| Summary: | <p> A number viruses are known to infect roses, ranging from those in the genera Nepovirus, and Ilarvirus, which have been reported since the inception of rose virology, to recently discovered viruses in the genera Carmovirus, Closterovirus, Emaravirus, Luteovirus, Rosadnavirus, and Potyvirus. Of the viral diseases in rose, arguably the most damaging is Rose rosette (RRD), which is associated with the Emaravirus, Rose rosette virus (RRV). The objective of this thesis is to fill in the gaps in knowledge on the epidemiological aspects of RRD and RRV. There has been significant progress in the epidemiology of the RRD agent prior to the discovery of Rose rosette virus (RRV). The elusive agent was known to be graft transmissible, vectored by the eriophyid mite, Phyllocoptes fructiphilus in an uncharacterized manner, and associated with virus-like double membrane-bound bodies. RRV, the putative casual agent, was detected in all plants with RRD symptoms. However, this correlation does not prove causation of the disease. Given the complex symptomology observed the question of whether RRV causes RRD solely or as part of a virus complex, as is the case of numerous disorders of perennial plants, once thought to be caused by a single virus, was still unclear. Resistance is an important first line of defense when managing any disease, and here we identified potential sources resistance for producers, rosarians, and breeders. To date few viruses, believed to be transmitted by eriophyid viruses have been conclusively demonstrated to do so. The mode of transmission is elucidated for an even smaller subset of those viruses. In this study Koch’s postulates were fulfilled for RRV; additional RRV genome segments were discovered; Phyllocoptes fructiphillus was verified as a vector of RRV; resistant rose varieties were identified; and the acquisition and inoculation access periods (AAP and IAP respectively) for RRV were determined.</p>
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