Question
My yellow roses developed red spots last fall on the petals and this year they have them too. What can I do? I was very careful last fall to remove all leaves from the bed and covered the roots with stones. The rose died back almost to the ground over winter. (Winnipeg)

Answer
Roses get mainly two different types of spots on the leaves and both are fungal diseases. Black Spot as the name suggests, is larger purplish black spots which then go yellow and kill the leaf. However there is another type of fungal disease called Cercospora and it is is characterized by the appearance of numerous tiny maroon to purple oval leaf spots that are scattered  across the leaf surface  Later, the center of these spots turn tan to almost gray in color while the margin of the spot remains maroon to dark purple. Heavily spotted leaves will turn yellow and are prematurely shed. It seems that ground cover roses are the ones that are prone to it the most. Any spray for black spot will get rid of both of these infections. Orthos Rose Pride seems to get good reviews. But you can also use garden sulphur but just don't use any spray if the temperatures are hot.