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Full-Text Articles in Life Sciences

Characterization And Management Of Auxin-Resistant Palmer Amaranth In Tennessee, Delaney C. Foster Dec 2022

Characterization And Management Of Auxin-Resistant Palmer Amaranth In Tennessee, Delaney C. Foster

Doctoral Dissertations

Palmer amaranth has a long history of evolving resistance to herbicides to the point it has become a significant row crop production obstacle. Cotton and soybean growers were offered new technologies in 2016, expanding in-crop herbicide options to include dicamba or 2,4-D. Within three years of commercialization, dicamba use in these crops increased ten-fold and growers began to report Palmer amaranth escapes in west Tennessee auxin-tolerant production systems. A survey of Palmer amaranth escapes in dicamba and 2,4-D-tolerant cotton and soybean fields in Tennessee was conducted in the fall of 2021 with the objective of determining if poor control was …


Evaluation Of Cotton Management Decisions: Cover Crops, Weed Control, And Injured Stands, Savana D. Denton May 2022

Evaluation Of Cotton Management Decisions: Cover Crops, Weed Control, And Injured Stands, Savana D. Denton

Doctoral Dissertations

Herbicide-resistant weed species have altered the challenges faced by Tennessee cotton (Gossypium hirsutum, L.) producers. While the weed control and environmental benefits of cover crops have been well-documented, the integration of cover crops into cotton production systems has presented management challenges. In-season broadcast postemergence weed control options are limited in cotton. Furthermore, off-target movement of 2,4-D and dicamba can result in additional management challenges if susceptible cotton is injured. Studies were conducted from 2018 to 2021 to evaluate: 1) cotton response to cover crop termination timings and methods; 2) postemergence weed control programs in cotton without the use of …


Effect Of Herbicide Concentration On Atrazine, Pyroxasulfone, And Saflufenacil Dissipation Under Field And Lab Conditions, Randall Lee Landry May 2022

Effect Of Herbicide Concentration On Atrazine, Pyroxasulfone, And Saflufenacil Dissipation Under Field And Lab Conditions, Randall Lee Landry

Doctoral Dissertations

Widespread herbicide resistant weeds over the last several years have fueled a renewed interest in the utility of soil-applied residual herbicides. Residual activity of a herbicide is based on a myriad of factors within and among environments. A common assumption used in simulation models examining herbicide persistence is that herbicide degradation is independent of application rate. These studies compared herbicide concentration on dissipation with three commonly used residual herbicides under field and lab conditions. Atrazine, pyroxasulfone, and saflufenacil represent herbicides with a relative field persistence of medium, high, and low, respectively. Field studies were conducted over two years where herbicides …


Poa Annua: An Annual Species?, Devon E. Carroll May 2022

Poa Annua: An Annual Species?, Devon E. Carroll

Doctoral Dissertations

Poa annua L. is ranked the most troublesome turfgrass weed but can also be a highly desirable turfgrass species. As the Latin name annua implies, the species is thought to persist via an annual life cycle; yet there are many reports in literature of P. annua persisting perennially. Considering that P. annua senescence patterns do not align with other true annual species such as Triticum spp. and Zea mays L., we hypothesized that P. annua presents itself similarly to other perennial, cool-season, turfgrass species that are subject to a confluence of environmental factors in summer that can cause mortality. …


A Bioassay To Determine Poa Annua Responses To Indaziflam, Benjamin D. Pritchard May 2022

A Bioassay To Determine Poa Annua Responses To Indaziflam, Benjamin D. Pritchard

Masters Theses

Herbicide resistance within Poa annua is widespread in managed turfgrass systems. In 2020, a P. annua collection from a golf course in the southeastern United States was reported to be resistant to indaziflam as well as six other mode-of-action groups. Considering P. annua is the most troublesome weed in turfgrass, a bioassay to screen other collections with putative indaziflam resistance is needed. A dose-response experiment was conducted with ten concentrations of indaziflam (0, 250, 500, 750, 1000, 1250, 1500, 2000, 4500, and 9000 pM) in Gelrite® culture during 2021 and 2022. An herbicide-susceptible (S1) collection of P. annua, a …