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| I am posting for my mom, who is seeing something odd on a few of her Knock-Outs.
A bud forms, grows, and before it opens it sends out leaves on the bud, then they dry up and drop. She writes: "Sometimes a branch on one of the knock-out rose bushes will get flower buds that look like they are going to open up, but they start getting covered with dark red, frilly, leaf-like growths. They never do open and eventually just turn rusty and dry up. Sometimes all the branches on the bush do this. Sometimes just one or two branches do it. The branch in the picture below was the only branch on the bush that was affected. Note the fading, normal looking blooms." Any clue what is going on?
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Follow-Up Postings:
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| Early signs of RRD? I wouldn't be concerned about the red growth by itself, but the buds turning into extra leafy growth instead of opening is suspicious. On the other hand, some varieties' buds can look like this and if the thrips are really, really bad, the buds will never open. Maybe the extra leafy growth is normal and only seems so when the buds don't open? |
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| I can't tell for sure, but it looks like the leafy growth is overdeveloped sepals. I've never encountered that, but you would suspect either herbicide damage or Rose Rosette Disease. |
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| Those are overgrown sepals which on normal Knock Outs would be simple with no fringes and much smaller and green. Those roses have Rose Rosette Disease. RRD can look much worse on Knock Outs. What you've shown is a version of what I was talking about in the thread linked below. Doubtless Henry will come on to tell you that it might be herbicide. Might be. But most probably isn't or else thousands of Knockouts across the Southeastern US are getting the identical dilute dosage and getting it again and again until they die at four to six years. Your Mother should know that it's nothing she did. You live in a part of the country where Rose Rosette Disease is. Go to my e-book, read the FAQ and the information about Rosa multiflora and try to remove the disease source plants that are upwind of your Mother's roses. |
Here is a link that might be useful: Check your nearby Knock Outs.
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| I was going to say RRD. I've seen weird growth like that on RRDs around town. |
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- Posted by henry_kuska z5 OH (kuska@neo.rr.com) on Sun, May 13, 12 at 16:29
| The following may be of interest: "Steve Hutton, President of The Conard-Pyle Company, which distributes the Knockout� family of roses and many other roses including the Romantica� Collection, Star� Roses and Drift� roses in the U.S., talked to us about new, disease-resistant cultivars, the star of which is Francis Meilland�, the 2013 AARS winner. I�m testing two Star� roses in my garden this summer, �Meikanaro� a/k/a Sunshine Daydream, the 2012 AARS winner, and another cultivar I�ve yet to identify�as it came without a tag. As Steve talked, all I could think about was Rose Rosette, and how it is spreading rapid-fire throughout central Oklahoma. After he finished, I asked him his thoughts about RRD. I was encouraged that Conard-Pyle is well aware of the problem. In fact, their company is funding research through the University of Arkansas. Here is their statement which they sent me when I emailed them after I returned home from Arkansas: "Conard-Pyle is working with Dr. Ioannis E. Tzanetakis at the University of Arkansas. Conard-Pyle is really committed to combatting RRD, and continues to aggressively fund and coordinate research on many different levels with many industry professionals." ------------------------- First please note the "I" above is not me. Professor Tzanetakis is one of the "bright stars" in the plant virus world. His laboratory also reported the seed transmitted rose virus, Blackberry chlorotic ringspot virus (BCRV). |
Here is a link that might be useful: link for RRD research comment above
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- Posted by cearbhaill Zone 6b Eastern KY (My Page) on Mon, May 14, 12 at 7:13
| Thanks everyone- we were completely unaware of this disease and are now terribly saddened. It can't be herbicide anything because she has never used any- we're both old school weeders. |
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- Posted by henry_kuska z5 OH (kuska@neo.rr.com) on Tue, May 15, 12 at 17:07
| I assume that by stating that she is not using herbicide, you also mean that she was not having her lawn treated for weeds. ------------------------------- I still feel that one comment needs addressing: "But most probably isn't or else thousands of Knockouts across the Southeastern US are getting the identical dilute dosage and getting it again and again until they die at four to six years." ------------------------------- H. Kuska comment. Once glyphosate is absorbed in the soil (either from the roots of a treated weed or from "fall out of the spray that misses the weed", it can be thought of as being similar to a time release fertilizer - the rose roots can slowly take it up for an extended time period. I have given scientific references for this behavior on my web page below. |
Here is a link that might be useful: my web page about RRV
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