Powdery mildew is the most common and widespread disease of this large, diverse crop group occurring in both field and protected-culture (greenhouse) crops. White, talcum-like, powdery fungal growth develops on both leaf surfaces and on petioles and stems. Symptoms usually develop first on older leaves, shaded lower leaves, and lower leaf surfaces. Powdery spots on lower surfaces may have yellow spots opposite on the upper leaf surface. Field-grown plants become susceptible when producing fruit or stressed. Infected leaves and then plants senesce prematurely. Rarely infection occurs on immature fruit of watermelon, gourd and cucumber. Read more and visit photo gallery.
