Growers have another 5-6 weeks to protect their pumpkin crop from insect pests such as squash bugs, spotted and striped cucumber beetles, and possibly aphids. Read the guidelines below for tips on how to manage these late season pests.
Squash bugs – These brown adults and gray nymphs are true bugs that have been slowly building in number through the summer and now seem to be everywhere in the field. They have sucking mouth parts, and feed by piercing the stems, petioles, leaves and fruit trying to get a meal. The time is past for spreading any diseases but in large numbers they can damage fruit and collapse foliage. Thresholds to control these bugs vary by stage but generally more than 1 egg mass per plant or more than 1 adult per plant can be used. Nymphs are generally easier to kill than adults but treatment is only recommended if squash bugs exceed the threshold. See insecticide options at the end of the article.
Striped and Spotted Cucumber beetles – These black and yellow striped or spotted beetles have been quietly residing in pumpkin and squash flowers for most of the season, but now that the fruit is maturing, fewer flowers if any are being produced. Beetles are now moving from the flowers back into the canopy and onto the fruit, where they can feed on the rind and the handles, causing significant cosmetic damage. To protect the quality of the fruit and handles, foliar insecticide applications should be made only if beetles are seen actively feeding and scarring the rind. See insecticide options at the end of the article.
Aphids – These small soft bodied sucking pests usually move into fields in mid to late August, and can be found on the lower leaf surface. As a consequence of treating for cucumber beetles and squash bugs, a rapid increase in aphids may be seen when foliar insecticides are used, as most broad spectrum insecticides knock out natural enemies of aphids such as ladybeetles, parasitoid wasps, green lacewings, etc. When large aphid populations inhabit a field, production of honey dew and subsequent blackish sooty mold can be found on the pumpkins. The sooty mold can be wiped off and does not damage the fruit.
Products used to control squash bugs, cucumber beetles, and aphids can be found in the Midwest Vegetable Production Guide chapter on Pumpkin (https://ag.purdue.edu/btny/midwest-vegetable-guide/Documents/2017/104_Cucurbits.pdf).