Pumpkin Leaves Stemming Out From the Roots Are Dying

Bacterial Wilt

• Pumpkin leaves that droop during the day but perk up overnight indicate bacterial wilt. Bacteria block and destroy vascular networks that circulate nutrients and water through pumpkin vines. Leaves develop yellow or brown edges, and the vine withers and dies within two weeks. The cucumber beetle, a 1/4-inch bug with black and yellow stripes or spots, spreads bacterial wilt. The beetle chews on the plant, carving an opening through which bacteria invade.

Leaf Spots

• Leaf spots begin as small brown or yellow marks on pumpkin foliage. Gummy stem spot browns leaves' edges first, and moves toward stems. Stems with the fungal infection split open and release a thick, amber fluid. Angular leaf spot causes wedge-shaped brown marks on foliage. The spots die and drop out of the leaf, leaving holes. Angular leaf spot spreads through contact with hands and tools that touched infected pumpkin plants. Pumpkin rot follows leaf spots. Humid weather and standing water on leaves encourage both diseases.

Mildews

• Fungal diseases, including powdery mildew and downy mildew, can devastate leaf growth on pumpkin vines. Powdery mildew is a white, talc-like substance that attacks and kills a vine's oldest leaves first. Widespread leaf loss subjects pumpkins to sunburn and causes incomplete ripening. Downy mildew starts as pale green leaf spots that turn yellow and take over entire leaves. Both mildews prefer wet or humid weather. Downy mildew prefers cooler temperatures of 60 to 70 degrees Fahrenheit, while powdery mildew grows best at 80 degrees Fahrenheit.

Alternaria Leaf Blight

• Alternaria leaf blight is a fungal disease affecting pumpkins, cucumbers and melons. Like mildews, the blight doesn't infect pumpkins, but it can affect squash growth and production through sun exposure following leaf death. Alternaria leaf blight starts in mature leaves near the vine's crown, as small, brown, irregular spots with yellow edges. They grow to 3/4 of an inch in diameter, sometimes forming a target-like pattern of concentric rings. Leaves eventually curl, wither and die.

Prevention

• Diseases that kill pumpkin leaves come from insects such as aphids or cucumber beetles, as well as infected plant debris left in the garden over winter. To control infestations, look for insects as soon as growing season begins. Handpick cucumber beetles from plants and drop them into a bucket of soapy water. For aphids or out-of-control beetle infestations, apply insecticide sprays with thiamethoxam, pymetrozine or carbaryl. Remove or till under garden debris at season's end. Fungicides containing horticultural oils, such as neem or jojoba, can control powdery or downy mildew. Don't water pumpkin vines from overhead, because standing water on leaves can encourage fungal growth. Place pumpkin vines 2 to 3 feet apart in sunny areas to keep leaves dry. Also, plant disease-resistant varieties. Cornell University recommends Iron Man, Corvette and Charger.