Plant Health Problems
Pumpkins are susceptible to many of the same diseases of other Cucurbits. See Cucurbit for a detailed discussion of the other common diseases of this host.

Diseases caused by Fungi:

Powdery mildew, Erysiphe cichoracearum.
Late in the summer this fungus will form a white, powdery growth on older leaves. This disease is relatively unimportant for cucumbers, melons, and winter squash, but may cause some loss for summer squash.

Control measures are usually not necessary for this disease since it usually doesn’t develop until mid to late summer. However, among the compounds registered for use in Connecticut are horticultural oil, chlorothalonil, myclobutanil, and copper hydroxide. Consult the label for dosage rates and safety precautions.

Insect Problems

Aphids.
Several kinds of aphids such as the melon aphid, Aphis gossypii, and the potato aphid, Macrosiphum euphorbiae, may occur on pumpkin. See Aphid fact sheet.

Melonworm, Diaphania hyalinata.
This insect also infests pumpkin. On occasion, pumpkin may be injured by slender, active greenish caterpillars with two narrow white stripes running the full length of their bodies. They feed mostly on the foliage, but may burrow into the fruit. They are rare, however, and no specific control measures have been needed.

Squash vine borer. Melittia cucurbitae.
This borer may cause injury to squash and pumpkin, but the damage to pumpkin is not usually severe enough to require control. The moth flies during the day. Its abdomen is ringed with orange and black stripes, the front wings are dark olive-green to black, and the hind wings are clear with a brown border. The adult moths lay eggs near the base of the plant from late June through July and early August, and the larvae enter the stems where they live as borers. Wilted runners and vines and deposits of frass near the base of the stems indicate their presence. The larvae are white with brown heads and about 1" long. When mature, they leave the plant and descend into the soil. There they spin a cocoon and remain until the following spring when they pupate. There is one generation a year.

Squash bug, Anasa tristis.
The squash bug commonly feeds upon pumpkin. The squash bug is dark brown, about 5/8" long, and hibernates in protected places. When disturbed, they produce a distinctive smell. The overwintered bugs feed upon the young plants as soon as they appear above ground. The bug punctures the plant and sucks the sap. Later, the females lay clusters of shiny brown eggs on the undersides of the leaves. After hatching, the nymphs pass through five molts in 4 or 5 weeks. There is one generation per year.

Because the squash bug prefers to hide near the plants, the use of mulch may increase squash bug populations. Control with insecticides is difficult, due to the habit of hiding under debris, and is rarely necessary. Squash plants beyond the seedling stage can tolerate heavy squash bug feeding. If needed, malathion, which is among the products registered for use on this insect in Connecticut, may be used on seedling plants. Consult the label for dosage rates and safety precautions.

Squash lady beetle, Epilachna borealis.
This insect sometimes feeds upon pumpkin. This ladybeetle and the Mexican bean beetle are two kinds of ladybeetles that injure plants in Connecticut. Most of the others are beneficial and devour aphids and scale insects. The squash ladybeetle hibernates in sheltered places and emerges to lay its eggs in June on the underside of the leaves. Both adults and larvae feed on the leaves. The larvae usually appear about the middle of July. They are about 5/8" long, bright yellow with six rows of long, black, branched spines. The adult is dull yellow and marked with 12 black spots.

There is one generation each season. Control is not usually necessary.

Striped cucumber beetle, Acalymma vittatum.
This insect may injure pumpkin seedlings early in the season. See Cucumber Beetle fact sheet.