Plant in well-drained soil that has the proper pH and fertility level. Avoid excessive nitrogen fertilization. When dieback occurs, prune out and destroy diseased twigs. Prune several inches below visible canker, and use a commercial wound dressing on all cuts. Spraying plants during wet periods and during the period of normal leaf drop with a fungicide will help control the disease.
Petal blight affects only the flower portion of the plant.
The first evidence of infection is the appearance of small, brown, irregular-shaped spots on the petals. Entire flower turns brown in 24-48 hours and usually drops. The disease generally occurs during the spring. Remove and destroy all infected plant tissue. Apply fungicide to the soil just prior to bloom to prevent germination of overwintering spores.