Greeneria uvicola causes bitter rot on Vitis vinifera (bunch grapes) and Muscadinia rotundifolia (muscadine grapes) inwarm moist temperate and subtropical regions. This study investigated the phylogenetic relationship of G. uvicola representativesfrom Australia (67 isolates), the USA (31 isolates), India (1 isolate) and Costa Rica (1 isolate) and comparedtheir pathogenicity and fungicide sensitivity. Differences in cultural and conidial morphology were observedbetween the isolates from Australia and the USA. Phylogenetic relationships were determined based on three generegions: the ribosomal DNA (rDNA) internal transcribed spacer 1 (ITS1'5'8S'ITS2), 28S large subunit (LSU) nuclearrDNA and b-tubulin-2. Greeneria uvicola isolates were clearly differentiated into four groups: isolates from Australiaand India; USA isolates from V. vinifera; USA isolates from M. rotundifolia; and the isolate from Costa Rica. All isolateswere pathogenic on V. vinifera (cv. Chardonnay) berries although those originating from M. rotundifolia werenot as aggressive as isolates from V. vinifera, irrespective of geographical origin. Sensitivity to pyraclostrobin andsalicylhydroxamic acid (SHAM) was studied. Despite differences in fungicide applications, hyphal growth inhibitionwas not significantly different for geographical location, cultivar, tissue, year of collection or different spray regimes.For the Australian and USA isolates, fungal growth inhibition was significantly greater for pyraclostrobin than forSHAM, and was significantly greater for the combined treatment than for each of the fungicides applied singly. Theaetiological and epidemiological knowledge of bitter rot collected through this study will aid better prediction and management strategies of this pathogen.
Samuelian, S., Greer, L., Cowan, K., Priest, M., Sutton, T. B., Savocchia, S., & Steel, C. (2013). Phylogenetic relationships, pathogenicity and fungicide sensitivity of Greeneria uvicola isolates from Vitis vinifera and Muscadinia rotundifolia grapevines. Plant Pathology, 62(4), 829-841. https://doi.org/10.1111/j.1365-3059.2012.02689.x