Question From: G. Asche - West Linn, Oregon, United States
Q: My andromeda branches have turned black and it doesn't brush off. It is on the leaves too, though that does brush off. Looks like soot.
Your shrub has sooty mold. The plant has aphids or scale which give off a honey dew that drips on to the leaves and sooty mold grows on it. Begin by getting rid of the insects. Horticulture oil or neem oil will do the job. The wash off the sooty mold by spraying the shrub with soapy water - I prefer the original Dawn. Rinse it well with clear water. Spraying is best done early in the am or just at sundown or on a cloudy day. Best And Happy Yardening, Nancy