Grubs In Soil Around Rose Bushes
I have many grubs in the soil around my knock out rose bushes. Every year there are many Japanese beetles. For the past 2 years, I've applied Bayer Advanced Rose and Flower Care that contains 0.22% imidacloprid. Is there any other treatment that you recommend for grub control? Thanks for your advice!
Frederick County Maryland
We do not recommend using imidiclopid on any flowering plants that are visited by bees (pollinators), as it can weaken their health. That alone will not solve your problem anyway.
Japanese beetles are strong fliers. They can came in from all over the neighborhood. If you have a great number in your lawn, you can try reducing their numbers by applying a product, such as Grub-Ex, with the ingredient Acelepryn. Acelepryn is a very safe insecticide.
Another approach is to periodically brush the beetles into a container of soapy water. Japanese beetles are not active all summer. They appear after roses have their initial flush of bloom. You can prune off the bloom and by the time new blooms get going, most beetles should be gone.
Read this carefully: http://extension.umd.edu/hgic/japanese-beetles
Only apply lawn grub control if their numbers exceed 8 per square foot. Having some grubs in the soil is normal, and it is not worth your time or money to treat a few when more can just fly in from elsewhere.