Symptoms Causal Organism Black rot of crucifer is caused by a bacterium, Xanthomonas campestris pv. The bacteria can overwinter in plant debris, in and on seeds from diseased plants, and in and on weeds. The pathogen may survive in diseased crop residue buried in soil for up to 2 years, but not more than 60 days free in soil. The major source of these bacteria is infected seeds, which enable long-distance spread of the disease. The pathogen is spread within and between fields by splashing water, wind, insects, machinery, and irrigation or drainage waters.
Free moisture is required for infection by the pathogen.
If source of the seeds is unknown, or infested seedlots must be used, treat seed with hot water to eradicate pathogenic bacteria. Cabbage, broccoli, and Brussels sprouts can be treated at 50 degrees C for 25 minutes, while seeds of cauliflower, kale, turnip, and rutabaga are treated for 15 minutes. However, this treatment may reduce the viability of seed. Therefore, some other chemical seed treatments, including, sodium hypochlorite, hydrogen peroxide, and hot acidified cupric acetate or zinc sulfate can be applied to eliminate the bacteria from crucifer plant seeds. Use certified disease-free transplants.