Evers, Gerald Wayne

Ocumpaugh, W. R.

Smith, Gerald R.

English

Texas A&M University

Improvement of Rust Resistance in Sweetclover

Texas A&amp;M Repository

    PUBLICATIONS 2006 IMPROVEMENT OF RUST RESISTANCE IN SWEETCLOVERG. R. Smith, G. W. Evers and W. R. OcumpaughBackground. Sweetclover rust (Uromyces striatus) has been noted at several locations inTexas in the past four years and was officially reported in Kansas in 2002 (Plant Dis. 86: 1404).The symptoms are the occurrence of orange to reddish brown pustules (uredinia) on the leaves,wilting and early leaf drop. The development of rust resistance in sweetclover was added as anobjective to the sweetclover breeding program.Research Findings. Twenty-five sweetclover (white flower, M alba) plant introductionlines (representing the core collection for this species) were planted at Beeville in November,2003 for evaluation of sweetclover rust resistance. Rust had been noted on sweetclover inprevious years at Beeville and severe rust was noted again in mid May, 2004 on the experimentalsweetclover lines. In early June four plant introduction lines were identified with some plant toplant variation for rust resistance. The remaining twenty-one lines were classified as rustsusceptible. The four lines with some variation for rust resistance did not flower at Beeville andhave been classified as biennials. A space planted selection nursery was established at Beeville toevaluate the four plant introduction lines that were identified with variation for rust resistance andone additional related line. Five hundred and seventy-five plants were transplanted in midDecember, 2004, including twenty-five plants of Hubam sweetclover as checks. The plants wererated for rust reaction on May 26. 2005. The following rating scale was used: R = resistant, norust pustules visible; MS = moderately susceptible, 2-10 pustules per leaflet; S = susceptible, 10-25 rust pustules per leaflet; HS = highly susceptible, >25 pustules per leaflet. Variation for rustreaction was confirmed for all five experimental lines and Hubam was confirmed as highly rustsusceptible (see graphs of rust reactions for each line). Three sweetclover lines were noted withexcellent rust resistance (78 to 54% rated as R) but with little forage production potential. Theselines (TX-SC-349, TX-SC-55I. and TX-SC-472) were all biennial types with very slow growth.Two lines, one biennial line with 51 % rust resistant plants and one annual line with 24% rustresistance, were identified with potential for good forage production in south Texas. The line TX-SC-625 was classified as biennial and was 12 to 30 inches tall on May, 26, 2005. The line TX-SC-624 was in late bloom and was 48 to 72 inches tall at this same evaluation date.Application. Sweetclover germplasm with rust resistance has been identified.Development of cultivars with combinations of rust resistance, low coumarin and multi-stemmedcrowns is in progress.65100ca 80-0-- 600-c 40Q)(J~Q) 200..0Hubam.-~r-l100ca 80-0-- 600-c 40Q)(J~Q) 200..0TX-SC-349..--l-I-l-n nR MR SRust reactionTX-SC-551HS R MR SRust reactionTX-SC-472HS,----Hlli100S 800-- 600-c 40Q)(J~Q) 200..0R MR SRust reactionTX-SC-624HS100ca 80-0-.... GO0-c 40C1)~C1) 20c..01-"---- IlnR MR 5 HSRust reactionTX-SC-625100ca 80-0-- 600-c 40Q)(J~Q) 200..0..--HI 1I100ca 80-0-- 600-c 40C1)0...Q) 200..0..--I--I--11 n nR MR SRust reactionHS66R MR S HSRust reaction

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Improvement of Rust Resistance in Sweetclover

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Texas A&M University

Texas A&M Repository

Improvement of Rust Resistance in Sweetclover

Abstract

Similar works

Full text

Available Versions

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository