Don’t let beetles bug your plants

Question: I planted several fruit trees this spring, and they are doing great, but now the Japanese beetles have arrived and are feeding on the foliage. There are clumps of the beetles all over the plants, and I'm really worried that they'll kill them. What should I do?

Answer: Japanese beetles emerge in Western Pennsylvania around the last week in June and feed for several weeks. If left unchecked they can defoliate young plants and trees like yours. While it's extremely rare for a Japanese beetle infestation to actually kill a plant, the effects of the defoliation can be stunted growth and decreased vigor. I have a few suggestions for controlling the beetles on your young fruit trees.

First, and easiest in my opinion, is to cover each tree with a sheet of floating row cover. This lightweight fabric is available at most local garden centers and can just be laid over the plant and fastened around the trunk lightly with a piece of twine. Because light, air and water can easily pass through the fabric, you can leave it in place until the beetles are gone. Plus, you can reuse it for several years. It also keeps birds away from the ripening fruit. Although this may not be an option in a few years when your trees are bigger, it is certainly the most effective, one-time control for now. I use it on my blueberry bushes every summer.

There are two natural product controls that are effective against Japanese beetles. The first is neem. It is derived from the seeds of the tropically grown neem tree and it's highly effective, widely available and safe for even organic gardens. The second product control is spinosad (it is sold under several different brand names including Deadbug Brew and Monterey Garden Insect Spray among many others). Derived from a fermented soil bacteria, spinosad works well against a broad range of munching insect pests including many species of beetles and caterpillars. It's fairly new to the market, but it's a really wonderfully effective product. Both neem and spinosad are organic, but you'll need to use care when applying them around bees and other beneficial insects as they are also susceptible to sprays. Please be sure to follow all label instructions and manufacturer's directions when using any garden products, even those labeled for use in organic production.

To help control next year's beetle population, you may want to consider these ideas as well. The eggs and young grubs need water to survive, so don't irrigate your lawn in high summer. This might sound odd, but when your grass has gone dormant due to lack of rainfall (it's brown, not dead -- I promise), the next generation of beetles is dying. If you water your lawn through the summer, you are promoting Japanese beetles. Applying Milky Spore and/or beneficial nematodes to your lawn according to label instructions controls the beetles in their larval form (commonly called grubs) and also will reduce next year's population.

Insect control