Q.Insecticide Damage To Knockout Rose.
I bought my 93 yr old mom a knockout rose. During the hot dry summer she noticed insects on the leaves, and sprayed it with bug spray. When I was there she pointed out that the rose wasn’t looking well and told me what she had done with the bug spray. I removed most of the dead leaves and sprayed the bush with water to remove any residue. Should I cut it back to remove any damage done, or leave it alone to hopefully recover.
I would ask the manufacturer of the insecticide for their input. There is usually an 800 too free number.
https://www.gardeningknowhow.com/plant-problems/environmental/herbicide-plant-damage.htm