Abstract: Cucurbit Crops

Small Group Session: Cucurbit Crops (Squash, Pumpkins, Cucumber, and Melons)

Integrated Pest Management for Cucumber Beetles

Mike Hoffmann, an entomologist from New York, outlined the life cycle and possible management methods for striped cucumber beetle, Acalymma vittatum. These beetles are most damaging when they feed on cotyledons or young seedlings. The larvae feed on cucurbit roots, but the importance of the damage is unknown. Striped and spotted cucumber beetles also carry bacterial wilt, which is a severe disease of cucumbers and most melons.

There are consistent differences in beetle preferences among varieties. Highly preferred varieties can be used as trap crops in combination with beetle traps. Traps baited with an attractant can trap 60% of the beetles in the field. A yellow cloth with a small amount of insecticide (not organic) is used to kill the beetles.

Mike’s laboratory has determined that pumpkins can tolerate high levels of leaf damage (up to 80%) without loss of yield, if moisture is sufficient.

Mike’s laboratory is also working on the effects of cultivation on beetle survival over the winter, the effects of cucurbitacin in the beetles’ host plants on their survival through the larval stages, and on biological control.

Squash Vine Borer Control with Cotton Row Cover

Bryan O’Hara, an organic farmer from Connecticut, researched the effects of cotton row covers and planting date on pest damage and yield. He had to hand-pick striped cucumber beetles from the rows that were not covered; otherwise the beetles would have destroyed the early plantings. He found that the row covers, which were held above the plants on wire hoops and attached to the ground with wire staples, effectively kept the cucumber beetles and squash vine borers, Melittia cucurbitae, off of the plants until flowering, when the covers had to be removed to allow pollination. The greatest yields were obtained from the earliest planting (started in the greenhouse May 6, transplanted May 25), and the row cover increased yield in this planting, although not necessarily in all the others. However, the row cover eliminated many hours of labor in hand-picking cucumber beetles.

Harvesting Greens as a Strategy to Control Squash Bugs (Anasa tristis)

Eero Ruuttila, an organic farmer from New Hampshire, learned from his Cambodian workers that young tips of squash and pumpkin vines are peeled, put in soup, and eaten in their cuisine. Eero found that the young tendrils and leaves of squash and pumpkin vines were also favored oviposition sites for squash bugs. By harvesting one-third of the young vines from his plants during six weeks in July and August before the eggs hatched, he virtually eliminated the population of squash bug nymphs, sold the tendrils and male blossoms to the Cambodian customers, and also got a good yield of squash and pumpkins from the female blossoms that are set closer to the center of the plant.

Discussion: Cucurbits

In response to a question, Eero Ruuttila said that he used to have striped cucumber beetles, but they are no longer a problem, so he doesn’t need to spray them. Mike Hoffmann discussed the possibilities of trapping out striped cucumber beetles, using a chemical attractant, preferred varieties of squash, and traps. He also mentioned that he had experimented with using nematodes against the larval stages of the striped cucumber beetle, but without much success.

There was a also a discussion of the possibility of using nematodes against squash vine borer and of using deep plowing to kill the overwintering larvae of squash vine borer in the soil.