Ruth Ann Asked
Something is eating the leaves on my Knock Out rose bushes. What is the best remedy?
The Gardener’s Answer
Hello, Ruth Ann: I cannot be certain what is eating the foliage of your roses without seeing a sample, but we have seen a lot of damage from the rose slug on Knock Out roses this year. They overwinter in the soil and emerge to start feeding early in May. They are tiny larvae that feed on the underside of the foliage. If you go out and look at the underside of the leaves you should see the culprits. They look like a caterpillar. Control depends on the amount of damage. If only some of the foliage is damaged you can remove it, and be sure to discard it so the insects are removed from the plant as well. If the damage is more severe you can use Sevin, a product that contains the chemical chlorpyrifos, which will kill these insects. You should be able to find this product at your local garden center. It is not an organic so be careful when spraying and follow application instructions. Sanitation is important in reducing the number of these insects. Be sure to remove all fallen foliage and other plant debris throughout the year. For a positive identification take a sample to your County Cooperative Extension Service or to your local garden center.