Can Moss cause leaf spot on ornamental shrubs? As I was cleaning around the base of my rose bushes, I noticed small patches of Moss. I'm wondering if this may have caused some of my Black Spot problems this year.
Rose Black Spot
Moss will not cause blackspot as such, but will certainly harbour the fungal spores and should be removed. The best treatment is a fungicidr applied once or twice early in the season before the disease appears - also by now dispose of all the infected leaves.