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Japanese Beetle Issues

Photo Credit: The Ohio State University. Japanese beetles cause leaves to appear skeletonized.

This is turning out to be a more significant year for Japanese beetles in central Ohio than we have had in a few years. Favorite hosts, such as roses, sand cherries, purple plums, and lindens are sustaining more damage than we have seen in some time.

Look for leaves that are “skeletonized” (only veins remaining). This is a tell-tale sign of Japanese beetles. Good horticultural practices, including watering and fertilizing, will reduce the damage caused by these beetles, but oftentimes you simply need to get rid of them.

Here are some ideas:

Row Covers Protect your plants from Japanese beetles with row covers during the 6- to 8-week feeding periods.

Hand Pick Unfortunately, the most effective way of getting rid of Japanese beetles is to hand pick them. It’s time consuming, but it works, especially if you are diligent. When you pick them off, put them in a solution of 1 tablespoon of liquid dishwashing detergent and water, which will cause them to down.

Use a Drop Cloth Put down a drop cloth. Then, in the early morning when they’re most active, shake them off and dump them into a bucket of soapy water.

Insecticides If you wish to spray or dust with insecticide, speak to your local garden center about approved insecticides in your area. Apply sprays in the morning and never in full sun or at temperatures above 90-degrees (F). If your plants start to wilt, rinse the leaves immediately with clean water.

Traps Japanese beetle traps can be helpful in controlling large numbers of beetles, but they also might attract beetles from beyond your yard. We don’t recommend this!

Fruit Cocktail You can buy Japanese beetle traps of all sorts, but most are no more effective than a can of fruit cocktail. Make sure you let the can sit in the sun for a week to ferment. Then place in a light-colored pail of water filled to the top of the can of fruit. Place the pail about 25 feet from the plants you want to protect. The beetles will head for the sweet bait, fall into the water, and down.

For Roses... Note that insecticides will not fully protect roses, which unfold too fast and are especially attractive to beetles. Nip the buds and spray the bushes to protect the leaves. Timeliness and thoroughness of application are very important. Begin treatment as soon as beetles appear, before the damage is done.

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