Thursday, November 12, 2015

Roses losing the battle with Rose Rosette Disease

Roses have been losing the battle with Rose Rosette Disease (RRD) all over Collin County. As a plant pathologist I had seen and worked with this disease in the past, but never have I seen this level of disease pressure, infection rate, and wide spread infection. There are lot of theories on how and why this has happened, but likely they will just remain theories. At our recent Rose Rosette Disease Seminar held at Collin College, we heard from a rose breeder, plant diagnostician, and virologist. They presented research information about this disease and strategies for managing the problem. There were several new discoveries presented that shed some light on the disease and how it is spread.

In late 2014 the Rose Rosette Eradication Alliance (RREA) was formed in an effort to educate the landscape industry, property managers, government officials, homeowners, and the general public. During 2015, the RREA has organized numerous conferences, seminars, and presentations to help increase the availability of information about this disease and how to manage it. The RREA has helped to develop publications, videos, and recommendations for RRD, and assisted with getting out message out.

There is no cure for this viral disease of roses. The management strategy relies heavily on removing roses exhibiting symptoms of the disease so the spread of disease is limited. The virus that causes the disease is spread by a microscopic mite. In North Texas there are countless landscape beds densely planted with roses, which has made it easy for the disease to spread. Landscapes should be designed with a diverse species of plants to prevent the spread of RRD, as well as other disease and insect problems.

New information presented at the recent seminar was the incubation period for this disease is much longer than we previously thought. The incubation period is the time between when the plant is infected and symptoms develop. Current data suggest this can be from 2 weeks to 18 months. A longer incubation period makes managing the disease more difficult, because roses could be a source of infection for a long time before the symptoms develop. Meaning that a healthy rose can be infected, but we just don't know it yet. Therefore removing symptomatic roses, while still very important, won't have as quick of an impact on controlling the spread of the disease as we once hoped. Gardeners should remain vigilant with the community wide effort to remove RRD symptomatic roses.

We have compiled information about Rose Rosette Disease and posted it our our Collin County Master Gardener website. You can watch the following 5 minute video or visit our YouTube channel. New videos from our recent seminar are posted at: Dealing with Rose Rosette Disease - Dr. Kevin Ong.

Written by Greg Church, Ph.D., Horticulture Agent, Texas A&M AgriLife Extension