Rose Disorder: Blackspot
Author(s) M. F. Heimann, G. L. Worf.
Blackspot is common and potentially serious throughout Wisconsin. The symptoms that positively identify this disease are spots visible especially on the upper sides of leaves. The number of spots per leaf varies, and so do the number of spots required to cause a leaf to drop off. Leaf drop commonly follows infection, and the leaves may yellow before they drop. Premature leaf fall from blackspot makes roses more susceptible to winter kill.
Find out how to spot, prevent, and treat blackspot on the roses in your garden with this helpful fact sheet (2 pages).