Deterring Striped Cucumber Beetles in Organic Cucurbit Production Systems

Striped cucumber beetles will feed voraciously on all plant parts, and small seedlings are particularly susceptible to injury and may be killed. As cucurbit plants mature (4–5 true leaves), they become a bit more tolerant to striped cucumber beetle feeding.

Adult striped cucumber beetles lay their eggs at the base of cucurbit plants. Once the larvae hatch, they feed on the plant's roots and crowns. A new generation of striped cucumber adults will typically emerge in July and will feed on pumpkins and other cucurbit fruits in late summer to early fall. 

While striped cucumber beetle feeding injury can be significant, the bigger threat lies in the striped cucumber beetle’s capacity to disseminate bacterial wilt to zucchini squash, cantaloupe, cucumbers, and other cucurbit crops. Watermelon is considered resistant to bacterial wilt. Cucurbit crops are very vulnerable to bacterial wilt between emergence and the bloom stage. After the successful transmission of bacterial wilt by striped cucumber beetles to cucurbits, growers will first see a few individual leaves wilt, followed by a few stems wilting on the infected plants. Bacterial wilt will continue to progress until the entire plant wilts and then dies (usually within 7–14 days after the onset of symptoms).

Management of striped cucumber beetles on any farm requires an integrated approach. Growers should first consider less attractive varieties to the striped cucumber beetles or select cucurbit varieties less susceptible to bacterial wilt. Cucurbit varieties that contain lower levels of the compound cucurbitacin also tend to be less attractive to striped cucumber beetles, but it may be difficult to obtain this information from breeders. Cucumber varieties Shintokiwa, County Fair, Arkansas Little Leaf, and Little Leaf are reported to be tolerant or resistant to bacterial wilt, as per Cornell University.

Crop rotation and sanitation are used to delay but not eliminate the infestation of cucurbit crops by the striped cucumber beetle. Cucurbit crop debris should be plowed down or incorporated after harvest to reduce overwintering sites for the adult beetles. Locating the cucurbit fields a long distance from the previous year’s cucurbit plantings may help minimize early-season infestations.

Kaolin clay, marketed as Surround, is used by organic growers throughout the Mid-Atlantic region as a deterrent for some insect pests. Kaolin clay is white in color, and when sprayed on plants, it leaves a white or chalky film on the leaf and/or stem surface. Organic growers typically apply kaolin clay or Surround approximately twice a week early in the growing season as a deterrent for striped cucumber beetle.

Striped cucumber beetles are attracted to the color yellow, and some growers have been successful in reducing striped cucumber beetle populations in fields by suspending yellow sticky tape or bands over the crop canopy. Yellow sticky tape will become quickly filled with a variety of insect pests, so it must be replaced periodically to maximize its trapping efficiency.

Entomopathogenic nematode applications to cucurbit plant root systems have been utilized by some growers to reduce striped cucumber beetle numbers with mixed success. Research data indicates that the application of entomopathogenic nematodes to the soil around cucurbit plants will reduce striped cucumber beetle populations but that these beneficial nematode applications may not effectively control the next generation.

Floating row covers can also be deployed in vegetable production systems to prevent striped cucumber beetle feeding injury. Row covers are usually left on to protect cucurbit crops until the onset of flowering. Research at Iowa State University looked at leaving row covers on for a period of 10 days after flowering in muskmelons to prevent bacterial wilt. The data in the Iowa State University study demonstrated that by delaying row cover removal by 10 days (after flowering begins), they were able to significantly reduce the incidence of bacterial wilt infection in their muskmelon trial without reducing overall yields.

Perimeter trap cropping is another method that growers can deploy to reduce striped cucumber beetle infestations. Blue Hubbard Squash contains high concentrations of the striped cucumber beetle attractant, cucurbitacin. Growers using a perimeter trap crop system plant Blue Hubbard squash completely around the cucurbit crop that they wish to protect. Striped cucumber beetles are attracted to the Blue Hubbard Squash as a food source, and growers can then concentrate their insecticide applications on the Blue Hubbard Squash to effectively manage the feeding striped cucumber beetles.