Rose Rosette Disease, RRD, has appeared in area rose gardens in recent years. It is a viral disease spread by a tiny mite, Phyllocoptes fructiphilus, which is blown in on the wind. It can only be seen by microscope. This mite is different from the spider mite that infects our roses in dry hot weather.
Symptoms of RRD include witches broom, which causes new shoots to grow out from a single location in broom-shaped clusters with elongated leaves. Leaves and stems are often burgundy-red and deformed. The new growth on many roses is red, but RRD growth will be different from normal growth. Canes may be large and fleshy with many more thorns than normal. The thorns may be soft and rubbery.
There is no cure for the virus. If only one cane is affected, it can be removed, but if the virus appears again on other canes the entire bush should be removed. It will eventually kill the bush, although it can take from a few months to several years during which time the virus may be spreading to the other healthy roses in the garden and neighborhood. The best thing to do is dig up the bush, put it in a plastic bag and discard with the garbage. Do not compost infected plants. This will only keep the virus around to spread.
RRD was introduced to kill wild multiflora roses that were used as a windbreak in the Midwest in the 1930s. The roses became invasive and the farmers needed to get rid of them. Multiflora roses are very susceptible to Rose Rosette Disease. The virus has spread over much of the country since that time, infecting ornamental as well as wild roses. Almost all roses are susceptible to the virus. Unfortunately, the highly popular and disease-resistant rose, Knockout, is very susceptible to RRD.
At its Oct. 15 meeting, the Rowan Rose Society is hosting Ann Peck, who has conducted and compiled considerable research on Rose Rosette Disease. Peck is on the advisory board for research being conducted by the University of Tennessee and will share with us the latest information available on this lethal virus. Go to a website devoted to Rose Rosette Disease — www.rosegeeks.com/index.htm — for more detailed information. The public is invited to attend the meeting that will be held at 7 p.m. in the Fellowship Hall of John Calvin Presbyterian Church, 1620 Brenner Ave. (across from the VA hospital). Light refreshments will be provided after the presentation.
Carolyn Alexander is a Cooperative Extension Master Gardener Volunteer in Rowan County and Master Consulting Rosarian certified by the American Rose Society.