I'm no expert, but from what I've read....it's better to mix in other plants with the roses. That's what they did at the Brooklyn Botanical Gardens and it seemed to help. Also, try shrubs and other perennials around the roses. Maybe as perimeter plantings?

My understanding is that a cottage garden effect gives you enough diversity that you might make it through the threat. So sorry that you're having to deal with this. One thing about knock out roses....people like to plant them 'en masse' which seems to be part of the problem.

I would ask how they determined that so many roses had rose rosette virus at once.

Unless they had the actual specific PCR test done, I would then ask how they ruled out herbicide damage.

https://sites.google.com/site/roserosettevirus/

I reported that I thought it was RRD although I mentioned the possibility of damage from Roundup; however, I saw two or three witches' brooms yesterday in another bed as I drove past in the car--went by a second time just to confirm what I had seen. The landscaper was sufficiently alarmed to remove the roses and reported to the developer's representative, who reported to me, that he had seen other infected roses in the area.

Lindsey

Lavender Lass--Yes, there are too many Knockouts everywhere--they seem to have become a favorite plant for developments of every kind. Although I don't particularly like them, I can understand their popularity. They are easy roses until RRD strikes.

Thank you for your suggestions. I do have other plants in the area although most of my European roses are together in a small protected area on the northeast side of the garden where they do well. I have already decided not to cut down 15 ft tall forsythias which shield them.

Teas, Chinas, and Noisettes, with a couple of exceptions haven't done much, so maybe they are too small to be targets.

Indica Major is big and I have a big Cherokee rose in an area I consider risker so I'm not sure what to do with that--also New Dawns and related roses along a fence which fronts on an open area.

Two big musks are close to the house and probably as safe as any rose could be.

Cl. Devoniensis and Lamarque were quite large, but have been greatly reduced by the past two winters and increasing shade.

Lindsey

When RRD arrived here, it came from a totally unexpected direction, and hit totally unexpected areas. I still don't understand the wind flow patterns that would drop anything in the area I've had 3 separate outbreaks. Forget about 15 ft forsythias, these are 'protected' by 90 ft white pines on the east, and an established tree shelter belt to the west.

Mad Gallica--I'm sorry to hear that trees and tall shrubs don't offer much protection. I have plenty of tall trees, too.

Did you destroy all of your infected roses or were you able to save some of them by pruning?

Lindsey

The only one we destroyed outright was a multiflora. A nearby R. eglanteria had one infected branch about 5 years ago. I cut off the branch and the basal break supporting it, and haven't seen any recurrence. A massive Seafoam was cut to the ground three years ago. Last spring, a piece of it reappeared, and so far seems fine. The most recent victim, a Jacques Cartier in a different part of the garden, was completely cut down last week. Whether or not a healthy piece reappears may depend on how separate the crowns are underground.

Something to remember is that this is not a kind climate for roses. A large, infected Alba Meidilland about a mile away apparently died off totally this past winter. Infected multiflora is even less likely to survive winter because it hates the soil. Possibly something like a neglected Harison's Yellow could be a reservoir for infection, but most roses just aren't going to be able to survive with that many strikes against them.

That's encouraging. I eliminated multiflora some years ago after first hearing about RRD and will probably eliminate other varieties now. My priorities are the oldest Europeans, Damasks and their hybrids-- I have several of Jacques Cartier/Marchesa Boccelli), Moschata, and the stud roses or their closest relatives.

Since we are warmer here, I suppose infected plants are more likely to survive winter, although our past two winters have been harsh.

Lindsey

Until controlled research for RRV and roses shows otherwise, you may try adding chemicals to your roses (before they are infected) that have been shown to increase the resistance of other plants to other viruses.

For example:

Use of Trichoderma harzianum T-22:

Article Title: "Beneficial effects of Trichoderma harzianum T-22 in tomato seedlings infected by Cucumber mosaic virus (CMV)"

https://www.researchgate.net/profile/Antonella_Vitti/publication/267624971_Beneficial_effects_of_Trichoderma_harzianum_T-22_in_tomato_seedlings_infected_by_Cucumber_mosaic_virus_%28CMV%29/links/5453d7e70cf26d5090a55218.pdf

Thank you, but I don't use chemicals. My plants have to flourish under completely natural conditions--one reason why the old Europeans are becoming my favorites. They ask for nothing and aren't troubled by harsh temperature swings.

Lindsey

The statement was made: "Thank you, but I don't use chemicals. My plants have to flourish under completely natural conditions..."

H. Kuska comment: Sorry, I probably should not have used the following wording: " you may try adding chemicals to your roses (before they are infected) that have been shown to increase the resistance of other plants to other viruses."

I probably should have presented the concept in the following way: I suggest that you adjust your garden conditions such that you encourage a high concentration of Trichoderma Harzianum (to me this is not any different than selecting a spot where your roses get sufficient sunlight or sufficient moisture or have sufficient drainage.

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In my web page on RRV I state:

"The April 15-16, 2013 conference on rose rosette virus recommends: "Current control strategies include keeping roses in good vigor, pruning, mite control, and cultural controls such as reducing water on leaves."

H.Kuska comments:

I assume that the "good vigor" is to keep the immune system at its best. Thus, you may want to utilize known immune system boosters such as hydrogen peroxide and/or salicylic acid (home gardners normally use aspirin as a salicylic acid substitute). "

https://sites.google.com/site/roserosettevirus/

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Back to the present.

I did not list the above two chemicals (hydrogen peroxide and aspirin) due to your stated restrictions. But, I assumed that your restrictions ("My garden is all natural--no sprays or treatments, organic or chemical, of any kind-- and will remain all natural.") would allow you to encourage a high concentration of Trichoderma Harzianum (which your non spray soil already contains at some level).

The introduction in the paper that I presented states: "

Biological control is a safe method to reduce plant disease incidence without collateral damages to the environment and to human health induced by synthetic chemicals (Tucci et al. 2011). Some microorganisms, such as fungi belonging to the genus Trichoderma, are used as biocontrol agents (BCAs) to antagonize plant pathogens through a series of mechanisms including competition for nutrients and space, fungistasis, antibiosis and/or modification of the rhizosphere ..........."

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The simplest way (that I can think of) to encourage Trichoderma Harzianum growth is to supplement your standard potting soil mixture with cornmeal.

Thanks Henry. That is an interesting paper. So if I understand correctly, the presence of T-22, which has been isolated as a naturally found chemical in plants, can be used as a means of boosting the plant's (roses in this case) natural immunity to diseases by increasing or aiding or promoting the formation of the hormones ROS, JA,SA and Et, which are hormones that many pathogens attempt to inhibit as a means of colonizing the plant. Those hormones aid in the plant's immune responses. So T-22 boosts the immune system and helps prevent diseases.? Is T-22 available as a supplement or bio-control agent commercially? If so what is it's commercial name? If using cornmeal, how much is necessary to increase the immune response sufficiently to help increase resistance to RRD? How would you recommend application?

roseleighz9b, concerning availability, the following is a Google search. If you do not grow your roses in a "chemical dump". you probably already have it in your soil.

https://www.google.com/webhp?hl=en&authuser=0&gws_rd=ssl#newwindow=1&hl=en&authuser=0&q=Trichoderma+harzianum+T-22+

I appreciate the explanation, Henry--sorry if I jumped to conclusions. Thank you for the additional links--after looking at some of those photographs I understand why you asked whether the roses had been tested. I have reported three suspicious cases over the past seven years. I thought the first was RRD and maybe the third although I "recognized" symptoms only from pictures and descriptions in Ann's book.

At Hollywood Cemetery, an expert was dispatched the following day from the Charlottesville company that maintains the cemetery and he "confirmed" the outbreak and recommended removal of six roses, pruning of several others, and spray for the entire collection.

The second case was at our church and did not look exactly like RRD to me. Since Roundup had been used near the rose showing symptoms, we decided that Roundup was probably the cause and no action was taken other than to restrict use of chemicals on the grounds.

I reported the third case about 10 days ago as either RRD or herbicide damage, On Friday morning I noticed several witch's brooms, and on Friday afternoon I learned that the landscaper for the project had removed 15 roses and reported seeing infected roses elsewhere in this area. So I would say no tests were done in either case #1 or case #2 unless they were done after the fact.

Growing conditions should be reasonably good at Hollywood, but the entire landscape at the nearby development is distressed because developers follow a scorched earth policy--ie remove all vegetation and topsoil during construction, grade and smooth entire area with rollers and other heavy equipment, and once construction is complete, apply only a thin layer of topsoil before planting trees and shrubs.

By contrast, the soil in my garden has not been disturbed in 60 years and then only at the house site. Plants naturalize here, and in a rainy summer, growth of all kinds is exuberant. This is not to say that conditions are ideal for roses because we have large trees, lots of shade, and in certain areas the soil is naturally dense enough to inhibit root formation.

How much cornmeal and aspirin and how often and when? I don't object to either.

Lindsey

PS I was encouraged by the high percentage of negative tests in Texas. Perhaps we are all too quick to identify unusual growth as RRD.

My roses are pretty randomly planted, with a fair amount of cottage garden interplanting. When I had my outbreak here in 2010 (I lost 60+/- roses), roses with multiflora in their genes seemed to fair the worst, and wichurana was runner up. Thus, I lost a lot of Hybrid Musks and Polys. The Rugosas were not hit at all, and I lost one Alba, but no Gallicas. And sometimes, regardless of class or size, with two roses side-by-side, one would get it and the other not.

We dont seem to have answers for how suseptible some classes are over others or how many mite bites it takes to infect a rose or how contagious an infected rose is two years later or how many mites (infected or otherwise) just hang out in the average garden on an average day. Maybe just a few mites landed on the gallicas and that wasn't enough. I had 9 little polys planted in a circle around a burning bush. Six got it, three didn't, spacing and position seemed irrelevant.

I held on to several large roses until the bitter end, cutting canes back, season by season, hoping I could save them (I didn't save any). But I didn't lose any more because of their presence. I have 1. acres, and it took about 9 months for the "drift" from the initial wind flow to polish off the infection. But nothing since then, despite the infected the roses.

I have no advice, but if you get it, please take careful notes.

I'm sorry you had such a terrible experience--sorry to hear, too, that roses with wichurana ancestry were particularly vulnerable. I have New Dawn and a couple of others on a fence--also have the species or cemetery rose as a ground cover in one part of the garden. The only rose I know of with multiflora ancestry is Veilchenblau, although I do have a Noisette with hairy stipules which I thought was Manettii.

I don't have any Polyanthas or Hybrid Musks, but I do have eight Albas and I don't know how many Gallicas as well as Damasks and other Europeans. I hope they have greater resistance. Since they are close together, I'm glad that spacing doesn't seem to be a factor.

Lindsey