Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Cabbage and Cauliflower (Brassica) -- Bacterial Soft Rot Erwinia
 
Cause: The soft rot bacterium, Erwinia carotovora subsp. carotovora, enters through wounds caused by insects, other disease organisms, or by mechanical means. Under warm, humid conditions, uninjured tissue may become infected through natural openings. Pseudomonas spp. have been isolated from diseased heads and are thought to actively infect the host. Prolonged moisture from rain or irrigation and mild temperatures encourage disease development. Bacteria may be spread by insects, tools, rain, clothing, or affected plant tissue. The bacteria survive in soil and plant debris.
Symptoms: Small, water-soaked areas appear and rapidly enlarge. Tissue becomes soft and mushy, and within a few days the affected plant part may collapse. An offensive odor usually is present.
Cultural control:

  1. Set out plants in rows to allow good air drainage.
  2. Cultivate carefully to minimize injuring plants.
  3. Control frequency and source of irrigation water.
    1. Avoid frequent irrigation during head development.
    2. Time irrigation to allow the head to dry rapidly.
    3. Use well water which generally is free of bacteria.
    4. Avoid stagnant water sources.
  4. Clean and spray storage walls and floors with copper sulfate solution (1 lb/5 gal water). Bactericides such as Clorox, Lysol, and quaternary ammonium products also are effective.
  5. In storage, use a buffering material such as straw or paper to prevent injury to the heads.
  6. Keep storage house humidity between 90 and 95% and the temperature between 32 and 39oF.
Content edited by: Cynthia M. Ocamb on January 1, 2009
 
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