Colorado Potato Beetles and Cucumber Beetles
Posted: June 30, 2014
Colorado potato beetle larvae can quickly defoliate potatoes, eggplant and even tomatoes or peppers.
It is always surprising the first time you realize that Colorado potato beetles (CPB) love eggplant even more than they love potatoes. If you have not seen them yet, you are likely to. Colorado potato beetles overwinter as adults, hibernating in the soil near where previous crops were grown. They emerge in the spring and primarily crawl to their new hosts where they feed and lay eggs. The resulting larvae can defoliate the crop very quickly! CPB prefers potatoes and eggplants but can also be a problem on tomatoes and peppers.
Crop rotation is the first line of defense. A barrier trench lined with plastic between a new field and an old field will catch many crawling adults and trap them. Mulching crops with straw before adults arrive reduces and delays pressure (difficult on potatoes that are hilled). For plantings less than two acres hand picking may be practical if CPB pressure is low. For organic growers Entrust (spinosad) has very good control (14 of 14 trials) on larvae. Pyrethrin, Neem and Beuvaeria products are also OMRI approved. See Northeast IPM Organic Potato Production Guide for details. For conventional controls see the Commercial Vegetable Recomendations for your state.
Flea beetle pressure which seemed lower than normal this spring is also mounting. Tiny, black insects, they often jump when disturbed. Their feeding causes small holds in the leaves. Eggplant is especially attractive and the “swiss cheese” effect can permanently stunt small plants if not protected. Row covers work well and generally promote earlier yields of eggplant. However, if you do not have plants covered before the insects come in, row cover will not be effective. For organic growers spinosad, neem, capsaicin, pyrethrum and kaolin clay (surround) may give some control. Trial results are variable (see Resource Guide for Organic Insect and Disease Management). For conventional controls see the Commercial Vegetable Recomendations for your state.
Flea beetle on eggplant.
Striped cucumber beetles are ¼ inch long with black and yellow stripes. Adult beetles are often easiest to find in the flowers and also congregate on leaves. Small seedlings are very susceptible and can often be killed. When plants are small is also when it is most likely that beetles will transmit bacterial wilt. Commonly organic growers dip transplants in Surround (kaolin clay) and cover with row cover immediately upon planting. Plants then have a double layer of protection until row covers must be removed at flower. Then the larger plants can tolerate more feeding and are less susceptible to bacterial wilt. Transplants that were not protected with row cover can be sprayed with kaolin clay which acts as a physical barrier and irritant. Insects have a harder time finding plants whose color is masked. If they do land on the treated surface particles of kaolin clay break off and attach to the insects body triggering an excessive grooming response that distracts the pests. For additional controls see Organic Cucumber and Butternut Squash Production or the Production Guide for your state.
Striped cucumber beetle.