Alternaria Leaf Spot – Alternaria brassicicola – Alternaria brassicae – Alternaria raphani

Alternaria Leaf Spot Common name Alternaria leaf spot Causal Agent Alternaria Leaf Spot is a fungal disease that is caused by three pathogens, and all belong to the genus Alternaria. These pathogens can infect any member of the Brassica family, but broccoli and cauliflower are more prone to them. Scientific name Alternaria brassicicola Alternaria brassicae Alternaria raphani Symptoms & Signs Alternaria leaf spot is a common disease of brassica crops that mainly affects the foliage of the plants. At first, tiny black spots appear on the leaves that gradually increase to form concentrated brown rings with a yellow halo around them. The rings appear like lesions on both sides of the leaves and can easily tear through the middle. It often affects older leaves first and then spreads toward the younger ones. Severe infection can cause the leave to fall off from the plant. Transmission It can transfer from infected seeds, residues, and soil. The fungi produce spores that are carried away via water, wind and farm equipments to the healthy crop where they cause disease. Warm temperature (60-78 F) and high humidity (90%) favor its spread. Time of Concern Early spring to late summer Common Hosts Cabbage Kale Cauliflower Broccoli All members of Brassica family