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Pathological factors affecting persistence in alfalfa with emphasis on diseases incited by Fusarium and Colletotrichum species

Ariss, Jennifer J.

Abstract Details

2005, Doctor of Philosophy, Ohio State University, Plant Pathology.
Enhanced disease resistance to lethal pathogens may contribute to increased individual plant survival and long-term persistence of alfalfa stands. In order to investigate the effect of disease on alfalfa persistence, experiments were undertaken to examine the role of lethal and chronic fungal pathogens on alfalfa. Disease incidence and severity data were recorded over six years on sixteen cultivars representing six decades of cultivar improvement. The major diseases present considered to be limiting to plant survival were Fusarium wilt (FW) and anthracnose. Disease incidence over the six years for both diseases was highest in cultivars released prior to 1980. In the fourth year, a sample of surviving plants from six cultivars were selected from the field study, established in the greenhouse and randomly intermated, creating six new populations. Progeny of the populations that had undergone one cycle of field selection were tested against the progeny of the same unselected plant material as was planted at the field site. Percent of resistant individuals for FW and anthracnose was higher in the populations that underwent field selection than the corresponding parent material. These results provide evidence that the survivors possessed resistance to the lethal diseases present. During the previous study, an isolate of Colletotrichum trifolii was identified in modern cultivars with high resistance to anthracnose. This isolate, designated OH-WA-520, was retained for further studies to determine the isolate’s race. Results of these studies show a reaction inconsistent with C. trifolii race 1 or race 2. Previous studies in Australia have shown similar results and have termed these isolates C. trifolii race 4. This is the first reported isolate consistent with C. trifolii race 4 in the US. One documented chronic disease is Fusarium crown rot (FCR), caused by the infection of cortical-rotting Fusarium species. While no commercial cultivars are specifically marketed for FCR resistance, grazing-tolerant cultivars are thought to be less affected. To assess resistance in modern cultivars, a greenhouse trial was conducted. The results of this study provide evidence that differences in FCR resistance exist in modern cultivars and agronomic type does not inherently contribute to FCR resistance.
Landon Rhodes (Advisor)
118 p.

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Citations

  • Ariss, J. J. (2005). Pathological factors affecting persistence in alfalfa with emphasis on diseases incited by Fusarium and Colletotrichum species [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1117417525

    APA Style (7th edition)

  • Ariss, Jennifer. Pathological factors affecting persistence in alfalfa with emphasis on diseases incited by Fusarium and Colletotrichum species. 2005. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1117417525.

    MLA Style (8th edition)

  • Ariss, Jennifer. "Pathological factors affecting persistence in alfalfa with emphasis on diseases incited by Fusarium and Colletotrichum species." Doctoral dissertation, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1117417525

    Chicago Manual of Style (17th edition)