Generally tropical and subtropical regions
Leaf spots vary in color from pale green to white and are bordered by brown tissue and general chlorosis. Lesion may be circular or angular in appearance. Severely affected plants may defoliate.
Conditions for Disease Development
The fungus can be seedborne, but more commonly survives in volunteer plants and weeds. Spores are spread by wind, rain and irrigation water, or mechanically by equipment and people. High relative humidity and temperatures between 13-18°C (55-64°F) generally encourage disease development.
Eradicate cruciferous weeds and volunteers. Apply fungicides early and often to achieve adequate disease control.