These are designed to prevent severe infection, which can defoliate plants by mid-season. Control starts with growing cultivars resistant to black spot. Most garden catalogs will identify cultivars resistant to black spot and other rose diseases. For the home gardener who wants to grow a few roses in the landscape, but does not want to be burdened with a fungicide spray program, black spot resistant roses offer a suitable solution. For those dedicated enough to follow a weekly fungicide spray program, black spot susceptible cultivars offer a challenge.
Successful control requires weekly application to protect the newly emerging foliage.
Apply fungicide sprays in the evening when there is less wind and temperatures are cooler. Cover both sides of the leaf when spraying. It is a good idea to use a different fungicide each season or alternate between fungicides during the growing season. Anyone using a fungicide should first carefully read the label and apply as instructed. References to fungicide products in this NebGuide are for the reader's convenience.