Univ. of Calif. Davis roses

Has any one used the University of California Davis Foundation Plant Service for virus indexed roses? From the web page they have a good selection of understock as well as 400 different cultivars that are virus free.

It’s too late for ordering for hardwood cutting, but scions can be purchases in the Spring and Summer.

Link: fpms.ucdavis.edu/rose.html

I haven’t ordered from them because it didn’t work out for timing for what we needed for the virus research I’m helping Dr. Ben Lockhart and Dimitre Mollov with. One thing to keep in mind is that these roses from UC Davis are virus indexed and shown to be free of particular viruses, but are not necessarily “virus-free” of all viruses. Ben has discovered 7 new rose viruses and some have significant sytmptoms. I enjoy helping him and his grad student Dimitre by giving them roses with strange symptoms which sometimes confirm a new virus we are already working with or a new virus entirely. Patrick Cullen and others have been a part of this sending roses with odd symptoms. I help Ben and Dimitre with grafting for graft transmission studies. This involves helping to select which roses from general similar genetic background would be a good candidate to try infecting with a particular virus.

Since Ben routinely uses an electron microscope in addition to modern DNA tools that rely on virus DNA sequence, he is able to make significant progress. He takes samples with symptoms and purifies extracts to look for virus particles under the electron microscope. Based on size and shape he can get an idea of class of virus and begin using primers unique to that class of virus to try to amplify up sequence and get the sequence determined to compare it to known viruses or see if that sequence he may obtain is of a new uncharacterized virus of that class. The next thing is to demonstrate the at the symptoms are actually associated with that virus. We take roses of similar genetic background he can show do not have that virus (best of course is to also include that same cultivar if we can get our hands on it that doesn’t have that virus, but that is challenging) and do graft transmission studies to try to get the virus into one that was free of that virus. We look to see if we can find those same symptoms develop and with the introduction and confirmation of the virus. Ben also does studies to see if a virus is aphid or mite transmitted, mechanically transmitted, etc.

Antibodies can hopefully be generated then from that virus (gather up lots of tissue, purify virus, have a rabbit injected, harvest the antibodies, test if they work well, etc.) and a more simple ELISA test possible to screen for the virus. Places like UC Davis may take a rose and give it a heat treatment and eventually test and know they cleaned up some stock for a particular virus they are indexing for, but that doesn’t necessarily mean it is free of all other viruses. Heat treatment may inadvertently get rid of some other viruses along the way which is great. There are some we are working with that seem much more persistent and at particular points dramatic sytmptoms emerge, but then the plant can supress the virus again to some degree keeping it in check and without symptoms.

I think it is a great resource to have virus indexed plants for characterized, basic rose viruses known for decades and as time goes by more viruses can be included for indexing. It is great to take advantage of the best stock we possibly can for propagation and to try to keep our stock as clean as possible. The work at UC Davis and by Malcolm Manners is very valuable. Some nurseries like to say “virus-free” for the stock they build and sell from such resources, although that is not correct. It sounds good to the final consumer and is simpler to say.


Thanks David:

For better or worse I have been looking at propagating roses to sell to the local nurseries. More of a hobby business than anything. I’ve been looking at some sources, but none of them have anything to say about virus indexing, “virus free” or whatever. I’m just looking for the cleanest stock I can find as a foundation for my propagation. I have a bunch of roses that I’ve purchased here locally and I’m going under the assumption that they are infected with RMV. I understand what you said about virus free plants and that is not a reality.

Thanks for your input.


Maybe liquid nitrogen treatment followed by tissue culture regeneration will allow the science trained hybridizer to do his own virus cleaning.

I would expect that most (all?) universities have liquid nitrogen and tissue culture can sometimes (often?) be done at home ( http://www.hometissueculture.org/ ).

Link: www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TD1-4VKK6VW-1&_user=10&_coverDate=03%2F31%2F2009&_rdoc=2&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235185%232009%23999859996%23972061%23FLA%23display%23Volume)&_cdi=5185&_sort=d&_docanchor=&_ct


I tried some home tissue culture but didn’t have much luck. I’m sure you know that there are many variables that come into play. I think one of the most critical is the PPM of cytokinin. I think things like the Ph, measuring/calculating micro nutrients are other issues that I not willing to take on. Each protocol for the particular cultivar would probably need to be adjusted. I say that based on the ease/difficulty that differnt roses have when trying root cuttings. Some root easily and others not at all. Then to introduce liquid nitrogen into the equation is pushing things one step further away for me.

For me as a hobbiest, and not a chemist or other professional in life sciences, finding virus indexed stock is the most practical way to go.

To future tissue culture tryers. Instead of the link that I gave, you may find this one of more immediate use (my link on their page no longer works):


Link: www.kitchenculturekit.com/tcinfo.htm

A virus report in which Dave Zlesak is one of the authors is available at:


Link: md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=10271717&q=mollov+lockhart+zlesak&uid=788314617&setcookie=yes

Thank you Henry for the post of the abstract. Dimitre presented the work this past summer in Oregon. Since the submission of the abstract we learned more. The “damask” rose is a one time bloomer and we weren’t able to identify it very well and the best I could do was guess it may be a damask rose of some sort. Ben found it in his neighborhood in someone’s yard as he walked to and from campus. Dimitre has a number of potted plants of it and took one out of the cooler in summer and it finally bloomed! With the help of the RHA community and the forum the concensus is that it is Dr. Merkeley, a Rosa cinnomomea hybrid.

Anyways, it’s interesting that this virus was found on a number of roses in New York in a public rose garden growing in close proximity for some time (probably root grafts spread it) as well as someone’s back yard in St. Paul on Dr. Merkeley!! A lot of these “new” viruses being characterized (it’s fun to be a part of it with Ben and Dimitre) seem pretty wide spread and in multiple public rose gardens. Some are in stock of new rose cultivars. It’s amazing what is out there that we don’t necessarily think of looking for or attribute to other things as in the cases of these viruses that don’t have the typical rose mosaic virus symptoms. I know that before I was mentored by Ben and Dimitre I had more of a tendency that when I saw some yellowing I would sort of ignore it or just think it was something nutritional and hope it would go away with good fertilization practices.

Stay tuned for more virus information as time goes by!!


Hi Dave,

You commented that: “(probably root grafts spread it)”.

Davis in their published 2007 paper


used a Round-Up test which they thought showed root-grafting spread. Unfortunately Round-Up has been shown to travel from the roots of one plant through the soil and then be taken up by other plants. Are there any public domain research papers/meeting reports to support their conclusions? (I could of asked you in a private e-mail, but I do not want to put you in a position where someone later could accuse you of releasing confidental information).


That’s a very good point Henry. I don’t know off hand if there are other reports that partition out conclusively the movement of Round-Up by root grafts versus movement from one root through the soil to being picked up again by another plant’s root system. It would be worth following up on to grow a virus infected rose in close proximity (such as in the same pot) to one we know at first doesn’t have a particular virus and see if over time we can document root grafts and virus transmission. Most of these viruses are transmitted when the vascular systems of stem tissue are united by grafting. It would be great to better document root grafts in roses in general. I suspect it is just challenging since it would be difficult to carefully dig up roses and know what root is from what rose and where a graft may occur. Maybe if people had some roses in an undisturbed site for a long time, it may be easier to dig a couple up and see some heaftier grafts. Maybe there are alternative things to Round-Up worth trying that we can follow moving from one plant to the next if they are truly united by root grafts.

Thanks again for the good consideration.

Take Care,


One question is: is the underground transfer through root grafts or by nematodes. If the soil was treated by nematode poisons during an in ground experiment, that would at least remove the nematode variable.

There was a study on a different plant (orange trees)similar to your suggestion

where they did dig up the roots, but I also expect that that would be much easier to do with tree roots than rose roots.

I wonder why they did not dye the sap of the infected rose with fuchsin:


Roots grafts are much more likely with cloned rootstocks or ownroots. Higher virus occurence in the US compared to Europe where most rootstocks are seed raised is possibly related.

By the way nematods also are favored by reduced roots genetical diversity.

About virus underground contamination there were/are many studies about vitis as there are some quite nasty ones in vineyards.

1680 occurences with many pertinent ones at:


Recently, (in 2009) A University of California Davis -Ventura County article on rose virsus has appeared:


This article brings the attention back to above ground spread. I also find it interesting that it appears that they have payed attention to the U. of Minnesota recent research as they have dropped the vague/confusing term “Rose Mosaic Virus” and now simply state: “There are eleven known viruses that infect roses.”.

Hops seem to have the most thorough virus spread studies of a rose infecting virus.

"A full 2000 paper by Pethybridge et.al can be read in the link below. Note that they feel that “plant intertwining” is a contributer.

In a 2005 paper they changed the virus name from PNRSV to the closely related Apple Mosaic virus (ApMV). The abstract of this paper is at http://www.cababstractsplus.org/abstracts/Abstract.aspx?AcNo=20053143821

I have the full 2005 paper. Of interest is their efficiency of virus spread contributions (Table 4, page 141):

Pruning using scalpel blades contaminated after pruning virus-infected plants - 11%

Pruning using scalpel blades contaminated by dipping scalpel blades in inoculum -35%

Shoot contact simulated by fan - 60%

Shoot contact simulated by agitation - 23%

Root contact - 0%

Root grafting - 20%

Based on this investigation I feel that shoot contact (branches of nearby roses rubbing against each other) should be investigated. Of course, because I feel that many of these viruses are temperature sensitive, I suggest that a northern University would provide the most unambigious results.

Link: ceventura.ucdavis.edu/Coastal_Gardener/Rose_Virus.htm

Jeff, I helped Mel Hulse and two other volunteers from the San Jose Heritage Rose Garden de-bud and stick a quantity (100 sticks or so) of virus-indexed Manetti from U.C. Davis. The rootstock comes in bundles of maybe 25 8-inch long, little-finger- sized hardwood sticks that appear to have been in cold storage. Before placing the sticks (hopefully right side up) in bands of potting soil, we de-eyed them, leaving one bud eye to root at the bottom and leaving two bud eyes to sprout at the top of each stick. These were dipped in rooting hormone, stuck, and then misted and placed in a cold greenhouse over the winter. The strike rate was very high, close to 100%. The rooted rootstock was then used that season for budding. That’s the long, slow way.

If you want to use Multiflora, Steve of Wisconsin Roses sells seedling multiflora that can also be purchased in bundles of 25 for $20. That’s the immediate gratification way.

Link: wiroses.com/maiden_explanation.html


I like immediate gratification. I’m finding that with roses that is not very likely to happen.

I’ll probably order from Steve and also make a trip to UC Davis in the spring.

Jeff, I’m pretty sure you can do all your business with UC Davis over the phone.

The virus that Dave et.al. found was a caulimovirus. Is it spread by aphids on roses?

Title: The acquisition of a caulimovirus by different aphid species: comparison with a potyvirus

Published in: Annals of Applied Biology, Volume 111 Issue 3, Pages 571 - 587.

Authors: P. G. MARKHAM 1 , M. S. PINNER 1 , B. RACCAH 1 , * R. HULL 1

Authors affiliation: 1 John Innes Institute, Colney Lane, Norwich NR4 7UH

*Institute of Plant Protection, Bet Dagan, Israel.

Copyright 1987 Association of Applied Biologists

ABSTRACT: "The acquisition and transmission of cauliflower mosaic virus (CaMV) by six aphid species and three clones of aphids was studied and compared with that of turnip mosaic virus (TuMV) with Myzus persicae. Two clones of Aphis fabae were unable to transmit CaMV, but the other species, Acyrthosiphon pisum, Brevicoryne brassicae, Megoura viciae, M. persicae and Rhopalosiphum padi transmitted in a bior multi-phasic manner. There was no statistical evidence of a bimodal transmission pattern. R. padi is recorded as a vector of CaMV for the first time.

The transmission efficiency of CaMV varied with time of acquisition and suggested that accumulation of the virus occurred with two peaks of efficiency within the anterior region of the insect gut. The time at which these two peaks occurred varied between the species, but the basic pattern was common to all transmitting aphid species in this study. This pattern contrasted with that of TuMV. The transmission data are discussed in terms of bimodal transmission, the influence of feeding behaviour, the role of a helper protein associated with both TuMV and CaMV and the evidence for site specific attachment of CaMV."

Also, see the review:

“Caulimoviruses have narrow host ranges and are spread,plant-to-plant, by aphids or via propagative material, but not through seed.”


So do most of these viruses affect only roses?

I was also wondering if there is any evidence of roses having root grafts with other species of plants? I have seen this happen to a certain degree in certain trees. I would think that there might be a good change of root grafts especially with other members of the rose family like hawthorns or apples. Maybe even some things that are not related.

Regarding do the viruses that infect roses infect other plants? The following link is from 1985 so it is out of date, but it will give you an idea for PNRSV one of the more common viruses that infect roses.


Root graphs (to roses and to other plants) MAY be an important route in hot climates for temperature sensitive viruses, but Davis has still not published a definitive study on this point. (In their 2007 paper they said:

"…PNRSV and ApMV, was observed in plantings where infected and healthy roses were planted in close proximity. Translocation of the herbicide Roundup

A recent Davis full paper concerning Rose Spring Dwarf is available for general viewing:


See Table 1 for the results of their aphid spread tests.

Also, of interest is that it appeared in their virus indexed plantings:

“In this test, RSDaV was detected in many different rose species and cultivars from the Foundation Rose Collection at FPS. In all, 129 plants in this collection were tested, and 77 were positive for RSDaV. Some of the hybrid rose cultivars tested positive for RSDaV included Queen Elizabeth, China Doll, Heirloom, Lowell Thomas, Jack Frost, New Dawn, Uncle Joe, Bridal White, Butterscotch, and Cynthia. It is interesting that the virus was detected in more than 69 plants in two rows (total number of plants in these rows was 89) of the collection which were planted in the mid 1990s. In all, 162 samples of R. multiflora from the virusindexing rose blocks also were assayed in the spring and RSDaV was found in 94 plants. The majority of RT-PCR-positive R. multiflora plants were symptomatic. Another 40 additional plants from the same virus-indexing blocks were tested in the summer and 6 were positive.”

Link: apsjournals.apsnet.org/doi/pdfplus/10.1094/PDIS-92-4-0508