When a rose is "heat treated", the rose isn't. A growing twig is taken, and kept alive and only the apical bud is of interest. That apical bud is then bud grafted onto clean rootstock. Not all apical buds grow fast enough, nor do they graft in a really soft state.

Paul,

Thanks for the clarification.

Since RRV is a virus, couldn't an inoculant be made, administered to clean or even virused plants, thereby rendering the RRV neutralized?

Moses

Ann,

So it's just the apical tissue that is heat treated. After cleansing, is it then tissue cultured, or is it customarily used as a grafting scion?

Why couldn't an entire bush be heat treated? Is it impossible/impractical to do, or just not done through common practice in the case of RMV?

Moses

Moses, it's my understanding that the entire bush simply will not survive the heat that the treatment would require. You have to realize you're talking about bare roots, woody parts and soft growth, thick canes and thin twigs. The thicker the wood, the longer it would have to be exposed to high temperature to even reach the virus, and the more likely you'd be killing thinner growth. It just can't be done. With a twig, you're talking about one piece that is fairly consistent in size end to end, so that you're not cooking some parts in order to reach the virus in other parts. To reiterate Paul's point, this is concerning RMV, NOT RRV.

As far as inoculating a rose with a vaccine, it would have to be done through genetic manipulation, I fear. Roses, or any plant, just don't hang on to chemical treatments for very long. That's why even with "systemics", you have to reapply every two weeks. And as Paul pointed out, roses are constantly being re-exposed to the virus. Even if you could "clean out" the virus with a treatment, next week another mite drops in. Plus, a rose's immune system doesn't work like a human's, in that they don't create actual antibodies or killer cells that actively attack invading viruses.

john

John,

Thanks for the info. I was thinking, if the treatment temperature for RMV is, say 116 degrees F., an entire bush may just survive the cure at this temperature with minimal damage?

Do you know the temperature that kills RMV?

Moses

Moses, they DO submit entire plants to the heat treatment, but they are only attempting to obtain virus free apical meristem cells (the buds). Most apical meristem cells are already free, or nearly free of viruses.The heat reatment doesn't create virus free plants, just virus free (hopefully) buds.

I think the temperature used is around 100F, for a long period of time ( a month? I'm not sure). To free the entire plant of the virus, I presume a much higher temperature would be needed, which would cook the plant. The buds are used because they are ALREADY nearly virus free, and so can be "cleaned" by a less than fatal (to the rose) temperature.

The virus indexed plants you hear of have been heat treated, buds harvested and grafted, grown on, then tested. The INDEXING is the test, not part of the treatment. It is how the plants are proven to be virus free.

Where's Malcolm when you need him? lol

John,

I elect you to be the official science consultant for the Roses Forum! You bring things down to a layman's understanding level. You must be an educator?

Now I know why having a rose virus indexed is so expensive.

Thanks again!

Moses

To anyone who may be a bit confused these viruses are not related in terms of what happens to your rose. Rose mosaic virus / RMV is a term being used to describe several viruses that can infect roses. They are not good but not fatal to the rose.

Then there is RRV/rose rosette virus. It is a virus that is 100% fatal to roses.

So rose mosaic virus can be successfully eliminated with heat treatments.

Rose rosette virus is a whole different animal.

To clarify, in case fig_insanity didn't make it clear already, the heat treatment used to clear RMV from a rose involves keeping the plant at 100F for a month, and does not cure the original plant. The heat treatment seems to prevent the virus from infecting new growth.

New growth emerging after that time is removed and propagated to create a new plant, either by budding or by rooting. This new plant will be grown, and then pieces will be removed and grafted onto a clean plant of the rose 'Mme Butterfly', which is very sensitive to RMV. If symptoms of infection appear on the previously clean 'Mme Butterfly', then the virus wasn't cleaned from the original rose. Presence of the virus can also be detected by an ELISA test. If the newly-propagated roses produced from removing new growth emerging after heat treatment pass the tests for detecting the virus, the newly-propagated roses are deemed clean.

But the original rose plant which endured the heat treatment and from which propagation material was obtained will still be infected. So even if RRV responds to heat treatment similarly to RMV, it won't cure the original plant. All it will do is allow for uninfected new growth to emerge, which can be harvested to propagate a new plant. Frankly, it's easier to just buy a new plant than try and make a new uninfected one this way. The benefit of heat treatment for RMV is that in many cases, uninfected plants of particular cultivars are simply not available for purchase.

Often, if RMV status isn't known, the rose will simply be tested first, and heat-treated only if deemed infected. If found to be clean, it is simply labeled VI or VID to show that it passed the tests for RMV.

:-)

~Christopher

I am not aware that RRV is a temperature sensitive virus (not all rose viruses are). See for example: https://sites.google.com/site/roseyellowmosaicvirus/

One approach that is currently under investigation is given in the following thread:

http://forums2.gardenweb.com/discussions/4708222/florida-rose-rosette-immune-system-research?n=4

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There is a Rose Clean Plant organization:

http://rosebreeders.org/forum/viewtopic.php?f=2&t=55690

Moses, thank you for the nomination, but the word to describe me would be "generalist", lol. Christopher provided a more detailed, nuanced description of the thermal treatment and subsequent testing. I know just enough about a multitude of topics to be deadly dangerous at Trivial Pursuits. Having an insatiable curiosity and a pack rat memory helps. I've often said I know just enough about almost everything to get someone hurt, lol.

Though I'm a songwriter by trade, I am a teacher at heart, which is why I tend to "bring things down to a layman's understanding level". But I owe a lot of my rose science knowledge to Ann, Paul, Kim, Malcolm and so many others who share their expertise on the forums. I just happen to know who to go to when I need an answer, lol.

john

John,

You imparted your introductory knowledge to me. Thank you, again. I may have never heard from Christopher. Grateful I am that he expanded upon your groundwork.

Songwriters have a special gift. Mozart composed the music for his operas, but he had librettists (songwriters), create the words, and fit them into the music. He, as brilliant as he was, knew that without the talents of a librettists, he was sunk. If you write the music and the words to your songs, you have a double gift even Mozart did not have.

Moses