Enhancing the Detection Process, Prevention and Sustainable Management of Soilborne Diseases in Tennessee Nursery Production
Phytophthora and Rhizoctonia root rot diseases are the most important problems to nursery grown ornamentals. First objective of this study was to develop methodology for reliable and sensitive screening of irrigation water for the presence of Phytophthora spp. in the commercial nursery operations. Among three concentration methods, filtration was the most effective and sensitive method for detecting low level of zoospores in the water followed by baiting and centrifugation. Middle Tennessee nursery irrigation water samples were confirmed as Phytophthora positive (P. syringae, P. cryptogea, P. drechsleri and P. hydropathica) using baiting and filtration methods followed by culturing on PARPH-V8 medium, serological and molecular detection assays. Second objective of this study was to evaluate the efficacy of selected biocontrol products and fungicides against Phytophthora root rot of hydrangea cultivars and Rhizoctonia root rot of Viburnum odoratissimum in greenhouse and field experiments. Both greenhouse and field experiments showed that Segovis, Empress Intrinsic, Subdue Maxx, MBI110 and TerraClean 5.0 + TerraGrow program significantly reduced Phytophthora root rot severity; but Mural, Empress Intrinsic, Paegant Intrinsic and TerraClean 5.0 + TerraGrow program significantly reduced Rhizoctonia root rot severity compared to the non-treated inoculated control and other treatments. Third objective of this study was to evaluate the efficiency of soil solarization with and without organic inputs to control soilborne diseases. Soil solarization by itself and incorporated with selected biofumigant cover crops (mustard, mighty mustard, turnip, radish and astro arugula) good quality compost and mustard meal amendments were evaluated against soilborne pathogens under field conditions. On-farm experiments of solarization with or without incorporated biofumigant cover crops as well as mustard meal and compost amendments significantly reduced root rot diseases in Kwanzan flowering cherry cuttings compared to the non-treated, inoculated control. In TSUNRC field experiments, solarization with or without incorporated biofumigant cover crops as well as mustard meal and compost amendments significantly reduced Phytophthora root rot disease of boxwood rooted cuttings and Rhizoctonia root rot disease of V. odoratissimum compared to the non-treated, inoculated control plots. There were no significant differences among the treatments in reducing root rot disease severities in both on-farm and TSUNRC field experiments. ^
Md Niamul Kabir,
"Enhancing the Detection Process, Prevention and Sustainable Management of Soilborne Diseases in Tennessee Nursery Production"
ETD Collection for Tennessee State University.