Downy mildew affects roses throughout the U.S.
Infection begins on young plant growth. Leaves develop dark purplish to dark brown spots. Symptoms may resemble burns caused by pesticide toxicity. Humid, cool conditions favor downy mildew infection.
If downy mildew has been a problem in the past, begin spraying with a copper soap when new spring growth emerges. Repeat every 7-10 days for as long as needed to control disease. Fixed copper is one of the oldest fungicides and bactericides used to control a wide range of plant diseases. 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.