Reaction of Twenty Cultivars of Tall Fescue to Stem Rust in Controlled and Field Environments
- R. E. Welty and
- R. E. Barker
Stem rust, caused by Puccinia graminis Pers.:Pers. subsp, graminicola Z. Urban, is a serious disease of tall rescue (Festuca arundinacea Schreb.). Reliance on field evaluation of resistance ran be unreliable when climatic factors do not favor disease development. The objective of this study was to develop an effective controlled-environment screening procedure for stem rust resistance and to compare response to disease in controlled environments with disease responses in the field. Twenty cultivars of tall rescue were used to evaluate the infection responses to stem rust in 5- and 10-wk-old seedlings in controlled conditions and disease severity on the same plants grown in the field during three consecutive years. Although there was a significant difference (P = 0.001) among cultivars for both 5- and 10-wk-old plants for stem rust infection types, all cultivars were rated susceptible. Some cultivars (e.g., Mesa, KY31-F, and Arid) had smaller average infection types (AIT) and more stem rust resistant plants within a cultivar. Stem rust severity differed significantly among cultivars on each date of assessment in 1990, 1991, and 1992. Conditions were favorable for stem rust development in 1990 and 1992. In 1991, stem rust was slow to develop with 74% of the plants remaining rust free. When individual plant responses were compared at 5-wk, 10-wk, and on the final assessment date in the field (29 May 1992), 81.1% retained the same rating for resistant or susceptible as young plants and field plants, 15.8% were rated susceptible as young plants and resistant in the field, and 3.1% had mixed responses for resistance or susceptibility. A reliable glasshouse/field screening program was developed enabling rapid progress in producing stem rust resistant cultivars of tall rescue.
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