How to recognize and combat powdery mildew on pumpkins

Podosphaera xanthii and Sphaerotheca fuliginea are two species of fungi responsible for causing powdery mildew in various cucurbits, including pumpkin. These pathogens develop mainly in conditions of high humidity and moderate temperatures, and their cycle begins with the germination of conidia that adhere to the surface of the leaves. The spores germinate and form haustoria that penetrate the epidermal cells of the plant to extract nutrients. The mycelium of the fungus spreads over the surface of the leaves and produces new conidia in chains that are dispersed by the wind to other parts of the plant or to nearby plants. Podosphaera xanthii and Sphaerotheca fuliginea can survive on plant debris and in plant buds during the winter, resuming their activity in the spring. The development of these fungi is favored by warm and dry climates during the day and humid at night, which facilitates their spread and the rapid appearance of symptoms.