Photo by Jessica Walliser
We have several multiflora roses in our woods that have had signs of rose rosette disease (RRD) for the past few years. Now, sadly, one of our cultivated roses is showing signs, as well.
Thought to be caused by a virus, RRD has become prevalent in the wild multiflora rose population and is now spreading to cultivated roses, as evidenced by my own garden. Multiflora roses were introduced into the wild for erosion control and wildlife habitat beginning in the 1930s. They have since become in invasive species here in Pennsylvania, as well as in many other states. Unfortunately, they are very susceptible to RRD.
Scientists aren’t sure of the disease’s transmission vector, but they do know that the virus can be transmitted by a species of mites. The mites can readily travel on the wind from wild infected multiflora roses into your garden.
The first recognizable symptom of RRD is rapid, straight, upright rose growth in early spring. This new growth will then develop witches brooms, tight clusters of small, deformed and distorted leaves. Many times these leaf clusters are red or wine colored. If flowers do develop, they’ll also be distorted and mottled, and the stem might grow excessive numbers of thorns, as well. Infected plants often die within a few years. Unfortunately, there is no control once the virus takes hold.
Because the disease is so readily transmitted, it’s important to get rid of any infected plants as quickly as possible, something I should have done to the wild multiflora specimens on our property years ago. Infected plants should be burned or thrown into the trash. Any root pieces left behind can re-sprout; these root pieces will also contain the pathogen and can easily transmit it to other roses.
While we only have four cultivated roses on our property, for the sake of the neighbor’s roses, I plan to head out to the woods this winter and get rid of any multiflora roses I can find. No doubt, it will be a daunting task.