Which species is known to cause Alternaria leaf spot in cole crops?

The species associated with causing Alternaria leaf spot in cole crops is Alternaria brassicae. This fungal pathogen specifically targets plants in the Brassica family, which includes various cole crops such as cabbage, broccoli, and cauliflower. The disease is characterized by the formation of dark, circular leaf spots that can lead to significant defoliation and reduced crop yield if not managed effectively.

The other choices represent different pathogens or disease types that do not cause Alternaria leaf spot. Colletotrichum spp. is known for causing anthracnose diseases in various crops. Pythium spp. primarily results in root rot and damping-off diseases in seedlings. Botrytis cinerea, often referred to as gray mold, affects a wide range of plants but does not specifically cause Alternaria leaf spot. Understanding the specific pathogens that affect crops is essential for effective disease management and control.