It looks like Blackspot or similar fungus. Blackspot, “Diplocarpon rosae”, is a nasty fungus that manifests itself on rose bushes as black spots on leaves progressing to black spots fringed with yellow rings on both sides of the leaves. As they develop the spots enlarge. Eventually, as the disease spreads, the entire leaves will go from green to yellow and then drop to the ground. With time the entire rose bush may become defoliated. Leaves less than two weeks old are the most susceptible to this disease.
The worst case scenario can be avoided with some preventative measures, a keen eye and diligence. While plants are dormant in spring, spray thoroughly with fungicidal soap and wettable sulphur (both readily available at the local plant nursery).

By | 2017-09-11T15:49:01-07:00 April 4th, 2016|Plant Diseases|0 Comments

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