ARS | Publication request: RESISTANCE OF DAYLILY CULTIVARS TO RUST

Submitted to: Southern Nursery Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 15, 2005
Publication Date: February 1, 2006
Citation: Li, Y.H., Windham, M.T., Trigiano, R.N., Fare, D.C., Spiers, J.M., Copes, W.E. 2006. Resistance of daylily cultivars to rust. Southern Nursery Association Proceedings 50:275-277.

Interpretive Summary: This research documents symptoms that can be used to identify highly resistant, resistant, moderately resistant, and susceptible daylily cultivars to daylily rust. While highly resistant and resistant cultivars differed in the development of very small and few yellow or brown spots, both inhibited the fungus from producing spores. Moderately resistant cultivars developed small and a limited number of yellow spots and allowed the fungus to produce a reduced number of spores. Susceptible cultivars developed many yellow spots that can combine into large yellow areas and allowed the fungus to produce an extensive number of spores. This research will directly benefit research and extension scientists and daylily producers and enthusiasts who want to compare differences in tolerance of daylily cultivars to daylily rust.

Technical Abstract: Resistance reactions of eight daylily cultivars to Puccinia hemerocallidis were investigated ten days after inoculating detached leaf segments. Leaves of highly resistant cultivars, ‘Prairie Blue Eyes’ and ‘Bertie Ferris’, were characterized as having tiny yellow spots or no symptoms at the point of penetration by the fungus. Leaves of resistant cultivars, ‘Buttered Popcorn’, ‘Chicago Apache’ and ‘Stella De Oro’, showed a hypersensitive reaction and uredia were not formed. Leaves of moderately susceptible cultivars, ‘Mary Todd’ and ‘Chorus Line’, exhibited a hypersensitive reaction, but uredia and urediniospores formed. Leaves of susceptible cultivars, ‘Pardon Me’, supported abundant spore production without a hypersensitive reaction. Rust development on abaxial and adaxial leaf surfaces of ‘Pardon Me’ were compared in combinations of the side of the leaf inoculated and the orientation of the leaf during incubation. Infection efficiency was significantly lower and latent period delayed on adaxial leaf surfaces compared to abaxial surfaces regardless incubation sides.