Last time, we announced the possibility of an outbreak of Rose Rosette Disease here in the rose gardens of the north-central Texas area. Samples of these suspect plants were collected and forwarded for further evaluation to Dr. George L. Philley, Extension Plant Pathologist for Texas A & M University in Overton and the central point of contact for monitoring this disease in Texas.
Jim McCarty, ARS Consulting Rosarian, coordinated the collection efforts and, as such, has become the point of contact for this area along with Dottie Woodson of the Agricultural Extension Service. Jim reported back to me on Dr. Philley's findings.
Of the samples submitted, those four from our reader were positively identified as having contracted this disease. The finding was verified by the presence of Phyllocoptes fructiphilus, a mite suspected as the vector of this disease. Although the mites could not be found on the samples collected from the two other gardens experiencing the same leaf and cane symptoms, if it looks like a duck, walks like a duck and quacks like a duck, it must be a duck.
Of concern at the time was the fact that all of the roses, save one, could be traced to either of two nurseries in the Texas rose industry that either wholesale to other nurseries, directly sell to the public, or ship mail-order to rosarians across North America - hence, the concern that the industry may be sending out disease-infected stock across the continent.
Dr. Philley's response to this concern was that this fact, in and of itself, does not positively point the finger at either of these two nurseries. Rose Rosette has been in east Texas since 1990, and the mite that is suspected as the carrier is very mobile. They have the ability, as do many mites, to "balloon" from plant to plant and can travel for long distances by simply letting the wind carry them aloft. There is also some evidence these mites can actually ride on the backs of aphids. If this is proven so, they could have come from anywhere since the Rose Aphid is ubiquitous.
In tracking these suspect critters, Dr. Philley suggests they prefer the antique roses possibly because of their petiole structure. However, this does not mean they cannot attack the modern roses or shrub roses, as was evidenced by the 'Graham Thomas' with this disease.
Dr. Philley suggests some control methods if you discover your rose might have Rose Rosette.
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