When Wisconsin rosarians talk about bug concerns in their garden, that conversation is frequently about spider mites, aphids or Japanese beetles. After eliminating pesticides in my garden for the past two years, I have observed a few different “bugs” in my garden. I am not sure if my new interest in bugs is making me more observant or if my not using chemicals encourages a wider variety of bugs – good and bad. I honestly don’t remember leafhoppers ever being a concern.
Leafhoppers are small insects, typically about 1/8 – 3/16 inch in length, elongate and somewhat wedge shaped. Female leafhoppers insert eggs into tender new plant stems leaf veins and tissues continuously throughout the spring and summer, producing multiple generations per year. The nymphs are active insects, moving readily when disturbed, often with crab-like side-to-side walking. Adults are winged and fly readily, leaping from plants with their enlarged hind legs. In the fall, the female leafhoppers deposit eggs into woody stems and twigs where they safely overwinter until spring. Fall egg laying by leafhoppers can wound the canes and open the door to fungal pathogens. There are more than 2,500 species of leafhoppers in North America. Different species favor different crops. The Rose Leafhopper uses roses for overwintering and trees such as oak, apple, maple, hawthorn and poplar for summer hosting. Interesting that this group of trees is prevalent in the woods surrounding my garden.
Leafhopper damage may appear as stippling on rose leaves, like spider mite damage. It may also appear as brown damaged leaf edges, as if the plant did not receive enough water or perhaps looks like spray damage. While in general leafhopper damage is not considered fatal to the plant it can be unsightly and lead to nutritional deficiencies. Confirming the root cause of your plant damage is important before determining solutions
The stippling appearance from leafhoppers appears as the insect feeds on the sap using their piercing sucking mouthparts to feed on the nutrient rich fluids inside leaves and stems. While the stippling looks like spider mite damage, look for the tiny sand looking particles and/or active spider mites and webbing on the underside of the leaf to diagnose as spider mites. If the leaf is missing those signs, you see the small hoppers or perhaps their white, papery shed cast skin stuck to the underside, leafhoppers may be the cause.
Some species of leafhoppers can produce a condition known as hopperburn, by injecting a toxin into the plant’s vasculature which slows water and nutrient movement. This can cause injury to the vascular system of the plant, resulting in the curling, drying or yellowing of the leaves. I have experienced this in my garden this year. Hopperburn damage can resemble aphid damage, so it is important to look on the underside of the leaf to find either the leafhopper or aphid culprits.
Leafhoppers can be managed during the growing season by spraying the underside of leaves with water, hanging yellow sticky traps to catch jumping adults, or applying insecticidal soap or horticulture oil on the leaf undersides. Apply horticulture oil in the evenings to prevent damage to daytime pollinators. Avoid broad-spectrum sprays early in the growing cycle to keep beneficial insects in the garden. Lacewings, assassin bugs and ladybugs will help control leafhoppers. Petunias, scented geraniums, and aromatic herbs naturally repel leafhoppers. I now realize that those pretty zinnias I have added as a pollinator plant for beneficial insects attract leafhoppers. I may need to reconsider my choices of pollinator plants for next year.
Because rose leafhopper overwinter eggs tucked in the bark of rose canes, spring cleanup of damaged or scarred canes is important. Always clear away fallen leaves and garden debris around the base of your roses to eliminate hiding spots. Leafhoppers are also a fan of dandelions and certain weeds, so controlling weeds in your garden will also help with control.
Greater Milwaukee Rose Society 