Seed vs clonal propagation of species (and rootstock)

nikthegreek(9b/10a E of Athens)July 16, 2014

Now this is a general question not limited to rose species. I thought I would ask here since many knowledgeable people seem to frequent this forum. Are there any reasons (scientifically proven or not) to believe that a (genetically stable) plant grown from seed can be more / less vigorous than a clonal plant (such as one grown from a cutting)? I know somebody who advocates that fruit trees should be grafted to rootstocks grown from seed rather than from cuttings but I'm not sure why.

In the same vein, I understand that most rose rootstock (at least rootstock used in Europe) is grown from seed. In fact I know there are seed farms in places like Turkey that provide seed to European rootstock farms. I believe this is done for production cost reasons but maybe there's another reason also? What about rootstocks used in the States?
Nik

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AquaEyes 7a New Jersey

Using seed-grown rootstocks eliminates the transmission of common viruses -- that's the main benefit I hear cited most often.

:-)

~Christopher

    Bookmark   July 16, 2014 at 10:15AM
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jerijen(Zone 10)

In the U.S., for a long time, almost all commercially-grown roses were budded onto Dr. Huey rootstock grown from cuttings.

That does spread, as Christopher notes "common viruses."

    Bookmark   July 16, 2014 at 4:28PM
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true_blue(Mtl Can Zone 4b)

Nik here is the link from Pickering, where they explain the why, if you want Christopher's and Jeri's expanded version:-)

Just go to What rootstock do you use and why does it matter?

Here is a link that might be useful: Q: What rootstock do you use and why does it matter?

    Bookmark   July 16, 2014 at 4:38PM
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roseseek

There is the potential virus transmission issue using rooted stocks, but there is also the issue of not all seedlings are equal. Some are more vigorous, better suited to various soil/water types and even might be easier to bud and more accepting of scions. Supposedly, seedlings produce a more desirable root system over cuttings, but that is debatable. It is much more difficult to eliminate the crown suckering from many seedlings compared to rooted cutting stocks. Each has benefits and downsides, much like the debate between strictly own root and strictly budded enthusiasts. For the amount of propagation I do, I use both own root varieties as well as budding on rooted cuttings from mother plants of the stocks which are NEVER budded ON to so they remain as free from virus issues as possible. Kim

    Bookmark   July 16, 2014 at 11:14PM
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nikthegreek(9b/10a E of Athens)

Thanks guys for bringing the virus thing up, I knew about the virus issue, this was not the purpose of my question though. I wanted to know if there are any other pros and cons such as the ones Kim has mentioned.

Kim you mention that not all seedlings are equal. Are you refering to seedlings from the same mother plant? I understand in seed farms specially selected mother plants are used. You also mentioned that seedlings may sucker more easily but Pickering seems to be saying the opposite in the link above. You bring up the root system issue, would the existence of a tap root in seedlings make a difference? Although this, of course, is pruned when the seedling is uprooted from the field.
Nik

This post was edited by nikthegreek on Wed, Jul 16, 14 at 23:56

    Bookmark   July 16, 2014 at 11:54PM
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roseseek

I'm not familiar with the specific strains used by the commercial stock producers, Nik. They may have homogenized them to the point seedlings are fairly uniform. I can attest that seedlings raised from other roses (and many plants) are far from uniform, including those from other "species" I've played with. I raised a sample of self set seedlings from Rum 10, the thornless multiflora selection Ralph Moore obtained from his Australian agent, Roy Rumsey, years ago. There was quite a surprising spread of vigor in the population of the forty or so seedlings. Some had incredible root systems, while a few of them had rather weak excuses for roots. It was similar to what I see in the usual range in seedlings from my deliberate crosses as well as from Hugonis and Xanthina self set seed. Some are overly vigorous while others are surprisingly weak. I've raised enough seedlings to know that lack of vigor indicates substandard root formation. Vigorous, healthy seedlings have amazing root systems. Weak, sickly seedlings have awful root systems. I don't find great roots on sick, weak seedlings.

I can easily see the buds on cutting grown stocks and, as long as they are properly excised, suckers aren't generally issues. Raise seedlings and watch how easily they produce "basal growth", what would be considered suckers if they were budded on. I don't know that a tap root is that necessary for a standard rose bush. I don't see what you would call "tap roots" on most seedlings. What I do regularly see are multiple larger roots radiating out from the crown of the plant, with numerous more fibrous roots. Maybe those types the nurseries raising them for stocks form tap root type roots. I don't know. Kim

    Bookmark   July 17, 2014 at 12:31AM
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malcolm_manners

Just to add a bit to the already good discussion above, once you find a really good, reliable, vigorous rootstock, it may not be possible to reproduce it from seed. E.g., 'Dr. Huey' seedlings would be quite heterogeneous, because of the hybrid complexity of the parent. And 'Fortuniana', which we use almost exclusively, doesn't produce any seeds. Attempts by Dr. Basye to repeat the 'Fortuniana' cross (R. laevigata x R. banksiae) produced less vigorous plants that were not 'Fortuniana' and did not have its superior qualities as a rootstock.

As Kim mentions, in a tree crop the main advantage of a seedling (regardless of genetics) over a cutting-grown plant in many species, is that a seedling tends to send down a primary taproot, which gives wind resistance, whereas cuttings tend to send out more-or-less horizontal roots that then bend downward, leaving a 90° angle junction at the stem. In violent wind conditions, that can be a problem even years later. Hurricane Andrew neatly ripped big, old lime and lychee trees out of the ground with all their roots snapped off, in the case of plants grown from air layers, whereas plants budded to seedling rootstocks, while heavily damaged, often managed to stay put in the ground.

But in the case of a rose garden, that sort of thing is probably the least of one's worries in a category 5 hurricane situation, and cutting-grown roots do eventually go about as deep in the soil as their seedling counterparts.

So the thing I like about clonal, cutting-grown rootstocks is their complete predictability, as to vigor and performance. If you are careful not to spread viral problems through them.

    Bookmark   July 17, 2014 at 6:50AM
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nikthegreek(9b/10a E of Athens)

In Europe canina cultivars (including Laxa) are mostly used and these, to my knowledge, are produced from seed. Canina is notorious for its variability in the wild, but it seems this does not create a problem to the industry. In Southern Europe and the Med basin R. indica Major is still used widely both for garden roses and for the cut flower trade and this, I believe, is propagated by cuttings. Some viral infections affecting the cut flower trade have been blamed on this.
Nik

    Bookmark   July 17, 2014 at 8:13AM
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jacqueline9CA

I have a question I have always wondered about on a related but slightly different topic. Forgive my ignorance, but you guys know so much about all of this (and I know nothing) that I thought this would be a good time to try and get it answered!

I have several rose bushes in my garden which are or were actually (that very bush) very old - we think the oldest one surviving right now was planted in the 1920s (from the testimony of my FIL who was born in 1913 - it was there in his childhood). I have been told by some folks that it is good to take cuttings of these roses if I want another bush of that rose, instead of purchasing them, because some roses have "declined in commerce".

An example I just did last year is Peace. Our original Peace bush, accd to my FIL, was planted in the late 1940s. When we moved here, it was growing under and in the shade of a large pomegranate, but still grew and bloomed, and had decided to be a climber, and was up to the top of the pomegranate. Anyway, when it started to die last year I managed to get one cutting from it to root, which was planted 3 months ago, in its own bed in the sun. It looks as healthy and vigorous as its parent - it has not bloomed yet, but has shot straight up, and has lovely foliage.

So, I am willing to believe what people say. My question is: why do some roses "decline in commerce" (and is it true at all?)? Is it because of mutations? Thanks so much for your thoughts - I am just curious.

Jackie

    Bookmark   July 17, 2014 at 11:11AM
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henry_kuska

The selection of buds based on their position on the mother plant is thought to be a factor which influences whether a new plant is as good as its "mother".

I suggest a Google search for plant Topophysis

The following is from the link below:
"Furthermore, the smallest percentages of non-rooted cuttings and blind shoots originated from positions 2±4
demonstrating that the upper- and lower-most node
positions should be avoided in order to obtain uniform
growing plants."

http://aob.oxfordjournals.org/content/78/2/215.full.pdf+html

Here is a link that might be useful: link for above quote

This post was edited by henry_kuska on Tue, Sep 2, 14 at 16:46

    Bookmark   July 17, 2014 at 11:56AM
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jerijen(Zone 10)

In addition to own-roots, I have only grown roses on three rootstocks: Huey, Multiflora, and Pink Clouds . . . And I grow Fortuniana as a garden rose (one with truly astonishing vigor and reach).

Huey does well here, despite being virused.
Pink Clouds does "OK."
Multiflora . . . OMG. We have had quite a large number of roses on Multiflora, mostly from Hortico. MOST of them have been notable for their ability to sucker to an astonishing degree. Grown in squats in the ground, they will push up suckers growing 6-7 feet away from the original plant.
I think we are down to one plant on Multiflora. It's a huge Golden Celebration, from Hortico, planted about 20 years ago. It grows vigorously, but suffers from chlorosis often. (This is not a problem with the 3 GCs on Dr. Huey which flank it, nor with the own root plant, grown from a cutting from the old one.)
So, in MY conditions, I won't ever buy another rose on Multiflora.

    Bookmark   July 17, 2014 at 12:29PM
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roseseek

Hi Jackie, there could be several possible explanations. J.H. Nicholas wrote in A Rose Odyssey in 1937 that injudicious bud selection had "ruined" HPs in this country. He visited the grand son of the introducer of General Jacqueminot and found bushes which had been refined nearly to the "quality of HTs" through proper bud selection. He reported the HPs in the US had been ruined to the point of producing climbing growth, running rampant with few flowers and much blind growth. He stated appropriate material had been secured from the grand son's nursery to produce the proper General Jack here at J&P. What Henry's link describes.

"He who shall remain nameless", who owned and operated a nursery in Central California (and may still), offered that roses containing strongly Foetida influence do not tolerate long, dry, cold storage as it devitalizes them, many plants never recovering. Peace, Sterling Silver, Angel Face, Grey Pearl, Pernetianas, etc. would all fit into that category. Mauve modern roses traditionally have strong Foetida influence and may be subject to dry, cold storage deterioration. When you observe vigorous, vital plants of these varieties growing in the production fields then see the stunted, runt plants being sold of the same varieties, it isn't difficult to imagine.

Of course, you also have the possible/probable increased viral load many of them likely suffered. Nursery #1 could easily have infected the variety with one type, with each successive producer adding different types or even different strains of the same virus to the load with each successive budding. How much each virus as well as their combined effects affect the variety depends upon many factors including the plant's immune system, the climate in which it is grown as well as the cultural style of the person growing it. Some have suggested that obtaining material from very early produced plants might result in plants free from infection, but I doubt it in most cases. MANY modern roses were introduced infected, often with their viral load being increased each time someone else produced them. Perhaps if material from a very old variety, something produced long before the 1920s when "infectious chlorosis", an early term to describe the symptoms, was observed and described, it might be possible to grow cleaner stock. But for something such as Queen Elizabeth or Iceberg, or many other very popular types produced in this country mid century or later, the only stock put on the market was already infected with at least one type.

There are definitely degenerative mutations which occur when any plant is rapidly reproduced. Cutting grown plants may not suffer such extreme degeneration as long as the type is suited to own root production and growth. But, when each plant depends upon solely ONE bud for its characteristics, it's very easy for something to happen. There are several instances of degenerative mutations making it to market of quite popular modern roses. There were extra vigorous mutations of French Lace, Angel Face, Circus and some others which grew larger, huskier than their original forms and all had muddier colored, inferior shaped flowers. The stories I heard many years ago were that it cost J&P many tens of thousands of dollars to replace and rough out the deteriorated French Lace plants. I have seen the two variations of Angel Face. The deteriorated form is definitely a superior plant to the original. It grows much more vigorously and isn't quite as much a martyr to black spot, but the flowers hardly resemble the original. It's very easy to imagine how and why they made the sales inroads they did. When a probably less experienced, lower paid worker is sent out to a particular row in the field with the instruction to collect a number of buds from a variety, of course the worker is going to go for the more vigorous growth where he/she can harvest more material from a smaller area. That is very likely what resulted in the accidental selection of Dr. Huey as a root stock over Ragged Robin. To the person collecting root stock cuttings, they looked enough alike and were positioned sufficiently closely for Huey material to be collected with the Ragged Robin. It wasn't until budded plants were produced on the Huey and were found to perform better in the field rows the mistake was discovered. This kind of mistake is also often the reason climbing sport plants are provided in place of the bush type. Yes, it's also possible inattention in packing can also accidentally put a "Cl" whatever in the box instead of the bush form, but it's also very likely material was collected from the extra vigorous climbing mutation and thought to be the bush form.

Of course, there could also easily be the issue of "romantic memory" where what is remembered of past types is so romanticized that nothing in reality can compare. Like memories of old romances, "the good old days", etc., reality seldom measures up to the memory. Add to it the memory of viewing some break through with early Twentieth Century eyes then observing the same traits through Twenty-First Century eyes. In comparison, the older traits can seldom measure up to the improvements made each decade through breeding and selection. What appeared "vigorous", or "dazzling scarlet" to 1920 eyes can easily be described as awkward or ungainly with dull red blooms to ours. I lusted after K of K thirty years ago. I WANTED that rose to include in my single HT bed. The written description of "dazzling scarlet" genuinely appealed to my 1980s eyes. You can imagine my disappointment when I finally saw growth resembling Dr. Huey suckers studded with dull red semi double flowers. It probably did look "dazzling scarlet" to those eyes observing it sixty years earlier, but there had been tremendous advances in health, vigor and color in the six decades between the description and my eyes.

It isn't as easy for that to be possible when you consider the original descriptions for Peace written back in 1956-7 of "five foot bushes with five inch flowers", then observe the two foot plants with inch and a half to three inch flowers. Something definitely is at play for those and the runt, stunted plants of Peace, Angel Face and the rest which have obviously changed from their original types. Precisely which "something" that "something" is, is anyone's guess. Kim

    Bookmark   July 17, 2014 at 1:29PM
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jacqueline9CA

Thanks so much, Kim! You have, as usual, a very good ability to explain complicated and confusing issues like this one (which it sounds like could be one or more of several issues).

Just an aside about my Peace rose - my recollection is that the blooms were certainly at least 5 inches in diameter. I will take pics of my new baby rose flowers when it blooms, holding them next to a ruler, to find out for sure. Of course, I looked and I have hardly any pictures of my original old Peace rose - I basically took it for granted, as I knew who/what it was, and concentrated on the old teas and other roses all over my garden which were mysteries to me.

Here is one pic I found of the old Peace rose growing through the pomegranate bush - just for your amusement. It looks weird and sort of like an impressionist painting because this is a blown up small part of the original picture, which was taken through an old wiggly glass Victorian era window (everything about my house/garden is old!) from far away.

Jackie

    Bookmark   July 17, 2014 at 2:45PM
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mashamcl

Jackie, what a gorgeous rose!

Kim, the depth of your knowledge is amazing. Thank you fo much for sharing with all of us.

I am wondering how far back one has to go to find roses that have not been budded on virused rootstock at some point. It seems hopeless with HTs...

Here is a picture of my Mrs. Wakefield Christie-Miller.

Masha

    Bookmark   July 17, 2014 at 3:09PM
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roseseek

That's actually beautiful, Jackie! It impresses me as the water lilies in Monet's garden painting. You're welcome! I'm sure there are other potential issues to answer your question, but these are the ones which come to my mind. When encountering difficulties propagating older rose bushes, Clair Martin, former Curator of Roses at The Huntington, advised creating a young, new bush to "reintroduce juvenility" into the plant, then begin propagating from that plant. It worked. I tried unsuccessfully for the longest time to root Isobel, the early Twentieth Century single HT until finally one succeeded. From then on, we'd root new flowering shoots from that plant and they rooted quite easily. Perhaps that might also be some of the difficulty with the devitalized commercial plants? Maybe the material taken from older stock plants is too geriatric to produce suitable results? Not quite old enough to prevent success but not juvenile enough to give good results? I don't know, but producing new plants from younger plants certainly took care of the propagation issues we encountered with many of the older types there. Kim

    Bookmark   July 17, 2014 at 3:10PM
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roseseek

Thank you, Masha. Those symptoms had been observed and written about by the mid 1920s in the ARS annuals. That's where I learned the term "Infectious Chlorosis", so there were at least the beginnings of viral infection in commercial production by then. Like measles and other diseases spread rapidly through school classrooms, you can imagine how quickly and easily infection spread through commercial production. American producers simply didn't view it as an issue for at least half a century, perhaps more. I would imagine, if you could find a plant produced prior to at least the early 1920s, your chances may be decent for it not being infected. You can't base it upon the age of the variety as so many were commercially propagated by many sources all the way through the late 1970s with a number continuing to be budded by ROYAT through the early 1990s. Armstrong budded and sold almost all classes of roses in their mail order catalog through almost the end of the 70s. They were well known for producing virused stock. When J&P bought them, John Walden, Keith Zary's assistant at the J&P Research Facility at Somis, CA, told me it was for their patents. The stock was "burned in the fields" due to the severity of the viral infection. Armstrong was the official introducer of the majority of the AARS winners, that program beginning in 1940, so you can imagine the potential for their being infected. Malcolm Manners has stated after being treated for RMV, roses regained much of their vigor, so perhaps seeking out treated material might be the answer for finally seeing what previous generations and even the roses' creators saw in them. Kim

    Bookmark   July 17, 2014 at 3:37PM
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mashamcl

Kim, that's why I included a picture if that particular rose, dating from 1909. Somehow, in my ignorance, I didn't expect to find RMV on it...

Didn't ROYAT bud everything, including OGRs?

    Bookmark   July 17, 2014 at 3:52PM
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roseseek

Yes ma'am. It's my understanding they budded everything from at least the 1940s forward, perhaps Tillotson's budded, I'm not sure. But, at least post WW II, budding seemed their method of production and remained so until the end of the Patricia Wiley era. The current permutation of the company appears to purchase budded plants as well as either purchase or generate own root varieties for sale. I have no idea what the sources of their own root material are. Hopefully, not the old ROYAT display garden. I doubt if there were any plants there which weren't of their retail stock.

Your photo of your infected plant is what I had regularly seen in private and public gardens from the early eighties through the early 2000's. Disappointing. Fortunately, the newer the variety, the less likely they have been to demonstrate those symptoms. Virtually every older type I saw in the early days looked very much like that. Kim

    Bookmark   July 17, 2014 at 4:03PM
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mashamcl

Kim, thank you again. How sad.

    Bookmark   July 17, 2014 at 4:17PM
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jerijen(Zone 10)

Probably depends upon the HTs in question. There are a fair number of plants around of 'Lady Mary Fitzwilliam,' (See Below.)

She was bred by Henry Bennett, UK, before 1880, and she's a beauty. I'd rather by far grow that . . .

If I'm growing one that came from a mid-19th-Century grave, and it shows no signs of virus, I'm thinkin' it's likely clean.

But I can't dismiss the possibility that the decendent's G-G-G Granddaughter bought a virused plant from ROY&T, in 1969, and planted it. So, the only way to REALLY know that a rose is not virused is to have it tested.

If I'm growing a rose like that, and it's going great guns, I'm likely not to have it tested, because it's doing fine for ME.

Oh, and it's worth noting that there are any number of virused plants around of "Ragged Robin," which are clearly rootstock revisions. That's reasonably good evidence that virus was circulating before Dr. Huey, poor guy, entered the picture.

    Bookmark   July 17, 2014 at 4:21PM
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mad_gallica(zone 5 - eastern New York)

Dr. Huey is a fairly late introduction in all of this. Numbered multiflora selections were the rootstock of choice for the big nurseries like J&P until they left the east coast for the west. Prior to that, Dr. Huey was a speciality rootstock that had to be sought out. My guess is that it was harder to find in the 50's than Fortuniata is now.

    Bookmark   July 17, 2014 at 4:33PM
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mashamcl

Jeri, that's such a lovely rose. I have seen a plant of Lady Mary Fitzwilliam at the Heritage and it looks like your rose, but not like my Mrs. Wakefield. The blooms on my plant appear to be smaller, have fewer petals and are brighter pink on the reverses. Mine does not repeat at all, and I really need to find time to take it out. I am glad you found what appears to be a virus-free plant.

Mrs. Wakefield Christie-Miller

    Bookmark   July 17, 2014 at 6:12PM
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malcolm_manners

While bud position and "over propagation" have long been blamed, there is no documented evidence for such a cause of decline in roses. And if there were random mutations, you would expect them here and there, not across an entire variety. A local nursery observed for years the differences between plants produced, based on the position on the stem of the bud, to test that idea. What they found was that, at first, there was a marked difference. But by the second or third growth flush from the graft, there were no differences.

On the other hand, it does make sense that viral infection can cause such "decline," not necessarily rose mosaic, but could be other viruses as well. In any case, we've observed (with 'Peace' and some other older "declined" roses), that heat therapy for mosaic also rejuvenates the variety. So our 'Peace' plants are as vigorous and brightly colored as people remember from back in the day.

    Bookmark   July 17, 2014 at 9:08PM
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Tessiess, SoCal Inland, 9b, 1272' elev

Interesting about your Peace rose Jackie. At Great Rosarians of the World at the Huntington in 2012, Alain Meilland, whose family bred Peace, brought up the changes in the plant. Specifically how many in the US did not look like the original. So he put up an image and said this is what Peace is supposed to look like. I took a picture, and here it is.

Melissa

    Bookmark   July 17, 2014 at 10:25PM
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Tessiess, SoCal Inland, 9b, 1272' elev

One more picture of Peace from Alain Meilland's presentation in 2012 at Great Rosarian's of the World.

Melissa

    Bookmark   July 17, 2014 at 10:29PM
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malcolm_manners

And here is heat-treated 'Peace' at Florida Southern. (Sorry, I can't seem to get embedding the photo directly here to work)

Here is a link that might be useful: Peace rose photo

    Bookmark   July 17, 2014 at 11:41PM
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Tessiess, SoCal Inland, 9b, 1272' elev

Malcolm, which nurseries have the heat-treated Peace?

Melissa

    Bookmark   July 18, 2014 at 1:38AM
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jacqueline9CA

Thanks Melissa and Malcolm! Your pictures are just what my old Peace rose looked like - I am so looking forward to the new baby one blooming!

Malcolm - so wonderful that you have figured out how to restore it!

Jackie

    Bookmark   July 18, 2014 at 11:45AM
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malcolm_manners

Melissa, Sorry to say that we did not keep records of who all got it from us. It has been widely distributed. You might ask Heirloom where theirs came from. Vintage had it, but of course they are not selling roses. So anyone who got it from them should also be ok. Also FPMS (UC Davis's heat-therapy program) has it, so they have likely distributed it to many nurseries, but whose names I don't know.
Malcolm

    Bookmark   July 18, 2014 at 11:49AM
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Glenburn(z8/z9 Mudgee, NSW Aust)

Jackie, your 'Peace' is the color that it should be IMO. It is MY belief that roses(buds) taken from the mother plant or as close as possible produce the same color/characteristics of it. The further away from it, I am talking 'Peace' here, it has lost it's color, nearly a white, instead of the cream/yellow in your photo Jackie.
As for Niks original question about rootstock, one of our older nurseries(now retired) had on thier books, over 100 forms of rootstock, many of these were 'multiflora'. Because of our soil types in Australia 'multiflora' is the choice of our major nurseries, except Western Australia because of nematodes and sandy soils, but there is a swing away from it to /The Doctor'. now. In the past(twenty pus years ago) from one wholesale nursery in South Australia(a state of Aust) they used 'The Doctor' with results of VERY bad nursery practice of suckering, that has now been corrected.
From talks I have had with rose nurseries in England they use a form of "Laxa" seedling grown rootstock from a farm in the The Netherlands. At present they(seed farm) are looking at 'fortuniana' as a stock for a couple of reasons, nematodes and government intervention in relation to chemical sprays. They are trying to source seed from 'fortuniana'(or a form of it) to start clean mother plants.
As for how these seedling grown rootstocks are budded I will have to ask a couple of people at David Austins that and get back to you on it.

Regards David.

    Bookmark   July 18, 2014 at 2:33PM
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roseseek

Good luck to them finding Fortuniana seed, David. I have never found self set hips on any Fortuniana I have ever encountered; it has never formed any hips from anything I have ever hit it with, nor have I ever been successful collecting enough pollen from its flowers to do anything with. Beileve me, I've tried! Kim

    Bookmark   July 18, 2014 at 2:46PM
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malcolm_manners

No, as far as I know, 'Fortuniana' never matures a hip. I've not seen one in over 30 years of growing it. And if it did, since it is a primary hybrid of two quite different species, the offspring should be quite variable.

    Bookmark   July 18, 2014 at 4:36PM
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nikthegreek(9b/10a E of Athens)

Laxa and other canina rootstocks are grown by specialized rootstock growers, often in the Netherlands or Germany and sold to the nurseries as seedlings. The seed itself is not produced by them but by specialised seed farms further south in the warmer climes.
Nik

    Bookmark   July 19, 2014 at 1:32AM
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roseseek

That was the issue with Pickering not being able to ship to the US. They imported root stocks from Europe then budded the plants in Canada. Our import restrictions require all plant parts to originate in the exporting country. Had their stocks been generated in Canada, then budded there, they would have had no problems. That's why Hortico and the rest could continue shipping here. They either grew their own stocks, or obtained them within Canada. Kim

    Bookmark   July 19, 2014 at 1:46AM
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true_blue(Mtl Can Zone 4b)

This has been one of the most interesting threads, I've read so far. Thank you all.

In Thomas Christoper's book, In Search of Lost Roses, Page 220, he affirms that micropropagation from an infected plant, yields pathogen free plantlets.

Is this method still used or heat therapy is much more practical method of clearing viral maladies?

Bob

    Bookmark   July 24, 2014 at 3:35PM
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nikthegreek(9b/10a E of Athens)

I understand tfrom what I've read that neither method is 100% safe, A combination is a good way of ensuring minimum risk. Now, why do I have this hunch that a particular person is going to chime in any time now?
Nik

    Bookmark   July 24, 2014 at 4:04PM
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roseseek

Nope, neither is fully safe and cutting grown stocks are significantly faster and easier for the home gardener to generate and handle. Particularly if you're interested in something like Fortuniana which won't breed nor set seed. Kim

    Bookmark   July 24, 2014 at 4:15PM
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true_blue(Mtl Can Zone 4b)

I understand that none of these methods are not practical for the home gardener, but what about commercial growers?

Does that mean that regardless the method the plants won't be 100% virus free?

Kim, I'm a bit confused. Do you mean a cutting grown stock from a virused plant, will produce a reasonably ok, plant?

    Bookmark   July 24, 2014 at 5:22PM
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roseseek

Both seedling and rooted cutting grown stocks have been used commercially for nearly a century. When we speak of "virus free", it needs stating the definition is "free from Rose Mosaic Virus" as there are other viruses which are potentially present. If the original plant has no RMV (rose mosaic virus) which is the primary virus for which treatment is traditionally available, and it is not grafted or budded together with an infected plant, anything produced from it should remain free from RMV. If a plant is infected with RMV it is entirely possible for root successful plants from it, which will all be RMV infected. It is also entirely possible they will thrive, even flourish, often for many years. What might inhibit their success includes MANY variables, such as the susceptibility of the rose to the virus; the strength of the particular virus strain; "viral load" such as how many types of viruses are present in the particular plant; how well the plant roots and grows own root to begin with; how suitable the particular variety is to the specific climate in which it is grown; the specific culture style employed by the person growing it; and I'm sure, quite a few others. So, to answer your question, yes it is possible to raise a "reasonably OK" plant from RMV infected plants. As proof, I offer the tens of millions (perhaps hundreds of millions) which the US rose industry pumped out for a good portion of the past three-quarters of a century which contained possibly at least one virus, and succeeded in producing acceptable garden plants in many instances. Though, as Malcolm Manners has shown, those which appear to have "lost vigor" often regain it once cleaned from RMV. Whether infected plants might be successful everywhere or desirable to everyone are entirely different matters. Kim

    Bookmark   July 24, 2014 at 5:50PM
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malcolm_manners

As far as I know, no one has ever routinely used micropropagation to clean up roses. It is used in fruit trees for the same viruses, and some research has been done on it for roses, but no real production. One of the big challenges there is that roses are not particularly easy to tissue culture, particularly when very tiny explants are used, and for virus removal, you want a very small cutting indeed. Heat therapy, in my experience, is 100% effective IF the rose survives (many do not). But we've never had a rose come through the full treatment and then test positive later (even many years later). Not to say it could not happen, but in 30+ years, I've not seen it happen. So we always do index the rose by multiple methods after treatment, to be sure.

    Bookmark   July 24, 2014 at 6:47PM
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roseseek

That was supposed to be one of the reasons for the Armstrong/Delbard "Roselings" years ago, Malcolm. I bought a Mr. Lincoln Roseling and my best friend bought a Double Delight, both tissue culture plants. This was back somewhere in the 1990s and they cost about $20 each retail. Expensive, but novel, so we 'bit'. Lincoln grew well, Double Delight didn't. Kim

    Bookmark   July 24, 2014 at 7:00PM
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malcolm_manners

Yes, Kim, the commercially made tissue cultured roses were generally made from a larger explant -- much easier to work with, but far less likely to have been cured of mosaic, if they had it to start with. We've had good success with larger explants, just for propagation purposes. To rid a microcutting of a virus, you have to make it so small that there are no phloem cells present. You take a rapidly growing terminal bud and cut it above where phloem has differentiated. Perhaps 0.1 mm long. Rather like a spider mite's leg. Make it just a hair too small and it will die. A bit too large and it's still infected. But get the perfect size and you may end up with a clean plant. (Goldilocks would be impressed with that, I think.)

This post was edited by malcolm_manners on Thu, Jul 24, 14 at 19:33

    Bookmark   July 24, 2014 at 7:29PM
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true_blue(Mtl Can Zone 4b)

Thanks Kim & Malcolm for detailed response. Much appreciated and makes learning much fun!

    Bookmark   July 24, 2014 at 9:33PM
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true_blue(Mtl Can Zone 4b)

Malcolm you said IF the rose survives heat therapy (many do not).

Are there any classes which survive the heat therapy better than others, or does it depend on the individual plant itself?

    Bookmark   July 25, 2014 at 8:19PM
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malcolm_manners

true-blue, yes, it's counterintuitive, but heat-loving roses (Chinas, Teas, Noisettes, some HTs, etc.) tend to die far more often than do Rugosas, Albas, etc. The latter just seem to go into a heat-induced shock, not growing at all, but not dying either, until the treatment is complete. But there is a lot of individual variability as well. I usually keep some backup plants, and ultimately get one through the treatment. I think the only one we've never been able to heat-treat was 'Don Juan', and fortunately, the folks at Davis were successful with it.

    Bookmark   July 25, 2014 at 9:14PM
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true_blue(Mtl Can Zone 4b)

Thanks Malcolm. I had a "feeling" that hardy roses would take heat better!

There must be a great satisfaction to be able to treat a a virused rose in order to "create" healthy roses from it.

Bob

This post was edited by true-blue on Sat, Jul 26, 14 at 18:40

    Bookmark   July 26, 2014 at 8:12AM
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mad_gallica(zone 5 - eastern New York)

Malcolm, I seem to remember you saying many years ago that you were having trouble getting Rose de Rescht through heat treatment. Did that one finally make it?

    Bookmark   July 26, 2014 at 11:59AM
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true_blue(Mtl Can Zone 4b)

Malcolm in your experience, has heat therapy helped with other ailments of plants, or is indexing specific to RMV?

    Bookmark   July 26, 2014 at 6:55PM
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malcolm_manners

mad_gallica -- 'Rose de Rescht' is available clean, but not due to our heat therapy. We got it from Heirloom, who apparently imported a clean one from Europe. We indexed it here and found it clean.

true-blue -- I've heard people make claims for resistance to fungal diseases and other "miracle cures," but I have no reason to believe any of them. Removing the viruses that cause mosaic will alleviate any symptoms those viruses may cause, which may include fewer, smaller flowers, shorter stems, less longevity, less cold-hardiness, etc. And in at least some varieties that are said to have "declined," it seems to help reverse that. But no, I'm not aware of (nor would I expect) other major benefits.

I'm sure by "indexing," you mean the heat therapy process. Actually, indexing follows therapy -- it is the series of tests done to demonstrate freedom from the viruses, after we've removed them.

    Bookmark   July 26, 2014 at 9:57PM
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AquaEyes 7a New Jersey

Malcolm, while I have your attention here -- have you ever put striped roses through heat treatment and have them come out stripe-less? There was a thread elsewhere about striped roses and this was mentioned. I read conflicting information on this topic.

:-)

~Christopher

    Bookmark   July 27, 2014 at 11:33PM
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malcolm_manners

We treated Camaieux, many years ago, after hearing a claim that striped gallicas were caused by a virus. Of course in the case of Rosa Mundi, that doesn't make sense, since that can sport back and forth to gallica Officinalis. But Camaieux came out still as striped as ever. That doesn't prove that it's not a virus -- some viruses may survive heat therapy. But it's not one of the mosaic viruses. I can't think of any other striped varieties we've worked with.

    Bookmark   July 28, 2014 at 10:02AM
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true_blue(Mtl Can Zone 4b)

Yes Malcolm that's what I meant.

In your excellent article on ARS,
I misinterpreted "virus" as any virus instead of the different strains of RMV when you write about the ELISA indexing method:

"It is a quick (less than one day) laboratory test, and not only tells whether any virus is present, but can often determine exactly which virus, and sometimes even which specific strain of a virus, is present.

By the way do you still use all 3 methods of indexing?

    Bookmark   July 28, 2014 at 10:25AM
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malcolm_manners

"By the way do you still use all 3 methods of indexing? " We do, although it's been a while since we sent any for 'Shirofugen' indexing.

    Bookmark   July 28, 2014 at 4:15PM
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henry_kuska

true-blue, you may find this 1983 Ph.D. thesis of interest regarding classical (pre PCR) indexing methods.

http://muir.massey.ac.nz/handle/10179/3563

If you use the Adobe search function with the keyword "index" you will find his material covering indexing methods. (Because of his copyright restrictions, it appears that I cannot post more detail,))

Here is a link that might be useful: link to thesis

This post was edited by henry_kuska on Fri, Aug 1, 14 at 12:06

    Bookmark   August 1, 2014 at 11:35AM
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true_blue(Mtl Can Zone 4b)

Thanks Henry. Much appreciated.

    Bookmark   August 1, 2014 at 5:26PM
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Tessiess, SoCal Inland, 9b, 1272' elev

Malcolm, when roses are being heat-treated, do you give them any water?

Melissa

    Bookmark   August 2, 2014 at 6:24PM
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malcolm_manners

Tessiess, Yes, they're in the heat for 28-30 days, and would die quickly without water. We irrigate about 4 times a day. That's one reason the plant in the heat is never cured -- its root system cools off a bit every time you water it. So we cut buds from high on the stem, directly from the heat, to bud onto mosaic-free rootstocks, to make the clean plants. The original plant is then discarded. There are other methods, used for other viruses or in other crops. For example, some citrus viruses are cured by soaking budwood for a few minutes in quite hot water -- almost enough to kill the wood. But that system doesn't work well with the viruses causing mosaic in roses. They respond better to the 100°F for a month.

    Bookmark   August 2, 2014 at 8:22PM
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