Planting Guidance...Rose Rosette
Rose Rosette Disease Symposium Gardens of the American Rose Center
8877 Jefferson Paige Road Shreveport, LA 71119
September 28, 2018 9:00 am to 12:30 pm
Rose rosette disease confirmed in north Louisiana-
What do you need to know-
The virus is believed to be spread by tiny mites that can carry the nasty disease from bush to bush, infecting many bushes and covering much territory. The mite is named Phyllocoptes fructiphilus and the type of mite is called an eriophyid mite (wooly mite). They are not like the spider mite most of us are familiar with, as they are far smaller. Miticides used against the spider mite do not appear to be effective against this tiny wooly mite. The virus does not appear to be spread by way of dirty pruners either, but only by the tiny mites. Research indicates that the virus was first discovered in wild roses growing in the mountains of Wyoming and California in 1930. Since then it has been a case for much study at plant disease diagnostic labs. The virus has recently been placed into a group known as Emaravirus, the genus created to accommodate a virus with four ssRNA, negative sense RNA components.
Control of Rose Rosette
The highly disease resistant knockout roses seemed to be an answer for disease problems with roses. Unfortunately, even the knockout rose bushes have proven to be susceptible to the nasty Rose Rosette disease. First detected in the knockout roses in 2009 in Kentucky, the disease has continued to spread in this line of rose bushes. Due to the huge popularity of the knockout roses and the resulting mass production of them, the disease may well have found its weak link to spreading within them, as the disease is readily spread through the grafting process. Again, the virus does not appear to be able to spread by pruners that have been used to prune an infected bush and not cleaned before pruning another bush. This is not to say that one does not need to clean their pruners, as it is highly recommended to do so due to the spread of other viruses and diseases in such a manner.
How to Treat
The best thing we can do is to learn the symptoms of the disease and not buy rose bushes that have the symptoms. If we see such symptoms on rose bushes at a particular garden center or nursery, it is best to inform the proprietor of our findings in a discreet manner. Some herbicide sprays that have drifted over onto rosebush foliage can cause foliage distortion that looks very much like Rose Rosette, having the witches broom appearance and the same coloration to the foliage. The tell-tale difference is that the growth rate of the sprayed foliage and canes will not be extremely vigorous as the truly infected bush will be. Again, the best thing to do when you are certain a rose bush has the Rose Rosette virus is to remove the bush and destroy it along with the soil immediately around the infected bush, which could harbor or allow overwintering of the mites. Do not add any of the infected plant materials to your compost pile! Be vigilant for this disease and act quickly if observed in your gardens.
Read more at Gardening Know How: What Is Rose Rosette Disease: Control Of Rose Rosette And Witches Broom In Roses https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-rosette-disease.htm
Here's an excellent article on the recent discoveries in Louisiana.
Shreveport Times News Article – Rose Rosette in Shreveport and Bossier (August 2018)
Here's an excellent information sheet from LSU:
Early Symptoms of Rose Rosette Disease:
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