Cabbage Black Rot
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Plant Diagnostician
Phone: (479) 575-2727
Email: ssmith@uada.edu
Jason Pavel
Diagnostician
Phone: (479) 575-7257
Email: jpavel@uada.edu
Office:
University of Arkansas System Division of Agriculture
Cralley Warren Building
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Fayetteville, AR 72704
Cabbage Black Rot
Plant Health Clinic Disease Note Issue 29
Sherrie Smith and Jason Pavel
Black rot caused by Xanthomonas campestris pv. campestris is one of the most damaging diseases of crucifers wherever they are grown. Susceptible hosts include broccoli, Brussels sprouts, cabbage, cauliflower, kale, rutabaga and turnip, as well as weeds in the cruciferous family such as shepherd’s purse and wild mustard.
What causes black rot and what are the symptoms?
Yield and quality losses may be high when environmental conditions are conducive for disease development. On seedlings, cotyledons may turn black and drop off. Lesions appear on leaves as yellow, V shaped spots along the leaf edge, with the base of the V usually directed along a vein. As the lesions expand, the tissue wilts and becomes necrotic. The infection may move up or down the petiole and spread through the stem into the roots. The veins of infected leaves, stems, petioles, and roots become black as the bacterium multiplies and shuts off the flow of nutrients to plant parts. When affected stems are cut crosswise, the vascular ring appears black. Yellow bacterial ooze may exude from cut tissues.
How do I manage black rot?
The use of clean seed is important in preventing disease. Seedling rates should not be too high as the dense foliage aids in disease development. Sprinkler irrigation should be avoided. Fields should only be worked when the foliage is dry. Transplants or seed should not be grown in a spot that has been in crucifers the last 3 years. Plants with visible symptoms should be pulled up and removed from the vicinity of the field. Deep plowing helps break down crop residue faster and should be practiced where practical.
Take Aways:
• Use clean seed.
• Avoid dense seeding rates.
• Avoid overhead irrigation.
• Practice at least a 3-year crop rotation away from crucifers.
• Remove infected plants.
• Deep plow, when possible, at the end of season.
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This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006- 27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture.
