Disease: Pollution injuryPathogen: ozone (O3)Host: Watermelon, Citrullis vulgaris
Air pollutants affect and injure all species of cucurbits (melon or cucumber family), including watermelon. Watermelon and squash are the most sensitive of the cucurbits to ozone injury. The injury begins with premature chlorosis, leading to bleaching, then necrosis. Early symptoms (left) and late symptoms (right).