Weed Science Commons^™

Assessing Integrated Pest Management Protocols For The Invasive Aquatic Weed Giant Salvinia (Salvinia Molesta), Samantha Lee Prinsloo

LSU Doctoral Dissertations

Giant salvinia (Salvinia molesta) is free-floating aquatic fern that originates from South America. Through human introduction, giant salvinia has escaped its native range and is listed as an invasive species across multiple continents causing negative socio-economic and environmental impacts. This research aimed to expand our understanding of integrated pest management for controlling giant salvinia by combining chemical and biological control. The objectives were to assess the effects of rainfastness, carrier volume, and growth stage on herbicide efficacy, assess augmented biological control and optimal weevil release densities, assess weevil populations in the field, determine herbicide and surfactant toxicity to …

Distribution Mapping And Modeling Of The Invasive Japanese Knotweed, Jossalyn Rogalski

Masters Theses

This thesis investigates the distribution of invasive Japanese knotweed across Michigan. This plant poses significant challenges to land management due to its rapid growth, environmental impacts, and difficulty of removal once established. Using geographic information systems (GIS), remotely sensed data, and secondary environmental datasets, this research maps current infestations and analyzes key factors influencing the species’ growth and dispersal, such as soil composition, hydrology, land use, and a range of environmental variables, including climatic (annual mean temperature, temperature seasonality, annual precipitation, precipitation seasonality), elevation, vegetation and hydrological indices (NDVI, EVI, NDWI), percent tree cover, and distance to roads. Spatial analysis …

An Analysis Of Systemic And Contact Herbicide Usage Trends In Illinois Corn Production Systems, Paige E. Mckittrick

Murray State Theses and Dissertations

Herbicide use is central to weed management in Illinois corn production; however, long-term changes in the balance between systemic and contact herbicides have not been well quantified at the statewide scale. This study analyzes herbicide trends in Illinois corn from 1982 to 2016 using secondary data from the USDA Agricultural Chemical Use Survey, paired with climate, regulatory, and herbicide resistance information. Herbicide active ingredients were classified into systemic and contact functional categories and grouped according to Weed Science Society of America (WSSA) mode-of-action (MOA) codes. For each survey year, total herbicide load (lb a.i./acre), functional proportions, MOA-specific contributions, and a …

Characterization Of The Genetic Diversity Of Curlyleaf Pondweed (Potamogeton Crispus L.) In The Contiguous United States And Canada And Analysis Of Possible Hybrid Potamogeton Crispus Lineages, Mallory M. Kaiser

All Graduate Theses, Dissertations, and Other Capstone Projects

Curlyleaf Pondweed (Potamogeton crispus L.) is a prolific invasive species that has spread across the United States and into parts of Canada since its introduction to North America in the 1840s. It causes extensive economic and environmental damage across its invasive range, and its control and eradication are of utmost importance to agricultural, ecological, recreational, and transportational stakeholders. Developments in molecular ecology and invasive management have found that genetic diversity and hybridization of aquatic macrophytes may affect their susceptibility to herbicide treatments, and genotype or lineage identification are important control variables that must be considered in field and …

Kentucky Bluegrass (Poa Pratensis L.) As A Perennial Groundcover: Establishment And Weed Management In Corn, Kiera S. Searcy

Theses and Dissertations--Plant and Soil Sciences

Perennial groundcover (PGC) systems offer a cost-effective alternative to annual cover crops, by providing continuous soil cover, reducing soil erosion, and contributing to integrated weed management (IWM) in corn (Zea mays L.) production systems. Kentucky bluegrass (Poa pratensis L.) has been proposed as a perennial groundcover for corn due to its low growth habit and seasonal dormancy; however, successful adoption is limited by challenges associated with establishment-phase weed competition and compatibility with weed management programs during corn production. The objectives of this research were to (1) evaluate weed management strategies that support Kentucky bluegrass establishment and (2) assess …

A Comparative Analysis Of The Ecophysiology Between The Invasive Macroalgae Starry Stonewort And The Native Macroalgae Chara To Predict Invasion Potential, Thomas J. Zellmer

All Graduate Theses, Dissertations, and Other Capstone Projects

Starry stonewort (Nitellopsis obtusa) is an invasive macroalga from Eurasia. Currently, starry stonewort’s invasive range consists of the upper Midwest and Great Lakes region, including the Mississippi River. Starry stonewort poses recreational and ecological problems by forming dense canopies that extend through the water column. Starry stonewort occupies a late-season niche space with dense biomass occurring in late July and persisting well into autumn. There is a lack of information on the ecophysiology of starry stonewort. In this study, two populations of starry stonewort, Minnesota and New York, were analyzed to compare regional differences in ecophysiology, along with chara (native …

Assessing Grafted Triploid Watermelon And Yellow Nutsedge Growth In Saline Agroecosystems, Joseph F. Bazzle

All Theses

In an effort to better understand how saltwater intrusion events will impact watermelon growers a field trial was conducted to study how saline irrigation water will impact weed growth and seedless watermelon productivity at a joint Clemson University and USDA ARS facility. Weed management has always been a hurdle in vegetable crop production systems, requiring extensive labor even in a conventional setup. For organic growers, often the only economical approach is a combination of mechanical weed control techniques, including plastic mulches, tarps, and hand weeding. For watermelon growers, plastic mulch remains the most effective form of organic weed control available. …

Field Journal: The Excluded Middle, Carrie E. Kouts

Masters Theses

What does it look like to engage with organisms and landscapes at the periphery of anthropocentric value structures? How does one break the internalized myth that the “built” environment is excluded from the natural world? When does a hyper-mobile and hyper-commodified society confront the exponential crisis of animal death? Within this series of journal entries, field notes, collection observations, weird prose, and sensory musings, one will find questions on the nature of being human and the complex narratives of care we encounter in a world shared with more-than-humans. Each handwritten vignette and photograph from daily life weaves a non-linear and …

Impact Of Glufosinate On Sugarcane Yield And Yield Components When Applied Post-Directed And Its Efficacy In Controlling Emerged Itchgrass (Rottboellia Cochinchinensis), Warner R. Simon

LSU Master's Theses

Weed control is extremely important in the Louisiana sugarcane (Saccharum spp.) industry, as it is a perennial crop that grows back after each harvest. Fields are kept weed free using mechanical and chemical methods to prevent weed-crop competition and further establishment of weed populations. The weed itchgrass (Rottboellia cochinchinensis) has become problematic for Louisiana sugarcane producers. Sometimes, itchgrass can still emerge after farmers have made a pre-emergence (PRE) herbicide application. These weeds are usually controlled using the herbicide paraquat dichloride (paraquat) in post-emergence (POST) directed applications. In recent year, 2016-2024, the United States Environmental Protection Agency …

Rejuvra's Effect On Soil Seed Banks, Blake J. Roeslein, Bryan Endress, Abby Mcmurtry, Akasha Faist

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Invasive annual grasses are a major driver of grassland degradation globally. In perennial grasslands, invasion can heavily impact biodiversity, including potential changes to the soil seed banks. Seed banks, the living seeds stored in the upper soil column, play an important role in healthy systems, or can harbor invasive species. To reduce negative invasion outcomes, whether in the seed bank, or aboveground vegetation, pre-emergent herbicides are a commonly used tool for land managers. Pre-emergent herbicides work by targeting seeds as they germinate and begin emerging from the soil. Thus, our study asks 1) how does pre-emergent herbicide influence germination and …

Impact Of An Herbicide Treatment In An Annual Grass Invaded Sagebrush Steppe, Jordan Dino Santia

Undergraduate Scholarship

Globally, rangelands are being threatened by invasive annual grasses (IAGs) that alter fire regimes, drive vegetation type conversion, and alter ecosystem function. This study evaluates vegetation responses to an Imazapic treatment applied in 2020 to control a population of Taeniatherum caput-medusae, an IAG, that flourished following a severe wildfire in 2013. The site, located on a Bureau of Land Management (BLM) grazing allotment east of Klamath Falls, Oregon, has been monitored annually using the Assessment, Inventory, and Monitoring (AIM) protocol since the Summer of 2022. Over this period, very little T. caput-medusae has been detected while bare ground has …

Machine Learning And Uass For Managing Autumn Olive (Elaeagnus Umbellata) On Reclaimed Surface Mines, Sean Michael Keane

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research introduces an innovative approach for managing autumn olive (Elaeagnus umbellata) on reclaimed surface mines through the integration of machine learning algorithms and unmanned aerial systems. The proliferation of autumn olive presents significant ecological challenges on disturbed landscapes, necessitating more efficient detection and control methods. This study evaluated Random Forest classification and deep learning approaches using the U-Net architecture for identifying autumn olive across four phenological stages using high-resolution imagery. The RGB U-Net model achieved F1-scores of 0.927, 0.912, and 0.871 for autumn olive detection during peak, late, and senescence stages respectively, outperforming both multispectral and vegetation …

Screening Herbicides For Use In Newly Established Short Rotation Coppice Shrub Willow Plantations, Alex Thomas Smith

Graduate Theses, Dissertations, and Problem Reports (ETD)

A major setback for the establishment of short rotation coppice willow plantations is the control of competition from weeds. Weed competition has been found to cause increased mortality which lowers biomass yields when left uncontrolled. Mechanical weed control methods are the most used method of weed control, but their use can be complicated by cost, labor availability and site topography. Chemical weed control is also complicated by the fact that willow species are particularly sensitive to herbicides. Across three trials, we screen 11 herbicides for their potential to control weeds without significantly decreasing the vertical growth of willow trees. This …

Cover Cropping Strategies For Improving Weed Suppression, Yashar Askarzadeh

Electronic Theses and Dissertations

Cover crops (CCs) play an essential role in sustainable agriculture by providing multiple ecosystem services. However, adoption remains low due to concerns about economic returns, management complexity, and potential yield reductions in cash crops. Applying CCs uniformly across fields without accounting for spatial variability can result in inconsistent outcomes. A precision cover cropping system (PCCS), which incorporates site-specific management zones (MZs), offers a more targeted approach to improving performance while minimizing costs and uncertainties. This study explores the interaction between CCs and field variability through complementary field and greenhouse experiments. The field experiment demonstrates that field heterogeneity significantly influences CC …

Evaluation Of Poaceae Species And Suppression Application Methods For Perennial Groundcover In Corn, Hallie A. Sandeen

Theses and Dissertations--Plant and Soil Sciences

Intensive grain production aims to provide food security but has depleted once-perennialized land. Perennial groundcover (PGC) offers ecosystem services to intensive annual corn (Zea mays L.) production. In past research conducted in the U.S. Midwest, Kentucky bluegrass (Poa pratensis L.) has been the standard PGC species. However, it is slow growing and difficult to suppress. To characterize the PGC system in the midsouth, two separate field trials in Lexington, Kentucky, were conducted to (i) compare the first-year establishment of alternative cool-season species to Kentucky bluegrass, with and without a spring-applied broadleaf herbicide, and their impact on corn grain …

Zoysiagrass Tolerance To Selective Herbicides For The Removal Of Bermudagrass And The Distribution Of The Annual Bluegrass Weevil (Listronotus Maculicollis) In Kentucky, Kenneth D. Clayton

Theses and Dissertations--Plant and Soil Sciences

Bermudagrass (Cynodon dactylon) may be a problematic weed within zoysiagrass (Zoysia spp.) swards across its entire range. The objective of this study was to determine the efficacy of the herbicide safener metcamifen + trifloxysulfuron-sodium, in conjunction with fluazifop-P-butyl, at removing bermudagrass from zoysiagrass and how varying levels of treatment affected bermudagrass control and zoysiagrass tolerance. Field studies tested rates of metcamifen + trifloxysulfuron-sodium applied with fluazifop-P-butyl compared to treatments of fluazifop alone and fenoxaprop with triclopyr. All treatments controlled bermudagrass, and treatments with the herbicide safener remained under the 20% injury threshold for zoysiagrass for ≤ to 15 days compared …

Improving Reduced Tillage Vegetable Systems For The Northern Great Plains: How Does Early Season Soil Tarping (Solarization And Occultation) Reduce Weeds, Affect Soil Health, And Protect Yield?, Hannah Voye

Electronic Theses and Dissertations

Soil tarping (solarization and occultation) is a no-till weed management practice gaining popularity in the United States for small scale vegetable growers. While many studies have been conducted using variations of this tool in the Northeast United States, minimal research has been done in the windier, sunnier, Midwest climate. Our research explored the effectiveness of early spring solarization and occultation to manage weeds and produce viable onion yield in Eastern South Dakota. Occultation tarps placed in early spring included double sided black and white silage tarps with tarps placed black side up or white side up, each placed 6-, 4-, …

Texas Panicum (Urochloa Texana (Buckley) R.D.Webster) Management In South Carolina Peanut (Arachis Hypogaea L.) Production, Alexis Clobas-Celiz

All Theses

Texas panicum (TP) is a persistent weed in South Carolina peanut fields, challenging growers with its season-long emergence and the limited availability of effective mid- to late-season herbicide options. Residual herbicides typically applied within 40 days of planting, fail to control late-emerging TP cohorts, making postemergence (POST) herbicides like clethodim and imazapic essential for managing this weed. Clethodim efficacy, however, depends on the TP growth stage and environmental conditions during application. To optimize control, this research evaluated clethodim applied at various TP growth stages (5 to 60 cm) and with different adjuvants. Clethodim was applied singly or in sequence, with …

Eastern Baccharis Control In Newly Planted Wetland Reserve Programs, Lucas Stamper

LSU Doctoral Dissertations

The Lower Mississippi Alluvial Valley is a high-priority region for restoration of bottomland hardwood forests. Restoration of these forests is facilitated through conservation easement programs, such as the Conservation Reserve Program (CRP) and the Wetland Reserve Program (WRP), which focus on retiring marginal agriculture land and restoring bottomland hardwoods. A prominent issue that reduces hardwood establishment success is the failure to suppress competing vegetation, like eastern baccharis (Baccharis halimifolia L.), that aggressively colonize a site after seedlings are planted. Eastern baccharis is a frequent woody invader of disturbed bottomland sites throughout northeast Louisiana. There are few chemical options for …

Environmental Physiology Of Medical Cannabis, F. Mitchell Westmoreland

All Graduate Theses and Dissertations, Fall 2023 to Present

Cannabis (Cannabis sativa L.) is increasingly being cultivated for industrial and medical uses. Medical cannabis is grown for cannabinoids and terpenes, compounds that continue to show promising therapeutic potential. Cannabidiol (CBD) and delta-9- tetrahydrocannabinol (Δ9-THC) are the two most common cannabinoids, but more than 150 have been identified in cannabis. The 2018 Farm Bill federally legalized cannabis containing less than 0.3% THC and high-THC medical cannabis is legal in 38 states. There is a need to understand environmental effects on yield and quality to ensure safety and quality for medical use.

The cultivation of medical cannabis is centered around …

From Pixels To Plants: Remote Sensing Of California Invasive Plants, Kenneth Rangel

Master's Projects and Capstones

Invasive plants cause significant impacts to ecosystems, the economy, and human health. California has experienced significant plant invasions and is well suited to future invasion because of its Mediterranean climate and human disturbance. Eradication or control of invasive plant species requires a detailed understanding of their spatial distribution, which typically involves on the ground surveys that can be expensive or inconsistent. Remote sensing offers a potential alternative or supplement to in-person invasive plant mapping. This study performed a comparative analysis of 41 remote sensing studies that mapped the distribution of California invasive plants. I found that while high spectral resolution …

Vegetation Management During Establishment Of Native Grasses And Forb Plantings On Roadsides And Prairie Restoration, Rachel Woody-Pumford

Graduate Theses and Dissertations

North American prairies have been shrinking due to agricultural production, overgrazing, development of cities and towns, and climate change. However, integrated roadside vegetation management (IRVM) creates the opportunity to reestablish prairies along roadsides through planting native grasses and forbs. Utilizing postememergence (POST) herbicides registered for use along rights-of-way has the potential to remove invasive species and create space for newly establishing native grass and forb species. The use of clopyralid, florpyrauxifen-benzyl, metsulfuron, and quinclorac were found to be safe for use in plantings containing big bluestem (Andropogon gerardii Vitman) and butterfly milkweed (Asclepias tuberosa L.). However, florpyrauxifen-benzyl injured and stunted …

Salinity Tolerance Of Flowering Rush, Butomus Umbellatus, Andrew Coomes

Master's Theses

Flowering rush is an invasive aquatic plant in North America that causes deleterious effects to native ecosystems. There are two cytotypes, a triploid and diploid, and multiple genotypes contained within the diploid cytotype currently established in the U.S. Despite its presence in river drainages connected to estuarine areas, documentation on the salinity tolerance of flowering rush is scarce. Currently, information is limited to anecdotal reports suggesting intolerance to saline conditions. A better understanding of the osmotic tolerance of this species is essential to providing insight into its’ invasive range and better inform management efforts. These studies investigated vegetative propagule germination …

Impact Of Early-Season Postemergence Co-Applications Of Foliar And Residual Herbicides On Crop Injury, Growth, And Yield In 2,4-D- And Dicamba-Tolerant Cotton (Gossypium Hirsutum L.), Logan N. Vallee

LSU Master's Theses

Studies were conducted in 2021 through 2023 at the LSU AgCenter Dean Lee Research and Extension Center near Alexandria, LA to determine the sensitivity of 2,4-D- or dicamba- tolerant cotton (Gossypium hirsutum L.) to an early season application of a Group 15 and foliar-only herbicides. Both studies were randomized complete block designs with a two-factorial arrangement of treatments with four replications. In the dicamba-tolerant cotton study, Factor A consisted of no foliar-herbicide, dicamba alone, glyphosate alone, or dicamba plus glyphosate. Factor B consisted of either no Group 15 residual herbicide, acetochlor, or S-metolachlor. In the 2,4-D- tolerant cotton …

Halosulfuron Plus Prosulfuron And Propanil Interactions For Weed Control In Louisiana Rice Production, John A. Williams

LSU Master's Theses

A greenhouse study was conducted on November 18, and December 2, 2020 at Louisiana State University in Baton Rouge, Louisiana to evaluate the interaction between a pre-packaged mixture of halosulfuron plus prosulfuron mixed with propanil for alligatorweed control. Antagonism occurred when halosulfuron plus prosulfuron at 55 g ha-1 was mixed with propanil at 2,242 g ha-1 at all evaluation dates and antagonism was also observed with halosulfuron plus prosulfuron at 83 g ha-1 mixed with propanil at 2,242 g ha-1 at all evaluation dates except 14 DAT with observed controls of 69 to 77% compared with expected controls of 94 …

Ms Environmental Biology Capstone Project, Sarah Luper

Regis University Student Publications (comprehensive collection)

Recreational trails and the presence of invasive species such as Bromus inermis can both disturb grassland community composition. Trails can act as dispersal corridors for plant material, but can also be a source of trampling and compaction. Invasive grasses like Bromus inermis can easily establish in grasslands and decrease species richness by increasing competition. Understanding these effects, this study aims to understand how both the presence of recreational trails as well as the presence of Bromus inermis affect species richness and overall community composition at Two Ponds National Wildlife Refuge. Belt transect sampling took place in fall 2019 and again …

Exploring The Impact Of Invasive On Grassland Diversity: A Study In Montana, Ella Gaffney

Undergraduate Theses, Professional Papers, and Capstone Artifacts

For the capstone project with the University of Montana Davidson Honors College, I investigated the diversity index of grassland and rangeland plots across the state of Montana. My study, conducted from June to August 2023, includes data collected by my team. The purpose of this research project was testing the hypothesis that the diversity index decreases in plots containing invasive grass species.

During the summer of 2023, the Spatial Analysis Lab surveyed over 1000 plots in rangelands and grasslands across the state of Montana to locate an invasive grass, Ventenata dubia. Data collected includes species identification, ocular estimates of …

Quantifying The Ecological Effects Of Salix Fragilis On Riparian Habitat In Kittitas County, Washington, Landon Shaffer

All Master's Theses

Invasive species threaten plant community structure and function globally. Riparian areas, the zone near streams where water influences vegetation, are especially sensitive to invasive species colonization, suffering large-scale shifts in community composition. Salix fragilis (crack willow) is a nonnative riparian species abundant in the lower elevation tributaries of central Washington. Some speculate whether this willow should be listed as invasive in Washington, despite a lack of regional supporting evidence. I studied riparian communities dominated by either S. fragilis or native species in the Kittitas Valley and measured biodiversity, quantified differences in solar attenuation, and compared leaf decomposition rates to learn …

Genetic And Ecologic Effects Of Seed Dormancy Genes On Seed Aging, Soil Seedbank Longevity, And Microbiome In An Isogenic Background Of Rice ( Oryza Sativa L.), Bhupinder Singh Batth

Electronic Theses and Dissertations

No abstract provided.

Evaluation Of The Management Of Italian Ryegrass (Lolium Perenne Ssp. Multiflorum) Using Harvest Weed Seed Control At Winter Wheat Harvest In Kentucky, Hayden Love

Theses and Dissertations--Plant and Soil Sciences

With increasing herbicide resistant weed populations in Kentucky winter wheat, producers are looking for new weed control options for Italian ryegrass (Lolium perenne L. ssp. multiflorum Lam.). A field study was conducted to better understand Italian ryegrass seed dispersal and the effectiveness of the Redekop seed control unit at winter wheat harvest in Kentucky. During harvest, the number of Italian ryegrass seeds shattering at the combine header, in the chaff, and contained in the grain tank was not significantly different. When the grain and chaff samples were combined, significantly more Italian ryegrass seed entered the combine. The integrated …