Symptomatic thorns on roses caused by rose rosette Photo by S. Debolt Photo by Jim Yearwood
Mowing and burning operation Physical Control of stands of ‘R. multiflora ’ Rose bushes cut with a chain saw during the winter months After spending approximately 2 months cutting Multiflora rose bushes, burning them was very satisfying
Rose Stem Girdler Photo by Whitney Cranshaw Girdled cane caused by larva Photos by James W. Amrine Jr. A "flag" caused by the break of a cane at the girdle Close up of girdle and broken cane Agrilus aurichalceus (Coleoptera: Buprestidae)
Rose Seed Chalcid Wasp Photo by James W. Amrine Jr.
Cold Weather Affect on New Rose Growth Spring Dwarf Disease?
‘R. multiflora’ and RRD Early Identification of RRD infected ‘R. multiflora’ Physical Control – cutting/burning Herbicide/Chemical – Round Up, Krenite, Banvel Biological Control – Eriophyid Mite Rose Seed Chalcid Rose Stem Girdler
What The Future Holds … The reduced populations of multiflora rose remaining after the RRD epidemic are likely to be infested by the seed chalcid at the same rate (90-95%) as plants in Korea and Japan. Multiflora rose will then be another occasional plant in the environment, and not the noxious weed that it is today. It is estimated that this scenario will transpire within the next three to five decades. Farmers and others wanting eradication of multiflora rose desire human intervention to increase the rate of spread of the disease, the mite and the torymid into uninfested areas. However, many rosarians desire that all augmentation work with RRD and the mite cease. The rose seed chalcid could be intentionally released in areas wherever infestation rates are below 50-60%. Risk to other rose species from this seed chalcid appears to be minimal. Even if not deliberately spread, its range will increase by birds. Eventually, multiflora rose will be reduced to low levels, occurrence of RRD will become minimal and problems for farmers and rosarians alike should be greatly reduced.
Dr. Keith Zary (VP of research for Jackson & Perkins) has encouraged breeders to concentrate their efforts on hybridizing roses that are RRD resistant and RRD tolerant. A species called the McCartney rose, which exists as a weed in Texas, is susceptible to RRD but resistant to feeding by the mites that transmit the disease. It may be possible, through breeding techniques, to incorporate this mite resistance into cultivated roses in the future. In the meantime, it would be wise to assume that all cultivated roses are potentially susceptible to the disease and to be on the lookout for symptoms of rose rosette. Additional Considerations…
Program Services Committee John Mattia, Chairman Jolene Adams Richard Donovan Pat Hibbard Larry Peterson Mary Peterson Diane Schrift