Grow Spectacular Spuds
The Colorado potato beetle is a formidable pest. This native beetle has spread throughout most of North America. The adults are slow-moving beetles that overwinter in crop debris. Although they can fly, they often walk across fields in the spring to find new potatoes.
Clusters of yellowish-orange eggs hatch into plump reddish-brown larvae that eat leaves with a vengeance. If uncontrolled, the larvae from a single cluster of eggs can defoliate a young potato plant.
As soon as the plants emerge from the soil, I routinely look at the underside of each leaf of every plant for egg masses. I squash these (as well as larvae and adults).
There are many interesting and unusual methods of beetle control, but the following methods are proven to help control the beetle damage.
Rotate crops. Don’t plant potatoes where any nightshade (pepper, eggplant or tomato) has grown in the last four years.
Cover the soil with mulch 4 to 6 inches deep.
Dig a trench (4 to 6 inches deep) between the new and old potato patches. Line this with black plastic. As the beetles migrate, they will fall into this and die. Note that if the plastic becomes covered with soil, they may be able to climb out.
Delay planting for a month.
Provide habitat for natural predators, such as toads, birds and ladybugs. The rose-breasted grosbeak is also called the “potato bug bird” because of its appetite for the beetles and larvae.
Squash the beetles, larvae and egg masses by hand.As a last resort, apply pesticides made from Bt ( Bacillus thuringiensis var. tenebrionis), rotenone and/or pyrethrum. Note that these may affect beneficial organisms, and beetles quickly develop resistance to pesticides.