Weed Science Commons^™

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 …

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 …

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 …

Understanding The Basis For Increased 2,4-D Tolerance In Red Clover (Trifolium Pratense): Field Evaluations, Metabolism, And Gene Expression, Lucas Pinheiro De Araujo

Theses and Dissertations--Plant and Soil Sciences

Incorporation of red clover (Trifolium pratense L.) into grass pastures offers several benefits. However, red clover cultivars available for Kentucky producers are highly susceptible to synthetic auxin herbicides, such as 2,4-D (2,4-dichlorophenoxy acetic acid), used for pasture broadleaf weed control. To overcome this problem, UK2014 red clover was bred for increased tolerance to 2,4-D. We compared the field performance of UK2014 to Kenland, a standard cultivar grown in the transition zone of the United States. UK2014 and Kenland were seeded in the springs of 2017 and 2018. Single applications of 0, 1.12, or 2.24 kg ae ha^-1 2,4-D …

Glyphosate Plus Dicamba Spray Solution Deposition, Coverage, And Efficacy As Influenced By Spray Nozzle Design And Weed Density, Madison Dru Kramer

Theses and Dissertations--Plant and Soil Sciences

Dicamba injury to sensitive soybean and other broadleaf crops due to drift is a major issue and label restrictions have been created to mitigate dicamba drift. One restriction is the mandated use of low drift nozzles to spray dicamba; these nozzles produce larger droplets and minimize the production of driftable fines. Experiments were conducted to evaluate herbicide coverage, deposition, and efficacy. Three spray nozzle designs and different weed densities were the main factors in the analysis. Dicamba plus glyphosate was applied to 5 to 10 cm tall weeds with a Turbo TeeJet (TT11005) nozzle and two drift reduction nozzles approved …

Evaluation Of The Influence Of Dicamba Exposure On Crop Injury And Canopy Closure Of Glufosinate Resistant Soybean, Zachary K. Perry

Theses and Dissertations--Plant and Soil Sciences

Dicamba-resistant soybean along with lower volatility dicamba formulations have been introduced in an attempt to control herbicide resistant weeds such as Amaranthus palmeri. This introduction has increased the amount of dicamba being applied later in the growing season increasing the prevalence of dicamba off-target movement. Dicamba damage was simulated by applying low rates of dicamba directly on soybeans at rates (0.5 g ae ha^-1, 1 g ae ha^-1 and 5 g ae ha^-1 dicamba) and five-exposure timings from June 1 to July 10. The experimental design was a randomized complete block with four replications at …

Optimizing Cover Crop Rotations For Water, Nitrogen And Weed Management, Cintia Soledad Sciarresi

Theses and Dissertations--Plant and Soil Sciences

Winter cover crops grown in rotation with grain crops can be an efficient integrated pest management tool (IPM). However, cover crop biomass production and thus successful provisioning of ecosystem services depend on a timely planting and cover crop establishment after harvest of a cash crop in the fall. One potential management adaptation is the use of short-season soybeans to advance cover crop planting date in the fall. Cover crops planted earlier in the fall may provide a greater percentage of ground cover early in the season because of higher biomass accumulation that may improve weed suppression. However, adapting to short-season …

Integrating Cover Crops And Herbicides For Horseweed [Conyza Canadensis (L.) Cronq.] Management Prior To Soybean [Glycine Max (L.) Merr.], Austin Sherman

Theses and Dissertations--Plant and Soil Sciences

Horseweed (Conyza canadensis (L.) Cronq.) is prevalent in Kentucky and can be difficult to control. Research has shown multiple weed control methods to be more sustainable than relying on chemical control alone, so the use of multiple methods for horseweed management was examined in this study. The main objective was to determine best practice(s) to reduce horseweed prior to soybean [Glycine max (L.) Merr.]. Treatments included: fall-planted cover crop [CC; cereal rye (Secale cereale L.) or none], fall-applied herbicide (saflufenacil or none), and spring-applied herbicides (dicamba, 2,4-D ester, or none). We hypothesized horseweed densities would be reduced …

Interseeding Cover Crops To Suppress Weeds In Corn- Soybean Rotations In Kentucky, Victoria Leigh Stanton

Theses and Dissertations--Plant and Soil Sciences

Cover crops are typically sown between cash crops and can suppress weed emergence and growth. If cover crops are sown after cash crop harvest the system is left susceptible to weed emergence while they establish. Interseeding cover crops into a standing cash crop may limit this bare period by allowing cover crops to become established, go into dormancy, and then revive around cash crop senescence. Studies were conducted in Princeton and Lexington, KY, to determine (i) which corn pre-emergent herbicides and mixtures of herbicide active ingredients commonly used by Kentucky growers would impact interseeded cover crop density and biomass, (ii) …

Comparison Of Soil-Applied And Postemergence Herbicides With Multiple Sites Of Herbicidal Activity On Two Populations Of Herbicide-Resistant Palmer Amaranth In Kentucky, Nicholas J. Fleitz

Theses and Dissertations--Plant and Soil Sciences

With the introduction of herbicide resistant Palmer amaranth into Kentucky during the past 10 years there has been an increasing concern for effective control measures in grain production. Field trials were performed in 2016 and 2017 near Barlow and Paris, KY to determine efficacy of chemical control programs targeting herbicide resistant Palmer amaranth. Percent visual control, effects on plant density and plant height were measured in 2016 to determine treatment effectiveness. Treatments containing four different sites of herbicide activity achieved an average of 98% control. Treatments containing only 3, 2 or 1 site of activity only achieved 64%, 45% and …

Selection And Basis For 2,4-D (2,4-Dicholorphenoxyacetic Acid) Tolerance In Red Clover (Trifolium Pratense), Tara L. B. Lewis

Theses and Dissertations--Plant and Soil Sciences

A red clover (Trifolium pratense) population (UK), from a cross between the cultivar Kenland and a 2,4-D tolerant population (Florida), was recurrently selected for 2,4-D tolerance with evaluations after the 6^th, 7^th, and 8^th selection cycles. All UK populations were more 2,4-D tolerant than Kenland. The 2,4-D tolerance following the 6^th selection cycle was similar to the Florida population and tolerance was increased following 7 and 8 cycles of selection by removing plants showing 2,4-D injury and doubling the rate of 2,4-D used for selection.

Yield and forage quality were evaluated in …

Reduced Inputs Turfgrass Through White Clover Inclusion, Bret Andrew Sparks

Theses and Dissertations--Plant and Soil Sciences

Most managed turfgrass species require frequent inputs to maintain an acceptable level of quality. Among these inputs, nitrogen (N) fertilization is usually the most limiting in terms of growth and development. However, N fertilization is also linked to non-point source (NPS) pollution. White clover (WC) is known for its ability to provide N when mixed into stands of turfgrass, and does not pose a threat for NPS pollution. Two field studies were designed to investigate the effects of WC inclusion in stands of cool-season turfgrasses. In the first field study, three cultivation techniques were examined for establishment of WC into …