Rose rosette disease (RRD) is incited by a negative-sense RNA virus (genus Emaravirus), which is vectored by a wind-transported eriophyid mite (Phyllocoptes fructiphilus). Symptoms include witches broom/rosette-type growth, excessive prickles (thorns), discolored and distorted growth, and, unlike most other rose diseases, usually results in plant death. RRD is endemic to North America and was first described in Manitoba, Wyoming, and California in the 1940s. It has spread east with the aid of a naturalized rose species host and has become epidemic from the Great Plains to the East Coast of North America on garden roses in home and commercial landscapes where losses have been high. The disease was suggested to be incited by a virus from the beginning, but only recently has this been confirmed and the virus identified. The presence of the vector mite on roses has been associated with RRD since the first symptoms were described. However, more recently, the mite was demonstrated to be the vector of the disease and confirmed to transmit the virus itself. As a result of the RRD epidemic in North America and its effects on the national production and consumer markets for roses, a research team comprising five major universities (Texas, Florida, Tennessee, Oklahoma, and Delaware), a dozen growers and nurseries (all regions), six rose breeding programs (California, Wisconsin, Texas, and Pennsylvania), the major rose testing programs (Earth-Kind and AGRS), the major rose organization (American Rose Society), and the major trade organization AmericanHort has formed. This research project has been funded by the Specialty Crops Research Initiative through the U.S. Department of Agriculture (USDA) with the short-term objective of improving and disseminating best management practices (BMPs) and the long-term goal of identifying additional sources of resistance and developing the genetic tools to quickly transfer resistance into the elite commercial rose germplasm.
