Although rust is widespread, it is most consistently a problem in Western states.
Yellow "rust" spots appear on the topsides of leaves during cool weather in spring or late fall. Infected leaves become twisted and dry. Spores infect leaves when rain, dew or fog occurs at temperatures from 55° to 75°F.
When rust is first noticed, pick off and destroy infected leaves and spray plants with a copper soap. Repeat sprays every 7-10 days as long as conditions favor rust infection. Remove and destroy diseased leaves and twigs in the fall. We recommend Soap-Shield Flowable Liquid Copper Fungicide.*
*NOTE: Soap-Shield may cause copper toxicity on some rose varieties. Copper toxicity appears as purple spots and is more likely to occur outdoors than in greenhouses.