What is Rose Rosette Disease?
Rose Rosette Disease is a disease that is fatal to roses. It is a threat to potentially all cultivated roses, regardless of cultivar. Roses with this disease will not recover becoming ugly and misshapen by Rose Rosette in a short amount of time. The only cure for Rose Rosette Disease is prevention. Once your roses have Rose Rosette, the only option is to destroy affected plants.
What does Rose Rosette Disease Look Like?
Rose Rosette Disease can look like some other rose diseases that aren’t as serious, so before you remove any plants it’s best to be sure your roses actually have the dreaded disease.
Here are some things to look for:
- Stressed growth in leaves, canes, and blooms. This appears as growth that doesn’t look normal. Stunted, dwarfed growth in canes, narrow leaves, leaf distortion, and odd looking blooms.
- Bunching of stems, clustering, broom like appearance of stems giving it the name witches broom of roses.
- Bright red leaves and stems (not always abnormal, as many rose cultivars have fresh new growth can is red or crimson). Look for mottled coloration and redness that doesn’t go away. This growth will also appear unusual.
- Overall death and decline of the plant.
What causes Rose Rosette Disease?
Rose Rosette Disease is caused by a virus. This virus is spread by a mite that feeds on roses called eriophyid mite, or the wooly mite. These are not spider mites. They’re much smaller mites that are almost impossible to see with the naked human eye. They move on wind currents from rose to rose. It’s thought that this virus first showed up in wild, native rose populations in the US. It then spread to multiflora roses which are considered invasive, imported from Asia to serve as a plant solution for windbreaks and screens. From these invasive roses, the virus spread to infect landscape roses including the once thought to be disease resistant Knock-Out Roses series, and the Drift series.
I thought my Knock-Out Roses were resistant to disease!
The biggest feature of the Knockout Roses was that it was resistant to Rose Rosette. However with the extensive propagation of the variety, that feature has dwindled over time. Because gardeners and landscapers have relied so heavily on both the Knock-Out and Drift series of roses for their ease of care and beauty, the Rose Rosette Disease has done a lot of damage in wide areas. It’s not known why some roses still seem resistant to Rose Rosette, but it’s been shown that Knock-Out and Drift roses are not immune.
What do I need to do if my roses have the Rose Rosette disease?
- Destroy the plant - dig up plant and roots, then bag and destroy
- Limit use of the surrounding soil
- Remove multiflora roses within 100 yards of roses - if cannot then try not to plant roses downwind from the multiforas
- Watch for regrowth from any remaining roots and remove
- Avoid planting any new rose varieties back in the same soil
My ag inspector who lives down the road, stopped by recently and we talked about this rose issue. Her information said the soil where diseased plants were located could be tainted for up to 5 years.
How can I prevent Rose Rosette, or treat what I have now?
The mite is extremely difficult to kill, as typical mite killing chemicals don’t often work well on this species of mite. However, some pesticides may offer some protection such as Sevin, bifenthrin, horticultural oils and insecticidal soap when applied weekly during June and July.
The best course of action is prevention. When receiving your roses, inspect them carefully and look for the above signs of Rose Rosette. Only plant disease-free plants. When planting, give your roses plenty of room to breathe and allow air to circulate, as this can help keep the mites from spreading from one plant to another, although this isn’t very foolproof. And finally, don’t rely on one type of rose in your landscape. We’re not referring to color. Instead choose different species. If there are multiflora roses growing wild nearby, consider destroying them if possible as the mite can catch a summer breeze to your roses.
We hope this helps you avoid and end your infestation of Rose Rosette. It’s a heartbreaking disease, but with proper prevention and planning, you can avoid or diminish its effects on your garden and landscape.
Here at Greenwood Nursery, we are committed to monitoring all new growth of container roses coming in from different growers. The Knockout and Drift Rose series are anticipated to be in short supply over the next couple of years as many growers will be discontinuing their growing rights for these plants due to this terrible disease.
I will keep in conversation with my agricultural agent on this topic and update you as new or more information is revealed. In the meantime, the best prevention is to plant different rose varieties and continually search your area for multiflora rose bushes as the source of this problem.
