THE SCOTT ARBORETUM’s Garden Seeds

Rose Rosette Disease

Becky Robert July 15, 2009

If you have visited the Dean Bond Rose Garden this growing season, you may have noticed a large section of the climbing and hybrid tea beds now contains marigolds, Tagetes patula cultivars, instead of roses. This April we removed about 17 rose shrubs because they were infected with Rose Rosette Disease (RRD).

RRD was first observed by a local gardener and Scott Associate, Judy Penney, on her climbing rose in Swarthmore. The disease has since devastated her once prolific rose and symptoms have begun to appear in the Dean Bond Rose Garden.

Symptoms

Symptoms of RRD are highly variable depending on the species and cultivar of rose. These symptoms include: rapid elongation of new shoot; witches’ brooms with small, distorted leaves; excessive growth of unusually soft and pliable red or green thorns; canes that appear thicker than parent canes; and new growth’s traditional red pigmentation never matures to a green tone. To see a complete list of symptoms read the Plant Disease Fact Sheet from Virginia Cooperative Extension. In the Rose Garden, we have observed witches’ brooms with small, distorted leaves and conspicuous red pigmentation as well as rapid elongation of shoots with excessive thorniness.

Caused

RRD is believed to be caused by a virus originally introduced to control the invasive Rosa multiflora. While this virus is effective at overwhelming R. multiflora, cultivated roses are also highly susceptible to it. The disease is transmitted by a microscopic wingless mite, Phyllocoptes fructiphylus, or by grafting. These mites are known to travel on wind currents from infected to healthy plants.

Control

At this time there is no effective control available for infected plants. It is recommended to remove all infected plants to prevent transmission to healthy specimens. The pathogen can survive on old root pieces in the soil, thus be sure to thoroughly remove all parts of the infected plants. Where permitted, burning can be used as removal technique. Once uprooted be sure to remove infected plants from the vicinity of remaining healthy roses. At this time no resistant species or cultivars have been identified.

Because there is no direct treatment for the virus, we are attempting to control the carrier of the disease, the microscopic wingless mite. We are applying a miticide, Avid, along with other treatments on the garden.

Historically, marigolds have been used in vegetable gardens to help mitigate the effects of many problematic pests. In England, marigolds have also been planted in rose beds where roses have been removed to help reduce the effects of Rose Replant Disease, which is another problem in the Dean Bond Rose Garden. It is our hope that the marigolds will ward off the mites. Thus we have planted Tagetes ‘First Lady’, ‘Inca Orange’, and ‘Sweet Cream’ in an attempt control RRD.

Other efforts include sterilizing pruners between pruning and deadheading as well as monitoring and removing any newly infected plants.

This fall the marigolds will be removed and the bed will be replanted with roses. Check back with GardenSeeds to see which species and cultivars we will reintroduce to this location of the Rose Garden.

Comments RSS

1. Barbara Shaw July 15, 2009 at 12:24 pm

   I’m glad the blog is up and running again. Thanks for the rose info!

2. Becky Robert July 15, 2009 at 12:29 pm

   Thank you, Barb. We have fixed some of the access problems. We are working on some the problem with calendar and lower menu bar. We hope to have it back to 100% soon.

   Thanks for continuing to read.

3. Susan Washburn July 23, 2009 at 10:20 am

   I was happy to find this after diagnosing a client’s RRD. Please post the cultivars you chose to replant with and their progress. RRD has quickly killed a 15yr.old White Dawn climber and my devastated client would like to replant if possible.

4. Becky Robert July 23, 2009 at 10:29 am

   I will post as soon as our collection committee decides which roses to try. We have another member of the Scott Arboretum who is also losing a beautiful old climbing rose.

5. L.S. August 22, 2009 at 12:34 pm

   Some say spraying an anti-transpirant such as wilt-pruf on the roses every few weeks during the summer might help. The anti-transpirant creates a barrier between the mite and the leaf where it lands, preventing the mite from realizing it has reached a food source. Instead of settling in on the rose, the mite would supposedly hoist sails and drift away to a different plant.
   The following site contains more information than you’ll ever want to know about this awful disease:
   http://www.rosegeeks.com/

6. elizabeth paschall April 23, 2010 at 5:15 am

   thank you for this site. unfortunately it did show me what was wrong with my hybrid roses. rose rosette is alive in west tenn.

7. Brett Flournoy September 10, 2010 at 8:53 am

   Just yesterday I discovered the facts of this disease, long after it has taken over my extensive front yard rose beds. 18 Nearly Wild Rosas lined by sidewalk in spectacular fashion for the last seven years, supplemented by three Knockouts and two unknown Grandifloras – all now infected with two dead already. I’m in shock, if not depression, here in the DFW area, west side.

8. Karen October 17, 2011 at 5:57 pm

   After my visit to RoseGeek.com I too have come to grips that my 7 knockout roses just planted in April 2011 have Rose Rosette. My husband and I were amazed at their rapid growth (4ft in 2-3 weeks!) and after I cut them back within a month they were 4 ft tall again. Had no Idea they were in trouble until the new leaves and buds appeared deformed and unattractive. Now I know I had no green thumb, I had an effected rosebed growing rapidly from the disease. I am terrible with blackspot on roses here in humid Metairie, Louisiana so I thought I’d try the knockout “DISEASE RESISTANT!!!!!!!” roses. So sad, I’m going to miss them.

Comment on this Post

name (required)

e-mail (required, will not be published)

website