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Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett May 2017

Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett

Electronic Theses and Dissertations

Lilium grayi (Gray’s Lily), a southern Appalachian endemic species, is threatened by a Lilium-specific fungal pathogen, Pseudocercosporella inconspicua. The disease is characterized by tan lesions that can cause early senescence, while also lowering seed production and viability. This project tested for P. inconspicua conidia and accessed health at nine locations. The disease was present and ubiquitous across the range of L. grayi. Through identification of P. inconspicua conidia in the field, L. superbum (Turk’s Cap Lily) was identified as an additional host, while L. michauxii (Michaux’s Lily) was disease-free. However, infection was inducible in both species. With …


Managing Phomopsis Stem Canker Of Sunflower Using Improved Diagnosis And Quantification Of The Causal Pathogens, Taylor Rae Olson Jan 2017

Managing Phomopsis Stem Canker Of Sunflower Using Improved Diagnosis And Quantification Of The Causal Pathogens, Taylor Rae Olson

Electronic Theses and Dissertations

Phomopsis stem canker is a disease that severely affects sunflower (Helianthus annuus) in the United States. From 2001 to 2015, disease prevalence has increased from 1.5% to 61%, and two new causal agents, Diaporthe gulyae and Diaporthe stewartii, have been described along with Diaporthe helianthi, which was always regarded as the main causal pathogen of the disease. At this time, options to manage the disease are limited. Currently, no commercial sunflower hybrids have resistance to all three species of Diaporthe, and no fungicides are labeled for control of Phomopsis stem canker of sunflower in the United …


Molecular Characterization Of Spot Blotch And Bacterial Leaf Streak Resistance In Bread Wheat, Girma Ayana Jan 2017

Molecular Characterization Of Spot Blotch And Bacterial Leaf Streak Resistance In Bread Wheat, Girma Ayana

Electronic Theses and Dissertations

Spot blotch (SB), caused by Bipolaris sorokiniana (Sacc.) Shoem, and bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa (Smith et al.), two important foliar diseases of wheat in the major production regions of the US and the world. Deployment of adequate host resistance against them depends on determining the resistance genes or quantitative trait loci (QTLs) responsible for the trait and identification of genetic markers linked to QTL that facilitate markers assisted breeding. We conducted two independent studies and characterized QTLs for BLS and SB resistance. In the first study, we constructed a genetic linkage map of 1,211 …


Mitigating Risks Of Ochratoxin A Contamination In Oats, Bandana Dhungana Jan 2017

Mitigating Risks Of Ochratoxin A Contamination In Oats, Bandana Dhungana

Electronic Theses and Dissertations

Ochratoxin A (OTA) is a toxic metabolite produced by several species of fungal genera Penicillium and Aspergillus. The major OTA producer in temperate regions (i.e. U.S., Canada, Europe) is Penicillium verrucosum. Oat (Avena sativa), like any other cereal grain, can be contaminated with OTA when storage conditions are favorable for fungal growth. The presence of OTA exceeding the European Union maximum limit of 3 ppb in processed food has been reported in some samples of oat-based breakfast cereals from the US. The use of oat genotypes with limited OTA accumulation would be an effective way to …


Characterization Of Pyrenophora Tritici-Repentis In Wheat And Rye To Study Tan Spot Susceptibility And Insights Into Its Relationship With Stem Rust Resistance, Sidrat Abdullah Jan 2017

Characterization Of Pyrenophora Tritici-Repentis In Wheat And Rye To Study Tan Spot Susceptibility And Insights Into Its Relationship With Stem Rust Resistance, Sidrat Abdullah

Electronic Theses and Dissertations

Tan spot, caused by the ascomycete fungus, Pyrenophora tritici-repentis (Ptr), is a major foliar fungal disease of wheat worldwide. To date, Ptr isolates have been grouped into eight races based on the production of three host selective effectors (toxins), Ptr ToxA, ToxB, and ToxC, which are associated with necrosis and chlorosis symptoms on wheat differential lines. In order to see the correlation between stem rust resistance and tan spot susceptibility in 1970’s, to know the pathogen virulence profile, and explore the sources of tan spot resistance, we recovered isolates from wheat and rye and evaluated wheat and rye lines with …