Agronomy and Crop Sciences Commons^™

First Record Of The Invasive Chenopodium Aphid, Hayhurstia Atriplicis (Linnaeus, 1761) (Hemiptera: Aphididae), In Colombia, Takumasa Kondo, Roberto Rosero, Jackeline Gaviria

Insecta Mundi

The chenopodium aphid, Hayhurstia atriplicis (Linnaeus, 1761) (Hemiptera: Aphididae), is reported for the first time in Colombia. The aphid was found on the aerial parts of the quinoa plant, Chenopodium quinoa Willd. (Amaranthaceae), especially on the leaves, in five municipalities in the department of Cauca, Colombia. Brief information on its natural enemies, distribution and biology is provided. This is the only aphid in Colombia known to cause malformations on the leaves of quinoa plants. In South America, this aphid has been found previously only in Ecuador, where it was reported for the first time in 2023 based on specimens collected …

Predicting The Potential Distribution Of Pseudococcus Longispinus (Targioni-Tozzetti) (Hemiptera: Pseudococcidae) In South Korea Using A Climex Model, Su Bin Kim, Soo-Jung Suh

Insecta Mundi

Pseudococcus longispinus (Targioni-Tozzetti) (Hemiptera: Pseudococcidae) is a widely-distributed pest that feeds on many economically important hosts, particularly tropical fruits and ornamentals. The potential distribution of this mealybug pest in South Korea remains a primary concern because of its high incidence of interceptions screened during inspection. Hence, this species prompted a modelling effort to assess its potential risk of introduction. Potential risk maps were developed for this pest with a CLIMEX model based on occurrence records under environmental data. The potential distribution of these pests in South Korea in the 2020s, 2050s and 2090s was projected based on the RCP 8.5 …

Pollinator Communities And Their Ecosystem Services At Conservation Grasslands And Adjacent Croplands, Araceli Gomez Villegas

Department of Entomology: Dissertations, Theses, and Student Research

Pollinators are intrinsically linked to the success of unmanaged and managed ecosystems by providing pollination services that aid in the reproduction of wildflowers and many crops. Land use change, habitat loss, fragmentation, and related landscape-level phenomena (for example, increased pesticide exposure) threaten pollinators and have been associated with population declines. In the Midwestern region of the United States, land conversion of native prairies and grasslands to row-crop agriculture has been one of the largest contributors to pollinator habitat loss. Conservation programs, such as the Conservation Reserve Program, have worked towards removing environmentally sensitive lands from agriculture production and enrolling them …

Teaching Agroecology: Preparing Students For Navigating Uncharted Territory, Charles A. Francis, Steve Gliessman

Department of Agronomy and Horticulture: Faculty Publications

Agroecologists understand that farming and food systems are more complex than the aggregation of their components. This realization drives our choices of learning strategies and activities that will prepare students for complexity and uncertainty. Our quest for a just, sustainable, and nutritious food system adequate to equitably serve everyone on the planet today and into the future is an enormous challenge. An undertaking of this magnitude will be met only with major adjustments informed by thoughtful teaching and practicing problem solving skills through a new educational lens. The principles of agroecology help us focus this lens on the wicked problems …

Soybean Gall Midge (Resseliella Maxima Gagné): Insecticide Efficacy And Seasonal Larval Abundance, Vilma Maria Montenegro Castro

Department of Entomology: Dissertations, Theses, and Student Research

Soybean gall midge, Resseliella maxima Gagné was recently identified as a new species injuring soybean in Nebraska, Iowa, South Dakota, Minnesota, and Missouri. Resseliella maxima injury is caused by its three instars that feed on tissues within the soybean stem. Infested plants exhibit a darkening of the stem, disrupting nutrient flow within the plant and can lead to wilting or death of plants. Total yield losses can occur in the first 30 m of the field in heavily infested sites. The biology and behavior of this newly described insects is not well understood and management strategies for the management of …

Winter Cover Crop Impacts On Weed Dynamics In Eastern And Central Nebraska, Elizabeth Ann Oys

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

Reducing tillage in cropping systems causes weed management to be dependent on chemical and cultural methods for weed control. Over time, herbicide-resistant weeds have developed due to the continuous selection pressures from herbicides, particularly in the Midwest Corn Belt. Integrated weed management strategies, such as cover crops, can be used to mitigate some of these issues. Cover crops are primarily known for their soil health benefits, but there is evidence that cover crops can suppress weeds. However, less research has been done at the field-scale level to address cover crop impacts on the weed seedbank and aboveground weeds during the …

American Burying Beetle, Plant Richness, And Soil Property Responses To Collapse Of Juniperus Virginiana Woodlands With Fire, Alison Ludwig

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

Grasslands are declining in the Great Plains due to land use changes, woody plant encroachment, and loss of historic fire cycles. Prescribed burn associations have utilized prescribed fire to collapse invading woodlands and allow the restoration of grasslands. This fire is considered “extreme” because it is capable of changing the structure and function of an ecosystem. Our study site is the Loess Canyons Experimental Landscape, a long-term, ecoregion-scale experiment to apply prescribed fire across the region to restore grasslands. The Nebraska Natural Legacy Project established the Loess Canyons ecoregion as a Biologically-Unique Landscape in 2005 with the state’s wildlife action …

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.

Fungicide Sensitivity Of Sclerotinia Sclerotiorum Isolates Selected From Five Different States That Use Different Fungicide Treatments, Cristian Wulkop Gil

UCARE Research Products

Sclerotinia sclerotiorum is a plant pathogenic fungus that causes a disease called white mold that can infect more than 450 plant species including soybeans, dry beans, green beans, canola, and sunflower. This pathogen is capable of up to $252M in losses every year (U.S. Canola Association, 2014). Fungicides are widely used in developed agricultural systems to control disease. However, resistance to the most effective fungicides has emerged and spread in pathogen populations and there have been multiple reports of S. sclerotiorum isolates becoming resistant to certain fungicides. Since different fields in different states use different fungicide treatments on plants and …

Use Of Uav Imagery And Nutrient Analyses For Estimation Of The Spatial And Temporal Contributions Of Cattle Dung To Nutrient Cycling In Grazed Ecosystems, Amanda Shine

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

Nutrient inputs from cattle dung are crucial drivers of nutrient cycling processes in grazed ecosystems. These inputs are important both spatially and temporally and are affected by variables such as grazing strategy, water location, and the nutritional profile of forage being grazed. Past research has attempted to map dung deposition patterns in order to more accurately estimate nutrient input, but the large spatial extent of a typical pasture and the tedious nature of identifying and mapping individual dung pats has prohibited the development of a time- and cost-effective methodology. The first objective of this research was to develop and validate …

Field Pea Response To Seeding Rate, Depth, And Inoculant In West-Central Nebraska, Strahinja V. Stepanovic, Charles Burr, Julie A. Peterson, Daran Rudnick, Cody F Creech, Rodrigo Werle

West Central Research and Extension Center, North Platte

Increased market demand and larger adoption of field pea (Pisum sativum L.) in semiarid west-central Nebraska has provided opportunities to replace summer fallow and diversify crop rotations. As a relatively new crop, its response to different seeding practices has not been evaluated in this eco-region. Field pea grain yield response to seeding depth (25, 50, and 75 mm), inoculation with Rhizobium leguminosarum bv. viciae (yes and no rhizobia inoculant), and seeding rates (35, 50, 65, 75, 90, 105, and 120 plants m^–2) was investigated in 2015 and 2016 at five sites in Perkins County, NE. There were …

Effect Of Dung Beetles On Dung Decomposition And Nuntrient Cycling In A Nebraska Rangeland, Kenneth Shay Evans

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

Management practice can have impacts on the abundance and frequency of dung beetle populations and nutrient cycling in grazing systems. Also, agriculture and livestock production land use is a considerable source of anthropogenic greenhouse gas (GHG) emissions, which are known to be one of the causes of global climate change. In this study, we evaluated the effect of dung beetle presence on the fluxes of greenhouse gasses (GHG’s) from dung pats in the semi-arid Sandhills region of Nebraska, by using closed chambers to measure the fluxes of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N …

Evidence Of Field-Evolved Resistance To Bifenthrin In Western Corn Rootworm (Diabrotica Virgifera Virgifera Leconte) Populations In Western Nebraska And Kansas, Adriano E. Pereira, Haichuan Wang, Sarah N. Zukoff, Lance Meinke, B. Wade French, Blair Siegfried

Department of Entomology: Faculty Publications

Pyrethroid insecticides have been used to control larvae or adults of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, a key pest of field corn in the United States. In response to reports of reduced efficacy of pyrethroids in WCR management programs in southwestern areas of Nebraska and Kansas the present research was designed to establish a baseline of susceptibility to the pyrethroid insecticide, bifenthrin, using susceptible laboratory populations and to compare this baseline with susceptibility of field populations. Concentration-response bioassays were performed to estimate the baseline susceptibility. From the baseline data, a diagnostic concentration (LC99) was determined and …

Introducing Green Manures In An Organic Soybean-Winter Wheat-Corn Rotation: Effects On Crop Yields, Soil Nitrate, And Weeds, Katja Koehler-Cole

School of Natural Resources: Dissertations, Theses, and Student Research

In organic soybean– winter wheat – corn rotations, animal manure is a common choice to maintain high yields, but leguminous crops grown as green manures after wheat harvest and incorporated into the soil before corn planting, can be an alternative when animal manure is not accessible. Forage legumes with high dry matter (DM) production and high biological N fixation have been shown to meet corn N demand. However, in Eastern Nebraska, lack of precipitation can reduce green manure growth and N fixation, leading to an insufficient N supply for corn, but corn growth can also be impacted by green manure …

Historical Common Names Of Great Plains Plants, With Scientific Names Index. Volume Ii: Scientific Names Index, Elaine Nowick

Zea E-Books Collection

Containing thousands of entries of both vernacular and scientific names of Great Plains plants, the literature that informs this exhaustive listing spans nearly 300 years. Author Elaine Nowick has drawn from sources as diverse as Linnaeus, Lewis and Clark, and local university extension publications to compile the gamut of practical, and often fanciful, common plant names used over the years. Each common name is accompanied by a definitive scientific name with references and authority information. Interspersed with scientifically-correct botanical line drawings, the entries are written in standard ICBN format, making this a useful volume for scholars as well as lay …

The Trehalose Pathway In Maize: Conservation And Gene Regulation In Response To The Diurnal Cycle And Extended Darkness, Clémence Henry, Samuel W. Bledsoe, Allison Siekman, Alec Kollman, Brian M. Waters, Regina Feil, Mark Stitt, L. Mark Lagrimini

Department of Agronomy and Horticulture: Faculty Publications

Energy resources in plants are managed in continuously changing environments, such as changes occurring during the day/night cycle. Shading is an environmental disruption that decreases photosynthesis, compromises energy status, and impacts on crop productivity. The trehalose pathway plays a central but not well-defined role in maintaining energy balance. Here, we characterized the maize trehalose pathway genes and deciphered the impacts of the diurnal cycle and disruption of the day/night cycle on trehalose pathway gene expression and sugar metabolism. The maize genome encodes 14 trehalose-6-phosphate synthase (TPS) genes, 11 trehalose-6-phosphate phosphatase (TPP) genes, and one trehalase gene. Transcript abundance of most …

Refining Thresholds In Coupled Fire–Vegetation Models To Improve Management Of Encroaching Woody Plants In Grasslands, Dirac L. Twidwell Jr, Samuel D. Fuhlendorf, Charles A. Taylor Jr, William E. Rogers

Department of Agronomy and Horticulture: Faculty Publications

1. Restoration priorities are typically established without quantitative information on how to overcome the thresholds that preclude successful restoration of desirable ecosystem properties and services. We seek to demonstrate that quantifying ecological thresholds and incorporating them into management-oriented frameworks provide a more comprehensive perspective on how the threshold concept can be applied to achieve restoration goals.

2. As an example, restoration actions have been largely unsuccessful when based on prevailing ecological knowledge of fire-based thresholds in nonresprouting Juniperus woodland. We build on previous threshold-based research and link well-established models from applied fire physics with a widely applied ecological positive feedback …

Ecology And Invasive Properties Of Musk Thistle (Carduus Nutans) In The Central Prairies Of Nebraska, Chengchou Han

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

Musk thistle (Carduus nutans) is an herbaceous monocarpic herb introduced to the U. S. from Eurasia. The invasion of musk thistle can reduce forage area, soil stability, and reduce recreation and open areas for humans and wildlife.

Resistance of warm season and cool season perennial grass communities to musk thistle invasion is important for land managers to consider, especially where disturbance has made an area particularly susceptible. Our results show that disturbances, such as overgrazing can open up niches in canopies of warm season grass communities and facilitate invasion but not in cool season grass communities. The mechanism …

Herbicide-Resistant Risk Assessment: Response Of Common Nebraska Weeds To Dicamba Dose, Roberto J. Crespo

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

Dicamba-resistant soybeans are being developed to provide an additional herbicide mechanism of action that can be used in soybean, and to provide a tool to help manage or mitigate the evolution of other herbicide-resistant weed populations. The objectives of this thesis were to assess the risk of common Nebraska weeds developing resistance to dicamba, quantify baseline dose-response to dicamba of high-risk weed species, and survey the variability in dicamba dose-response among populations of those species. Twenty-five weed scientists were asked to estimate the risk likelihood of ten weed species evolving resistance to dicamba following the commercialization of dicamba-resistant soybean. Palmer …

Biology, Systematics, Phylogenetic Analysis And Dna Character-Based Species Diagnosis Of The False Root-Knot Nematode Nacobbus Aberrans (Thorne, 1935) Thorne & Allen 1944 (Nemata:Pratylenchidae), Angel Ramirez-Suarez

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

The False Root-Knot nematode Nacobbus aberrans is a plant parasitic nematode that causes yield losses in several crops and plant protection agencies have established regulations to prevent infestations from spreading to new agricultural areas. The taxonomic status of the nematode has been the subject of controversy due to wide degree of variation exhibited by the species. This variability has led to the suggestion that N. aberrans is actually a species complex rather than a single species. In order to test this hypothesis, we compared twelve N. aberrans populations, which include isolates from western Nebraska, two distinct regions of Mexico and …

Limits To Maize Productivity In The Western Corn-Belt: A Simulation Analysis For Fully Irrigated And Rainfed Conditions, Patricio Grassini, Haishun Yang, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Unlike the Central and Eastern U.S. Corn-Belt where maize is grown almost entirely under rainfed conditions, maize in the Western Corn-Belt is produced under both irrigated (3.2 million ha) and rainfed (4.1 million ha) conditions. Simulation modeling, regression, and boundary-function analysis were used to assess constraints to maize productivity in the Western Corn-Belt. Aboveground biomass, grain yield, and water balance were simulated for fully irrigated and rainfed crops, using 20-year weather records from 18 locations in combination with actual soil, planting date, plant population, and hybrid-maturity data. Mean values of meteorological variables were estimated for three growth periods (pre- and …

Agroecosystems Analysis From The Grass Roots: A Multidimensional Experiential Learning Course, Mary Wiedenhoeft, Steve Simmons, Ricardo Salvador, Gina Mcandrews, Charles A. Francis, James W. King, David Hole

Department of Agricultural Leadership, Education, and Communication: Faculty Publications

An intensive, experiential travel course in Agroecosystems Analysis was conducted in Iowa, Minnesota, and Nebraska (United States) during summers of 1998 and 1999. The intended student audience was advanced undergraduate and beginning graduate students. Pretravel readings and a week-long series of farm visits, which consisted of in-depth interviews with the farmers and their families, prepared student teams to analyze and evaluate the production, economic, environmental, and social sustainability of 10 farms. Students shared their analyses both orally and in written reports. Based on a multifaceted student evaluation process, we found that participants were highly motivated, strongly engaged with the course …

Can Genetically Engineered Crops Become Weeds?, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

There are significant differences if the distribution of weedy characteristics among weeds, normal plants, and crops. The world’s most serious weeds possess on the average 10 or 11 of these characters, a random collection of British plants have an average seven of the traits, and crop plants only five. For the average crop to become as “weedy” as the average weed, it would need to acquire five weedy traits. Even using the unlikely assumption that those traits are single loci in which a dominant mutation would provide the weedy character, this would require the simultaneous acquisition of five gene substitutions. …

Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch

School of Biological Sciences: Faculty Publications

Detailed studies on soil texture and moisture retention indicate a close association between edaphic features and the distribution and composition of plant communities along topographic gradients at Arapaho Prairie, a typical, semi-arid Nebraska Sandhills prairie. The vegetation characteristics of three major habitat types (ridge, slope, and valley) and several minor subtypes (swale, stable ridge, and eroding ridge) are recognized and quantitatively described. Texture analysis indicates that the soils of dune slopes and ridges are largely azonal and are very coarse with substantially lower fine fractions (silt-clay ~ 13-15%) than soils of the more lowland swale and valley sites where surfact …

Effect Of Time Of Cutting On Yield And Botanical Composition Of Prairie Hay In Southeastern Nebraska, Elverne C. Conard, Vincent H. Arthaud

Historical Research Bulletins of the Nebraska Agricultural Experiment Station

Approximately three and one-third million acres of native prairie are harvested annually in Nebraska for hay. In the four-year period 1948-1951, the State ranked first in wild hay production with an average yield of more than two and one-quarter million tons per year. This crop is an important natural resource in Nebraska's livestock industry. Studies were initiated in 1945 to determine the effects of time of cutting on the yield and feeding value of prairie hay in southeastern Nebraska. The studies were continued through the summer of 1952 to determine the effects of different cutting treatments on the vigor and …

Microorganisms And Soil Structure, T. M. Mccalla

Department of Agronomy and Horticulture: Faculty Publications

SUMMARY

Laboratory tests were made to determine the effectiveness of different compounds and microbial groups in increasing the stability of Peorian loess lumps against the action of falling water drops. The influence of these on percolation tests in the laboratory was also determined.

Many organic substances-dextrose, sucrose, starch, peptone, cullulose, and gum arabic-did not themselves contribute directly to soil-structure stability, though these substances do furnish energy material for soil microorganisms, which can convert them readily into either microbial tissue or decomposition products that increase soil-structure stability. Lignin, proteins, oils, fats, waxes, resin, and paraffin increased the stability of lumps of …