R. multiflora var. watsonia

Has anyone tried budding clean budwood onto a R. multiflora var. watsonia to determine whether the leaf variegations are due to a virus or not? Or has this been proven to be true variegation and not symptoms of a viral infection?

I meant watsoniana :frowning:

There is only one published reference to this. It’s in a decades old Royal National Rose Society annual and it talked about growing out seeds from watsoniana and they looked like ‘normal’ multiflora.

I’ve looked for more recent papers after reading Quest Ritson’s attributing the form to viruses, but could find nothing on CAB or Agricola or some other scientific search engines.

I hope Pierre will come on because I’m going from memory on this, but on another forum years ago I think I remember his describing the watsoniana-ization of some roses planted near watsoniana.

I have a list of things I check on on academic search engines every year or so. This is one of them and there just hasn’t been much info.

FWIW, mine has Powdery Mildew until fall, every year and then the fall leaves are healthy. And mine doesn’t bloom at the same time as R. multifloras about a hundred feet away from it. Not just a day or two off, but weeks apart. Often watsoniana’s buds are frostdamaged; multiflora blooms in early to mid May, long after frosts.

Thankyou for the reply Ann :slight_smile: I think it would be a good experiment to try to see if virus-free varieties budded onto watsoniana develop similar variegations. I have just acquired a small specimen and will be planting it some distance from any other roses to avoid issues of root grafting. When it gets big enough, over the next few years (we have just begun Summer here so with any luck it will throw a few good canes before winter), I’ll bud some clean wood onto it and see how things turn out.

Beware watsoniana difference is from virus infection only. A virus I saw disseminating along a different vars and species collection line that was promptly destroyed in order to stop dissemination.

How was it being transmitted? Direct contact or by some other means/vectors/etc

Pruning tools were the first suspects with nematods an option. Just as was virus build up.

Until past year when I got a few seedlings with in my opinion definite “watsoniana syndrom”. Now pricking insects are probable guilty as is a non identified single virus strain.

It seems I had inquired about such in an earlier post, but I cannot find it referenced. I do know that David had posted some thoughts on periclinal chimeras in a thread on the variegated wichuriana species sport.

Virus are commonly the cause of variegation in Tulips, for instance, but since asking years ago about such in roses, I have subsequently acquired a knee-jerk reaction to viri in roses and haven’t pursued information on such.

On a slight parallel, Arno, what is the story on your variegated sport of Eliza?

Link: www.rosehybridizers.org/forum/message.php?topid=16347#16381

The following very recent paper describes a virus that apparently is “probably widespread in Rosa germplasm” in the U.S.

Link: apsjournals.apsnet.org/doi/abs/10.1094/PDIS-92-12-1706B

Fascinating. Thanks Henry!

So coming back to the original question… has anyone tried budding something onto it to see if the variegation spreads to the scion?

Simon,

I don’t think anyone has tried budding.

I expect you will try it, and this might help:

Budding questionable scions onto seedling multiflora is one of the accepted ways to test if the scions have Rose Rosette Disease. (This is done on plants maintained in quarantined conditions.) According to someone who has done this successfully, his best ‘takes’ for the budding are done in spring (Northern Hemisphere); that’s when he can get the bud and the rootstock to take the best.

Extrapolation: from rootstock to scion may be better in spring as well, when the rootstock is multiflora.

He found that often summer and fall buddings didn’t transmit the disease, in part because the buds were not as good a take.

Yes… when mine is larger I think I will try it and see. Should be interesting. Multiflora grows very strongly here in spring with very high sap flow. I did some budding the other day and the cut sections of the multiflora undertock actually dripped fluid from the wound. My watsoniana plant doesn’t seem overly vigorous at the moment and may need some TLC to get it going. I’ll just keep it well away from everything else for the time being and see if I c get it thriving. I am interested in this because, as you say, people have introduced viruses of various species into plants deliberately create a particular floral or foliage effect. I’m curious what effect this would have on more readily available roses if it is in fact a virus. It strikes me as unusual that R. multiflora var. watsonaina has been around for as long as it has and little is known about the answer to this question.

“and little is known about the answer to this question”

That little was published or marketed does not mean nothing was observed. I saw some that were rejected after preliminary examination with vegetative centered flowers, short green petals and overlong sepals.

Even for decorative plants viruses are considered with caution and are actually forbiden crossing most borders.

I’m just curious Pierre… I just want to know whether it is or not :slight_smile: Not planning on releasing loads of virus-induced variegated plants :wink: