Controlling powdery mildew in outdoor roses

The experimental fungicide El 273 provided excellent control of rose powdery mildew when applied in these tests on a 14-day spray schedule when mildew was severe before spray applications began. (Unfortunately, El 273 will not be marketed by the manufacturer.) Triforine gave good control with data from these and previous trials suggesting applications before appearance of rose powdery mildew, and on a nine-day spray schedule.