Funginex with Triforine as the active ingredient and Benlate, used as directed on the label, will give reasonable control. Blackspot, anthracnose, rust and verticillium wilt are not serious problems on roses in Colorado. Funginex will give good control of blackspot and rust. Anthracnose is similar in appearance to blackspot but has clear-cut margins around the spots instead of the ragged or feathery margins typical of blackspot. Verticillium wilt usually is a problem when roses are planted in soil previously planted to tomatoes or other plants that were infected with the disease.
Symptoms usually begin with yellowing of the lower leaves on a portion of the plant.
The yellowing includes the veins of the leaflet, but generally there are green spots or blotches mostly near the edges of the leaflet. Wilting of the plant is indicated by the drooping blossoms or buds. In most cases, die back of the canes begins at the tips, turning yellow, then brown and causing death of the cane. New growth may continue with some growth appearing completely normal. However, some new canes usually appear with very pale foliage.