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Filtering by: Creator Johnson, Nicole Brooke Remove constraint Creator: Johnson, Nicole Brooke Degree Field Botany and Plant Pathology Remove constraint Degree Field: Botany and Plant Pathology

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  • Pyrenophora tritici-repentis : investigation of factors that contribute to pathogenicity

    Creator:
    Holman, Thomas W.
    Abstract:
    Pyrenophora tritici-repentis (Ptr) is the necrotrophic fungus responsible for tan spot of wheat (Triticum aestivum). Ptr causes disease on susceptible wheat cultivars through the production and secretion of host-selective toxins (HSTs). HSTs are compounds that are only known to be produced by fungi and considered to be primary determinants of...
    Resource Type:
    Masters Thesis
    Full Text:
    committee members, Tom Wolpert, Ken Johnson, and Dave Myrold, for all of their support and advice

  • Host and Pathogen Genetics in the Sharp Eyespot Disease of Wheat

    Creator:
    Liu, Jiang
    Abstract:
    Wheat sharp eyespot (SES), caused by the soil-borne fungus Rhizoctonia cerealis is a common stem disease of wheat globally. The disease caused a severe and extensive epidemic throughout the Willamette Valley of Oregon in 2014 and has remained one of the most important wheat diseases in this region. However, litte...
    Resource Type:
    Dissertation
    Full Text:
    . Robert Zemetra, Dr. Kenneth Johnson, Dr. Niklaus Grunwald, and Dr. Weihong Qiu as my committee members

  • Dynamics of Zymoseptoria tritici Fungicide Resistance in the Willamette Valley of Oregon

    Creator:
    Hagerty, Christina H.
    Abstract:
    The development of resistance to multiple fungicide classes is currently limiting disease management options for many pathogens, while the discovery of new fungicide classes has become less frequent. To address this pressing issue, a three-part study with different layers of complexity, objectives, and experimental approaches was conducted using the model...
    Resource Type:
    Dissertation
    Full Text:
    wonderful committee members including Carol Mallory-Smith, Dave Gent, Ken Johnson, Ed Peachy, and Karen

  • Seeing Genes: Multiscale Phenotyping Reveals Gene Functions in Maize Pollen

    Creator:
    Warman, Cedar D.
    Abstract:
    Plant sexual reproduction requires a broad array of molecular mechanisms to proceed successfully. Some of these mechanisms are well-studied, but our knowledge of them as a whole is fundamentally incomplete. Pollen tube growth is a key part of this process, facilitating the delivery of the sperm cells to the female...
    Resource Type:
    Dissertation
    Full Text:
    ​(Johnson et al., 2019)​). As the number of pollen tubes is far greater than the number of ovules, pollen

  • Seed and seedling ecology of Artemisia tridentata in a restoration context

    Creator:
    Wijayratne, Upekala C.
    Abstract:
    The semi-arid sagebrush steppe ecosystem is one of the largest biomes in North America. The steppe provides critical habitat and forage for wildlife and is economically important to recreation and livestock industries. However, the ecosystem is threatened primarily due to several negative effects associated with expansion of the exotic annual...
    Resource Type:
    Dissertation
    Full Text:
    lab members for assistance and an all around good time — Jessi Brunson, Nicole DeCrappeo, Elizabeth

  • The effects of defoliation on Bromus tectorum seed production and growth

    Creator:
    Mayer, Kara Hempy
    Abstract:
    Cheatgrass (Bromus tectorum L.) is a widespread exotic weed in the Intermountain sagebrush steppe. An annual grass, it is highly prolific and very competitive with native perennial grass seedlings. A clipping experiment carried out at two cheatgrass-dominated sites (Lincoln Bench and Succor Creek) in eastern Oregon analyzed effects of defoliation...
    Resource Type:
    Masters Thesis
    Full Text:
    Lab," including Kristen Harrison, Steven Bekedam, Scott Schaff, Nicole DeCrappeo, Cindy Salo in

  • Yield responses of invasive grasses to carbon doses

    Creator:
    Brunson, Jessi L.
    Abstract:
    The sagebrush steppe ecosystem of the northern Great Basin is severely degraded and continues to decline due in large part to the invasive, non-native annual grasses Bromus tectorum L. (cheatgrass) and Taeniatherum caput-medusae (L.) Nevski (medusahead). Restoration of invasive-dominated areas is difficult, but can be enhanced by adding a carbon...
    Resource Type:
    Masters Thesis
    Full Text:
    , Jessica Boyd, Scott Shaff, Elizabeth Schwartz, Upekala Wijayratne, Nicole DeCrappeo, Cedar Hesse, Emily

  • Litter decay processes and soil nitrogen availability in native and cheatgrass-dominated arid rangelands

    Creator:
    Harrison, Kristen S.
    Abstract:
    As large-scale restorations of degraded rangelands are initiated, land managers need to understand how decades of dominance by the invasive annual grass, cheatgrass (Bromus tectorum L.), have altered ecosystem processes. One way to assess such alterations is by observing differences in decay rates, since decomposition is determined by factors such...
    Resource Type:
    Masters Thesis
    Full Text:
    many people who helped in the field and the lab, including Nicole DeCrappeo, Scott Shaff, Steven

  • Scratching the Surface of the Potato Geocaulosphere: Characterizing the Microbiome of Seed Tuber Tare Soil and its Impact on the Rhizosphere Microbiome

    Creator:
    Delventhal, Kayla D.
    Abstract:
    For tuberizing crops like potato (Solanum tuberosum), the geocaulosphere, or the zone of soil in contact with and influenced by the tuber, is a distinct sphere of microbial life and represents an important interface between the potato crop and the soil environment. Upon potato harvest, specific geocaulosphere soil called tare...
    Resource Type:
    Masters Thesis
    Full Text:
    , Nicole, and Shoshanna Delventhal for thinking I’m awesome and supporting me in all of my endeavors big

  • Establishment tolerance of six native sagebrush steppe species to imazapic (PLATEAU®) herbicide implications for restoration and recovery

    Creator:
    Bekedam, Steven
    Abstract:
    Scientists and land managers realize that integrated weed management (IWM) strategies are needed to attain successful and lasting improvements of weed infested landscapes. At this time no broadly reliable and environmentally safe IWM strategy has been developed to control exotic annual grasses that dominate many ecosystems of the northern Great...
    Resource Type:
    Masters Thesis
    Full Text:
    , Nicole, and Joe. I owe you three a heap of gratitude. I thank my parents Shirley Rainwater and Don