Not in My Garden!
by Judy Paniccia, CR
In the late spring of 2009 my rose garden looked wonderful. The blooms
were full and the roses looked healthy. This was going to be my best year
ever (of course I always say that).
After the first flush I was checking out my roses. All were fine except for the David Austin Heritage shrub. I had planted Heritage in the fall of 2005 so I knew how it should be growing. It had some distorted, red colored leaves on the new growth. The stems were quite wide, wider from the stem from which they came. When I just touched the stems they would break off. I had never seen this strange growth before.
I brought it to our rose society meeting and asked a few people what this might be. They said it could be herbicide damage caused by the spray touching the rose. I asked Bob, my gardening partner, if he sprayed for weeds. He had used Roundup, but assured me that he was very careful using the herbicide and that he was never that close to the Heritage rose.
I watched the rose and the strange growth continued throughout the summer. I then took photos and brought them to the district meeting. Several people looked at the photos and mentioned that it had some symptoms of Rose Rosette Disease or RRD. I had just read an article in the ARS about this disease. Something clicked.
On December 10th I wrote a letter to Jim LaMondia, Ph.D. at the CT Agricultural Experimental Station (CAES) in Windsor, CT. I enclosed copies of my recent rose photos and cutting samples. He called and said that my samples had some of the symptoms of RRD, but not all.
The symptoms vary from rose to rose depending on the severity of the infection and the type of rose. These are the main symptoms of Rose Rosette Disease:
1) Witches’ Broom – leaves and stems are a reddish purple growth on contorted,
smallish leaves with an irregular texture (mine had the red color and twisting,
but not as severe as he had seen).
2) A cane thicker than the cane from which it emerges which grows rapidly
(mine had this symptom). Stems that emerge from the cane may be a mass
of twigs or a form of witches’ broom.
3) Thorns/prickles that grow fast and remain soft (mine did not have this
Jim LaMondia suggested to move the rose to another area and watch it grow or take it out. The pathogen can possibly go to another rose. He said not to grow anything in the infected area for two years.
I have since done more reading about RRD. The multifloral wild rose is a host to a microscopic mite which infects the wild rose. The mite then travels on the wind to cultivated roses. Diseased multifloral roses are now found in the Mid-West, South, and parts of the Eastern U.S.
I do not know for certain if I had RRD on my Heritage rose. Currently there are no laboratory tests to confirm the presence of RRD. This spring after seeing some red leaves appear again, and knowing that it can infect the entire garden, I decided to dig it out and bag if for disposal.
Gardening with roses is always challenging. There are new pathogens always on the horizon. But for now I will enjoy my beautiful blooms while observing carefully and staying vigilant.
Photos of the Heritage rose with possible Rose Rosette