Waging war in the garden CUCUMBER BEETLES
By Stephanie Hughes
OSU Ext. master gardener volunteer
This year we have studied, laid out our plan, and are ready to take on this devastating plague on the homeowner garden - the cucumber beetle.
First, identify the beetle. There are two kinds of cucumber beetles in Ohio. The first is about º-inch long and has a yellow/green body and 3 black stripes on its back. The second is the same yellow/green body, same º-inch length, but has 12 black spots on its back. The adults overwinter in leaf and other debris in the garden. In late spring and early summer, the adults emerge and feed on seedling of the cucurbit family. This is cucumbers, squash, melons, zucchini, pumpkins and gourds. As they eat, they lay eggs either on host plants or in soil. The larvae feed on the roots of the seedlings, killing them. They pupate, and emerge as adults to feed on the vines of our valued garden plants, ruining summer and Halloween at the same time.
In the beetles’ gut, a bacteria lives and as they chew plants and deposit feces, they are infecting the plants with it – bacteria wilt. One day you have beautiful vines with blooms and fruit, the next day the vine is wilted and dying. There is no cure. This bacteria multiplies rapidly throughout the vascular system, clogging it, so the plant cannot uptake needed water. Death comes quickly.
Thus, our strategy. In the fall, clear off all debris from the garden. Rototill the garden to overturn soil and expose the insects. In the spring plant trap crops (like ‘Blue Hubbard’ and ‘Turk’s Turbin) around the perimeter of the garden to lure them, and then destroy them. These should be planted two weeks before the crop you want to grow. Cover seedlings as they grow, so the beetles cannot get to them. Remove any weeds that can be potential hosts. Mulch with straw or black plastic, so the beetles cannot get to the seedlings easily, and predatory insects can hide close to the plants.
Second, plant crop in the last week of June, avoiding the peak time for adults. Rotate crops (away from original planting), and do not plant by host crop plants – corn, beans, grasses and weeds. Also, plant non- or low-preference varieties of seeds. Monitor plants daily.
Dusting baby plants with kaolin clay is an option, as the beetles do not like the feel of it in their mouths. You can place imidacloprid in the furrows as you plant, but water properly. Read all label instructions and follow directions on organic and conventional pesticides. Let’s win this war.
Read more about this insect and see photos at http://go.osu.edu/cukebeetle.