In the past few decades, Rose Rosette Disease (RRD) has spread from its source in western North America through the Mid-West to the East coast. It now threatens to decimate the US rose industry.
What is Rose Rosette Disease?
Abstract Rose Rosette Disease (RRD) is caused 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 caused 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 (TX, FL, TN, OK, DE), a dozen growers and nurseries (all regions), 6 rose breeding programs (CA, WI, TX, PA), 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 US Department of Agriculture with the short term objective of improving and disseminating Best Management Practices 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.
To read the full paper please consult: Pemberton What is Rose Rosette Sept 19 2017
The Project and Grant
A proposal was developed in collaboration with the rose industry beginning with the Rose Rosette Conference organized by Star Roses and Plants and the Garden Rose Council in April of 2013. This conference brought together trade associations, growers, breeders, landscape management firms, botanical gardens, federal regulatory agencies, biocontrol corporations, consultants, state plant disease diagnostic laboratories and researchers from both the state and federal levels to develop a plan to direct future research and serve as an outline for the resultant proposal. Over several months, a research and extension team was developed to tackle RRD which involved plant pathologists, rose breeders and geneticists, plant physiologists, molecular geneticists, an entomologist, agricultural economists, marketing experts and extension personnel. This team is from state, federal, and private organizations from Texas, Oklahoma, California, Florida, Tennessee, Delaware, Pennsylvania, Wisconsin, and Connecticut. The rose industry also committed their resources to the project. The research was also supported by two research grants from the American Rose Society. One went to the University of Tennessee (Mark Windham) to assess the efficiency of various mite control procedures on RRD and the other to Texas A&M University (David Byrne) to develop a new approach to generate molecular markers in rose. These grants were important in developing preliminary information essential for the development of the proposal
The immediate goal of the Combatting Rose Rosette Disease Project is to develop management practices, develop educational materials based on host, virus, and vector biology in order to help minimize the effects of rose rosette. The long-term goals of this project include assessing which rose varieties show disease resistance, by way of both replicated field trials and observational data from collaborators, developing molecular tools to effectively incorporate disease resistance into elite rose germplasm, and developing strategies to increase rose sales with the use of sustainable rose cultivars. Main points of this study are focusing on the marker-trait association for rose rosette resistance and consistent flower productivity.
The A&M University sector of this project, under Dr. David Byrne, is supported by a research grant from the American Rose Society. Its sister grant went to the University of Tennessee, under Dr. Mark Windham. The grants allowed for the formation of preliminary information necessary to the development of the project proposal. This particular sector of the project is focused on developing a new approach to generating molecular markers. Markers can be used to accelerate the breeding process, to identify the genes associated with disease resistance, and to help assess if the newly bred populations contain the same resistance genes.
When we began this project, only a few species and no cultivated roses were reported resistant to RRD. We took two approaches to find sources of resistance. First was to collect observational data on which roses show symptoms and which do not when growing in gardens with RRD infections. Five hundred and fifty roses were identified as susceptible to RRD and another 50 that have not yet shown symptoms and need to be tested further (Byrne et al., 2015).
To read more about the specifics of the grant and programs it funds please consult: Acta Hort Combating RRD Oct 1 2017