Agriculture Commons^™

Measuring And Preliminary Modeling Of Drift Interception By Plant Species, Jonnie B. Dunne, Shanique L. Grant, Jeffrey A. Golus, Jeffrey W. Perine, Stefan Wolf, Michael Winchell, T. Mark Ledson, Ian Whenham

West Central Research and Extension Center, North Platte

Currently, the concept of plant capture efficiency is not quantitatively considered in the evaluation of off-target drift for the purposes of pesticide risk assessment in the United States. For on-target pesticide applications, canopy capture efficiency is managed by optimizing formulations or tank-mixing with adjuvants to maximize retention of spray droplets. These efforts take into consideration the fact that plant species have diverse morphology and surface characteristics, and as such will retain varying levels of applied pesticides. This work aims to combine plant surface wettability potential, spray droplet characteristics, and plant morphology into describing the plant capture efficiency of drifted spray …

Impact Of Maize Hybrid Selection On Water Productivity Under Deficit Irrigation In Semiarid Western Nebraska, Strahinja Stepanovic, Daran Rudnick, Greg R. Kruger

West Central Research and Extension Center, North Platte

The future economic and agricultural sustainability of semiarid western Nebraska will largely depend on more efficient utilization of the declining groundwater resources. The scope of this research was to evaluate the maize hybrid yield, water productivity (WP; i.e. grain yield produced per unit of water consumed), and irrigation water productivity (IWP; i.e. increase in grain yield per unit of irrigation water applied) across a range of semiarid climatic conditions (i.e. drought, normal, and wet) and irrigation treatments. Total of 13 maize hybrids were evaluated under full irrigation (FI), deficit irrigation (DI, receiving ~50% less irrigation water than FI), and dryland …

Differences In Soil Water Changes And Canopy Temperature Under Varying Water × Nitrogen Sufficiency For Maize, Tsz Him Lo, Daran Rudnick, Kendall C. Dejonge, Geng Bai, Hope Njuki Nakabuye, Abia Katimbo, Yufeng Ge, Trenton E. Franz, Xin Qiao, Derek M. Heeren

West Central Research and Extension Center, North Platte

Crop nitrogen (N) status is known to affect crop water status and crop water use. To investigate further the N effects on soil water changes and on canopy temperature, three water levels × four N levels were imposed on two growing seasons of maize in west central Nebraska, USA. Soil water changes were measured using a neutron probe, whereas canopy temperature was measured using infrared thermometers on a ground-based mobile platform. At all water levels, soil water losses over monthlong intervals were generally greater as N levels increased. Given equal water levels, early afternoon canopy temperatures were usually lower with …

Diurnal And Seasonal Activity Patterns Of Drosophilid Species (Diptera: Drosophilidae) Present In Blackberry Agroecosystems With A Focus On Spotted-Wing Drosophila, Katharine A. Swoboda-Bhattarai, Hannah Burrack

West Central Research and Extension Center, North Platte

Drosophilid species with different life histories have been shown to exhibit similar behavioral patterns related to locating and utilizing resources such as hosts, mates, and food sources. Drosophila suzukii (Matsumura) is an invasive species that differs from other frugivorous drosophilids in that females lay eggs in ripe and ripening fruits instead of overripe or rotten fruits. We hypothesized that there may be diurnal and/or seasonal patterns associated with the movement of drosophilid species into and out of crop fields and their attraction to fermentation-odor-based monitoring traps, and that D. suzukii would conform to similar patterns. To test these hypotheses, we …

Comparison Of Water-Sensitive Paper, Kromekote And Mylar Collectors For Droplet Deposition With A Visible Fluorescent Dye Solution, J. Connor Ferguson, Andrew J. Hewitt, Chris C. O’Donnell, Greg R. Kruger

West Central Research and Extension Center, North Platte

The study was conducted at the University of Nebraska Pesticide Application and Tech-nology Laboratory in North Platte, Nebraska in July 2015. Two application volume rates (100 and 200 l · ha−1) and three nozzle types (XR, AIXR, TTI) were selected at two flow rates (0.8 and 1.6 l · min−1) and at a single application speed of 7.7 km · h−1. Each collec-tor type [Mylar washed (MW), Mylar image analysis (MIA), water-sensitive paper (WSP), and Kromekote (KK)] was arranged in a randomized complete block design. Each nozzle treatment was replicated twice, providing six cards of each collector type for each …

Herbicide Drift Exposure Leads To Reduced Herbicide Sensitivity In Amaranthus Spp., Bruno Viera, Joe Luck, Keenan Amundsen, Rodrigo Werle, Todd A. Gaines, Greg R. Kruger

West Central Research and Extension Center, North Platte

While the introduction of herbicide tolerant crops provided growers new options to manage weeds, the widespread adoption of these herbicides increased the risk for herbicide spray drift to surrounding vegetation. The impact of herbicide drift in sensitive crops is extensively investigated, whereas scarce information is available on the consequences of herbicide drift in non-target plants. Weeds are often abundant in field margins and ditches surrounding agricultural landscapes. Repeated herbicide drift exposure to weeds could be detrimental to long-term management as numerous weeds evolved herbicide resistance following recurrent-selection with low herbicide rates. The objective of this study was to evaluate if …

Geographic Distribution Of Bacillus Thuringiensis Cry1f Toxin Resistance In Western Bean Cutworm (Lepidoptera: Noctuidae) Populations In The United States, Brad S. Coates, Craig A. Abel, Katharine A. Swoboda-Bhattarai, Debra E. Palmquist, Débora Goulart Montezano, Sarah N. Zukoff, Yangzhou Wang, Jeffery D. Bradshaw, Christina D. Difonzo, Elson Shields, Kelley J. Tilmon, Thomas Hunt, Julie A. Peterson

West Central Research and Extension Center, North Platte

The western bean cutworm (WBC), Striacosta albicosta (Lepidoptera: Noctuidae), can be a severe pest of transgenic corn in the western Plains and Great Lakes regions of North America, including on hybrids expressing the Bacillus thuringiensis (Bt) Cry1F toxin. The level and geographic distribution of Cry1F resistance are not completely known. Neonate S. albicosta from 10 locations between Nebraska and New York state were subjected to dose–response trypsin-activated native Cry1F toxin overlay bioassays. In 2017, the mean estimated lethal concentration causing 50% larval mortality (LC50) ranged from 15.1 to 18.4 μg Cry1F cm−2, and were not significantly different among locations. In …

Planting Date, Cultivar, Seed Treatment, And Seeding Rate Effects On Soybean Growth And Yield, Thandiwe Nleya, Matthew Schutte, David Clay, Graig Reicks, Nathan Mueller

West Central Research and Extension Center, North Platte

Soybean [Glycine max (L.) Merr.] yield is a function of many factors including genetic attributes of the cultivar, environmental conditions, and management practices. Temporally variable weather patterns in North America, especially in the northern Great Plains, have resulted in the re-examination of how spring production practices interact with the environmental conditions to influence yield. This study evaluated the impact of four plantings dates, four seeding rates, and two soybean maturity groups (MGs) using treated and untreated (control) seed on soybean growth, seed yield, and composition. The study was conducted at Volga, SD, in 2014, 2015, and 2016. The planting …

Influence Of Burner Position On Temperature Distribution In Soybean Flaming, Miloš Miloš Rajkovic, Goran Malidža, Strahinja Stepanovic, Marko Kostic, Kristina Petrovic

West Central Research and Extension Center, North Platte

The main objective of this study was to identify optimal burner orientation for a newly designed flame cultivator by quantifying the flame temperature distributions of cross, back, and parallel position of burners at different heights of the soybean canopy (distance from the soil surface). Flame temperatures were measured within-row for three burner orientations at seven propane doses (20–100 kg/ha) and eight different canopy heights (0–18 cm above soil surface). Soybean plants in V3 growth stage were flamed with the same doses and burner orientations, and 28 days after treatment (DAT) crop injury (0%–100%), plant height (cm), dry matter (g) and …

The Impact Of Cow Size On Cow-Calf And Postweaning Progeny Performance In The Nebraska Sandhills, Rob L. Ziegler, Jacki A. Musgrave, Tanya L. Meyer, R. Funston, Elliott James Dennis, Kathy Hanford, J. C. Macdonald, Travis Mulliniks

West Central Research and Extension Center, North Platte

Optimizing beef production system efficiency requires an understanding of genetic potential suitable for a given production environment. Therefore, the objective of this retrospective analysis was to determine the influence of cow body weight (BW) adjusted to a common body condition score (BCS) of 5 at weaning-influenced cow-calf performance and postweaning steer and heifer progeny performance. Data were collected at the Gudmundsen Sandhills Laboratory, Whitman, NE, on crossbred, mature cows (n = 1,607) from 2005 to 2017. Cow BCS at calving, prebreeding, and weaning were positively associated (P < 0.01) with greater cow BW. Increasing cow BW was positively associated (P < 0.01) with the percentage of cows that conceived during a 45-d breeding season. For every additional 100-kg increase in cow BW, calf BW increased (P < 0.01) at birth by 2.70 kg and adjusted 205-d weaning BW by 14.76 kg. Calf preweaning average daily gain (ADG) increased (P < 0.01) 0.06 kg/d for every additional 100-kg increase in cow BW. Heifer progeny BW increased (P < 0.01) postweaning with every additional 100-kg increase in dam BW. Dam BW did not influence (P ≥ 0.11) heifer puberty status prior to breeding, overall pregnancy rates, or the percentage of heifers calving in the first 21 d of the calving season. Steer initial feedlot BW increased by 7.20 kg, reimplant BW increased by 10.47 kg, and final BW increased by 10.29 kg (P ≤ 0.01) for every additional 100-kg increase in dam BW. However, steer feedlot ADG was not influenced (P > 0.67) by dam BW. Hot carcass weights of steers were increased (P = …

Droplet Size And Nozzle Tip Pressure From A Pulse-Width Modulation Sprayer, Thomas R. Butts, Liberty E. Butts, Joe D. Luck, Bradley K. Fritz, Wesley C. Hoffmann, Greg R. Kruger

West Central Research and Extension Center, North Platte

Pulse-width modulation (PWM) sprayers can improve application accuracy through flow control, turn compensation, and high-resolution overlap control by pulsing an electronically-actuated solenoid valve which controls the relative proportion of time each solenoid valve is open (duty cycle). The objective of this experiment was to identify the droplet size distribution and nozzle tip pressure when influenced by PWM duty cycle, nozzle technology, and gauge pressure to provide PWM guidelines. The experiment was conducted in a low-speed wind tunnel at the Pesticide Application Technology Laboratory using a SharpShooter® PWM system. In general, for non-venturi nozzles, as duty cycle decreased, droplet size slightly …

Fungicide Application Technology For Controlling The Sugarcane Orange Rust, Thales Cassemiro Alves, João Arantes Rodrigues Da Cunha, Rafael Marcão Tavares, Guilherme Sousa Alves, Sérgio Macedo Silva

West Central Research and Extension Center, North Platte

With the epidemic onset of the sugarcane orange rust, fungicide applications of the Strobilurins and Triazoles groups have become necessary in susceptible varieties. This study aimed at evaluating the operational conditions of fungicide application in sugarcane (SP81-3250 variety), in relation to the spray deposition on the upper canopy and the effectiveness of the orange rust control. Treatments consisted of two application volumes (30 L ha-1 or 40 L ha-1) and three nozzle deflection angles (0 º, 90 º or 135 º), plus a ground application at the rate of 200 L ha-1, sprayed with a uniform flat spray nozzle of …

Assessment Of Cover Crop Management Strategies In Nebraska, Us, Maxwel C. Oliveira, Liberty Butts, Rodrigo Werle

West Central Research and Extension Center, North Platte

Adoption of cover crops has the potential to increase agricultural sustainability in the US and beyond. In 2017, a survey was conducted with Nebraska stakeholders in an attempt to evaluate current cover crop management strategies adopted in soybean (Glycine max [L.] Merr.), field corn (Zea mays L.), and seed corn production. Eighty-two Nebraska stakeholders answered the survey, of which 80% identified themselves as growers. Eighty-seven percent of respondents manage cover crops, and the average cover crop ha planted on a per farm basis is 32%. The primary method of establishing cover crops following soybeans and field corn is …

Droplet Size Impact On Efficacy Of A Dicamba-Plus-Glyphosate Mixture, Thomas R. Butts, Chase A. Samples, Lucas X. Franca, Darrin M. Dodds, Daniel B. Reynolds, Jason W. Adams, Richard K. Zollinger, Kirk A. Howatt, Bradley K. Fritz, W. Clint Hoffmann, Joe D. Luck, Greg Kruger

West Central Research and Extension Center, North Platte

Chemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of …

Evaluation Of Foliar Insecticides For The Control Of Western Bean Cutworm In Field Corn, 2018, Katharine A. Swoboda-Bhattarai, Samantha R. Daniel, Julie A. Peterson

West Central Research and Extension Center, North Platte

The objectives of this field trial were to evaluate the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans that has undergone a rapid range expansion into the eastern Corn Belt during the last 18 yr. This study was conducted within the historic range of WBC, at the University of Nebraska-Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). An RCB design with a total of 16 treatments (including an untreated check) and four replications was used. Plots measured 20 …

Developmental And Reproductive Characteristics Of Beef Heifers Classified By Number Of Estrous Cycles Experienced By Start Of First Breeding, Andy Roberts, Jaclyn N. Ketchum, Richard N. Funston

West Central Research and Extension Center, North Platte

A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or >3 (n = 249). Heifers (P …

Approaches To Evaluating Grower Irrigation And Fertilizer Nitrogen Amount And Timing, Tsz Him Lo, Daran Rudnick, Charles Burr, Matt Stockton, Rodrigo Werle

West Central Research and Extension Center, North Platte

Diversity in the knowledge, mindset, strategies, and tools that growers use to manage irrigation and fertilizer nitrogen culminates in diversity in profitability and environmental impact among farms. As growers, academia, and industry strive together to tackle the technological and non-technological challenges impeding better irrigation and fertilizer nitrogen management, a science-based evaluation of grower input amount and timing becomes an important initial step in the process. Providing such valuable feedback to growers is a high-priority objective for the University of Nebraska-Lincoln Testing Ag Performance Solutions (UNL-TAPS) farm management competition. In this competition, each team of mostly growers made management decisions for …

Response Of Amaranthus Spp. Following Exposure To Sublethal Herbicide Rates Via Spray Particle Drift, Bruno C. Vieira, Joe D. Luck, Keenan L. Amundsen, Todd A. Gaines, Rodrigo Werle, Greg Kruger

West Central Research and Extension Center, North Platte

The adverse consequences of herbicide drift towards sensitive crops have been extensively reported in the literature. However, little to no information is available on the consequences of herbicide drift onto weed species inhabiting boundaries of agricultural fields. Exposure to herbicide drift could be detrimental to long-term weed management as several weed species have evolved herbicide-resistance after recurrent selection with sublethal herbicide rates This study investigated the deposition of glyphosate, 2,4-D, and dicamba spray particle drift from applications with two different nozzles in a low speed wind tunnel, and their impact on growth and development of Amaranthus spp. Herbicide drift …

Evaluation Of Foliar Insecticide Application Timing For The Control Of Western Bean Cutworm In Field Corn, 2018, Katharine A. Swoboda-Bhattarai, Samantha R. Daniel, Julie A. Peterson

West Central Research and Extension Center, North Platte

The objective of this field trial was to determine if application timing affects the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans in the North American Corn Belt. This study was located at the University of Nebraska- Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). The experimental design used was an RCB design with a total of 10 treatments (three insecticides applied at three application timings, plus an untreated check) and four replications; the treatment design was an …

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 …

Distribution Of Glyphosate-Resistant Amaranthus Spp. In Nebraska, Bruno C. Vieira, Spencer L. Samuelson, Guilherme S. Alves, Todd A. Gaines, Rodrigo Werle, Greg Kruger

West Central Research and Extension Center, North Platte

Background: Palmer amaranth (Amaranthus palmeri S. Wats.), common waterhemp (Amaranthus tuberculatus var. rudis), and redroot pigweed (Amaranthus retroflexus L.) are major weeds occurring in fields throughout Nebraska with recurrent grower complaints regarding control with glyphosate. The objective of this study was to investigate the frequency and distribution of glyphosate-resistant Palmer amaranth, common waterhemp, and redroot pigweed populations in Nebraska. The study also aimed to investigate how agronomic practices influence the occurrence of glyphosate resistance in the three Amaranthus species.

Results: Glyphosate resistance was widespread in common waterhemp (81% of the screened populations), few Palmer amaranth …

Seedbank Persistence Of Palmer Amaranth (Amaranthus Palmeri) And Waterhemp (Amaranthus Tuberculatus) Across Diverse Geographical Regions In The United States, Nicholas E. Korres, Jason K. Norsworthy, Bryan G. Young, Daniel B. Reynolds, William G. Johnson, Shawn P. Conley, Reid J. Smeda, Thomas C. Mueller, Douglas J. Spaunhorst, Karla L. Gage, Mark Loux, Greg R. Kruger, Muthukumar V. Bagavathiannan

West Central Research and Extension Center, North Platte

Knowledge of the effects of burial depth and burial duration on seed viability and, consequently, seedbank persistence of Palmer amaranth (Amaranthus palmeri S. Watson) and waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] ecotypes can be used for the development of efficient weed management programs. This is of particular interest, given the great fecundity of both species and, consequently, their high seedbank replenishment potential. Seeds of both species collected from five different locations across the United States were investigated in seven states (sites) with different soil and climatic conditions. Seeds were placed at two depths (0 and 15cm) for …

Effects Of Red Clover Isoflavones On Tall Fescue Seed Fermentation And Microbial Populations In Vitro, Emily A. Melchior, Jason K. Smith, Liesel G. Schneider, Travis Mulliniks, Gary E. Bates, Zachary D. Mcfarlane, Michael D. Flythe, James L. Klotz, Jack P. Goodman, Huihua Ji, Phillip R. Meyer

West Central Research and Extension Center, North Platte

Negative impacts of endophyte-infected Lolium arundinaceum (Darbyshire) (tall fescue) are responsible for over $2 billion in losses to livestock producers annually. While the influence of endophyte-infected tall fescue has been studied for decades, mitigation methods have not been clearly elucidated. Isoflavones found in Trifolium pratense (red clover) have been the subject of recent research regarding tall fescue toxicosis mitigation. Therefore, the aim of this study was to determine the effect of ergovaline and red clover isoflavones on rumen microbial populations, fiber degradation, and volatile fatty acids (VFA) in an in vitro system. Using a dose of 1.10 mg …

Profitability Of Developing Beef Heifers On Stockpiled Winter Forages, Zachary David Mcfarlane, Chris Boyer, J. Travis Mulliniks

West Central Research and Extension Center, North Platte

We estimate the profitability of developing heifers on one stockpiled cool-season grass and two stockpiled warm-season grasses during the winter months by comparing distributions of net present value (NPV) over an 11-year useful life. Furthermore, distributions of payback period and the break-even price for each calf over the heifer’s production life were generated for each forage species. These results are compared across forages as well as to a simulated drylot system for heifer development. Data comes from a grazing experiment in Tennessee, where heifers grazed big bluestem and Indian grass combination (BBIG), switchgrass (SW), or endophyte-infected tall fescue (TF) pastures. …

Climate Dynamics, Invader Fitness, And Ecosystem Resistance In An Invasion-Factor Framework, Stephen L. Young, David R. Clements, Antonio Ditommaso

West Central Research and Extension Center, North Platte

As researchers and land managers increasingly seek to understand plant invasions and the external (climate) and internal (plant genetics) conditions that govern the process, new insight is helping to answer the elusive question of what makes some invasions successful and others not. Plant invasion success or failure is based on a combination of evolutionary and ecological processes. Abiotic (e.g., climate) and biotic (e.g., plant competition) conditions in the environment and plant genetics (e.g., fitness) combine in either decreasing or increasing invasion, yet it has proven challenging to know exactly which of these conditions leads to success for a given species, …

Effect Of Biochar Type And Size On In Vitro Rumen Fermentation Of Orchard Grass Hay, Zach D. Mcfarlane, Phillip R. Myer, Emily R. Cope, Neil D. Evans, T. Carson Bone, Bryan E. Bliss, J. Travis Mulliniks

West Central Research and Extension Center, North Platte

Biochar, a byproduct from the biofuels industry, may be a potential feed additive in ruminant diets due to possible improvements in microbial fermentation. Therefore, the objective of this study was to determine the nutritive value, in vitro digestibility, volatile fatty acid (VFA) production, and gas production of biochar inclusion to an orchard grass (Dactylis glomerata) basal diet. The study was designed as a 3 × 2 factorial arrangement with 3 different biochar sources and 2 biochar processed sizes as the main effects factors. Experimental treatments were biochar from 3 different tree types: 1) Chestnut Oak (Quercus prinus …

Beyond Precision Weed Control: A Model For True Integration, Stephen L. Young

West Central Research and Extension Center, North Platte

Precision means being exact and accurate and is an important management component for cropping systems. However, precision does not mean integration, which encompasses spatial and temporal dimensions and is a necessary practice rivaling precision. True IWM merges precision and integration by incorporating advanced technology that allows for greater flexibility of inputs and enhanced responsiveness to field conditions. Examples of this approach are non-existent due to a lack of suitable technological tools and a need for a paradigm shift. Herein a potential model startup company is offered as a guide to advance beyond precision weed control to true integration. The critical …

The Effect Of Adjuvants At High Spray Pressures For Aerial Applications, Bradley K. Fritz, W. Clint Hoffmann, Ryan S. Henry

West Central Research and Extension Center, North Platte

Controlling droplet size is a critical part of making any successful agrochemical spray application. This is particularly true for higher-speed aerial applications where secondary atomization from air shear becomes the most dominant factor driving spray droplet size. Previous research has shown that higher spray pressures can result in larger droplet-sized sprays by increasing the exit velocity of the spray liquid from the nozzles, which in turn decreases the differential velocity between the spray liquid and surrounding airstream, reducing secondary breakup. This work explores the effects of higher-than-normal spray pressures on two typical aerial application nozzles in the presence of a …

The Paper Trail: An Arid Connection & A Book Of A Thousand Plants, Stephen L. Young, Peter Alpert

West Central Research and Extension Center, North Platte

Following my Ph.D., I moved on to Nebraska, where as a beginning faculty member I was able to start a research program in ecology and continue to study what intrigued me most: plant competition and stress. It was during this time that I came across the paper by Peter Alpert (see his article below) and his colleagues on “Invasiveness, invasibility, and the role of environmental stress in preventing the spread of non-native plants” (Perspectives in Plant Ecology, Evolution and Systematics 3:52–66). It was an “aha” moment in reading about biological invasion research and the current consensus at that time regarding …

Invasion During Extreme Weather: Success And Failure In A Temperate Perennial Grassland, James C. Han, Stephen L. Young

West Central Research and Extension Center, North Platte

Invasive and native plant species compete for resources in similar pools, with disturbances often favoring the invader. Yet, increased climate variability may be shifting the competitive edge back toward the natives. We conducted field studies in perennial grasslands to determine the effects of clipping and drought on resource availability (light and moisture) and subsequent establishment of Carduus nutans. We measured light penetration and soil moisture content in C. nutans monoculture, clipped and non clipped grassland with C. nutans, and bare ground control plots. We also tracked phenology of the invader and grasses. Our studies revealed that light was a limiting …