be infected.· When the plant is at the heading stage and only older leaves get infected, no action needs to betaken. The yield will not go down with a few black rot symptoms at old leaves. It is advisable notto grow crucifers for at least two years after harvest of this crop.· Sanitation: after harvest, remove all infected plants with roots from the field and either place themon a compost pile, feed them to cattle, or burn them. This will reduce bacteria surviving in the fieldon infected crop debris.· Biological soil sterilization or biofumigation could be options for testing. See sections 3.7.1.5 and3.7.1.6.¤Points to remember about black rot :1. Black rot is a bacterium that causes V-shaped yellow lesions at the leaf margins of older plants.2. Black rot survives on seed and residues of diseased plants and is spread mainly by water andon diseased seedlings.3. Use of resistant varieties where available, seed treatment, crop rotation, proper water managementand sanitation (removing infected plant material) are ways to prevent or reduce black rotinfection.8.3 Soft rot - Erwinia carotovoraSee plate 1 Fig. 6 and plate 2 Fig. 7Causal agent: bacterium – Erwinia carotovoraSigns and symptomsThe common name of this bacterial disease arises from the characteristic soft decay of the fleshy tissueof the plant. When soft rot affects a plant, the tissue softens, becomes watery and slimy. Cabbage plantsgive off an distinctive sulfurous odor. Affected heads decay rapidly and turn dark.157 Cabbage Ecological Guide - 2000