Pumpkins with yellow and dying leaves may have contracted a pest problem. Both spider mites and whiteflies cause pumpkin leaves to yellow, according to the University of California. It is important for gardeners to diagnose their pest infestation so they can perform proper chemical and cultural treatment practices.
Spider mites and whiteflies are nutrient-sucking pests. Gardeners may notice their pumpkin leaves not only turning yellow and dying, but also developing a fine stippling, according to the University of California. In addition, spider mites colonize on the backs of leaves, spin webs and reproduce rapidly during June through September, according to the University of California. When their population is allowed to skyrocket, gardeners notice damage occurring to their pumpkin crops. Reducing their numbers prevents pumpkin plants from declining in health.
Spider Mite Treatment
Remove dust accumulating around pumpkin plants. Spider mite outbreaks generally occur when the garden area or hills around the pumpkin plants are allowed to get dusty. Regularly apply water to dusty areas, as suggested by the University of California. Spray an insecticidal soap to treat your spider mite infestation. Certain insecticides that contain carbaryl actually make your spider mite problem worse, according to the University of California. Continue to apply the insecticidal soap during the summer to keep spider mites from harming your pumpkin leaves.
Whiteflies suck out the sap from pumpkin leaves, which causes yellowing and death, according to the University of California. Gardeners identify these tiny insects on leaves by their white waxy-coated bodies with yellow wings. In addition to damage caused to leaves, whiteflies secrete a substance called honeydew. Honeydew sticks to the entire pumpkin plant. Fungal spores floating in the air that cause a disease called sooty mold attach themselves to the honeydew. To prevent damage, gardeners must reduce their whitefly population and remove the honeydew.
Spray your pumpkin plants in the morning with a garden hose to remove sooty mold and honeydew. Watering in the morning allows time for water evaporation, which reduces the risk of fungal diseases. Remove infested leaves from your pumpkin plant, as recommended by the University of California. Bag up or burn infested debris, but do not place in your compost. Use an insecticidal soap or oil on your pumpkin plant. Avoid using insecticidal soap when temperatures exceed 80 degrees Fahrenheit, as recommended by the University of California.