Fall rose care
I had a beetle and black spot problem this year. I have 50 rose bushes and I am wondering the effectiveness or your recommendation for fall care. I did a google search and saw that some gardeners recommend Imidacloprid granules along the drip line. Others were concerned with the effect on the bees. I found Bonide (BND 952) with .22% imidacloprid ingredient. Is this effective? Thank you in advance for any advice. Rebecca Viola
Wayne County Michigan
Imidacloprid will control sawfly caterpillars and beetles. Applying as a granular will be effective against pests that feed on leaves, stems, roots, or woody parts of the plant.. The optimal time to apply a granular product is several weeks before the insects would emerge. If you must use insecticides, I would recommend waiting until mid-May - late June, as the product will lose its efficacy before Spring. Be sure to follow the label for instructions.
If a product is absorbed throughout the plant, there is some risk of adverse effects on pollinators. A foliar application (to the leaves) creates the biggest risk for bees, especially if the roses are blooming.