Curled leaves make it harder for a foliar spray to effectively control the pests if that is what you are suggesting. I guess it could be used as a maintenance procedure every so often when the bushes are healthy but with these large bushes I feel an even over-all application would be a challenge. Plus a foliar spray might still affect beneficial above ground insects. I have had good results with the drench, but switching to another product might give different results.
I am reading about neem oil, that might be a possible alternative
