Cause Although both Rhizoctonia solani (teleomorph: Thanatephorus sp.) and Cladosporium sp. have been associated with affected leaves, the causal agent has not been determined. The disease is severe in the 'Jade' variety.
Cause A bacterium, Pseudomonas syringae pv. maculicola, causes this disease, also known as bacterial leaf spot on cauliflower, broccoli, and Brussels sprouts. Bacteria survive on infested seed and crop residues as well as in soil. Cool, wet weather, common west of the Cascade Range, favors disease development before harvest in the fall.
