Agronomy and Crop Sciences Commons^™

Abrasive Weeding As A Vehicle For Precision Fertilizer Management In Organic Vegetable Production, Tran Kim Ngan Luong, Frank Forcella, Sharon Clay, Michael S. Douglass, Samuel E. Wortman

Department of Agronomy and Horticulture: Faculty Publications

Abrasive weeding is a nonchemical weed control tactic that uses small, gritty materials propelled with compressed air to destroy weed seedlings. Organic fertilizers have been used successfully as abrasive grits to control weeds, but the goal for this study was to explore the effects of fertilizer grit, application rates, and background soil fertility on weeds, plant available nitrogen (N) uptake, and crop yield. Field trials were conducted in organic ‘Carmen’ sweet red pepper (Capsicum annuum) and organic ‘Gypsy’ broccoli (Brassica oleracea var. italica) and treatments included organic fertilizer grit (8N–0.9P–3.3K vs. 3N–3.1P–3.3K), grit application rates (low …

Collapse, Reorganization, And Regime Identity: Breaking Down Past Management Paradigms In A Forest-Grassland Ecotone, Victoria M. Donovan, Caleb P. Roberts, Carissa L. Wonkka, Daniel R. Uden, David G. Angeler, Craig R. Allen, David A. Wedin, Rhae A. Drijber, Dirac Twidwell

Department of Agronomy and Horticulture: Faculty Publications

The identity of an ecological regime is central to modern resilience theory and our understanding of how systems collapse and reorganize following disturbance. However, resilience-based models used in ecosystem management have been criticized for their failure to integrate disturbance outcomes into regime identity. Assessments are needed to understand how well these classifications represent ecosystem responses that occur over management relevant time scales. We tracked post-wildfire forest and grassland dynamics 27 years after wildfire in eastern ponderosa pine savanna. We tested for differences between the assigned identity of a site (forest or grassland) versus classifications based on the site's disturbance history …

Wild Emmer Introgression Alters Root-To-Shoot Growth Dynamics In Durum Wheat In Response To Water Stress, Harel Bacher, Feiyu Zhu, Tian Gao, Kan Liu, Balpreet Dhatt, Tala Awada, Chi Zhang, Assaf Distelfeld, Hongfeng Yu, Zvi Peleg, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Water deficit during the early vegetative growth stages of wheat (Triticum) can limit shoot growth and ultimately impact grain productivity. Introducing diversity in wheat cultivars to enhance the range of phenotypic responses to water limitations during vegetative growth can provide potential avenues for mitigating subsequent yield losses. We tested this hypothesis in an elite durum wheat background by introducing a series of introgressions from a wild emmer (Triticum turgidum ssp. dicoccoides) wheat. Wild emmer populations harbor rich phenotypic diversity for drought-adaptive traits. To determine the effect of these introgressions on vegetative growth under water-limited conditions, we used image-based phenotyping to …

Seed-Shattering Phenology At Soybean Harvest Of Economically Important Weeds In Multiple Regions Of The United States. Part 1: Broadleaf Species, Lauren M. Schwartz-Lazaro, Lovreet S. Shergill, Jeffrey A. Evans, Muthukumar V. Bagavathiannan, Shawn C. Beam, Mandy D. Bish, Jason A. Bond, Kevin W. Bradley, William S. Curran, Adam S. Davis, Wesley J. Everman, Michael L. Flessner, Steven C. Haring, Nicholas R. Jordan, Nicholas E. Korres, John L. Lindquist, Jason K. Norsworthy, Tameka L. Sanders, Larry E. Steckel, Mark J. Vangessel, Blake Young, Steven B. Mirsky

Department of Agronomy and Horticulture: Faculty Publications

Potential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed-shatter phenology in 13 economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after physiological maturity at multiple sites spread across 14 states in the southern, northern, and mid-Atlantic United States. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate …

Guiding Principles For Using Satellite-Derived Maps In Rangeland Management, Brady W. Allred, Megan K. Creutzburg, John C. Carlson, Christopher J. Cole, Colin M. Dovichin, Michael C. Duniway, Matthew O. Jones, Jeremy D. Maestas, David E. Naugle, Travis W. Naumen, Gregory S. Okin, Matthew C. Reeves, Matthew Rigge, Shannon L. Savage, Dirac Twidwell, Daniel R. Uden, Bo Zhou

Department of Agronomy and Horticulture: Faculty Publications

No abstract provided.

Vision, Challenges And Opportunities For A Plant Cell Atlas, Plant Cell Atlas Consortium, Suryatapa Ghosh Jha, Marc Libault, David W. Ehrhardt, Seung Y. Rhee, 32 Other Scientists

Department of Agronomy and Horticulture: Faculty Publications

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, …

Intervention Of Climate-Smart Practices In Wheat Under Rice-Wheat Cropping System In Nepal, Janma Jaya Gairhe, Mandeep Adhikari, Deepak Ghimire, Arun Khatri-Chhetri, Dinesh Panday

Department of Agronomy and Horticulture: Faculty Publications

Besides a proper agronomic management followed by Nepalese farmers, wheat (Triticum aestivum L.) production has been severely affected by changing climate. There are many interventions, including climate-smart practices, to cope with this situation and possibly enhance crop and soil productivity. Field experiments were set up in a randomized complete block design with six treatments (TRT) with four replications in three locations (LOC) during wheat-growing seasons in Nepal from 2014 to 2016. Treatments included (i) Controlled Practice (CP), (ii) Improved Low (IL), (iii) Improved High (IH), (iv) Climate Smart Agriculture Low (CSAL), (v) Climate Smart Agriculture Medium (CSAM), and (vi) …

Effect Of Foliar Micronutrients (B, Mn, Fe, Zn) On Maize Grain Yield, Micronutrient Recovery, Uptake, And Partitioning, Zachary P. Stewart, Ellen T. Paparozzi, Charles S. Wortmann, Prakash Kumar Jha, Charles A. Shapiro

Department of Agronomy and Horticulture: Faculty Publications

Timing of micronutrient demand and acquisition by maize (Zea Mays L.) is nutrient spe‐ cific and associated with key vegetative and reproductive growth stages. The objective of this study was to determine the fate of foliar‐applied B, Fe, Mn, Zn, and Fe/Zn together, evaluate the effect of foliar micronutrients applied at multiple rates and growth stages on maize grain yield, and deter‐ mine their apparent nutrient recovery efficiency (ANR). Five Randomized Complete Block Design (RCBD) experiments were conducted in 2014 and 2015 at five locations across Nebraska. Total dry matter was collected at 5–6 stages, and separated into leaves, stalk, …

Genomic Resources In Plant Breeding For Sustainable Agriculture, Mahendar Thudi, Rajeev K. Varshney, James C. Schnable

Department of Agronomy and Horticulture: Faculty Publications

Climate change during the last 40 years has had a serious impact on agriculture and threatens global food and nutritional security. From over half a million plant species, cereals and legumes are the most important for food and nutritional security. Although systematic plant breeding has a relatively short history, con- ventional breeding coupled with advances in technology and crop management strategies has increased crop yields by 56 % globally between 1965− 85, referred to as the Green Revolution. Nevertheless, increased demand for food, feed, fiber, and fuel necessitates the need to break existing yield barriers in many crop plants. In …

Development Of Mping-Based Activation Tags For Crop Insertional Mutagenesis, Alexander Johnson, Edward Mcassey, Stephanie Diaz, Jacod Reagin, Priscilla S. Redd, Daymond R. Parrilla, Hanh Nguyen, Adrian Stec, Lauren A.L. Mcdaniel, Thomas E. Clemente, Robert M. Stupar, Wayne A. Parrott, C. Nathan Hancock

Department of Agronomy and Horticulture: Faculty Publications

Modern plant breeding increasingly relies on genomic information to guide crop im- provement. Although some genes are characterized, additional tools are needed to effectively identify and characterize genes associated with crop traits. To address this need, the mPing element from rice was modified to serve as an activation tag to in- duce expression of nearby genes. Embedding promoter sequences in mPing resulted in a decrease in overall transposition rate; however, this effect was negated by using a hyperactive version of mPing called mmPing20. Transgenic soybean events carrying mPing-based activation tags and the appropriate transposase expression cassettes showed evidence of transposition. …

Responses Of Soil Surface Greenhouse Gas Emissions To Nitrogen And Sulfur Fertilizer Rates To Brassica Carinata Grown As A Bio-Jet Fuel, Dwarika Bhattarai, Gandura O. Abagandura, Thandiwe Nleya, Sandeep Kumar

Department of Agronomy and Horticulture: Faculty Publications

Carinata (Brassica carinata A. Braun), a non-food oilseed crop and an alternative bio-jet fuel feedstock, has received attention for its potential as a low-input option for production in the semi-arid region of the Northern Great Plains of the United States. Research addressing the impacts of nitrogen (N) and sulfur (S) fertilizers on soils and greenhouse gas (GHG; CO2, N2O, and CH4) emissions from carinata production are limited. Thus, objective of this study was to evaluate the impact of different rates of N and S fertilizers applied to carinata on soil properties and GHG emissions. Field experiments were conducted in 2017 …

Household Smoke-Exposure Risks Associated With Cooking Fuels And Cooking Places In Tanzania: A Cross-Sectional Analysis Of Demographic And Health Survey Data, Mazbahul G. Ahamad, Fahian Tanin, Nawaraji Shrestha

Department of Agronomy and Horticulture: Faculty Publications

Household smoke-exposure risk (SER) can be defined through the assessment of cooking fuels (smoke and no smoke-producing) and cooking places (indoor and outdoor) related information, which represent different levels of household air pollution. This study aimed to explore the prevalence and geographical variations in smoke-exposure risks (SERs) associated with indoor and outdoor cooking practices and use of smoke-producing and non-smoke-producing cooking fuels in Tanzania. We further investigated the social and spatial features associated with household SERs. We defined an indicator variable, the household SER, using country-level, cross-sectional data on cooking fuels and cooking places obtained from the 2015–2016 Tanzania Demographic …

Officially Confirmed Covid-19 And Unreported Covid-19–Like Illness Death Counts: An Assessment Of Reporting Discrepancy In Bangladesh, Mazbahul G. Ahamad, Fahian Tanin, Byomkesh Talukder, Monir Ahmed

Department of Agronomy and Horticulture: Faculty Publications

Reporting discrepancies between officially confirmed COVID-19 death counts and unreported COVID- 19–like illness (CLI) death counts have been evident across the world, including Bangladesh. Publicly available data were used to explore the differences between confirmed COVID-19 death counts and deaths with possible COVID-19 symptoms between March 2, 2020 and August 22, 2020. Unreported CLI death counts totaled more than half of the confirmed COVID-19 death counts during the study period. However, the reporting authority did not consider CLI deaths, which might produce incomplete and unreliable COVID-19 data and respective mortality rates. All deaths with possible COVID-19 symptoms need to be …

Soil Erosion Modelling: A Global Review And Statistical Analysis, Pasquale Borrelli, Panos Panagos, Dinesh Panday, 64 More Co-Authors

Department of Agronomy and Horticulture: Faculty Publications

To gain a better understanding of the global application of soil erosion prediction models, we comprehensively reviewed relevant peer-reviewed research literature on soil-erosion modelling published between 1994 and 2017.We aimed to identify (i) the processes and models most frequently addressed in the literature, (ii) the regions within which models are primarily applied, (iii) the regions which remain unaddressed and why, and (iv) how frequently studies are conducted to validate/evaluate model outcomes relative to measured data. To perform this task, we combined the collective knowledge of 67 soil-erosion scientists from 25 countries. The resulting database, named ‘Global Applications of Soil Erosion …

Potential Amendments For Improving Productivity Of Low Carbon Semiarid Soil, Bijesh Maharjan, Dinesh Panday, Humberto Blanco-Canqui, Maysoon M. Mikha

Department of Agronomy and Horticulture: Faculty Publications

Applying soil amendments with high C content can potentially improve soil properties and increase crop yields. The objective of this 3-yr field study was to evaluate the effects of organic amendments on soil organic C (SOC), chemical properties, crop nutrient uptake, and crop yields in a low C sandy loam soil near Scottsbluff, NE. The field was planted to dry bean (Phaseolus vulgaris L.) in 2017, maize (Zea mays L.) in 2018, and sugar beet (Beta vulgaris L.) in 2019. Char at 22.3, 44.6, 66.9, 89.2, and 133.8 Mg ha^–1; biochar at 5.6 and 11.2 …

Loss Of Comt Activity Reduces Lateral Root Formation And Alters The Response To Water Limitation In Sorghum Brown Midrib (Bmr) 12 Mutant, Manny Saluja, Feiyu Zhu, Hongfeng Yu, Harkamal Walia, Scott E. Sattler

Department of Agronomy and Horticulture: Faculty Publications

Lignin is a key target for modifying lignocellulosic biomass for efficient biofuel production. Brown midrib 12 (bmr12) encodes the sorghum caffeic acid O-methyltransferase (COMT) and is one of the key enzymes in monolignol biosynthesis. Loss of function mutations in COMT reduces syringyl (S) lignin subunits and improves biofuel conversion rate. Although lignin plays an important role in maintaining cell wall integrity of xylem vessels, physiological and molecular consequences due to loss of COMT on root growth and adaptation to water deficit remain unexplored.

We addressed this gap by evaluating the root morphology, anatomy and transcriptome of bmr12 mutant. The mutant …

Improving Publicly Available Corn Nitrogen Rate Recommendation Tools With Soil And Weather Measurements, Curtis J. Ransom, Newell R. Kitchen, John E. Sawyer, James J. Camberato, Paul R. Carter, Richard Ferguson, Fabián G. Fernández, David W. Franzen, Carrie A.M. Laboski, D. Brenton Myers, Emerson D. Nafziger, John F. Shanahan

Department of Agronomy and Horticulture: Faculty Publications

Improving corn (Zea mays L.) N fertilizer rate recommendation tools is necessary for improving farmers’ profits and minimizing N pollution. Research has repeatedly shown that weather and soil factors influence available N and crop N need. Adjusting available corn N recommendation tools with soil and weather measurements could improve farmers’ ability to manage N. The aim of this research was to improve publicly available N recommendation tools with site-specific soil and weather measurements. Information from49 site-years ofNresponse trials in theU.S. Midwest was used to evaluate 21 rate recommendation tools for a single (at-planting) and split (at-planting + sidedress) N …

Adaptation And Forage Productivity Of Cool-Season Grasses In The Central Usa, Kenneth P. Vogel, Robert B. Mitchell

Department of Agronomy and Horticulture: Faculty Publications

Cool-season grass species (18) and cultivars (85) were evaluated for use in seeded grasslands in the tallgrass prairie and shortgrass steppe ecoregions of the central United States at the test locations of Ithaca and Sidney, NE, respectively. Both native and introduced grasses were evaluated in sward trails. Significant differences existed among species and cultivars for all traits evaluated except for in vitro dry matter digestibility (IVDMD) among cultivars within species at Sidney. The grasses that had the best establishment, persistence, and forage yields in the Ithaca trial were introduced wheatgrass (Thinopyrum) and bromegrass (Bromus) species. At …

Identification And Utilization Of Genetic Determinants Of Trait Measurement Errors In Image-Based, High-Throughput Phenotyping, Yan Zhou, Aaron Kusmec, Seyed Vahid Mirnezami, Lakshmi Attigala, Srikant Srinivasan, Talukder Zaki Jubery, James Schnable, Maria G. Salas Fernandez, Baskar Ganapathysubramanian, Patrick S. Schnable

Department of Agronomy and Horticulture: Faculty Publications

The accuracy of trait measurements greatly affects the quality of genetic analyses. During automated phenotyping, trait measurement errors, i.e., differences between automatically extracted trait values and ground truth, are often treated as random effects that can be controlled by increasing population sizes and/or replication number. By contrast, there is some evidence that trait measurement errors may be partially under genetic control. Consistent with this hypothesis, we observed substantial non-random, genetic contributions to trait measurement errors for five maize (Zea mays) tassel traits collected using an image-based phenotyping platform. The phenotyping accuracy varied according to whether a tassel exhibited …

Incorporation Of Summer Annual Mixtures Into Grazing Systems In Kentucky, Kelly Marie Mercier

Theses and Dissertations--Plant and Soil Sciences

Utilizing summer annual grass-legume forage mixtures has the potential to improve forage yield and nutritive characteristics, and/or animal performance during times when cool-season pasture growth is limited by high temperatures. Legumes can utilize atmospheric nitrogen, which can increase crude protein and forage digestibility in mixtures. As nitrogen application generally improves both the yield and nutritive characteristics of summer annual forages, but can have a negative effect on legume competitiveness, nitrogen fertilizer recommendations for legume-containing summer annual mixtures are not well established.

Two experiments were conducted to determine the feasibility of utilizing summer annual mixtures in Kentucky, USA. The first experiment …

Quantifying The Impacts Of An Integrated Crop-Livestock System On Plant Nutrient Accumulation, Crop Yield, And Economic Performance, Teerath Singh Rai

Electronic Theses and Dissertations

Integrated crop-livestock systems (ICLs), if managed properly, have the potential for enhancing crop production and economics. Cover crops in ICL can be grazed to provide feed for livestock and improve nutrient recycling. This dissertation focused on assessing the impacts of ICL on crop yield and economics using field and modeling studies. Specific objectives of this dissertation are: (i) evaluating the impacts of the ICL on crop yield, and economic performance in a 3-yr oat (Avena sativa L.) – maize (Zea mays L.) – soybean (Glycine max (L.) Merr.) rotation, (ii) assessing the impacts of the ICL on maize biomass accumulation, …

Genome-Wide Association Mapping And Genomic Prediction Of Anther Extrusion In Cimmyt Hybrid Wheat Breeding Program Via Modeling Pedigree, Genomic Relationship, And Interaction With The Environment, Anil Adhikari, Bhoja Raj Basnet, Jose Crossa, Susanne Dreisigacker, Fatima Camarillo, Pradeep Kumar Bhati, Diego Jarquin, Yann Manes, Amir M.H. Ibrahim

Department of Agronomy and Horticulture: Faculty Publications

Anther extrusion (AE) is the most important male floral trait for hybrid wheat seed production. AE is a complex quantitative trait that is difficult to phenotype reliably in field experiments not only due to high genotype-by-environment effects but also due to the short expression window in the field condition. In this study, we conducted a genome-wide association scan (GWAS) and explored the possibility of applying genomic prediction (GP) for AE in the CIMMYT hybrid wheat breeding program. An elite set of male lines (n = 603) were phenotype for anther count (AC) and anther visual score (VS) across three field …

Development Of Mping-Based Activation Tags For Crop Insertional Mutagenesis, Alexander Johnson, Edward Mcassey, Stephanie Diaz, Jacob Reagin, Priscilla S. Redd, Daymond R. Parrilla, Hanh T. Nguyen, Adrian Stec, Lauren A.L. Mcdaniel, Thomas E. Clemente, Robert M. Stupar, Wayne A. Parrott, C Nathan Hancock

Department of Agronomy and Horticulture: Faculty Publications

Modern plant breeding increasingly relies on genomic information to guide crop improvement. Although some genes are characterized, additional tools are needed to effectively identify and characterize genes associated with crop traits. To address this need, the mPing element from rice was modified to serve as an activation tag to induce expression of nearby genes. Embedding promoter sequences in mPing resulted in a decrease in overall transposition rate; however, this effect was negated by using a hyperactive version of mPing called mmPing20. Transgenic soybean events carrying mPing-based activation tags and the appropriate transposase expression cassettes showed evidence of transposition. Expression analysis …

Genomic Selection Of Forage Agronomic Traits In Winter Wheat, Frank Maulana, Ki-Seung Kim, Joshua D. Anderson, Mark E. Sorrells, Twain J. Butler, Shuyu Liu, P. Stephen Baenziger, Patrick Byrne, Xue-Feng Ma

Department of Agronomy and Horticulture: Faculty Publications

Genomic selection (GS) can improve genetic gain of complex traits in plant breeding. Phenotyping agronomic traits of winter wheat (Triticum aestivum L.) for dualpurpose use is expensive and time-consuming. In this study, we compared the prediction accuracies of four GS models (RR-BLUP, GBLUP, GAUSS, and BL) for forage yield (FY), plant height (PH) and heading date (HD) of the hard winter wheat diversity panel (n = 298) using random and stratified sampling methods. In addition, we determined the appropriate training population (TP) size and marker density for GS of the traits. Moderate to high prediction accuracies ranging from 0.66 …

Reducing Mowing Requirements In Home Lawn And Golf Course Turfgrass, Mark A. Keck

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Turfgrass systems are routinely managed by frequent mowing to increase aesthetics and function. Mowing is resource intensive with a high labor and energy demand. Reducing the number of mowings events in a growing season will decrease the labor and energy but may reduce quality as well. Previous work has looked at reducing mowing by changing the frequency and by using a plant growth regulator (PGR). Limited information is available about how to reduce mowing while maintaining acceptable quality. We looked at two different management practices to reduce mowing and maintain quality. The first study evaluated seven different mowing frequencies at …

Evaluating The Impact Of Grafting On Local Tomato Production In Nebraska, Raihanah Hassim

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Vegetable grafting has been known to improve plant production under both biotic and abiotic stresses. With an increase in interest among local growers towards grafting production, it is important to provide enough vegetable grafting information. Therefore, the objective of this study is to assess the impact of grafting, rootstock cultivar, and local conditions and management on the yield and quality of tomato across the diverse growing and environmental conditions, specifically in Nebraska. Three open-field and one limited growing condition study were conducted between 2018 and 2019 across Nebraska. In the open-field trial, two determinant fresh market tomatoes, ‘Nebraska Wedding’ and …

Assessment Of Grain Safety In Developing Nations, Jose R. Mendoza

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Grains are the most widely consumed foods worldwide, with maize (Zea mays) being frequently consumed in developing countries where it feeds approximately 900 million people under the poverty line of 2 USD per day. While grain handling practices are acceptable in most developed nations, many developing nations still face challenges such as inadequate field management, drying, and storage. Faulty grain handling along with unavoidably humid climates result in recurrent fungal growth and spoilage, which compromises both the end-quality and safety of the harvest. This becomes particularly problematic where there is little awareness about health risks associated with poor …

Optimization Of In-Vessel Food Waste Composting: Enzyme Activity And Microbial Dynamics, Ayawovi Selom Ametepe

Graduate Theses and Dissertations

A series of greenhouse-based, rotary-drum bioreactor experiments was designed to study microbial dynamics and enzyme activity during optimization of food waste composting. This work aims to optimize food waste composting by defining the best food waste-to-bulking agent proportion controlling conditions and by evaluating the food waste composting process when inoculated by a bacterial inoculant product compared to uninoculated compost. Three experiments were run in total. The two first experiments were conducted for 48 days with sampling at each step of composting, while the third experiment last 50 days and included one extra sampling date. In the first experiment, 50:50, 65:35 …

Influence Of Burning And Grazing Management Practices On Subirrigated Sandhill Meadow Hay Production, Tara M. Harms

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Subirrigated meadows are a valuable forage resource to Sandhills ranching operations being used for hay production, grazing, or a combination of both. Practices that sustain meadow productivity should be encouraged to ensure a consistent feed supply for cattle. The potential influence of prescribed burning or pre-freeze and post-freeze grazing on forage production and quality are not well understood on these meadows. In grasslands, including meadows, excess dead plant material can accumulate, causing a potential reduction in forage yield and quality. Results of our three-year field study suggest that burning meadows in the spring is a suitable management option to remove …

Fungicide Resistance: Surveillance, Risk Assessment And Evolution In Two Soil-Borne Pathogens, Nikita Gambhir

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Fungicide-resistant pathogens are an increasing threat to fungicide efficacy and plant health. The goal of this dissertation was to advance the foundational knowledge required to prevent and detect fungicide resistance development in the seedling disease pathogen, Rhizoctonia zeae and the white-mold pathogen, Sclerotinia sclerotiorum. Corn and soybean fields in 12 states (Iowa, Illinois, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Nebraska, South Dakota, and Wisconsin) were surveyed for R. zeae. In vitro fungicide sensitivity was determined for 91 isolates to fludioxonil, sedaxane, and/or prothioconazole. Rhizoctonia zeae was sensitive to all fungicides (EC₅₀ < 3 µg/ml) except azoxystrobin (EC₅₀ > 100 µg/ml). In …