Disease on Brassica leaves?
Thank you for using Ask an Expert for help with your brassica problem.
There may be more than one disease problem on your crop. I see signs of a fungus disease (downy mildew or light leaf spot) and perhaps of bacterial leaf spot. These diseases are common and encouraged by our wet weather conditions over winter and spring months.
For both diseases, it is important to remove and dispose of any foliage or other plant material that may have the organism left on it. Don’t compost it at home. Rotate your crops in this family to other parts of your garden, when possible. Remove any weeds in the brassica family (wild mustard, wild radish, and the like) which may also harbor the disease organisms.
Chemical sprays may be appropriate when symptoms first appear and on some vegeatbles. Review the labels of Fung-onil/daconil, potassium bicarbonate, Seranade, or Agri-fos for your specific crops and timing. Read and follow all directions and precautions.
Have a good gardening year,