New rose rosette research

henry_kuskaDecember 5, 2012

New research often will appear as a paper at a meeting before final publication in a scientific journal.

Here is a recent meeting abstract:

"Are emaraviruses mite viruses? The Rose rosette paradigm

Authors: A. G. LANEY (2), E. W. Kitajima (1), I. E. Tzanetakis (2)
(1) Escola Superior de Agricultura, Piracicaba, SP, Brazil; (2) University of Arkansas, Fayetteville, AR, U.S.A.
Phytopathology 102:S2.7

Rose rosette (RR) is a devastating rose disease, first described in the 1940s. RR is prevalent east of the Mississippi River and is characterized by elongated stems, malformed flowers and leaves, excessive thorns and witches� broom culminating in plant death in a few years. In the Midwest and the Southern United States, the main host is an invasive species, Rosa multiflora Thunb., though cultivated roses are also afflicted. RR has previously been shown to be transmitted by the eriophyid mite Phyllocoptes fructiphilus and has been proposed as a biological control agent for R. multiflora. Recently, a new member of the genus Emaravirus (family Bunyaviridae), named Rose rosette virus (RRV), has been found in close association with RR symptomatic roses.
Surprisingly, little diversity was seen in virus populations collected from eight different states. Given the low diversity and the fact that the genus Emaravirus belongs to the family Bunyaviridae, members of which replicate in their arthropod vector, it has been hypothesized that RRV replicates in its vector, P. fructiphilus. In order to facilitate testing this hypothesis, a quantitative RT-PCR assay was developed for both the genomic and virus complementary RNA. P. fructiphilus mites were collected from virus-positive R. multiflora and total nucleic acids were extracted. The RNA was then subjected to quantitative RT-PCR for the genomic or virus complimentary RNA strands. Additionally, the presence of capped virus mRNA in the mites was investigated using 5�RACER. The replication of RRV in its vector makes using RRV as a biological control agent unwise and care should be given to prevent the spread of RRV and its vector outside its current geographic range."

Here is a link that might be useful: 2012 Southern Division Meeting Abstracts

Thank you for reporting this comment. Undo

Hi Henry
You like to be on the science end of rose growing. Are you still growing roses? What's in your garden or what gardens do you like to visit? What kind of roses do you like best?

    Bookmark   December 5, 2012 at 10:39AM
Thank you for reporting this comment. Undo

I have Google automatically alert me when a new/revised article on rose rosette virus appears. This one appeared this morning:

Here is a link that might be useful: Paul Zimmerman article

    Bookmark   December 5, 2012 at 12:52PM
Thank you for reporting this comment. Undo

There appears to be two active U.S. groups doing rose virus research. The first includes the Arkansas group listed in the first post. The second is from Minnesota. A Ph.D. thesis defense of a study of four new rose viruses is scheduled for December 18, 2012.


"December 18, 2012
Ph.D. Defense Seminar: "Identification, transmission, and genomic characterization of four new viruses in cultivated rose." Dimitre Mollov, Ph.D. Candidate, Department of Plant Pathology, University of Minnesota"

Here is a link that might be useful: Minnesota link

    Bookmark   December 5, 2012 at 1:01PM
Thank you for reporting this comment. Undo

Kittymoonbeam, this season I completed a final phase down from about 1000 roses to about 60.,46868,46967#msg-46950

I started growing roses and hybridizing in the early 70s. In the 70s I liked to use the old rose annuals to hunt down the after world war II rose gardens that many communities had set up.

Now, the Columbus Park of Roses and the Wooster Rose Garden of Legend and Romance are about the only 2 left. Even the famous Ohio rose nurseries are gone. The 2 Toronto area rose nurseries are probably the closest. In northern Ohio it is probably safe to say that the Canadian, Poulson, and German roses were more useful than the standard American type roses (except for the Iowa State Buck roses).

Here is a link that might be useful: final phase down from about 1000 roses to about 60.

    Bookmark   December 6, 2012 at 3:02AM
Thank you for reporting this comment. Undo
mzstitch(Zone 7b South Carolina)

Henry, Thank you for posting the articles. I learned something new today from the Paul Zimmerman article, in that he cuts an infected cane down at the base if none of the rest of the plant is infected.
Now I have never had a case of RR, but as my rose garden grows it does make me nervous. My question to you is Do we know how long after a mite infects the plant the bad growth shows? Would the mites be long gone by the time the plant shows it has been infected?
Would you agree with Paul Zimmerman and just cut off that cane and hope for the best, or would you get rid of it. I have hard clay soil, so it takes me forever just to plant one rose plant, I would be very nervous that others could get infected while I wait to see if that one plant survives.

    Bookmark   December 6, 2012 at 6:51AM
Thank you for reporting this comment. Undo
michaelg(7a NC Mts)

mzstich, the mites are not "long gone" until the rose plant is long dead. The mite population explodes on infected plants. The mites crawl from infected to uninfected canes and to neighboring plants that are touching. Some of them sail away on windborne threads.

Keeping an infected plant in the garden is risky. Our resident expert Ann says that plants are usually not cured by removing a cane at the base. If you catch it early when only one cane shows symptoms, she recommends splitting an own-root plant's crown and throwing away half the root system along with half of the top growth. Movement of fluids within the rose's plumbing system is vertical rather than horizontal at first.

If you try removing an infected cane, I would recommend spraying the plant and close neighbors--generously-- with 5% Wilt Pruf solution. This would kill the mites that are contacted by the spray. Whether it helps in the long run has not been established. I also spray infected plants before removing them and then bag all the plant parts.

    Bookmark   December 6, 2012 at 9:39AM
Thank you for reporting this comment. Undo

The following was stated by michaelg: "Our resident expert Ann says that plants are usually not cured by removing a cane at the base. If you catch it early when only one cane shows symptoms, she recommends splitting an own-root plant's crown and throwing away half the root system along with half of the top growth."

H.Kuska comment: can you please supply a link for that statement so that it can be put into context? Does the above recommendation apply to all roses at all times in the growing season, or to only one (or a few types of roses such as climbers but not other types such as hybred teas, does it apply only to own root roses but not grafted roses, etc?

An example of an actual quote that she has made recently:

"Posted by anntn6b z6b TN (My Page) on Thu, Oct 11, 12 at 23:11

Cutting off an infected cane HAS to be done before the virus moves down into the roots (assuming stem meristem infection) and back out. I've saved several roses from different classes in my yard by catching the problem when only a single leaf node (or three on one side of the cane) were infected in fall. I saved an American Pillar in spring when it was out on a cane about ten feet from the roots. I've never saved a HT, and I've only seen RRD on HTs in spring. That may have something to do with the transmission times in fall to late fall."

The next 2 are posts that you recently made concerning cutting off canes in one thread ( ) :

"Posted by michaelg z6B NC Mts (My Page) on Mon, Sep 3, 12 at 9:45

A cluster of shoots and with crumpled leaves ( different from equally young growth on the same variety), these are additional RRD symptoms. If you remove such suspicious growth with pruners, be sure to sterilize them and bag the trimmings. Also you should take the underlying cane down to grade immediately."
"Posted by michaelg z6B NC Mts (My Page) on Mon, Sep 3, 12 at 12:40

KR, What I do if I have strong suspicion but am not fully convinced is to cut the plant down, removing most of the cane and all foliage, and see what grows back. I just dug a plant yesterday that came back funny. Another one that I cut back at the same time looks fine. The latter previously had probable RRD growth high on only one cane."

Ann's E-book is in a format that is difficult to search (I recommend a PDF format.).

In Chapter 2 she states: "A single symptom does not make a confirmation of RRD. When the growth character of a cultivar is known, appearance of multiple RRD symptoms will alert the rose owner to possible danger.

Some symptoms of RRD resemble herbicide damage; a thorough search of the area around the roses for signs of herbicide use must allow for long distance herbicide drift - especially in warm weather. A rose bush outgrows herbicide damage, RRD infections persist from year to year until the death.

Roses likewise outgrow �blind shoots� but the blind shoot looking growth on a rose in Georgia became more symptomatic of RRD two months later (Fig. 6).

Weather damage in spring or fall can also cause contorted new growth, but comparison with growth on other roses in the same garden can be used evaluate the problem. If the damage was weather caused, the rose will out grow it.

Because ot the chance of false diagnosis, each rosarian needs to think about the problem and decide in advance a course of action. Then when RRD enters a garden, the hard decisions have already been made.

If RRD has not been reported nearby, and there are symptoms that suggest it, you may choose to reduce the mite population that transmits the infection.

Digging up and isolating the questionable rose should also be considered. In addition, I would (and have had to) spray the bush in question and the surrounding roses at ten day intervals with Cygon 2E (following label precautions) while waiting for confirmation of RRD. Cygon 2E is the only spray that will kill the eriophyte mites. They are different from spider mites. Most chemicals approved for treatment of spider mites are not effective for the mites that transmit RRD. At present (2007) Cygon 2E is not readily available. There have been no tests to see if other miticides kill P. fructiphilus. Avid is approved for general use against eriophyid mites, but its efficacy in fighting RRD vectors is unknown."

H.Kuska comment: I interpret the above to suggest: "Digging up and isolating the questionable rose should also be considered." But that nothing was said about cane cutting.
In Chapter 4 the following appears: "When I find a RRD infected plant in our rose garden, it�s rogued out and burned fast. Surrounding roses are examined and sprayed. Canes of nearby roses that a mite could have fallen onto from the infected area (canes under the infection) are also removed. (To do this hurts because I hate to remove a healthy cane, but it's a logical sacrifice)."
" Leaving a RRD-infected rose in the middle of an otherwise healthy garden is the worst course of action. Spraying the infected plant and surrounding area then rogueing out the bush is still the best course of action, perhaps with the addition of pre-emptive spraying during hot dry spells, especially in late summer, the optimum breeding season for the mites that transmit the virus."
Also in Chapter 4: Our RRD infections so far: (H.Kuska comment, I will only list the "bushes that relate to cutting off the cane")
"'Charles Austin'- we saved the bush by cutting the cane off rapidly fall 2001"
"'Rouletti' we hope we have saved this by removing the sick cane early fall 2002"
"'Fuschia Meidiland' we cut off the cane, disease came back, it's gone spring 2003"
"''Gloire de Dijon' own root, first symptoms near root, one cut back didn't work spring 2005"

"'Peter Beales version of Parks Yellow Tea Scented China' spring 2005
first sick out on one long cane, we cut it back, RRD came back
fall 2005, we took out half the bush supporting that cane and lost
the whole plant fall 2006"
"'Golden Salmon Superior' Great ownroot Polyantha; tried removing the sick cane fall 2005
removed spring 2006"
"'Seven Sisters' one cane sick, removed it; two canes sick three months later , spring 2006
it's gone"
"'American Pillar' one sick cane cut off, so far rest of bush is healthy spring 2006"
Also in Chapter 4:

Dr. Kent Campbell lives near Bowling Green, Kentucky and has been living with Rose Rosette for a number of years. There are fences near him with wild multiflora and the multiflora is sick with RRD. He can't control the fences on other folks' property, but he can control the effects of the resulting RRD on his roses. He told me about his "One Strike and You're Out" rule. When he sees aberrant growth that he associates with rose rosette on a cane, he cuts that cane back to the bud union. That's strike one. Then he watches the plant. If the plant shows additional aberrant growth, it's out. He estimates that half of his infected roses recover with no additional signs of infection. He has experience and he knows what the disease looks like on the roses he grows. With what he has learned, he continues to grow roses and to enjoy them.

In 2001 I asked him to approve the summary above. He replied, "What you have written about me is essentially correct. However, I have mellowed just a tiny bit this spring. If the noted infection is "slight" and the bush is big and otherwise healthy, it becomes more like 3 strikes and you're out. Usually, though, the disease strikes with great force and much of the bush is covered with witches' broom and obvious abhorrent growth quickly." "
Still in Chapter 4: "I also believe there may be a seasonal element to the success of one strike and you're out. If, and I emphasize If, all the nutrient flow is one directional: roots TO leaves, then cutting a cane may work. If there is a continuing flux-with nutrient interchange roots to leaves to roots on a daily basis then no amount of cutting back may work. We are currently watching our plant of 'Charles Austin' which showed RRD symptoms (Figure 1) at the tip of one cane. We cut the cane off at the base within five minutes of seeing the ugly red growth. We are closely watching the area where the cane was cut next to the soil. I estimate that the growth happened in two days. We seem to have saved the bush; two years after we saw the "rooster tail" the rose remains symptomless."
Still Chapter 4. "By not removing roses that were known to be infected and trying to allow the maximum bloom from each bush, the entire garden was lost. A garden under this much disease pressure could possibly survive, but I wouldn't even use the "one strike and you're out policy". I would immediately remove suspect plants, which is what happens in our garden (under very low disease pressure) where we have had one half of one percent RRD loss. Something we don't do in our garden, premptive spraying with Cygon, would be advisable under the high disease pressure conditions to which the LMU garden is subject."
In Chapter 5: " One of the things we have tried to do this summer is to devise a list of subtle early symptoms that would alert a gardener to keep an eye on a particular rose and to know when to spray the mites to prevent potential spread from a suspect bush while it is under observation. This would reduce the chance of over reaction and killing healthy bushes simply because of a blind shoot or other false symptoms."

Ann summarises in a FAQ: "FAQ - How do you treat an infected garden":
"How do you treat an infected garden?

The best course of action if you are convinced one of your roses is infected is to first spray the area with Cygon 2E, then rogue it out and burn it (or bag it and send it to the landfill), and keep a sharp lookout for additional symptoms on other plants, especially on plants adjacent to and downwind of the infected plant. If you have the option, remove any wild roses that might be a source of infection. If you have a rose that is "iffy", that is, it might be sick, but you really don't want to rogue it out, then you may want to place it in isolation. The isolation can be chemical (spray often to make sure no mites from it travel to other roses) or physical (dig it up and keep it away from other roses.).

One way that we live with the threat of RRD is to space bushes far enough apart that we can see the individual canes and try to keep canes from one bush from contact with other plants. (This is just hypothetical in our old garden rose beds.) When in doubt, it�s better to dig up, isolate and closely observe a single infected plant. See Chapter 4 for more information."

H.Kuska comment. One of the advantageous of internet "publication" is that the article can be updated as additional information becomes available.

My web page information is at:

Here is a link that might be useful: My rose rosette web page

    Bookmark   December 6, 2012 at 7:27PM
Thank you for reporting this comment. Undo

I live near Fort Worth, Texas and it appears half of my large rose garden is infected with rose rosette. I started in the middle today and worked away from the roses that appear to still be healthy. The local garden center told me last year it might have just been round up poisoning, but new blooms this year show spreading and pictures resemble all I see on rose rosette. After 5 hours of cutting and bagging, I'm now reading to see if I can stop the spread. As far as I can tell (1) it is conveyed by mite that crawl from plant to plant or (2) mites that blow from infected rose to anohter rose. (3) The only killer of these varmits ais Cygon 2E which IS NOT available?? So, if Cygon is not available, is there another option? Last year I purchased and sprayed about 30 bottles of virus and MITE spray, which I now see would not have touched these little mites. If they are insects, would not something like Diatomaceous Earth work to kill them -- if I dusted the plants? I used animal grade product this summer to protect against spiders and other insects. I am just sick knowing it will take me days, if not weeks, to dispose of all the infected plants (Mermaids, David Austin Climbers and single red knockouts) and it still may travel to the other l/2 of my yard (knockouts). Has anybody tried Diatomaceous Earth? I feel like filling up the shop vac and nuking the rest of my garden with D Earth tomorrow as precaution....?? Or can we get Cygon2E by mail from someplace? Don't understand why, if it's the only thing that works, it's not available? Thanks!! HannahB

    Bookmark   February 24, 2013 at 7:57PM
Sign Up to comment
More Discussions
I will be converting my rose garden this spring
After two brutal winters where temperatures have reached...
Roses and their offspring
I would like to learn more about roses that have reputations...
Earth kind roses trials in northern gardens.
This should help us northern rose gardeners. Iowa State...
Patty W. zone 5a Illinois
Francis Meilland, suggestions on pruning and care?
I currently have him in a 15 gallon, he's at least...
Awesome Climber
This is a very popular spot to take photos in the San...
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™