Submitted to: Mississippi Nursery and Landscape Association
Publication Type: Trade Journal
Publication Acceptance Date: September 15, 2006
Publication Date: October 15, 2006
Citation: Copes, W.E. 2006. Research on Rhizoctonia Web Blight on Azalea. Mississippi Nursery and Landscape Association Newsletter. October/Fall:6,8,21. Technical Abstract: Rhizoctonia web blight is a reoccurring problem in compact varieties of container-grown azalea (Rhododendron sp.) in the Gulf Coast States. During the summers of 2002 and 2003, disease severity was measured weekly in the inoculated center plant of plots consisting of 49 ‘Gumpo’ azalea plants. Plant spacing within plots was set at 0, 6, 12, 18, or 24 cm, and plots were arranged in three randomized complete blocks. Evaporative potential (EP), leaf wetness (LW), relative humidity (RH), and temperature were monitored in each plot. EP increased significantly with plant spacing, but LW, RH, and temperature, summarized to reflect environmental requirements of R. solani, were not significantly different among treatments. Plant spacing also had no significant effect on disease severity in the 2 years. Disease increased steadily from mid-July to late August or early September, then decreased. In southern Mississippi, periods conducive for web blight appear to exist weekly during most of the summer. Daily irrigation and compact plant form likely contributed to the lack of effect of spacing on disease development.