I have white fungal type spots on canes of roses. Cure please?
Sound like powdery mildew. The very best cure I have found is a product called Green Cure. It is available on-line and at some good local garden centers. Apply it at the cure rate at least two sprayings 7 days apart. Then the prevention rate should work fine. The directions are on the label. Green Cure is a top notch earth friendly fungicide.
Stan the Roseman