University of Illinois Extension

Identifying Squash and Other Vine Problems

Squashes have numerous disease and insect pests. One of the more serious insect pests is squash vine borer. This insect tunnels into the stem within six inches of the soil line. The insect feeding is severe but would not generally be fatal to the plant. However a bacterial rot almost always follows the insect into the vine. This causes the vine to decay and turn “mushy.” Water and nutrients are cut off from the diseased area out to the tip. Thus the vine wilts and dies. Squash vine borer has been sprayed so often that the insect has resistance to most insecticides. However, homeowners may still get some control if they treat the plants once a week with carbaryl till the squashes start to form. Use according to all label directions and precautions. The first application is applied when the plant begins to vine out. Treat the plants’ crown and runners. A non-chemical control is to cover the plants with polyester row covers from the day planted until blooming starts. Make sure the edges are buried so the insects cannot get under cover.

Another pest of squashes is squash bug. This insect lays a mass of reddish eggs on the bottom side of the leaves. Destroy these eggs before they hatch. Keep garden free of debris. Lay down boards, during the day lift boards and destroy the bugs hiding under them says James E. Schuster, Extension Educator, Horticulture with University of Illinois Extension. Another control is to use pyrethrins. Use according to all label directions and precautions.

Cucumber beetles not only attack cucumbers but also squashes and melons. These insects can cause serious feeding damage. In addition, they can also carry a disease called Bacterial Wilt that is fatal to the infected plants. It takes about six weeks for the disease to kill the plant. If the insects infect the plants while they are seedlings, the plants will be dying or dead by fruit set. Carbaryl or rotenone can be used. Use according to all label directions and precautions. Apply in spring and continue till plants begin to bloom. Once flowering starts, the insecticides can still be used but only just before sunset to avoid killing off the bees necessary for pollination. A non-chemical control is to use the polyester row covers. These cucumber beetles tunnel in the soil when necessary. So the edges of the row cover needs to be buried fairly deep to help reduce the chance of the insects tunneling under the cover to get to the plants. Keep cover on till both male and female flowers are on the plant. The stems of male flowers are straight from vine to blossom. Female flower stems have a bulge just behind the flower. At first, only male flowers are produced. When the plants start to send out side shoots, the females develop on the main stem and the males are produced on the side shoots. Now the covers need to be removed so that bees can pollinate the flowers.

For more information on vine crop pests refer to this web site: www.urbanext.uiuc.edu/vegproblems/.