‘R. multiflora’ & Rose Rosette Disease The Good, The Bad, The Ugly The White Menace.

‘R. multiflora’ & Rose Rosette Disease

The Good, The Bad, The Ugly

The

White

Menace

This Program Services Committee

presentation created by:

Mary Peterson

Master Rosarian

‘R. multiflora’

Plants of ‘R. multiflora’

Fields overgrown with ‘R. multiflora’

Flower clusters of ‘R. multiflora’

Photo by John Lynch

Panicles of ‘R. multiflora’ flowers

Photo by James Miller

‘Achenes’ or rose seeds of ’R. multiflora’

Northern Mockingbird and Multiflora Rose HipsPhoto by Johann Schumacher

Distribution of ‘R. multiflora‘(green areas = areas of ‘R. multiflora’)

(white areas = none reported)

Photo by S. Debolt

‘R. multiflora’ infected with Rose Rosette

“Witches Broom”

Photo by James W. Amrine Jr.

Photo by M.A. Hansen

Photo by Ann Peck

Abiotic damage to foliage from RoundUp®

Photos by Baldo VillegasEntomology Dept. UC Davis

Photo by M.A. Hansen

Photos by Ann Peck

Reddish aberrant new growth on modern roses infected with RRD

Photo by Chris Evans

Typical Rose Rosette growth on ‘R. multiflora’ roses

Distorted bud formation on a modern rose infected with RRD

Photo by S. Debolt

Photo by James W. Amrine Jr.

Typical Red New Growth of RRD Infected plant

Twisted stem growth on RRD infected plant

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

Eriophyid Mites

Biological Control of RRD

Microscopic Eriophyid Mites

Phyllocoptes fructiphilus Keifer Phyllocoptes fructiphilus Keifer

Phyllocoptes fructiphilus Keifer

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.

Rose Seed Chalcid

Seed parasitism by the Chalcid Wasp

Rose hips damaged by Chalcid wasp

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 DonovanPat Hibbard

Larry Peterson Mary PetersonDiane Schrift

Program Services

Power Point programs on roses are available for download from the ARS website, ‘members only section.’

They are offered to our members for use by a local or district rose society or an ARS judging or consulting rosarian school.

These programs are copyright © ARS 2007

Commercial use is strictly forbidden.

The End