My roses look like they have some kind of disease, they have holes in the leaves and are not producing many roses. What can I do to help them get over this disease or whatever this is?
The Gardener’s Answer
Hi, Tammy: It sounds like your roses are being eaten by a common pest known as rose slugs. There are several species, all belonging to the sawfly family, and in the larval stage they attach themselves to the underside of the foliage and feed until they have skeletonized the leaves. These insects are not a slug or a caterpillar, they just resemble one and depending on species they can have more than one generation per year. They are hard to see since they are typically the same color as the leaves and they are only found on the underside. The good news is that even though they can make your roses look bad early on, they usually do not affect the overall health of the plant. If the damage is not severe, you can remove the foliage that does not look good. If the damage is severe, other control methods include hand picking, which may be feasible if they are not in abundant numbers; otherwise, spraying with a horticultural oil is an organic option and Sevin is also effective although not organic. Make sure to follow product instructions and remember to spray the underside of the leaves. It may take a few applications depending on population numbers. Good cultural practices are always important in terms of keeping our plants healthy. Make sure to clean up all plant debris around your roses and prune properly for good air circulation.