Answer: White spots can indicate sunscald, or simply be residue from foliar fertilizers. Sometimes a chemical spray or dusting will leave a residue that looks like white spots, and these can be rinsed off with water from the garden hose. Or, your rose might be suffering from powdery mildew. This fungal infection leaves a white powdery layer on the foliage and the foliage tends to be distorted as well. This can be treated with a baking soda based fungicide such as Remedy. Or, it might be evidence of a pest problem such as thrips. Since this type of damage is difficult to diagnose long distance you will have to put on your detective cap and investigate all the possibilities. Good luck with your roses.
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