Home Vegetable Gardening Black Rot in Cole Crops: Symptoms, Management, and Prevention

Black Rot in Cole Crops: Symptoms, Management, and Prevention

by Donna
3 minutes read

Black Rot: A Serious Disease Affecting Cole Crops


Black rot is a devastating disease that can wreak havoc on cole crops, a group of vegetables that includes cauliflower, cabbage, and kale. It is caused by the bacterium Xanthomonas campestris pv campestris, which can survive in the soil for over a year and infects plants through their pores or wounds.

Symptoms of Black Rot

The first signs of black rot on cole crops are dull yellow areas on the leaf margins that form a V-shape. As the disease progresses, the center of the affected area turns brown and dry, and the veins of the leaves, stems, and roots turn black. Infected plants may also become stunted, turn yellow to brown, and drop leaves prematurely.

Conditions Favoring Black Rot

Black rot thrives in warm, humid conditions with temperatures in the high 70s Fahrenheit (24 degrees Celsius). It is spread by workers, equipment, or rain, and injuries to the plant can make it more susceptible to infection.

Management of Black Rot

Once a crop is infected with black rot, there is little that can be done to save it. The best way to control the disease is to prevent it from occurring in the first place. Here are some effective management strategies:


  • Purchase only certified pathogen-free seed and disease-free transplants.
  • Rotate cole crops every three to four years to reduce the buildup of the bacteria in the soil.
  • Practice excellent garden sanitation by destroying any infected plant debris and disinfecting tools and equipment.

Cultural Practices

  • Avoid working in the garden when plants are wet, as this can spread the bacteria.
  • Space plants adequately to promote good air circulation and reduce humidity.
  • Water plants at the base to avoid wetting the leaves.

Chemical Control

  • If conditions are favorable for black rot, apply bactericides according to the manufacturer’s instructions.

Resistant Varieties

Some varieties of cabbage, black mustard, kale, rutabaga, and turnip have varying levels of resistance to black rot. Planting these varieties can help reduce the risk of infection.


Black rot is a serious disease that can cause significant losses in cole crop production. By understanding the symptoms, conditions that favor its development, and effective management strategies, growers can minimize the impact of this disease and protect their crops.

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