Is there any particular insecticide I can use to protect unaffected roses? Is it worth trying to save affected roses by cutting the diseased parts off?
To help protect the roses that are not infected, I recommend using a product called Bayer Tree and Shrub Granules. Apply per the label directions for ornamentals/roses.Or you can purchase a good mitacide and spray the rosebushes with that per the label instructions as the disease/virus is now believed to be spread by mites. Infected rosebushes cannot be saved by pruning out the bad looking parts. Rose rosette is a virus and thus exists throughout the rosebushes infected. Here is a link to a site that has great in-depth information on rose rosette virus: http://americanhort.theknowledgecenter.com/OnDemand/index.cfm?view=category&colid=143&cid=377