So there's something good about RRD?
But, seriously, folks.

Got photos, Ann?
Considering the overwhelming vigor of Fortuniana, I'd really like to see that. (At a remove. In a photo. NOT in person! REALLY!)

Jeri

I took many, many photos, some with pet for scale. We are going to save the da**ed thing and let it dry, sort of like we did with a faschiated cane several years ago.

I'll try to get one up by tomorrow night, right now I'm working on an email to a group I spoke to two weeks ago over in the Carolinas where I said that I didn't think that fortuniana got RRD although laevigata does.

Somewhere in the world, the mites must have enemies. Or diseases. Or parasites. But I suppose that would just get out of control next...

There was also probable RRD on a large R. x fortuneana at the Nat'l Arboretum early this summer. It was excised as quickly as possible and hasn't recurred to my knowledge, but I can't say it would have been the worst plant to lose to the dratted disease (not a huge fan, and greatly prefer the species parents). It also happened in a big way on the Rosa roxburghii f. roxburghii; I wasn't expecting that, but it was interesting to see. I'm not sure if photos were taken.

That's an interesting idea, Cat -- I wonder if there IS a biological control for the mite. I know, no one's come up with one for the Fuchsia Gall Mite. Instead, the fuchsia folks are frantically breeding for resistance.

Here, in SoCal, there's been real success in use of predatory bugs to fight bad bugs, including a minute parasitic wasp that's been a great control for whitefly here.

So -- MAYBE?

Stefan -- I hear what you're saying, but I really love Fortuniana. Ours came from an old NoCal cemetery, and it has grown huge here. For us, it repeats pretty well.

Jeri

Ann (who is having some computer hassles) asked me to post for her this image of the Fortuniana cane with RRD.

She said:
"Anyway, the stem in Larry's hand that he's holding up is the sole source of all the growth - it all moved through that relatively narrow stem, and made all that growth. And it made it fast. And all the regular growth is normal green on the rest of the rose, and here there's no normal green at all."

Jeri -- for Ann

Wow, that is crazy. All from one cane. Hopefully it was caught in time, and my Mdme Lambard too. Time will tell.

It's almost better if the RRD goes crazy fast. That way you can cut out the hopefully one cane that has it and save the plant. That's going to be my MO from now on. If I see something suspicious, cut out that cane and watch the rest of the plant.

Good grief, Ann. Please pardon my candor, but I find it difficult to believe that you, of all people, ever entertained the notion that Fortuniana harbored some kind of miraculous genetic (or other) attribute that rendered it impervious to RRD.

I am reminded of a remotely similar experience from my distant past . . . I spent many years as an employee of the U.S. Public Health Service. During the early 1980's when the agency was reeling from the onslaught of the AIDS epidemic, I was assigned to a task force that investigated, proposed and promoted prevention strategies. Much of my work was done in tandem with colleagues in the Indian Health Service, a sub-agency of the USPHS. It was an assignment that was frustrating and stress-producing in the extreme. The resistance we encountered was beyond belief.

At the time, the conventional wisdom among many on-reservation populations was that Native Americans were absolutely immune to the disease. Long story short, and needless to say, by the 1990's even remote populations had experienced the disease's impact, and the fact that ALL human beings were at risk was a foregone conclusion. Unfortunately, much valuable time had been squandered, and untold numbers of people among the target population suffered.

My point is: All plants within the genus Rosa must be considered subject to RRD infection.

Jax,
That fortuniana survived for a decade without catching a mite was the hope, that and its distance from R. multiflora on the part of both of its parents.
I wasn't going for a genetic salvation, but I hoped that there might be a cultural barrier tied to the preferred growth times of banksia and laevigata.

I had hoped that the 'off' growth cycle of fortuniana might be a saving grace, that it grows through winter when the mites aren't out. Mine was relatively dormant through summer, and post bloom spring pruning sufficed.

An example is R. setigera which doesn't get RRD often, even though R. multifloras in the same fencerows (unsprayed with herbicides) get RRD rather easily. R. setigera just doesn't get 'that' large nor is it actively growing through summers here. Not exactly a cultural barrier , but a reduced propensity to contract the disease.

There are so many instances where one rose appears to have avoided infection, and the more we know, we find that others of the same cultivar are infected.

Wind tunnels with a speeded up wind speed are not practical at all (although they work).

I have always expected RRD to infect all roses, but I had hoped that some barriers might exist in nature, a lesser propensity to infection for the ones that go to near dormancy in summer, ones who have a limited window of opportunity for the mites to feed on undifferentiated meristem tissue in axillary buds or at the ends of broken stems (the latter seems to be the problem here). Or maybe have really tight buds that the mite's feeder tube can't get through.

As to a pest that will take out the eriophyid mite: it's out there and was described early on in the Allington, Staplin and Viehmeyer paper. The predators are conventional spider mites; in the isolation labs at the University of Nebraska they were trying to study the eriophyids, but spidermites kept getting in and destroying the eriophyid populations.

Amrine and his students have also found some unnamed species of predaceous thrips will feed on erophyids AND thrips.

I don't use insecticides or acaricids on my roses. I haven't in a long time.

There are humans that appear immune to the effects of the AIDS virus:
( http://www.boston.com/news/health/blog/2010/11/in_people_immun.html ).

Since about 1990, it has become recognized that plants have an "immune system". Specifically, in this case, it appears that different roses can have different abilities to "resist" the rose rosette virus, as illustrated by the following quote:

"However over the following 15 years, as MDA has monitored the continuing eastward spread of RRD, it has become apparent that many of our cultivated rose varieties are susceptible to the disease as well. Many popular varieties have been noted exhibiting symptoms of the disease with apparent susceptibility ranging from very susceptible (plants die in one to two seasons) through resistant (plants exhibit symptoms but live for several years) to apparently immune. In field trials conducted by MDA, �Flower Carpet" varieties have proven to be very susceptible, Meidland cultivars, including �Alba� are moderately susceptible and the native species of roses; Rosa setigera, R. virginiana, and R. palustris and the naturalized R. rugosa seem to be very resistant to possibly immune to the disease."

http://www.mdinvasivesp.org/archived_invaders/archived_invaders_2011_07.html

Rosa setigera appears to not share many characteristics with European/oriental roses:
( http://download.bioon.com.cn/view/upload/month_0901/20090107_257f1322162f573420a3Kz2cQDXiOJ7B.attach.pdf )

(To me it appears very blueberry like.)

So I am not surprised that it may not "fit" what the virus "needs" spatially.

what horrid growth on that thing, all through that narrow life-line cane...

I must say,the cat appears to be sweet and very lovely.

Luxrosa

I don't suppose anyone knows what kind of chemical is being produced through RRD that causes such fast growth?

Harborrose,

What an interesting question. If it were some sort of growth hormone, it might even be useful. Minus the RRD of course.

Cath

Holy cow, Ann!! Keep that up your direction! No south blowing winds!

Tammy

Harborrose, the question is complex and includes what is causing the "hyperplasia" (which is excessive cell division or the growth of abnormally large cells, resulting in the production of swollen or distorted areas of the plant). The witch's brooms part may have nothing to do with the virus but could be due to something else (such as a hormone) that the mite is delivering to the rose. It could be as simple as a "cytokinin, a phytohormone, interfering with an auxin-regulated bud. Usually auxin would keep the secondary, tertiary, and so on apexes from growing too much, but cytokinin releases them from this control, causing these apexes to grow into witch's brooms".

http://en.wikipedia.org/wiki/Witch's_broom
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"The saliva of some Eriophyid mite species is found to contain plant hormones such as auxin and cytokinin analogs. When deposited onto or into plant cells, these hormones cause deformities in expanding plant tissue (Petanovi� and Kielkiewicz, 2010)."
http://www.extension.org/pages/33107/grape-rust-mite

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Here is a link that might be useful: Petanovi� and Kielkiewicz, 2010