Rose Rosette Disease
Find out how to protect your roses from this deadly killer.
Image courtesy of Dee Nash, RedDirtRamblings.com.
There is a rose killer on the loose and the only way to fight back is often uprooting your beloved blooms.
The murderer’s name? Rose rosette disease, or RRD for short.
“There is no treatment for RRD itself other than to pull up and destroy the infected plant, including all its roots,” says National Gardening Association horticultural editor Susan Littlefield. The disease is spread by microscopic eriophyid mites, so small they are carried on the wind to plants. And if recent news stories and gardener horror stories are to be believed, the disease has proven particularly devastating this season.
Though rose rosette disease was first identified in wild rose bushes in the 1940s, this pernicious killer soon spread to susceptible multiflora roses imported from Japan says Littlefield.
Recent buzz about RRD may be due to the prevalence of Knock Out roses in home gardens. The disease is not restricted to Knock Out roses, says Littlefield, though their popularity makes them easy targets. Oklahoma garden blogger Dee Nash of reddirtramblings.com speculates that a couple of factors might explain why RRD often seems particularly fond of Knock Outs: their speed of growth, which makes the disease show up more quickly—and the fact that they are often planted so close together, allowing the disease to more easily spread.
You’ll know your plants have RRD by these telltale signs says Littlefield, “red (or yellow on hybrid teas) new growth, rapidly elongating stems, and witches’ brooms; sections of multiple stems that are thick, red, have distorted leaves, and are covered with many thorns.”
“If you are unsure about whether your rose has RRD and want a confirmed diagnosis before digging up a prize rose, contact your local Cooperative Extension Service office,” advises Littlefield. “They can tell you how to submit a sample for accurate diagnosis.”
Susan Littlefield’s Tips for Keeping RRD Away
- Stressed plants are more susceptible to disease and insects. Keep your plants healthy and watered.
- Get rid of infected plants as soon as they show symptoms of RRD.
- Don’t put the infected plants you dig up in your compost pile. Wrap them in a plastic bag and send them to a landfill with your trash or burn them.
- It may also be possible to transmit the disease from plant to plant with pruning tools, so it’s a good idea to disinfect your pruners with rubbing alcohol, a product like Lysol, or a 10% household bleach solution when you move from one plant to another as you prune. Grafting can also transmit the disease, but this isn’t something that most home gardeners do.
- When purchasing plants, buy from a reputable nursery and look over plants carefully for signs of RRD before you buy.
- Spraying for the mites regularly from late spring through the summer with a miticide labelled for eriophyid mites may reduce disease transmission, but it hasn’t been show to give consistent control.
- Wild multiflora roses are a reservoir for infection, so removing any in the vicinity of cultivated roses can help as well.