The Free Press, Mankato, MN

June 11, 2014

Market Corner: Win the battle against cucumber beetles

The Mankato Free Press

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Win the battle against cucumber beetles

One of the most frequent and persistent pests is the spotted or striped cucumber beetle.

While some insects just target one plant or plant family, these beetles bother many crops, including flowers, and are particularly devastating to vine crops (such as melons, squash and pumpkins). The adults chew on the stem and leaf material. Usually it's not just the chewing that harms the plant, but the diseases that are carried in their mouth parts and spread to other plants as they chew.

These beetles are about the size of a ladybug, but more oblong. But by the time you see adults, they have likely laid eggs in the soil near the plant roots. The eggs hatch into larvae that feed on the roots, so damage is also happening to the root system.

Don't wait until you see a lot these beetles before doing something — they are already multiplying.

Several types of dusting powder, including organic types, are very effective (including sabadilla and rotenone).

Repeat dusting after a rain, or at least once a week until you no longer see the insects. The dust is only effective on the adults, so you need to keep dusting until all generations below the soil emerge. Dust lightly; don't submerge the plants as the leaves need to breathe, too.

Have some dust on-hand so you're ready for any potential infestation. Vine crops are long-season plants, requiring 90-100 days or more. Attack before it is too late as there is not enough time in Minnesota's short growing season to re-plant most vine crops.

I have also had issues with these insects chewing on pumpkins and squashes, damaging the skin. One of the best preventatives is good garden sanitation. At the end of the season, remove all the vines or plant material where the insects were active. This foliage should not go into the compost heap or tilled back into the garden. Most insect eggs are wintered over unknowingly by the gardener. The beetle sometimes migrates into an area, but most live in the garden in some form (egg, larvae or adult).

By Diane Dunham-Selly, Mankato Farmers Market

Stop by the new Farmers Market location at Best Buy from 8 a.m. to noon on Saturdays and 3:30-6 p.m. on Tuesdays and Thursdays.