Please help!! Is this rose rosette?!?

RNadlerJuly 8, 2014

Hello, new the the forum and also new to gardening. I planted 2 knockout roses about 30 feet apart last spring. They looked GREAT last year, and also looked good this spring but that has changed. I pruned them back in early June and over the last month I've noticed these weird growths on the 1 of the plants. The growths are sprouting VERY quickly. Not sure if they are normal, or the dreaded rose rosette. If is is rose rosette id like to dig these up ASAP and replace them with something else. Maybe it's just healthy growth, but the speed they are growing and weird leaves along with an abundance of thorns on the shoots is scaring me. The other rose is still very small with no growths like the one pictured. Any help is greatly appreciated!!

This post was edited by RNadler on Tue, Jul 8, 14 at 20:26

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RNadler

Additional pic

    Bookmark   July 8, 2014 at 8:24PM
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RNadler

Additional pic 1

    Bookmark   July 8, 2014 at 8:25PM
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RNadler

Additional pic 2

    Bookmark   July 8, 2014 at 8:27PM
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anntn6b(z6b TN)

Yes, based on a couple of things: the hyperthorny new cane. The really overly long and frilly sepals on the new buds. The fact that the new buds are singles, when darned near every Knock Out that's healthy grows small bouquets that come out at once.

I think that there are also a lot of asymmetric leaves, and growth that just is totally different than KO usually produces , which is a spray of blooms, and then, as those blooms are finishing, THEN and not before, new growth emerges farther down the cane in a single spurt from one leaf axil, NOT from almost all leaf axils and those before the terminal bud has even opened.

    Bookmark   July 8, 2014 at 9:17PM
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johnnycabot(Z4b MI.)

Looks like wonderful normal growth to me! Did you give it some type of whopper food? Whew!

    Bookmark   July 8, 2014 at 9:25PM
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RNadler

Not what I was hoping to hear=(. Should I bite the bullet and dig them up before it progresses any further??

    Bookmark   July 8, 2014 at 9:25PM
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anntn6b(z6b TN)

Johnnycabot, do you grow Knock Out? Do you know what Rose Rosette Disease is?

Do you understand how the new growth here is different from what it should be?

Rose Rosette is a disease of excessive, aberrant and unexpected growth.

If that were my rose, I would dig it up after putting a bag over the whole bush and tieing it tight around the base.

    Bookmark   July 8, 2014 at 9:52PM
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RNadler

I'm assuming I should plant something besides knockouts in its place?

    Bookmark   July 8, 2014 at 10:20PM
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johnnycabot(Z4b MI.)

Have not seen it here but learning about it upon reading this thread. Have one KO that had been pruned way down due to winter kill and she came back in many strong red sprouts. I fed her and she grew so much so fast, blooming her head off. Shes beautiful but frankly don't remember her begining buds. Will examine my shrub for future. I am reading they need to be a spray of buds but not a cluster like a witches broom. I see RN's buds are single as you point out but can't those buds be premature development? Learning here, Thank you Ann.

    Bookmark   July 8, 2014 at 10:25PM
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tigerloveroses

The canes are green.in rrd they would be red.i think its normal new growth for ko.

    Bookmark   July 9, 2014 at 12:07AM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

Ann is an expert on RRD, literally :) I'd trust her simply due to that.

But (I say as a non-expert!) those sepals are just tooooo whacky anyway, right? I mean that's very weird looking for a rose whose buds don't look like that. I'd not take any chances. That's weird growth, imho, if you look closely. I'm so glad you did. It does also look a lot like new growth can look, I think. What a weird one!

    Bookmark   July 9, 2014 at 12:37AM
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dublinbay z6 (KS)

I must admit that this type of excessive growth always puzzles me. It seems to be "too much" (as in RRD), but not into the "uglies" as I call the typical growth I associate with RRD. I had a case like this along my neighbor's property line and never could decide if it was RRD or damage from something like Round Up (which I do know my neighbor sometimes uses). After several months of dithering back and forth, I decided to treat it as RRD and dig it up (that section was a bit too crowded anyway). While I'm glad I dont' need to worry about it now, I can't really say for sure whether that was RRD or not. I guess I finally found peace by embracing "better safe than sorry."

As to what you replant there, I don't think it makes any difference, as long as it is healthy. Remember that the disease RRD is spread by microscopic mites blown around by the wind. Of course, to be on the safe side, I'd probably make extra sure I got out all the roots when I dug it up, but if those symptoms are fairly recent in origin, I doubt the whole bush could be infected yet.

I urge you to listen closely to Ann on this subject. She is the expert.

If it is any consolation, I've had to take out one rose bush per year for the past several years--due to RRD or what was suspected to be RRD although I was never completely sure that is what it was. Like I said, I'd rather be safe than sorry when it comes to my other roses--don't want any mites being blown around on the other ones, do I!

Kate.

    Bookmark   July 9, 2014 at 5:58AM
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buford(7 NE GA)

Looking at the pictures superficially, it looked like just new growth. But something was 'off'. I'm not an expert, Ann is and pointed out exactly what was wrong.

KOs are a dime a dozen so dig it up and bag it and throw it in the trash. And observe any other roses you have for signs of RRD.

    Bookmark   July 9, 2014 at 6:32AM
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holleygarden Zone 8, East Texas

Oh, man, I hate to say anything, since Ann IS the expert. But my Knock Outs look exactly like that. And always have. Yes, same frilly sepals, seemingly much too long for the bud. Although they look odd, they are normal for Knock Outs. (I've watched my Knock Outs for years do that.) New canes that are excessively thorny (ouch!), but grow out to be just very thorny canes (one reason I hate to prune my Knock Outs). Normal for my Knock Outs, too. Every picture looks exactly the way my Knock Outs grow, and they have no RRV.

Perhaps the hot weather affects their growth this way? I know I freaked a little when I saw this on my own Knock Outs after reading about the long sepals being a sign of RRV. But after years of close observance of my Knock Outs, I realized they just grow this way.

And, no, I have never actually seen RRV, so I admit I could be wrong, but if it were me, I would look for the witches' broom growth, or the canes that never stiffen and mature.

Of course, the easiest thing it to dig it up just to have peace of mind. But I would hate for everyone to dig up their Knock Outs based on these frilly, long sepals that are probably indicative of RRV in most roses, but are what I have seen for years as normal growth in my Knock Outs.

    Bookmark   July 9, 2014 at 8:58AM
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anntn6b(z6b TN)

Holley, what do the margins of your leaves look like? Third photo down, the leaf margins are not the same as the original leaves.

Do your canes put up sprays or singles? Does new growth emerge along the canes before the terminal bloom(s) open?

I've always said that I want three symptoms before declaring a problem. This bush has at least five.

    Bookmark   July 9, 2014 at 9:53AM
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Desertgarden- NW Las Vegas Z9a @ 2300 f

Is there a website that has definitive images of what to look for in diagnosing RRD that can be used for reference? Not being an expert can make things difficult when you want to be a responsible rose grower, protect the roses around you from this mite, but not fool-heartedly toss a rose that could be fine

I have two roses in my yard that I am concerned about now, and we have no multiflora growing wild, or cases of RRD that I know of, so one distinct possibility could be that those mites could arrive via ordered roses from a place that does, if they could even survive shipping? I know the roses could have been hit by pesticide spray for bugs and cannot find images regarding what that even looks like.

It would be great if there is a close to definitive guide that roses growers can use for such a plague.

I have been curious, is this mite resistant to miticide? I know if it has feasted on the rose , it's a goner, but can the mite be killed by traditional methods?

Sorry to hijack the thread but Ann is listening so to speak.... I hope...

Lynn

    Bookmark   July 9, 2014 at 10:38AM
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RNadler

Is it any regard that I DID douce these roses in Sevin at the beginning of the summer, and before these symptoms started??

    Bookmark   July 9, 2014 at 11:03AM
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anntn6b(z6b TN)

Lynn and all,

The problem with coming up with a definitive guide is that symptoms change as a rose gets sicker (presumed higher virus titer), symptoms change with time of year, symptoms are different for different cultivars. This makes for a miserable voyage we've been on trying to warn rose growers.

This is why I came up with the three adjectives to define when something goes wrong. So many other diseases are easy to define.

So often a rose grower sees something and knows instinctively that it's wrong. Black spot is easy to note.
Downey mildew isn't anywhere as easy to define, but with a microscope sometimes DM shows up as mycelia on the underside of infected leaves. RRD goes wrong on the cellular level, so we see something, but putting it into words is a lot harder. Even the change in color...sometimes and some species that reddish-purple color doesn't happen at all, and then there's a floribunda we found that was solid reddish-purple....the whole bush including leaves, stems and sepals, but the petals were normal pink.

Easy questions: no miticides have been proven 100% effective. The mite feeds and spreads the disease assuming that it has previously fed on an infected rose. Some female mites 'float pregnant' and don't need a male to make more mites. To make a rose a toxic substrate for the mites, the miticide would have to be in the cells of the rose and within the vascular system and the information about the translocation of any -cides within plants is precious hard to come by.

How long does a mite feed to spread RRD? Don't know. But the only study of a similar disease with a very similar vector is of a peach disease in California and Mexico. There published results indicated that the disease could be spread in as little as 15 minutes feeding time.

If you haven't, you might want to spend some time on my e-book. We haven't updated it with molecular reports, but it does represent a decade's work trying to summarize the published literature (big biography there) as well as a bunch of pictures.

And, RRD/RRV continues to spread, now getting into New England and moving south more slowly.

Here is a link that might be useful: Rose Rosette E-book

    Bookmark   July 9, 2014 at 11:15AM
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anntn6b(z6b TN)

Sevin didn't do this. your problem is at a cellular level and even molecular.

    Bookmark   July 9, 2014 at 11:21AM
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Desertgarden- NW Las Vegas Z9a @ 2300 f

Ann

Thank you for the link.

Lynn

    Bookmark   July 9, 2014 at 4:06PM
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Michaela .:. thegarden@902 .:. (Zone 5b - Iowa)

I am definitely no expert but I have a 2nd year KO in my yard that has been growing very quickly and it does not look like this. The tall canes and lack of leaves does not look normal to me.

I'm sure you can plant KOs again but I personally am NOT impressed with mine. I purchased it last year because lets be honest, they're everywhere and I thought that meant they were wonderful roses but I have been underwhelmed with mine. I may shovel prune mine next spring.

    Bookmark   July 9, 2014 at 4:16PM
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holleygarden Zone 8, East Texas

Ann, thanks for asking me questions. I want to learn, too, and appreciate your expertise. I am posting a few photos that I took this afternoon of my Knock Outs. On the last two, the growth is not as red as it is in spring. These photos were all taken from different bushes.

    Bookmark   July 9, 2014 at 4:42PM
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johnnycabot(Z4b MI.)

Perhaps it is the explosion of growth seen in RN's photo that seemed weird. It told us to wake up and notice, watch, to learn what in the world is going on here (?) and educate ourselves as to/ if action, what? is required to further maintain our healthy garden. How lucky we are to have every level of active gardener here to chime in with ideas, experiences to help with a given problem. Thank you for the insight Ann and link to E Book on Rosette Ds.
RN; Hope you do not have to dispose of your KO rose. Let us know what you see and what you decide, i would not even be able to dig out my 4 yr old shrub on my own. ACK.

    Bookmark   July 9, 2014 at 5:18PM
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dublinbay z6 (KS)

Holly, those pics all look like healthy growing roses to me.

Anyone else have an opinion about Holly's pics?

Kate

    Bookmark   July 9, 2014 at 7:24PM
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anntn6b(z6b TN)

Holly's first picture is really interesting. Look at the bud in the background on the right, and how short its sepals are. Then compare with the 'overgrown' ones on the left.

I think her bush is ok, but I hope she'll watch it closely for a couple of years and hopefully not see any of the stuff below:

In my part of the country there are a lot of KOs with both healthy and sickening growth. The sickening growth is much more severe that Holly's rose. Right now, Holly's blooms are just a bit overgrown.

Now, things to watch for after that almost one symptom:
Leaves on those canes a different shade of green than the leaves on the small sepaled canes.
Different timing of bloom on the two different canes (RRD happens faster).
Different colored petals on the blooms -RRD has a different color than normal KOs.
Canes that put out so much new growth of the un-good kind that the cane bends downward, sometimes touching the ground, other times the timing of the overloaded cane is so fast, that the blooms almost look like a candelabra.
Blooms that start missing sexual parts (recepticles).
Blooms that look like everything is going to be great, and then none open.
And when sicker, blooms that are so massed that they remind me of a southern (white) magnolia cone.
Then there are the canes were one side is sicker than the other and the canes grow in spirals.

As I said, symptoms vary, and when things start going wrong, they go really wrong.

I wish that somewhere, some KOs would show up that can resist the infection or minimize it. I know that there are proposals to do genetic modifications. But with the number of KOs out there, maybe some genes have found their own way?

    Bookmark   July 9, 2014 at 7:48PM
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meredith_e Z7b, Piedmont of NC, 1000' elevation

Maybe KO really does just have funky sepals sometimes as far as the sepal part goes? I don't grow him, so I don't know what's normal. They look strange to me, lol :D

    Bookmark   July 9, 2014 at 7:48PM
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henry_kuska

There is also the question as to whether Knock Out roses that have another virus infection are more susceptible to Rose Rosette Virus than clean Knock Outs.

    Bookmark   July 9, 2014 at 8:32PM
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poorbutroserich(Nashville 7a)

Ann, I appreciate your hard work and efforts to research RRV and share your learning with us.
Thank you!
Susan

    Bookmark   July 9, 2014 at 8:38PM
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holleygarden Zone 8, East Texas

Just to clarify, my pictures are of *normal* Knock Out rose growth. (Unless, as Henry alluded to, they have another virus of some sort.) This is the way my KOs have grown for almost 10 years. I was trying to show that my KO's normal growth looks very much (to me) like RNadler's.

I was really interested in learning how Ann could look at RNadler's pics and know it was RRV, when my KOs act very similar, and do not have RRV. I am obviously missing something very small, but important. I can usually see the symptoms on the pics people show, but RNadler's four original pics look no different (to me) than my KOs normal growth. The only pic that looks a little odd to me of the four pictures of RN's is pic 1, and even then, I wouldn't immediately think of RRV.

    Bookmark   July 9, 2014 at 10:13PM
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anntn6b(z6b TN)

Holley,
Your roses grow as mounds. RN's are putting up single canes (almost Hybrid Tea like) and they are very long, much longer than KOs ususally put out for their second growth.

Look at the margins of the leaves. They are irregular and that isn't normal.

THen look at where the new growth emerges. New growth on KOs comes AFTER the spray of blooms is almost totally gone and you can see the hips without petals (which have been dropped).

Now please look at RN's photos for these things. You'll see a distinct lack of multiple buds at the end of that cane. You have at least five buds on the growth you showed us. KOs have to make multiple buds- it's part and parcel of how they are. And all those breaks at every leaf axil. That is so abnormal for KO. All that new growth just isn't the way that KO grows.

I hope this helps. I've posted a lot here and maybe a slow read through it might help.

    Bookmark   July 9, 2014 at 10:33PM
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holleygarden Zone 8, East Texas

Thanks, Ann, for clarifying. I am used to seeing the odd growth of witches' broom in pics, but these symptoms are a bit more subtle, so I appreciate you taking the time to answer my question. I know everyone on this forum appreciates your expertise.

    Bookmark   July 9, 2014 at 10:54PM
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henry_kuska

Ann attempted to describe the problems involved in trying to identify if a rose is infected with rose rosette virus. Another way of appreciating this is too see what percentage of plants that appear to have rose rosette virus infections actually are infected:

"Rose Rosette Disease, otherwise known as Rose Rosette Virus, is an ever increasing problem in Texas, particularly in the Dallas-Ft. Worth area. In 2013, the Texas Plant Disease Diagnostic Lab received thirty-one symptomatic samples of different rose varieties that were tested for Rose Rosette Virus. Of those thirty-one samples, ten returned with positives finds."

The above quote is from the following 2014 paper presented at a meeting.:

Title: "Attempts in extracting RNA from eriophyid mites in search for Rose Rosette Virus"
Authors: A. BRAKE (1), M. Giesbrecht (2), K. Ong (2)
(1) Texas A&M University, College Station, TX, U.S.A.; (2) Texas A&M AgriLife Extension Service, College Station, TX, U.S.A.
Abstracts published: Phytopathology 104(Suppl. 2):S2.2

Here is a link that might be useful: link for above meeting paper abstract

    Bookmark   July 10, 2014 at 12:21AM
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anntn6b(z6b TN)

Henry,
Interesting catch, I wonder if they kept track of where on the rose the mites were recovered.
Also take a look at page 11 of the abstracts and the abst on wheat streak mosaic. Dr. Jensen, now retired, told me a decade ago to watch what scientists found about diseases related to RRD as there would never be heavy funding for RRD research. His involvement was with WSM.

    Bookmark   July 10, 2014 at 9:00AM
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