Rhizoctonia web blight is a persistent problem with Azaleas. It is a fungal disease that cannot be detected by the human eye, which makes it extremely difficult to control. The fungus can be present on stem cuttings and then transferred to nursery stock which can then infect entire Azalea crops, making a vicious circle of contamination.
Agricultural Research Service scientist Warren Copes and his university collaborator have discovered that dipping the Azalea cuttings in hot water effectively kills the pathogen. The cuttings are submerged in 122° F. water for 20 minutes just prior to sticking into the rooting media. Although the fungus is eliminated from the cuttings, re-contamination is possible at other areas of the production process. They are now working on where re-contamination is most likely, and how to minimize it.
More information on Rhizoctonia web blight on Azalea can be found at the US Agricultural Service website.
Success With Rhododendrons and Azaleas, Revised Edition
Rhododendrons & Azaleas: A Colour Guide
Growing Rhododendrons and Azaleas (Cassell Good Gardening Guides)
