Submitted to: Ornamental Workshop on Diseases and Insects
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/2012
Publication Date: 10/1/2012
Citation: Copes, W.E. 2012. Timing of fungicide sprays to prevent azalea web blight symptoms. Ornamental Workshop on Diseases and Insects. 1.
Technical Abstract: Azalea web blight is an annual problem on evergreen azalea cultivars grown in containerized nursery production in the southern and eastern United States. Fungicides are the only approach currently used to control Rhizoctonia web blight; however, control is poor in some years because the specifics of timing have not been well understood. Research investigated decision-based and weather-based prediction strategies. Both approaches provide advance predictive timing for fungicide applications. Weather-based risk predictions are simple models that provided an 80% prediction accuracy and advance notice of applications. The most reliable decision-based criteria involved the application on scheduled calendar dates. Scouting weekly for the number of leaf blight within the azalea shrubs interior canopy could be used in conjunction with calendar date to adjust timing in response to year-to-year differences in disease pressure. The research provides recommendations for timing fungicide applications at commercial nurseries and increased biological understanding of Rhizoctonia web blight that will benefit extension specialists and research scientists.