Tobacco Rattle Virus

[boomkweker]

Hi. I wonder if anybody here has any actual experience with TRV in Epimedium or Dicentra. How soon in the plant's life and in what weather conditions do the symptoms show up? Do they persist for long or eventually disappear? Does the disease spread to other plants nearby?

Here are TRV symptoms in Epimedium:
http://www.extension.umn.edu/yardandgarden/YGLNews/images/epimediumtrv-bel.jpg
http://www.negreenhouseupdate.info/images/stories/diseases/TRV_bd.jpg
https://mywebspace.wisc.edu/seitz/web/for%20sara%20or%20website/Tobacco%20Rattle%20Virus%20on%20Epimedium.JPG
in Dicentra:
http://hort.uwex.edu/sites/default/files/tobacco_rattle.png
https://datcpservices.wisconsin.gov/pb/artimages/dicentra.jpg
http://lclane.net/pics/bleedingheart.jpg
http://www.extension.umn.edu/yardandgarden/YGLNews/images/dicentratrv-bel.jpg
I am also interested in TRV in any other plants, in peonies, irises, anemones, daffodils, many others, but it is often not the only virus known to infect them, so there it may be more difficult to identify.

Hopefully it is not yet a problem in my garden, not to my knowledge, at least, but it looks like I should be prepared. According to http://www.perennialnursery.com/forums/viewtopic.php?f=1&t=54531, most barrenworts and bleeding hearts in the trade carry TRV.

TRV is native to Europe (and almost worldwide, but apparently it has a more restricted distribution in America), and it is not uncommon for a very large proportion of susceptible plants in cultivation to be infected. I have no idea if it is equally widespread in the wild, though.
It has an exceptionally broad host range, infecting many garden plants and native weeds. Epimedium and Dicentra can also be infected, as discovered by Ben Lockhart in 2000.
It is soil-borne and transmitted by omnipresent species of stubby-root nematodes of the genera Trichodorus and Paratrichodorus, which have a worldwide distribution and are impossible to control in the open.
Plants are reported to be rather good at defending themselves against this virus through RNA interference. Unless other unrelated viruses that are able to suppress plant defenses are present, TRV levels in the infected plant decline and the symptoms disappear, even though the plant remains a virus carrier indefinitely.
The infection is not always systemic (i.e. involving the entire plant), and some infected plants are still able to produce healthy vegetative offsets. On the other hand, if the infection becomes systemic, TRV, unlike many other viruses, can invade meristems and has a good chance of seed transmission (up to 10-40% in Viola arvensis).
This is what I know about it.

Given all that, the infection is usually relatively mild, but once in the garden, the virus is nearly impossible to eradicate, and it may well be already there. I am not entirely comfortable with the idea to just live with it, but, after all, it is probably impossible to keep plants absolutely free from viruses in the garden setting. So I am very interested in other people's experience with this sort of situation.
Thanks.

[Maggi Young]

Welcome Peter, good to have you join us.

I  believe you are correct in thinking that TRV is widespread .... both in its geographical spread and in the wide number of genera it will attack.

I have not seen it in either Epimedium or Dicentra, though I remember seeing it some time ago in a hosta collection.  The attack there was severe and the owner quickly burned all the plants and "treated " the soil in the area with several chemicals which I am sure are no longer available.... and who knows if they were even any use?

[WimB]

Hi Peter, and welcome to this forum! ("boomkweker", I guess you speak Dutch?)

I've never seen any signs of that virus in my Epimediums...but it is very possible that it is present in my garden. Have you tried asking this to the breeders of Epimedium in Europe?(Delabroye, Van Poucke, Monbaliu, Kramer, Van der Veen,...)

[boomkweker]

Thank you, Maggi and Wim.
Yes, Wim, I do, but not natively and not very fluently.
I haven't yet asked anybody else, as I've had nothing to complain about so far.
Alas, when there is something, it may be too late to research, so it may be a good idea.
But I am not persuaded that the virus is that scary, if we can do little to avoid it and the infection is relatively mild and often symptomless. Well, actually this is exactly what I am trying to find out.
By the way, I've just seen another discussion from 2009: http://www.srgc.org.uk/forum/index.php?topic=4053.0 I am not sure if the author is still active on this forum, but it would be interesting to learn about that case.
And I wonder if this virus has something to do with E. diphyllum 'Variegatum'...

[TheOnionMan]

Hello Peter,

Well, this is certainly a frightening read, I had no idea about the existance of this particular virus, and its association with Epimedium, among other plants.  I'm also puzzled by some of the information (such as with the Hallson Gardens perennialnursery.com link) making claims that almost all epimedium are infected with TRV, are such claims true?  

I have looked through the images showing the afflicted plants, and to me, they do depict plants that seem virused, with irregular leaf distortions on some but not all leaves.  With one exception (more about this, below), I have not seen anything similar on my epimediums here, but of course, now that I'm aware of the possibility of TRV, I shall be keeping a close look on my epimediums.

Regarding leaf variegation on plants, this is a familiar topic that sparks heated debate in various fora and listservs.  I am of the opinion that the leaf speckling on something like Epimedium diphyllum 'Variegatum' is not a symptom of disease, but is a quite stable variegation, the leaves always looking quite healthy, smooth to the touch, and lasting very late into December where it turns a gorgeous bronzy red color.  I have several plants of this, and they all look healthy, not at all like the leaves shown in the Epimedium TRV link:
http://www.negreenhouseupdate.info/images/stories/diseases/TRV_bd.jpg

Speckling and mottled leaf coloration is common in Epimedium, particularly in the spring flush of foliage.  One that has leaf speckling is E. youngianum 'Freckles', again which has leaves that seem smooth and healthy (not rumply or distorted from a virus), and passing along the speckled leaf characteristic to hybrid seedling plants.

Last year, I did have a plant of Epimedium grandiflorum 'Yubae' show signs of virus, with distorted "rumply" leaves, the leaf curling and distortion advancing quickly, so I dig up the plant, wrapped it in a plastic waste bag, disposed in the trash bin (dust bin).  Here's a photo of the plant, where you can see the start of some of the leaves in the lower right showing wrinkled distorted leaves. I thought I took photos showing more leaf distortion just before I disposed of the plant, can't readily find them, I shall look again.  This plant didn't show any problem in previous years, but in summer 2010 I moved the plant to the location shown here, growing very close to the household oil filling pipe, so I wondered if there might have been some contamination from oil dripped from the oil hose after getting our oil tank refilled.  But maybe, as some of the information suggests, there are different vectors for the disease, such as nematodes, maybe that was the cause?

You can be sure, I'll be watching very carefully now.

virused E. grandiflorum 'Yubae'

[boomkweker]

Thanks, Mark. I don't remember leaf distortion being listed as a sign of TRV anywhere. Couldn't that be due to a fungus, mites, foliar nematodes, weather or herbicide damage? And I don't worry about dark speckles, which is certainly an inherent trait of some species, but chlorotic mottling is another matter.

[TheOnionMan]

Thanks, Mark. I don't remember leaf distortion being listed as a sign of TRV anywhere. Couldn't that be due to a fungus, mites, foliar nematodes, weather or herbicide damage? And I don't worry about dark speckles, which is certainly an inherent trait of some species, but chlorotic mottling is another matter.

I'm not sure the cause of the virused appearance of my E. grandiflorum 'Yubae', but it certainly wasn't herbicide damage, don't use them.  Looking at photos of TRV in other plants such as Hosta, while there is chlorotic mottling, but often there are necrotic lesions and some leaf distortion, one site reports "plants infected at a young age may also exhibit a variety of leaf and stem deformities".  Here are a few links that show damaged Hosta leaves:
http://www.greenhouse.cornell.edu/pests/gallery/hostasum2.htm
http://www.ipmimages.org/images/768x512/5382292.jpg

Based on photo links you posted on epimediums with TRV, such as in:
http://www.extension.umn.edu/yardandgarden/YGLNews/images/epimediumtrv-bel.jpg
...its appearance certainly has a completely different pattern of irregular mottling, more like the start of lesions, than that of white paint-speckled variegated leaf as with E. diphyllum 'Variegatum'.  With that Epimedium, the very young leaves are heavily speckled with white spot, eventually disappearing to all green leaf as they mature, I don't think you have to wonder whether that cultivar has TRV.  Here's a photo in mid December when the leaves take on their red fall color, there is no speckling whatsoever at this late stage in the plant's growth cycle.

By the way, where did you find the photo of this cultivar that you send me in your PM to me, I can't find it any place.

[boomkweker]

By the way, where did you find the photo of this cultivar that you send me in your PM to me, I can't find it any place.

Here is it (found at http://www.srgc.org.uk/forum/index.php?topic=4769.msg155733#msg155733):

[TheOnionMan]

Thanks Peter.  The reason I couldn't find it, I had a "typo" in the species name, misspelled it "diphyllym", so naturally it was not found when I did a search on the forum (I fixed my typo).

In the photo you can see the effect I was speaking of, young leaves are heavily speckled white, more developed leaves begin losing the white spots, and by the time the leaves fully mature all spotting is gone, just the whitish leaf veins remain, quite the opposite sequence a virus attack.

[Lesley Cox]

I had that same speckling on two plants of Mertensia virginica which I bought in October '11. While wondering if a virus was involved, I also felt it could have been due to dry stress at the time. (It appeared after I bought them, not visible at buy time). They are underground now (NZ) but I'll keep a close eye when they hopefully reemerge and post pics here if there's any sign.

A question Mark, you mentioned that the red-leaved picture was sent to you in a PM. I haven't been able to add a pic to a PM. How is that done please? Or perhaps I should ask boomkweker instead.

[TheOnionMan]

A question Mark, you mentioned that the red-leaved picture was sent to you in a PM. I haven't been able to add a pic to a PM. How is that done please? Or perhaps I should ask boomkweker instead.

I wasn't sure how it was done either, but when I looked using the quote function to start a response, I see that he used the "Insert Image" command (3rd button on the left, bottom row), then pasted in the URL to a photo.

[Lesley Cox]

Oh, right, I can try that next time I need to. I'm not very good at cutting and pasting. Sometimes it works, sometimes not.

I had a look at the two pots with the Mertensia mentioned above. One has gone down completely but my finger can feel something hard under the surface so I think it's OK. The other still has some very distorted leaves, as in picture below. It was attacked badly by greenfly before I noticed and dealt to them so maybe that is cause of both the distortion and virus if it is a virus. Having taken these pic a few mins ago, I've now cut off the leaves at the surface and disposed of them but if a virus is involved, it may be too late. I'll isolate the pot anyway.

[boomkweker]

I am not good at handling pictures here at all, so I am not the right person to ask. Yes, this is how I did it, as it was the most obvious solution, but I don't even know how to resize them.

Maybe it is a healthy variegation in your case, Mark, I hope so, I just don't know enough about TRV to be sure. This is a recognized cultivar after all, though, as with some hosta and tulip cultivars, this guarantees nothing by itself. But I wouldn't expect a healthy variegation to be so irregular, and virus-induced mosaics don't always result in necrotic lesions, it depends on the virus and on the host plant. But we will never know just from pictures whether something is infected anyway.

Lesley, I am not sure. Maybe the leaves were damaged by insects, mites or fungi. What did the other side of the leaves look like? TRV is not transmitted by aphids, but there may be other viruses in Mertensia.

[Lesley Cox]

I think the back side of the leaves is OK. I can see the yellow spotting from the back but I'm seeing it through, if you see what I mean, because the leaves are quite thin. The spotting doesn't seen actually to be ON the backs.

[TheOnionMan]

So, with this dire warning raised, I'm not seeing a definitive follow through.  In the opening message of this thread, it was stated
"According to http://www.perennialnursery.com/forums/viewtopic.php?f=1&t=54531, most barrenworts and bleeding hearts in the trade carry TRV".  Peter, do you agree with that?

I have trouble with that link, as its a bold claim. I've seen little, if any, evidence of virus in Epimedium.  When one searches "Tabacco Rattle Virus host range" (which comes up as a suggested search), almost none of the many sites mention Epimedium, although there certainly are a few that do mention Epimedium and Hosta.

Do you believe that most epimedium are TRV infected?  Personally I've seen no evidence of this, and clearly re: E. diphyllum 'Variegatum' the effect whereby early spring leaves show white-spotted variegation, then those spots disappear as the leaves mature, is the complete opposite of the lesion-based increasing effects of tobacco rattle virus, why such a nebulous response back that doesn't acknowledge this opposite progression.  I believe the pursuit of E. diphyllum 'Variegatum' as a virused plant is barking up the wrong tree.  Why is Epimedium targeted here, when this virus can affect many hundreds of plants, what's the point?