Powder mildews consist of variety of fungal species which infect and cause diseases in many different species of plants. These diseases get their name from powder spores that appear on infected leaf surfaces. Symptoms usually begin on the older, lower leaves. As their capacity to conduct photosynthesis is hurt, plants may lose their color. Leaves may wither and die as the disease progresses. Powder mildew symptoms and favorable conditions vary between species.
Powdery Mildew in Solanaceous Crops
Different species of powdery mildew-causing fungi will produce different symptoms on solanaceous crops. Some species will cause the appearance of yellow or bright green spots on the upper sides of leaves. Other species will cause whitish-greyish powdery coating to appear on the upper sides of leaves. powdery coating may be found on the undersides of leaves.
Powdery Mildew in Cucurbits
White powdery spots will appear first on the undersides of leaves , and then the upper sides of leaves, stems, and petioles. Late in the growing season, small dark brown spherical structures may develop on the leaves – these protect the fungal spores during the winter and may become sources of infection in following seasons.
Powdery Mildew in Cannabis
White powdery spots will appear on leaf surfaces , petioles , and flowers. As the powdery mildew patched age , small spherical structures may appear and will change colors from yellow to black as they age which carry overwintering spores.