Rose rosette disease is transmitted by the eriophyid mite, Phyllocoptes fructiphilus , which develops in high numbers on shoots of RRD-infected multiflora roses. Many eriophyid mites are dispersed in air currents, and we believe that P. fructiphilus may also be disseminated in this manner. However, the spread of RRD the past two years has been slower than expected, suggesting that there may be a requirement for phoretic transport of P. fructiphilus by an unidentified insect that feeds on roses. We currently are conducting research on this possibility in West Virginia and neighboring states. Thus in warm weather, one generation may be produced per week.
Development is continuous throughout the season until weather turns cold in the fall.
In May 1987, Amrine et al. The site was heavily infested with both healthy and RRD-symptomatic multiflora roses. A total of 180 multiflora rose plants were marked and visited monthly during the growing season for the next five years. Mite populations were 14 times larger on symptomatic plants compared to healthy plants in 1987 and 1988. Mite populations were low and sporadic in April and gradually increased to peak populations by September in most years.