Evaluation of Rosa Species Accessions for Resistance to Eriophyid Mites1

Abstract Rose rosette disease, caused by rose rosette virus (RRV), is an epidemic affecting nearly every rose cultivar in the United States. The only hosts for Phyllocoptes fructiphilus, the eriophyid mite that vectors RRV, are Rosa species. Eighteen Rosa species were evaluated for mite resistance by collecting foliage samples from July to November in 2016 and 2017, from which mites were extracted. Mites were isolated through a series of sieves and counted using a stereomicroscope. The response variable was expressed as the number of mites per gram of optimal rose tissue. Mite data were evaluated to determine the peak week for mite populations for each year. The mite populations varied by rose species (α = 0.05) in 2016 but not 2017. Due to high variability in mite counts, the species were not as clearly distinguishable as expected. This high variability is likely due to factors such as differential growth rates of the roses, weather, presence of RRV in the rose, and the quality of the tissue collected throughout the season. Experimental design revisions are proposed for future studies looking at Rosa species resistance to eriophyid mite populations. Index words: rose rosette virus, rose rosette disease, Phyllocoptes fructiphilus Keifer, virus, vector. Species used in this study: Phyllocoptes fructiphilus (Keifer), Prairie Rose [Rosa arkansana (Porter), Forest Farm]; Carolina Rose [Rosa carolina (L.), Forest Farm]; Rosa clinophylla (Thory), Rogue Valley Rose; White Prairie Rose [Rosa foliolosa (Nutt.), Rogue Valley Rose]; White Prairie Rose [Rosa foliolosa (Nutt.) Antique Rose Emporium]; Father Hugo Rose [Rosa hugonis, Rogue Valley Rose]; Musk Rose [Rosa moschata (J. Herrm.), Antique Rose Emporium]; Multiflora Rose [Rosa multiflora (Thunb.)]; Shining Rose [Rosa nitida (Willd.), Rogue Valley Rose]; Shining Rose [Rosa nitida (Willd.), Antique Rose Emporium]; Nootka Rose [Rosa nutkana (C. Presl.), Rogue Valley Rose]; Tea Rose [Rosa odorata (Andrews), Foundation Plant Services, Davis, CA]; Swamp Rose [Rosa palustris (Marshall), Antique Rose Emporium]; Swamp Rose [Rosa palustris (Marshall), Ever Blooming Antique Rose Emporium]; Chestnut Rose [Rosa roxburghii (Tratt.), Antique Rose Emporium]; ‘Plena' Chestnut Rose [Rosa roxburghii (Tratt.), Rogue Valley Rose]; Rugosa Rose [Rosa rugosa (Thunb.), Bailey's Nursery]; ‘Alba' Rugosa Rose [Rosa rugosa (Thunb.), Bailey's Nursery]; Climbing Prairie Rose [Rosa setigera (Michx.), Antique Rose Emporium]; Rosa soulieana (Crép.), Ralph Moore; Virginia Rose [Rosa virginiana (Mill.), Forest Farm]; Porterfolia Memorial Rose [Rosa wichuraiana (Crép.), Antique Rose Emporium]; Mountain Woods' Rose [Rosa woodsii (Lindl.), Rogue Valley Rose].