Seeds and RRV

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matt lustig
Posts: 43
Joined: Sat Jan 28, 2017 10:05 pm

Seeds and RRV

Post: # 72168Post matt lustig
Wed Sep 30, 2020 9:47 pm

If I recall correctly, I believe that rose rosette virus is rarely (if ever) transmitted via seeds. Can anyone confirm whether this is correct? I recently had to rouge (based upon suspected RRV) a variety that I had wanted to use in breeding, and I hope to at least plant the seeds that I harvested from the plant before throwing it on the burn pile.

Thank you in advance for any helpful input.

Sincerely,
Matt Lustig

MidAtlas
Posts: 57
Joined: Mon Jan 28, 2013 8:49 pm

Re: Seeds and RRV

Post: # 72169Post MidAtlas
Wed Sep 30, 2020 10:15 pm

I can't speak to seed transmission without hunting down whatever literature might exist, but it seems unlikely that it would happen at a very high rate if it happens at all. However, if you are raising your seedlings indoors, you would probably have ample time to detect RRD and destroy any suspicious individuals before they are ready to go outside where they would be exposed to the eriophyid mites that could then transmit the disease to healthy plants. It might even cause seedling mortality fairly quickly. In addition, any small seedlings that did happen to be infected wouldn't have much surface area for mites to land on, certainly nothing comparable to the larger infected roses around that are already putting your garden roses at regular risk anyway.

I don't think there are any reasons not to germinate those seeds.

Stefan

henry kuska
Posts: 1047
Joined: Thu Dec 15, 2011 9:06 pm

Re: Seeds and RRV

Post: # 72170Post henry kuska
Thu Oct 01, 2020 12:40 am

Interesting question. Perhaps your experience could contribute to the science,

pacificjade
Posts: 746
Joined: Sat Dec 17, 2011 12:15 am

Re: Seeds and RRV

Post: # 72179Post pacificjade
Sat Oct 03, 2020 9:16 am

I don't recall it being an issue, but still....

I'd nuke it to high heaven :] But that's me.

Its the #1 thing that threatens rose culture as we know it, in strong competition with the ARS doing a poor job at attracting millennials, and now zoomers, to our culture.

MidAtlas
Posts: 57
Joined: Mon Jan 28, 2013 8:49 pm

Re: Seeds and RRV

Post: # 72180Post MidAtlas
Sat Oct 03, 2020 1:41 pm

I'd still consider fungal disease--especially black spot--to be a far more serious problem for garden rose culture (and attracting new rose lovers) overall, for a variety of reasons. A major challenge with Rose Rosette lies with humans rather than roses, in that whenever varieties were introduced that reliably avoided serious fungal diseases, they soon became the darlings of landscapers for mass "low-maintenance" plantings that are highly conducive to RRV establishment and spread. Those were often managed by people who didn't recognize and/or deal with the RRV-infected plants, and then they became sources of further infection across the landscape. Of course, there are also still problems where large feral R. multiflora populations continue to exist.

If a rose in a typical home garden contracts RRV and it has to be discarded, the gardener can plant the same variety again and it won't necessarily be doomed to the same fate (unless there is tremendous disease pressure around, which may be a self-limiting phenomenon over time). If a rose in a garden fails because of, say, black spot, that particular variety really should be avoided altogether unless the gardener is willing to put it on permanent chemical life support. For those hoping to enjoy roses without needing to spray them against fungal diseases, I think that uncertainty over the actual disease resistance of new varieties coming onto the market has had a cumulative chilling effect. The fact is, the "big rose" industry has always done an exceptionally poor job of testing and evaluating new varieties before introducing them, and their exploitative marketing efforts have made exaggerated claims of disease resistance for so many varieties that it is difficult to trust what they say. Some of those chickens are simply coming home to roost.

RRV is a bigger problem for industry rose producers in areas prone to the disease, at least where they are being field-grown, since they have fewer ways to completely avoid initial infection and spread--but at least they can develop tools and workflows to help minimize that, and consumers will only perceive the difference as a price tag increase.

Stefan
Last edited by MidAtlas on Sat Oct 03, 2020 10:46 pm, edited 2 times in total.

Larry Davis
Posts: 435
Joined: Fri Jan 10, 2014 5:37 pm
Location: Kansas

Re: Seeds and RRV

Post: # 72181Post Larry Davis
Sat Oct 03, 2020 7:33 pm

Several years ago (fall 2016) I went and deliberately harvested all the hips I could from a big bed of DKO roses badly infected with RRD. I stratified them in the usual way with 10 mM calcium nitrate, and potted up whatever seedlings were able to germinate. I never saw a sign of RRD amongst the seedlings that bloomed. I did not keep them more than a few months because I wasn't interested in the color of the flowers. I had enough seeds to set up 3 pkts of 104 sd each. I got 33, 41 and 40 germinations from those 3 pkts. Not bad for that CV. The hips were collected Sep 24 as those appearing ripe. The sproutlings were potted up Dec 29 and Jan 29 with exactly 50 on each date.The remainder showed up in March.

Of course this tells you nothing about other CVs or other years. But it looks good enough that I'm not going to worry.

pacificjade
Posts: 746
Joined: Sat Dec 17, 2011 12:15 am

Re: Seeds and RRV

Post: # 72182Post pacificjade
Sat Oct 03, 2020 11:50 pm

Hi, Stefan,

I disagree, and this is why: RRD can wipe out an entire wholesale nursery and their reputation. Black spot cannot. RRD can force wholesalers to never consider one of us as viable, as well. Similar can be said about mom and pop rose businesses that drive our niche, personalized markets. It is legitimately a direct threat to our culture.

Our beautiful culture needs to exist for way beyond our lifetimes.

roseseek
Posts: 5162
Joined: Sun Dec 11, 2011 6:54 pm
Location: Zone 9b Central California, Sunset Zone 15

Re: Seeds and RRV

Post: # 72184Post roseseek
Sun Oct 04, 2020 3:36 pm

Stefan, nearly all US commercial rose producers have sent out stock infected with downy mildew, black spot, mildew and rust and lived through it. Week's Roses brought RRD into their fields in Wasco and it resulted in MANY wholesale customers cancelling their orders. It also resulted in many retail customers completely avoiding Week's products and their varieties offered through second party vendors. I favored Week's for decades as they produced GORGEOUS plants. In this current permutation, not having anything to do with "Week's Roses" other than name, I won't buy anything they produce. I don't trust them. They have done unforgivably stupid, careless things to endanger their commercial product and expose the rose growing public to RRD.
Kim
California Central Coast
USDA Zone 9b
Sunset Zone 15
Cooler inland coastal valley with strong marine influence

MidAtlas
Posts: 57
Joined: Mon Jan 28, 2013 8:49 pm

Re: Seeds and RRV

Post: # 72185Post MidAtlas
Mon Oct 05, 2020 1:06 am

While I noted producers' struggles with RRV in my last paragraph above, I don't see a direct link between those problems that any eastern U.S. nurseries above the Deep South may have experienced, or might experience in the future, and the overall decline in rose growing and appreciation. Trends specifically among younger generations will certainly have much more complex causes, and I can't imagine that RRV is very high among them (they have to want and be able to afford homes with gardens, and they have to want and be able to spend time gardening, before roses will really even enter into the equation at all). Getting back to nurseries, though, those in our region will either find ways to adapt and gain/retain their customers' trust or potentially fail. Businesses come and go, and there will still be growers in areas where RRV is not widespread and probably never will be.

Nurseries sending out roses with active fungal infections was never really considered to be such a major issue, but then, those are somewhat less acutely menacing (depending on the disease and location) and have labeled treatments available for people willing to use them. I was only talking about the seemingly endless parade of new roses whose catalog descriptions extol their natural disease resistance when they really aren't adequately tested and proven. The cynic in me would find it completely unsurprising to see RRV being used as yet another excuse for rose producers to continue engaging in that sort of marketing practice. We may have already seen a preview with the introduction of Top Gun, which is now being reported infected with RRV in gardens. Is it time for its new and improved replacement to hit the catalogs? Why should anyone believe them when it does?

Trust me, I do believe that RRV is a serious problem, and breeders should be encouraged to take advantage of any knowledge about sources of resistance to the mite or RRV transmission (as I understand it, no rose has proven to be resistant to the virus, once truly exposed) to inform crosses and selection measures. There needs to be more science done to produce that knowledge. However, anything like a cure is a pipe dream at this point, and small-scale breeders have no way of proving resistance. I think that raising seedlings from an infected plant in an area where the virus is already endemic is almost certainly not going to do any harm, and might just do a little good.

Stefan

pacificjade
Posts: 746
Joined: Sat Dec 17, 2011 12:15 am

Re: Seeds and RRV

Post: # 72188Post pacificjade
Tue Oct 06, 2020 5:16 am

It's not a pipe dream. Members like David work very hard at researching it.

Anyway, the moral for members is that if a wholesaler or private nursery reads on any of these medias that a breeder has touched this stuff, they simply will give a hard no to working with the breeder. I don't want people to work hard on their projects only to be told to get lost. As someone that lives in the PNW, I have less access to roses than most of the people here. I cannot buy from half of the Amazon vendors, for example, because these states want to remain clean. If something like RRV makes it to the PNW, its hurts our economy.

So do what y'all want. It's a free country, but be forewarned that it can harm your potential to have an introduction.

roseseek
Posts: 5162
Joined: Sun Dec 11, 2011 6:54 pm
Location: Zone 9b Central California, Sunset Zone 15

Re: Seeds and RRV

Post: # 72189Post roseseek
Tue Oct 06, 2020 1:07 pm

Certified Roses doesn't want to touch anything from anyone in any state with RRD. That eliminates a whole lot of market potential.
Kim
California Central Coast
USDA Zone 9b
Sunset Zone 15
Cooler inland coastal valley with strong marine influence

MidAtlas
Posts: 57
Joined: Mon Jan 28, 2013 8:49 pm

Re: Seeds and RRV

Post: # 72190Post MidAtlas
Fri Oct 09, 2020 9:48 pm

Not that research alone causes something to be any less of a pipe dream (see time travel and telekinesis), but I'm pretty sure that folks aren't actually researching a cure for this. Consider for a moment just how curable every other plant virus in the world has proven to be; there is simply no working model for that. No, they're mainly trying to understand this problem better so they can find ways to prevent, detect, minimize, and mitigate infection on a rather more limited scale. That's all.

I suspect from the original question that the breeder in question lives in an RRV-infested state, like many of us here do; in any case, the parent plant already had the virus, so he has already had to "touch this stuff" like many of the rest of us in the East must do on a routine basis. What one does (up to and including the usual removal and destruction infected material) has virtually no bearing on the likelihood of another infection, and another, and another. It blows in on the wind; the disease vector can travel for many miles, and the reservoir of infected feral populations and poorly tended rose plantings is still vast. The small experiment we're discussing here clearly doesn't elevate risk above baseline, and doesn't warrant this sort of fear-mongering and aspersions-casting. Risk of RRV infection is an ever-present reality in areas where the virus spreads naturally, period. Hopefully there is still a chance to keep the virus out of Oregon if it really hasn't made it there already (though it was documented from California from the very beginning, and is considered to be present in counties bordering Oregon now).

Certified Roses must have greenhouses that isolate their stock from disease-carrying eriophyid mites, because their county (and nearby counties) has had PCR-confirmed cases of RRV. In such a setting, it should also be possible to quarantine new propagation stock and determine if it is infected (visible RRD symptoms are generally evident within a short period after infection and are strongly linked with virus-positive status), so those growers and others like them should not be blacklisting breeders from states with RRV for too much longer, if they actually do that. It's one thing to avoid nursery stock from growers whose material is demonstrably at risk for infection, but quite another to avoid small volumes of propagation stock when there are ways to assess and mitigate risk in those situations.

tsilvers
Posts: 249
Joined: Sun Dec 18, 2011 11:39 am

Re: Seeds and RRV

Post: # 72196Post tsilvers
Sun Oct 11, 2020 8:09 pm

Hey Matt, as another small piece of evidence supporting planting those seeds... when my F1 ('Fragrant Cloud' x carolina) contracted RRD, I did a "Hail Mary" cross on it the season before it died. I used 'Commander Gillette' pollen on the last few flowers and from the resulting hips, germinated 5 or 6 seedlings. I've never seen any signs of RRD on any of these and the 3 strongest ones have matured and flowered for several years now. I'm not suggesting that they are resistant but they definitely don't seem to have gotten RRD congenitally from their mother (who was severely infected when the seeds that grew them were set).

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