A more complete list of azalea problems is at azalea diagnosis . Follow their label safety precautions such as gloves and other protective measures to avoid personal harm, and follow their label rates of dilution and application to avoid harm to the plants and environment. Petal blight Flowers first appear spotted, and collapse and appear water soaked in a few days. Dead flowers turn brown and cling to the plants instead of falling to the ground. Petal blight is more severe in cool, moist springs.
Petal blight is caused by an airborne fungus which over-winters on the spent flowers.
Remove old mulch and replace with new in early spring. Drench soil area under plants with Terracolor in January. Spray with Thylate or Benomyl when blooms begin to open. Good coverage is essential. Bayleton may be used when the buds show color.