Sunday, July 21, 2013

Witches' Broom Arrives

The first words in my mind, about three weeks ago, as I discovered the potential disaster pictured to the right, was a horrible parody of Draco Malfoy in the first Harry Potter movie:  "It's true then.  Rose Rosette Disease has come to Hogwarts."  Read that statement with a really exaggerated English accent and you'll know how it sounded in my mind.  Crazy, I know, but somehow I must have neurons cross-firing between "witches' broom" and my mental images of the magical world of Hogwarts to make that connection.  And, yes, I'm a fan of the Harry Potter series, but, no, I haven't taken to calling my garden "Hogwarts."  I don't have a name for my garden.  Come to think of it, "Hogwarts" might be as good as any, but I'm guessing that Mrs. ProfessorRoush won't see the humor in it.

I digress, however, as I try to avoid the awkward subject at hand.  Although I'm not entirely 100% positive, I highly suspect that the misshapen foliage and canes show above are Rose Rosette Disease on my 'Golden Princess' rose.  I suppose there is always some faint hope that this was damage from herbicide drift, but that multi-prickled cane appearance and warped leaves are pretty damning evidence to the contrary.   The canes on this rose should look like the photo at the left, a more normal area of the bush. 

Either because of inborn psychology, or due to my veterinary medical training, I'm not one to wait around and ignore a potentially garden-fatal cancer.  I'm not Scarlett O'Hara in my garden, thinking I can worry about this tomorrow.  In my reading on Rose Rosette Disease, I know that immediate action is necessary to prevent spread to other roses.  Since I grow over 200 other roses, an epidemic of RRD is to dreadful to contemplate, a fear which also helped me take decisive action.

I immediately initiated the "one strike and you are out" philosophy used by other RRD victims.  I have chopped out every cane (yes, with an axe!) that appeared to have any disease and I included the roots of those canes, resulting in the small and normal- appearing remnant displayed to the right.  This rose has one chance, a chance possible only because it is an own root rose and I could divide it without splitting a bud union.  If it shows me any sign of RRD in the near future, then this remainder gets shovel-pruned immediately, day or night, rain or heat.  I know there is no wild multiflora rose within over 0.5 miles, so I don't know how it arrived here except in the Kansas wind, but I'm not going to baby a diseased rose in my garden.

In the interests of rose-related education, if you've never seen RRD, take a good look at that top photo.  Symptoms of RRD include excessive thorniness, leaf malformation, bright red leaf and stem pigmentation, enlarged cane diameter or elongated shoots, and "witches' broom", the latter characterized by a dense mass of leaves and stems growing from a single point.   The causal agent of RRD has recently been proven to be a negative-sense RNA virus in the genus Emaravirus (Laney AG, et al, J Gen Virology 2011:92:1727-1732), that is spread by the Rose Leaf Curl Mite (Phyllocoptes fructiplilus) mite.

One deformed leaf, and 'Golden Princess' is no more.  At least I've got another, ordered last Winter by mistake...or was it by fortuitous clairvoyant foresight?


  1. Thanks for spreading the word and educating your readership about this. Your one-strike policy is prudent ... an individual rose is not worth the potential to spread of the virus is contains.

    About wild multiflora ... remember that this is not the cause or the only source of the virus. It is just a reservoir. The virus in your garden may have drifted with the mites from garden to garden before it arrived to your rose.

    I hope you got to your Golden Princess before the virus spread to the remaining part of your plant.

    1. Thanks Connie, I know you've had your own run-ins with Rose Rosette. May our gardens be purified of this scourge....

  2. Sorry to hear that rose rosette has appeared in your garden. It's a nasty brute and has taken many roses from the Sedgwick County Extension grounds.

    1. Gaia, do you know what Extension is doing to control it?

  3. I had a case of it many years ago and tried to save the rose by cutting out the infected canes. That didn't do any good and it finally died. Thankfully it didn't spread. I've lost a handful of roses to RDD so don't panic.

  4. "Controlling the eriophyid mite that vectors rose rosette disease can be an effective deterrent in the spread of the disease, Bográn says.

    “Growers don’t have to be concerned that this mite will attack and spread the disease to other ornamental plants,” he says. “They have to be concerned about roses, in particular multiflora.”

    Three miticides (Avid, Akari and Judo) along with horticultural oil have been listed as controls in Conard-Pyle’s Rose Rosette Disease Guide.

    “We advise growers who use these miticides to rotate between the three chemicals,” Dobres says. “It is important to rotate these miticides so that the mites don’t build up resistance. These are contact controls and it is important to use them in rotation.”

    Bográn says growers should also consider testing Kontos, a systemic insecticide/miticide labeled for spider mites and other sucking insects, on greenhouse and nursery crops. It can be used as both a spray and drench application.

    “The benefit of using a systemic is that it is active in feeding sites that may not be reached by a spray application,” Bográn says. “Also, since the chemical is systemic and is taken up through the plant roots, a drench provides longer residual activity than a spray application.”

    pasted from

    and of course destroying all wild multi-flora roses in a 30 mile circular area of your garden...

    I might add you are emotionally handling this quite well. I would be in the tequila stage by now...


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