Rose rosette disease is lethal and there is no known cure. It has taken a toll on Knock Out® roses and multiflora roses, in particular. The virus is not limited to Knock Out roses, but their popularity makes them easy targets.
The virus has reached epidemic proportions in the Dallas/Fort Worth area. Unfortunately, there are a large number of infected plants and a hot, dry summer will increase the speed of its spread.
Rose rosette disease (RRD) can take up to 3 or 4 years to kill garden roses and infected plants can contaminate other rose plants in close proximity.
The disease is spread by the microscopic eriophyid mite and there are no products—chemical or biologic/organic control measures—that, as yet, have demonstrated complete success in eradicating the disease.
What about miticides?
Mite treatments are not effective since the mite is vulnerable on the surface of the plant for such a short period of time. Systemic insecticides kill mites after it has infected the plant.
How does Lambert’s control RRD?
Educate our clients about symptoms.
We are vigilant and react quickly to the appearance of RRD, to avoid the spread of the disease within our clients’ rose gardens.
• Remove and destroy of all infected plants, with the approval of the garden manager and client.
• Bag or cover and dispose of infected roses to prevent spreading the disease.
• Prior to replanting, inspect, clean and treat the soil and surrounding bed areas using: a) soil amendments – lava sand, green sand, cornmeal, compost and mulch, and b) compost tea spray.
Do the mites ever die-off?
If an RRD carrying mite infects a clean rose, the virus will die when the rose dies. The mites will die within a week of not having a live rose plant host.
Can you replant with more roses?
It depends on how much of a risk taker you are. Many are waiting until the epidemic subsides until they replant roses. Many cannot live without the beauty of roses. If we decide with our clients that it is safe to replant, Lambert’s makes sure that all parts of the infected rose are removed including the roots and we wait at least a week to replant.
Tips on keeping the disease at bay:
Stressed plants are more susceptible to disease and insects.
Keep plants healthy, nourished, and watered and drained appropriately.
Get rid of infected plants as soon as they show symptoms of RRD.
When cutting roses, it’s a good idea to disinfect pruners or scissors with rubbing alcohol or a 10% bleach solution to avoid the possibility of transmitting the virus.
Make sure that all new roses are sourced from a reputable nursery or grower.
Contact Lambert’s horticulturist and RRD specialist, Kathleen Rigodanzo at firstname.lastname@example.org for more information.