Two weeks ago at our Master Gardener training class Dr. Jim Jacobi, an Auburn pathologist, discussed the many diseases–viral and bacterial, etc. that can afflict our beloved plants. One of those that really caught my attention was Rose Rosette disease. This is not a new disease but due to the widespread use of Knockout Roses in landscapes the plant pathologists are seeing a huge rise in outbreaks of this disease. Knockout Roses appear to be very susceptible to this disease. It is spread by a mite on wild roses but the mites are finding our Knockouts and having a field day. Symptoms of RRD are witches broom on the rose stem, red pigmentation of new growth, and excessive thorns. Before you completely panic, new growth on all Knockouts is red but when you have RRD the growth stays red. Up in North Alabama hundreds of roses were taken out of a park. There is no chemical to treat this disease. The only way to rid your garden of it is to get rid of the rose–root and all. Then throw it away, do not compost it. The disease is in the branches so good hygiene is really essential when you prune your roses. Clippers should be cleaned with chlorox.
Pay careful attention to the next sentence. If you are concerned you may have RRD in your garden, do not start tearing your hair and roses out. Please take a sample down to the great folks at our Calhoun County Extension Office and let them send the sample to the pathology lab.
Here is a link to a very informative article:
PUBLICATION 450-620. Rose Rosette Disease. Chuan Hong, Extension Plant Pathologist, Hampton Roads Agricultural Research and Extension Center ...