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Rose Rosette Disease - Rose Virus Attacking Even Knock-Out Roses

What is Rose Rosette Disease?

Rose Rosette Disease is a disease that is fatal to roses, even Knockout Rose and Drift Rose cultivars. Rose plants that have this disease will not recover. They won’t be able to “cope” with this disease either, 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 symtoms can look like some other rose diseases that aren’t as serious, so before you begin removing affected plants it’s best to be certain your roses actually have the dreaded disease.

Here are common symptoms of Rose Rosette 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, and odd looking blooms.
  • Bunching of stems, clustering, broom like appearance of stems giving it the name of witches broom of roses.
  • Bright red leaves and stems (not always abnormal, as in many rose cultivars, fresh new growth can be 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!

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.

How can I prevent Rose Rosette, or treat what I have now?

Generally, once your rose has Rose Rosette, the only course of action is to destroy the plant and and limit any use of the soil surrounding it. 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.) 

Check with your hardware store or farmer's coop for any soil treatments for the Rose Rosette mite. The mite is extremely difficult to kill, as typical mite killing chemicals don’t often work well on this species of mite. The best course of action is prevention. When purchasing 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 you have multiflora roses growing wild nearby, consider destroying them if possible.

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 the new growth of our 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.