Agriculture Commons^™

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 …

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 (IA, IL, IN, KS, KY, MI, MN, MO, ND, NE, SD, and WI) 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 planta application of …

Critical Period Of Palmer Amaranth Removal And Effects Of Late Season Herbicide Applications On Palmer Amaranth Seed Production, Jose De Sanctis

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

Palmer amaranth is the most troublesome weed in agronomic crops in United States. Therefore, an integrated weed management approach is necessary to successfully manage this weed. The use of residual pre-emergence (PRE) herbicide applied at planting can delays the is one of the critical time of Palmer amaranth removal (CTPAR) giving farmers more time to prepare the weed control tactics and to preventing an unacceptable yield loss in soybean due to Palmer amaranth competition. Field experiments were conducted in 2018 and 2019 in a grower’s field infested with GR Palmer amaranth near Carleton, Nebraska, to determine the CTPAR in soybean …

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 …

Influence Of Cover Crop Management Practices On Rainfed Corn Production In Semi-Arid Western Nebraska, Alexandre Tonon Rosa

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

With the increased cover crop (CC) popularity, producers of semi-arid regions of western Nebraska are questioning whether they could successfully incorporate CC into their rainfed winter wheat (Triticum aestivum L.)-corn (Zea mays L.)-fallow rotations. The major concern is that CCs may deplete soil water affecting the subsequent crop. Therefore, three studies were established under rainfed conditions of western Nebraska to access the effects of CCs on soil water, soil compaction, nutrient cycling, weed demographics, residue coverage, and subsequent corn yield. The first study evaluated the influence of CC planting and termination times prior to corn establishment. …

Effects Of Tank Contamination And Impact Of Drift-Reducing Agents On Weed Control In Response To Dicamba Applications, Milos Zaric

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

Availability of dicamba-tolerant (DT) crops from 2017 provided farmers with additional herbicides for weed control management in row crops. However, the technology alike this one has concerns regarding dicamba off-target movement (OTM) causing undesirable effects on sensitive vegetation. Even though dicamba has high water solubility OTM that has often been overlooked when it comes to unintended crop exposure is dicamba tank contamination. Considering the complexity of spraying equipment soybean response may be expected even when small amounts of residues are left in the spray equipment. Typically, the same field spray equipment is used to perform herbicide application through growing season …

Effects Of Char On Nitrogen Management In Agricultural Soils Of Semi-Arid Western Nebraska, Dinesh Panday

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

Soils in western Nebraska are characterized by low soil organic C due to semi-arid environment in the region and further aggravated by disruption of soil aggregates and rapid C decomposition from intensive tillage, erosion, and frequent droughts. Proper management of soil C may improve soil properties, reduce N losses, and subsequently improve crop yields in this low C soil and low moisture condition. This dissertation focuses on C-rich coal char (henceforth “char”) as a potential strategy to overcome the existing problem of low C in semi-arid region. Char is an industrial by-product, resulting from inefficient coal burning during sugar beet …

Evaluating Opportunities For Integrated Crop Livestock Systems In Eastern Nebraska, Elizabeth Kay Christenson

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

Current agricultural systems focused on production of few commodities are facing production, economic, and environmental challenges. To address these challenges, Integrated Crop Livestock Systems (ICLS) have emerged through three primary methods 1) perennial grasslands for grazing and/or hay production, 2) crop residue grazing, and 3) cover crop grazing. To evaluate potential of ICLS mitigating current challenges, a field scale model ICLS was developed in 2015. The ICLS includes 4-ha each of ‘Newell’ smooth bromegrass (Bromus inermis L.), ‘Liberty’ switchgrass (Panicum virgatum L.), and ‘Shawnee’ switchgrass. The ICLS also included 8-ha of continuous corn (Zea mays L.). In 2016, only hay …

Weed Control Efficacy Of Bio-Based Sprayable Mulch Films In Specialty Crop Systems, Eliott Gloeb

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

A sprayable bio-based mulch film (biofilm) could present a more sustainable weed management tool for specialty crop producers than conventional plastic mulch films while also offering flexibility in application patterns and timing. From 2017 to 2019, six greenhouse trials and four field trials were conducted at the University of Nebraska-Lincoln to study the effects of biofilm application on weed suppression and crop yields. Multiple application rates (0.81 L/m² - 9.78 L/m²) and application times (prior to weed emergence and post weed emergence) were tested. Corn starch, glycerol, keratin hydrolysate, corn gluten meal, corn zein, and isolated soy …

Control Of Volunteer Corn In Enlist Corn And Economics Of Herbicide Programs For Weed Control In Conventional And Multiple Herbicide-Resistant Soybean Across Nebraska, Adam M. Striegel

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

With commercialization of multiple herbicide-resistant corn and soybean cultivars, producers have new management options for controlling herbicide-resistant weeds and volunteer corn. Corn-on-corn production systems are common in irrigated fields in southcentral Nebraska which can create issues with volunteer corn management in corn fields. Enlist corn contains a new multiple herbicide-resistant trait providing resistance to 2,4-D choline, glyphosate, and the aryloxyphenoxypropionate (FOPs). Field experiments were conducted in 2018 and 2019 at South Central Agricultural Laboratory near Clay Center, Nebraska with the objective to evaluate ACCase-inhibiting herbicides and herbicide application timing on volunteer corn control, Enlist corn injury, and yield. Glyphosate/glufosinate-resistant corn …

Buffalograss Diversity Assessment, Collin Marshall

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

Buffalograss [Buchloë dactylodes (Nutt.) Engelm. syn. Bouteloua dactyloides (Nutt.) Columbus] is a low input alternative turfgrass for the Great Plains region. Buffalograss is a dioecious stoloniferous warm season grass with wide variation of valuable traits and is well adapted for use in minimal maintenance landscapes. The obligate outcrossing nature of the species and wide variation of potentially valuable traits make buffalograss a prime candidate for cultivar improvement and genetic study. Limited information is available regarding buffalograss genetics. In effort to expand genetic resources around buffalograss, we developed buffalograss derived simple sequence repeat markers from previously available transcriptomes of buffalograss …

Reaction Of Tepary Beans To Eight Virulent Races Of The Rust Pathogen That Overcomes All Known Common Bean Rust Resistance Genes, Santos Barrera Lemus, Prabin Tamang, Carlos A. Urrea, Marcial A. Pastor-Corrales

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

Bean rust, caused by Uromyces appendiculatus, is a major disease of common and snap bean (Phaseolus vulgaris) worldwide (Stavely, 1984). Although host resistance is an important component of rust management (Mmbaga et al., 1996), populations of the rust pathogen comprise an extensive and shifting virulence diversity that could render susceptible all known rust resistance genes in common bean. Conversely, it has been suggested that certain tepary bean (Phaseolus acutifolius) accessions are broadly resistant to bean rust (Miklas & Stavely, 1998). The objectives of this study were to verify if tepary beans are resistant to …

Extreme Fire As A Management Tool To Combat Regime Shifts In The Range Of The Endangered American Burying Beetle, Alison K. Ludwig, Daniel R. Uden, Dirac Twidwell

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

This study is focused on the population of federally-endangered American burying beetles in south-central Nebraska. It is focused on changes in land cover over time and at several levels of spatial scale, and how management efforts are impacting both the beetle and a changing landscape. Our findings are applicable to a large portion of the Great Plains, which is undergoing the same shift from grassland to woodland, and to areas where the beetle is still found.

Spring Meadow Management Practices: What’S A Rancher To Do?, Tara M. Harms, Jerry D. Volesky, Mitchell B. Stephenson

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

• Subirrigated meadows are a valuable forage resource to ranching operations in the Nebraska Sandhills, being used for both hay production and livestock grazing. • The water table of these meadows is within one meter of the soil surface during the growing season. • In some years, wet conditions hinder meadow utilization, resulting in a buildup of standing dead and litter plant material which can lower forage production.

• Investigate if burning and mowing are effective strategies to remove dead plant material from meadows • Determine if burning or mowing interact with grazing to influence end of season forage production …

Herbicide Injury From Dicamba And 2,4-D: How Much Is Too Much In Lettuce?, Xinzheng Chen, Amit J. Jhala, Stevan Z. Knezevic, Samuel E. Wortman

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

Off-target herbicide injury from dicamba and 2,4-D is an increasingly common problem for specialty crop growers in the Midwest U.S. Lettuce (Lactuca sativa L.) is a common specialty crops grown in Nebraska, but proximity to corn and soybean production leaves growers vulnerable to crop injury and significant economic loss. The goal of this study was to quantify crop injury and yield loss in greenhouse grown lettuce after exposure to simulated sub-lethal drift rates of 2,4-D and dicamba. Sublethal doses were determined based on a percentage of the maximum labeled rate and ranged from 25% to 0.01%. Tested lettuce cultivars …

Soybean Response To Water: Trait Identification And Prediction, Shawn Jenkins

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

The rising demand for soybean [Glycine Max (L.) Merrill] taken in consideration with current climatic trends accentuates the importance of improving soybean seed yield response per unit water (WP). To further our understanding of the quantitative WP trait, a multi-omic approach was implemented for improved trait identification and predictive modeling opportunities. Through the evaluation of two recombinant inbred line populations jointly totaling 439 lines subjected to contrasting irrigation treatments, informative agronomic, phenomic, and genomic associations were identified. Across both populations, relationships were identified between lodging at maturity (r = -0.58, H = 0.86), canopy to air temperature differential …

Evaluating The Impact Of Grafting On Local Tomato Production In Nebraska, Raihanah Hassim, Samuel E. Wortman, Ashley A. Thompson, Stacy A. Adams

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

Grafting has been successfully used in vegetable production for tomatoes, peppers, eggplants, cucumbers, and watermelon. Besides its usefulness for managing soil-borne diseases, grafting can improve nutrient uptake and yield. However, few studies have assessed the effects of grafting and soil fertility management on yield of open field-grown tomatoes in the Midwest. Therefore, the objective of this two-year research was to better document the effects of grafting heirloom and hybrid tomato cultivar onto hybrid tomato rootstocks on tomato yield and quality. The field experiments were located at the University of Nebraska Lincoln - East Campus in Lincoln, West Central Research and …