Azalea Rust

Asked July 17, 2015, 12:35 PM EDT

I have a dozen large, mature, beautiful azaleas in my yard. Two have become entirely discolored with what I assume to be Azalea Rust. Can I save them, or do they need to go to protect the others. Should I treat the others before they go too? Is this treatment something a registered hortaculturist should do? I'm heartbroken.

New Castle County Delaware

1 Response

Your photo looks much more like azalea lace bug damage. It might be a good idea to bring a sample to the county extension office (461 Wyoming Road) for an accurate diagnosis. It is best to control lace bugs in May when the young first emerge. They can be controlled with insecticidal oil (summer formulation) or insecticidal soap. A systemic insecticide labelled for lace bugs can also be used. You should turn the leaves over and see if lacebugs are still present. If they are, you have to get complete coverage of the undersides of the leaves for adequate control. Here is a fact sheet from the University of Maryland about diseases and insects of azaleas and rhododendron.