Cucumber Beetles

Cucumber beetle spreads bacterial wilt disease

By: Sandy Feather 2009
Penn State Extension

Q. I am a new vegetable gardener. Cucumber beetles decimated my cucumbers this summer. How can I prevent this problem with my cukes next year?

A. Although you rightly blame striped and spotted cucumber beetles for your problems, their feeding damage alone did not kill your cucumbers. They transmit a disease called bacterial wilt to your cucumbers as they feed on foliage, stems and blossoms.
Bacterial wilt causes the vines of cucumbers and muskmelons (sometimes pumpkins and squash, known collectively as cucurbits), to wilt during the heat of the day. Initially, the plants recover when it cools off in the evening. However, they soon wilt and die.

Diagnosing Bacterial Wilt

To diagnose the disease, cut a wilted stem and touch the ends together. Pull them apart slowly. If bacterial wilt is the culprit, a white, stringy exudate will extend between the cut surfaces.


There is no chemical control for bacterial wilt. Controlling cucumber beetles is the only way to avoid the disease. Growing young plants under floating row covers (Reemay or Garden Blanket) physically excludes cucumber beetles from your cucurbits. Keep them covered from the time you plant them until they are in full bloom. Allow enough material to give the plants room to grow, and seal the edges with soil. Once the plants are in full bloom, the covers must be removed to allow pollination. By then, the plants are mature enough to produce a good crop, even if they become infected. If you like, you can start making insecticide applications to protect your plants once the covers are removed.

Look at all those fresh Cucumbers!

Cucumber Beetle controls

A combination of rotenone and pyrethrum and Sevin (carbaryl) are labeled to control the beetles. Begin applications as soon as the seeds germinate or you set transplants out in the garden. Continue applications at weekly intervals until the plants run and mature. Although the beetles are present and actively feeding throughout the season, it is most important to protect the young plants. Mature plants are less susceptible to the disease, and you are likely to get a good crop of fruit, even if they eventually succumb to it.


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