Phytophthora disease reported on winter squash and pumpkin
Many areas of Michigan have received a significant amount of rain that favors the development of phytophthora disease on winter squash and pumpkin plants. Other vegetables that are susceptible to Phytophthora capsici include cucumber, zucchini, summer squash, watermelon, cantaloupe, pumpkin, pepper, eggplant, tomato and succulent bean. The pathogen may overwinter in the soil and persist for more than 10 years. Phytophthora spreads readily via runoff or infested surface water used for irrigation; using well water for irrigation is strongly recommended.
The roots, crowns, stems, leaves, and fruits of winter squash and pumpkin are susceptible to phytophthora (Figure 1). On this year’s samples, water-soaked lesions on the petiole (Figure 2A) have resulted from rain splashing infested soil up into the plant canopy. These lesions expand rapidly and the tissue rots. Lesions may appear on the foliage (Figure 2B) during periods of excessive rain and extended periods of high humidity.
