@article{everman_thomas_burton_york_wilcut_2009, title={Absorption, Translocation, and Metabolism of Glufosinate in Transgenic and Nontransgenic Cotton, Palmer Amaranth (Amaranthus palmeri), and Pitted Morningglory (Ipomoea lacunosa)}, volume={57}, ISSN={["1550-2759"]}, DOI={10.1614/WS-09-015.1}, abstractNote={Greenhouse studies were conducted to evaluate absorption, translocation, and metabolism of14C-glufosinate in glufosinate-resistant cotton, nontransgenic cotton, Palmer amaranth, and pitted morningglory. Cotton plants were treated at the four-leaf stage, whereas Palmer amaranth and pitted morningglory were treated at 7.5 and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption of14C-glufosinate was greater than 85% 24 h after treatment in Palmer amaranth. Absorption was less than 30% at all harvest intervals for glufosinate-resistant cotton, nontransgenic cotton, and pitted morningglory. At 24 HAT, 49 and 12% of radioactivity was translocated to regions above and below the treated leaf, respectively, in Palmer amaranth. Metabolites of14C-glufosinate were detected in all crop and weed species. Metabolism of14C-glufosinate was 16% or lower in nontransgenic cotton and pitted morningglory; however, metabolism rates were greater than 70% in glufosinate-resistant cotton 72 HAT. Intermediate metabolism was observed for Palmer amaranth, with metabolites comprising 20 to 30% of detectable radioactivity between 6 and 72 HAT.}, number={4}, journal={WEED SCIENCE}, author={Everman, Wesley J. and Thomas, Walter E. and Burton, James D. and York, Alan C. and Wilcut, John W.}, year={2009}, pages={357–361} }
 @article{burke_thomas_allen_collins_wilcut_2008, title={A Comparison of Weed Control in Herbicide-Resistant, Herbicide-Tolerant, and Conventional Corn}, volume={22}, ISSN={["0890-037X"]}, DOI={10.1614/WT-07-184.1}, abstractNote={Experiments were conducted at three North Carolina research stations in 2003 to evaluate weed control and corn yield in glyphosate-resistant, glufosinate-resistant, imidazolinone-tolerant, and conventional corn weed management systems. Late-season control of common lambsquarters, large crabgrass, and yellow nutsedge increased with metolachlor PRE compared with no PRE herbicide treatment. Common lambsquarters, pitted morningglory, entireleaf morningglory, spurred anoda, and tropic croton control was improved by a single early POST (EPOST) application regardless of herbicide system. Control of common lambsquarters, pitted morningglory, entireleaf morningglory, and spurred anoda was similar for glyphosate and glufosinate systems for each POST over-the-top (POT) herbicide system. A single EPOST application of imazethapyr plus imazapyr to imidazolinone-tolerant corn controlled common lambsquarters, pitted morningglory, entireleaf morningglory, and spurred anoda and was better than a single EPOST application of glyphosate, glufosinate, or nicosulfuron. Tropic croton was controlled ≥ 95% with glufosinate or glyphosate, applied once or twice, or in mixture with metolachlor. A single EPOST application of imazethapyr plus imazapyr or nicosulfuron did not control tropic croton. Common lambsquarters, entireleaf morningglory, large crabgrass, Palmer amaranth, and yellow nutsedge control was greater with a late-POST–directed (LAYBY) of ametryn than no LAYBY. Systems that did not include a POT herbicide system had the lowest percentage in the weed-free yield and the lowest yield. Treatments that included a POT system with or without a PRE treatment of metolachlor yielded within 5% of the weed-free treatment, regardless of herbicide system.}, number={4}, journal={WEED TECHNOLOGY}, author={Burke, Ian C. and Thomas, Walter E. and Allen, Jayla R. and Collins, Jim and Wilcut, John W.}, year={2008}, pages={571–579} }
 @article{clewis_thomas_everman_witcut_2008, title={Glufosinate-resistant corn interference in glufosinate-resistant cotton}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/WT-07-085.1}, abstractNote={Studies were conducted at three locations in North Carolina in 2004 to evaluate density-dependent effects of glufosinate-resistant (GUR) corn on GUR cotton growth and lint yield. GUR corn was taller than GUR cotton as early as 11 d after planting, depending on location. A GUR corn density of 5.25 plant/m of crop row reduced late-season cotton height by 38, 43, and 43% at Clayton, Lewiston-Woodville, and Rocky Mount, NC, respectively, compared with weed-free cotton height. GUR corn dry biomass per meter of crop row and GUR corn seed biomass per meter of crop row decreased linearly with increasing GUR corn density at all locations. The relationship between GUR corn density and GUR cotton yield loss was described by the rectangular hyperbola model with the asymptote (a) constrained to 100% maximum yield loss. The estimated coefficient i (yield loss per unit density as density approaches zero) was 7, 5, and 6 at Clayton, Lewiston-Woodville, and Rocky Mount, respectively. Percentage of GUR cotton lint yield loss increased 4, 5, and 8 percentage points at Clayton, Lewiston-Woodville, and Rocky Mount, respectively, with each 500 g increase in weed biomass/m of crop row. The examined GUR corn densities had a significant effect on cotton yield but not as significant as many other problematic grass and broadleaf weeds. Nomenclature: Glufosinate, corn, Zea mays L. ‘Pioneer 34A55LL’ ZEAMX, cotton, Gossypium hirsutum L., ‘FM 958LL’}, number={2}, journal={WEED TECHNOLOGY}, author={Clewis, Scott B. and Thomas, Walter E. and Everman, Wesley J. and Witcut, John W.}, year={2008}, pages={211–216} }
 @article{thomas_everman_burke_koger_wilcut_2007, title={Absorption and translocation of glyphosate and sucrose in glyphosate-resistant cotton}, volume={21}, ISSN={["0890-037X"]}, DOI={10.1614/WT-06-125.1}, abstractNote={Studies were conducted to evaluate absorption and translocation of 14C-glyphosate in glyphosate-resistant (GR) cotton. Both commercial GR cotton events [glyphosate-resistant event 1, marketed as Roundup Ready®, released 1997 (GRE1), and glyphosate-resistant event 2, marketed as Roundup Ready Flex®, released 2006 (GRE2)] were evaluated at the four-leaf and eight-leaf growth stages. Plants were harvested at 1, 3, 5, and 7 d after treatment (DAT). Glyphosate absorption, as a percentage of applied, increased over time with 29 and 36% absorption at 7 DAT in four-leaf GRE1 and GRE2 cotton, respectively. In eight-leaf cotton, glyphosate absorption (33% at 7 DAT) was not different between events. Glyphosate translocation patterns were not different between events or harvest timings and exhibited a source–sink relation. Observed translocation differences between cotton growth stages were probably due to reduced glyphosate export from the treated leaf of eight-leaf cotton. An additional study compared absorption and translocation of 14C-glyphosate and 14C-sucrose in 5- and 10-leaf GRE2 cotton. Averaged over trials, 14C compounds, and growth stages, cotton absorbed 28% of the applied dose at 14 DAT. On the basis of the percentage of 14C exported out of the treated leaf, glyphosate and sucrose translocation patterns were similar, indicating that glyphosate may be used as a photoassimilate model in GRE2 cotton. Nomenclature: Glyphosate; cotton, Gossypium hirsutum L.}, number={2}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Burke, Ian C. and Koger, Clifford H. and Wilcut, John W.}, year={2007}, pages={459–464} }
 @article{thomas_everman_allen_collins_wilcut_2007, title={Economic assessment of weed management systems in glufosinate-resistant, glyphosate-resistant, imidazolinone-tolerant, and nontransgenic corn}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-054.1}, abstractNote={Four field studies were conducted in 2004 to evaluate corn tolerance, weed control, grain yield, and net returns in glufosinate-resistant (GUR), glyphosate-resistant (GYR), imidazolinone-tolerant (IT), and nontransgenic (NT) corn with various herbicide systems. No significant differences between hybrid systems were observed for weed control. Limited corn injury (< 5%) was observed for all herbicide treatments. A single early POST (EPOST) system withoutS-metolachlor and sequential POST over the top (POT) herbicide systems, averaged over corn hybrids and PRE and late POST-directed (LAYBY) herbicide options, provide 93 and 99% control of goosegrass, respectively, and at least 83 and 97% control of Texas panicum, respectively. A single EPOST system withoutS-metolachlor, averaged over corn hybrids and LAYBY treatment options, provided at least 88% control of large crabgrass. When averaged over corn hybrid and PRE herbicide options, a sequential POT herbicide system alone provided at least 98, 99, 98, and 100 control of large crabgrass, morningglory species, Palmer amaranth, and common lambsquarters, respectively. The addition of ametryn at LAYBY to a single EPOST system withoutS-metolachlor was beneficial for improving control of morningglory species, common lambsquarters, and Palmer amaranth, depending on location. However, the observed increases (7 percentage points or less) are likely of limited biological significance. Grain yield was variable between hybrids and locations because of environmental differences. Consequently, net returns for each hybrid system within a location were also variable. Any POT system with or without ametryn at LAYBY, averaged over corn hybrid and PRE herbicide options, provided at least 101, 97, 92, and 92% yield protection at Clayton, Kinston, Lewiston, and Rocky Mount, NC, respectively. Net returns were maximized with treatments that provided excellent weed control with minimal inputs.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Allen, Jayla and Collins, Jim and Wilcut, John W.}, year={2007}, pages={191–198} }
 @article{thomas_everman_clewis_wilcut_2007, title={Glyphosate-resistant corn interference in glyphosate-resistant cotton}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-007.1}, abstractNote={Studies were conducted at three locations in North Carolina in 2004 to evaluate density-dependent effects of glyphosate-resistant (GR) corn on GR cotton growth and lint yield. GR corn was taller than GR cotton as early as 25 d after planting, depending on location. A GR corn density of 5.25 plant/m of crop row reduced late season cotton height by 49, 24, and 28% at Clayton, Lewiston–Woodville, and Rocky Mount, respectively, compared to weed-free cotton height. At Clayton, GR corn dry biomass per m crop row and GR corn seed biomass per m of crop row decreased linearly with increasing corn density. The relationship between GR corn and GR cotton yield loss was described by the rectangular hyperbola model with the asymptote (a) constrained to 100% maximum yield loss. The estimated coefficient i (yield loss per unit density as density approaches zero) was 9, 5, and 5 at Clayton, Lewiston–Woodville, and Rocky Mount, respectively. The examined GR corn densities had a significant effect on cotton yield, but not as significant as many other problematic grass and broadleaf weeds. Nomenclature: Glyphosate; corn, Zea mays L., ZEAMX, ‘DKC 69-71RR’; cotton, Gossypium hirsutum L. ‘FM 989RR’, ‘ST 4892RR’.}, number={2}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Clewis, Scott B. and Wilcut, John W.}, year={2007}, pages={372–377} }
 @article{burke_schroeder_thomas_wilcut_2007, title={Palmer amaranth interference and seed production in peanut}, volume={21}, ISSN={["0890-037X"]}, DOI={10.1614/WT-06-058.1}, abstractNote={Studies were conducted to evaluate density-dependent effects of Palmer amaranth on weed and peanut growth and peanut yield. Palmer amaranth remained taller than peanut throughout the growing season and decreased peanut canopy diameter, although Palmer amaranth density did not affect peanut height. The rapid increase in Palmer amaranth height at Goldsboro correspondingly reduced the maximum peanut canopy diameter at that location, although the growth trends for peanut canopy diameter were similar for both locations. Palmer amaranth biomass was affected by weed density when grown with peanut. Peanut pod weight decreased linearly 2.89 kg/ha with each gram of increase in Palmer amaranth biomass per meter of crop row. Predicted peanut yield loss from season-long interference of one Palmer amaranth plant per meter of crop row was 28%. Palmer amaranth seed production was also described by the rectangular hyperbola model. At the highest density of 5.2 Palmer amaranth plants/m crop row, 1.2 billion Palmer amaranth seed/ha were produced. Nomenclature: Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA; peanut, Arachis hypogaea L. ‘Perry’.}, number={2}, journal={WEED TECHNOLOGY}, author={Burke, Ian C. and Schroeder, Michelle and Thomas, Walter E. and Wilcut, John W.}, year={2007}, pages={367–371} }
 @article{thomas_everman_collins_koger_wilcut_2007, title={Rain-free requirement and physiological properties of cotton plant growth regulators}, volume={88}, ISSN={["1095-9939"]}, DOI={10.1016/j.pestbp.2006.12.002}, abstractNote={Greenhouse studies were conducted to (1) evaluate the rain-free requirement for mepiquat chloride and mepiquat chloride plus cyclanilide with and without surfactant and to (2) evaluate absorption and translocation of cyclanilide, a component of a new cotton plant growth regulator. No significant differences in the number of nodes, leaf area, and plant organ fresh and dry weight were observed with any PGR treatment and rainfall simulation combination. Both plant growth regulators responded similarly to rainfall interval. As rain-free period increased, cotton height was reduced. Based on these data, a rain-free period of 8 h is needed to maximize efficacy, regardless of the use of surfactant. Absorption of cyclanilide ranged from 11 to 15% at 3 and 48 h after treatment, respectively. Averaged over harvest intervals, 18% of the applied cyclanilide remained in the treated leaf while 1.7 and 6.5% of the applied cyclanilide was found in the above and below treated leaf tissue, respectively.}, number={3}, journal={PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Collins, James R. and Koger, Clifford H. and Wilcut, John W.}, year={2007}, month={Jul}, pages={247–251} }
 @article{lassiter_burke_thomas_pline-srnic_jordan_wilcut_wilkerson_2007, title={Yield and physiological response of peanut to glyphosate drift}, volume={21}, ISSN={["0890-037X"]}, DOI={10.1614/WT-07-045.1}, abstractNote={Five experiments were conducted during 2001 and 2002 in North Carolina to evaluate peanut injury and pod yield when glyphosate was applied to 10 to 15 cm diameter peanut plants at rates ranging from 9 to 1,120 g ai/ha. Shikimic acid accumulation was determined in three of the five experiments. Visual foliar injury (necrosis and chlorosis) was noted 7 d after treatment (DAT) when glyphosate was applied at 18 g/ha or higher. Glyphosate at 280 g/ha or higher significantly injured the peanut plant and reduced pod yield. Shikimic acid accumulation was negatively correlated with visual injury and pod yield. The presence of shikimic acid can be detected using a leaf tissue assay, which is an effective diagnostic tool for determining exposure of peanut to glyphosate 7 DAT.}, number={4}, journal={WEED TECHNOLOGY}, author={Lassiter, Bridget R. and Burke, Ian C. and Thomas, Walter E. and Pline-Srnic, Wendy A. and Jordan, David L. and Wilcut, John W. and Wilkerson, Gall G.}, year={2007}, pages={954–960} }
 @article{burke_thomas_burton_spears_wilcut_2006, title={A seedling assay to screen aryloxyphenoxypropionic acid and cyclohexanedione resistance in johnsongrass (Sorghum halepense)}, volume={20}, ISSN={["0890-037X"]}, DOI={10.1614/WT-05-160.1}, abstractNote={A seedling bioassay was developed for the rapid diagnosis of resistance to clethodim and fluazifop-P in johnsongrass. The assay was based on differences in the coleoptile length of susceptible (S) and resistant (R) seedlings exposed to clethodim and fluazifop-P in petri dishes for 5 d. Bioassay concentrations of 0.09 mg/L clethodim and 0.18 mg/L fluazifop-P were chosen as discriminant based on rate responses of each biotype to increasing herbicide dose. At 5 d after treatment (DAT), the amounts of clethodim required to reduce coleoptile length by 50% (GR50) for the R and S seedlings were 462.5 and 24.8 mg/L, respectively, resulting in an R:S ratio of 18.7. The fluazifopGR50values for the R and S seedlings were 618.7 and 17.5 mg/L, respectively, resulting in a R:S ratio of 35.4.}, number={4}, journal={WEED TECHNOLOGY}, author={Burke, Ian C. and Thomas, Walter E. and Burton, James D. and Spears, Janet F. and Wilcut, John W.}, year={2006}, pages={950–955} }
 @article{thomas_britton_clewis_askew_wilcut_2006, title={Glyphosate-resistant cotton (Gossypium hirsutum) response and weed management with trifloxysulfuron, glyphosate, prometryn, and MSMA}, volume={20}, ISSN={["1550-2740"]}, DOI={10.1614/WT-04-257R1.1}, abstractNote={Field studies were conducted at three locations to evaluate glyphosate-resistant (GR) cotton response, weed control, and cotton lint yields to two formulations of glyphosate (diammonium salt– glyphosate and isopropylamine salt–glyphosate) and trifloxysulfuron applied early postemergence (EPOST) alone or to tank mixtures of trifloxysulfuron with each glyphosate formulation, with and without a late postemergence-directed (LAYBY) treatment of prometryn plus MSMA. Trifloxysulfuron and both formulations of glyphosate controlled common lambsquarters and pitted morningglory. Both glyphosate formulations provided equivalent control of common lambsquarters, goosegrass, pitted morningglory, prickly sida, and smooth pigweed. Trifloxysulfuron controlled smooth pigweed better than either glyphosate formulation but did not control goosegrass or prickly sida. Prometryn plus MSMA LAYBY improved late-season control of common lambsquarters, goosegrass, large crabgrass, and pitted morningglory for all EPOST systems and improved late-season smooth pigweed control for EPOST systems that did not include trifloxysulfuron. Cotton injury was 2% or less from both glyphosate formulations, while trifloxysulfuron injured ‘Deltapine 5415RR’ 7 to 16% at two locations. At a third location, trifloxysulfuron injured ‘Paymaster 1218RR/BG’ 24%, and when applied in mixture with either glyphosate formulation, injury increased to at least 72%. Cotton injury was transient at the first two locations and was not visually apparent 3 to 5 wk later. Cotton yield at the third location was reduced. High cotton yields reflected high levels of weed control.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Britton, TT and Clewis, SB and Askew, SD and Wilcut, JW}, year={2006}, pages={6–13} }
 @article{thomas_burke_spears_wilcut_2006, title={Influence of environmental factors on slender amaranth (Amaranthus viridis) germination}, volume={54}, DOI={10.1614/ws-05-54.2.316}, abstractNote={Germination response of slender amaranth to temperature, solution pH, moisture stress, and depth of emergence was evaluated under controlled environmental conditions. Results indicated that 30 C was the optimum constant temperature for germination. Germination of slender amaranth seed at 21 d was similar, with 35/25, 35/20, 30/25, and 30/20 alternating temperature regimes. As temperatures in alternating regimes increased, time to onset of germination decreased and rate of germination increased. Slender amaranth germination was greater with acidic than with basic pH conditions. Germination declined with increasing water stress and was completely inhibited at water potentials below −0.6 MPa. Slender amaranth emergence was greatest at depths of 0.5 to 2 cm, but some seeds emerged from as deep as 6 cm. Information gained in this study will contribute to an integrated control program for slender amaranth.}, number={2}, journal={Weed Science}, author={Thomas, W. E. and Burke, I. C. and Spears, J. F. and Wilcut, J. W.}, year={2006}, pages={316–320} }
 @article{koger_shaner_henry_nadler-hassar_thomas_wilcut_2005, title={Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)}, volume={53}, ISSN={["1550-2759"]}, DOI={10.1614/WS-05-010R}, abstractNote={Two rapid, nondestructive assays were developed and tested for their potential in differentiating glyphosate-resistant from glyphosate-susceptible biotypes of horseweed. In one assay, leaves of glyphosate-resistant and -susceptible corn, cotton, and soybean plants, as well as glyphosate-resistant and -susceptible horseweed plants, were dipped in solutions of 0, 300, 600, and 1,200 mg ae L−1glyphosate for 3 d, and subsequent injury was evaluated. In the second assay, plant sensitivity to glyphosate was evaluated in vivo by incubating excised leaf disc tissue from the same plants used in the first assay in 0.7, 1.3, 2.6, 5.3, 10.6, 21.1, 42.3, and 84.5 mg ae L−1glyphosate solutions for 16 h and measuring shikimate levels with a spectrophotometer. The leaf dip assay differentiated between glyphosate-resistant and -susceptible crops and horseweed biotypes. The 600 mg L−1rate of glyphosate was more consistent in differentiating resistant and susceptible plants compared with the 300 and 1,200 mg L−1rates. The in vivo assay detected significant differences between susceptible and glyphosate-resistant plants of all species. Shikimate accumulated in a glyphosate dose–dependent manner in leaf discs from susceptible crops, but shikimate did not accumulate in leaf discs from resistant crops, and levels were similar to nontreated leaf discs. Shikimate accumulated at high (≥ 21.1 mg ae L−1) concentrations of glyphosate in leaf discs from all horseweed biotypes. Shikimate accumulated at low glyphosate concentrations (≤ 10.6 mg L−1) in leaf discs from susceptible horseweed biotypes but not in resistant biotypes. Both assays were able to differentiate resistant from susceptible biotypes of horseweed and could have utility for screening other weed populations for resistance to glyphosate.}, number={4}, journal={WEED SCIENCE}, author={Koger, CH and Shaner, DL and Henry, WB and Nadler-Hassar, T and Thomas, WE and Wilcut, JW}, year={2005}, pages={438–445} }
 @article{koger_shaner_henry_nadler-hassar_thomas_wilcut_2005, title={Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)}, volume={53}, ISSN={["1550-2759"]}, DOI={10.1614/WS-05-010R.1}, abstractNote={Two rapid, nondestructive assays were developed and tested for their potential in differentiating glyphosate-resistant from glyphosate-susceptible biotypes of horseweed. In one assay, leaves of glyphosate-resistant and -susceptible corn, cotton, and soybean plants as well as glyphosate-resistant and -susceptible horseweed plants were dipped in solutions of 0, 300, 600, and 1200 mg ae L−1glyphosate for 3 d and subsequent injury was evaluated. In the second assay, plant sensitivity to glyphosate was evaluated in vivo by incubating excised leaf disc tissue from the same plants used in the first assay in 0.7, 1.3, 2.6, 5.3, 10.6, 21.1, 42.3, and 84.5 mg ae L−1glyphosate solutions for 16 h and measuring shikimate levels with a spectrophotometer. The leaf-dip assay differentiated between glyphosate-resistant and -susceptible crops and horseweed biotypes. The 600 mg L−1rate of glyphosate was more consistent in differentiating resistant and susceptible plants compared with the 300 and 1,200 mg L−1rates. The in vivo assay detected significant differences between susceptible and glyphosate-resistant plants of all species. Shikimate accumulated in a glyphosate dose-dependent manner in leaf discs from susceptible crops, but shikimate did not accumulate in leaf discs from resistant crops and levels were similar to nontreated leaf discs. Shikimate accumulated at high (≥ 21.1 mg ae L−1) concentrations of glyphosate in leaf discs from all horseweed biotypes. Shikimate accumulated at low glyphosate concentrations (≤ 10.6 mg L−1) in leaf discs from susceptible horseweed biotypes but not in resistant biotypes. Both assays were able to differentiate resistant from susceptible biotypes of horseweed and might have utility for screening other weed populations for resistance to glyphosate.}, number={5}, journal={WEED SCIENCE}, author={Koger, CH and Shaner, DL and Henry, WB and Nadler-Hassar, T and Thomas, WE and Wilcut, JW}, year={2005}, pages={559–566} }
 @article{thomas_pline-srnic_viator_wilcut_2005, title={Effects of glyphosate application timing and rate on sicklepod (Senna obtusifolia) fecundity}, volume={19}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-223R}, abstractNote={Greenhouse experiments were conducted to examine the effect of glyphosate on reproductive development in sicklepod. Glyphosate was applied postemergence over the top at 112 and 280 g ai/ha to sicklepod at 4-leaf stage (L), 8-L, 4-L followed by 8-L, and 12-L. A nontreated control was included. Immediately after the 12-L application, number of flowers was recorded for all treatments twice per week for 8 wk. Pollen viability was measured on 1 open flower/plant/sampling time using Alexander stain. The number of pods, pod length, seeds per plant, 50-seed weight, total seed weight, seed germination, seed viability, and dry weight of aboveground biomass were also recorded. No significant differences among the treatments were found for average pod length, 50-seed weight, seed germination, seed viability, and aboveground biomass. The nontreated had 18 flowers counted over 8 wk. Glyphosate applied at 12-L and sequentially at 4-L and 8-L, averaged over glyphosate rates, reduced cumulative flower production after 8 wk by 65 and 54%, respectively, compared with the nontreated. Similarly, glyphosate at 280 g/ha, averaged over treatment timings, reduced flower production by 58% compared with the nontreated. Because the number of flowers produced was limited by glyphosate treatment due to flower abscission, pollen viability measurements could not be analyzed because of large numbers of missing data points. The number of pods, seeds, and total seed weight were reduced by 79, 80, and 81%, respectively, with 280 g/ha of glyphosate compared with the nontreated. Nomenclature: Glyphosate; sicklepod, Senna obtusifolia (L.) Irwin and Barneby #3 CASOB. Additional index words: Alexander stain, pollen viability, tetrazolium chloride. Abbreviations: fb, followed by; IAA, indoleacetic acid; L, leaf stage.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Pline-Srnic, WA and Viator, RP and Wilcut, JW}, year={2005}, pages={55–61} }
 @article{koger_shaner_krutz_walker_buehring_henry_thomas_wilcut_2005, title={Rice (Oryza satiova) response to drift rates of glyphosate}, volume={61}, DOI={10.1002/pt.1113}, number={12}, journal={Pest Management Science}, author={Koger, C. H. and Shaner, D. L. and Krutz, L. J. and Walker, T. W. and Buehring, N. and Henry, W. B. and Thomas, W. E. and Wilcut, J. W.}, year={2005}, pages={1161–1167} }
 @article{thomas_troxler_smith_fisher_wilcut_2005, title={Uptake, translocation, and metabolism of sulfentrazone in peanut, prickly sida (Sida spinosa), and pitted morningglory (Ipomoea lacunosa)}, volume={53}, ISSN={["1550-2759"]}, DOI={10.1614/WS-04-085R2}, abstractNote={Studies were conducted to evaluate uptake, translocation, and metabolism of root-absorbed14C-sulfentrazone in peanut, prickly sida, and pitted morningglory. Peanut absorbed more than five and three times greater14C-sulfentrazone than pitted morningglory and prickly sida, respectively. All plant species translocated appreciable amounts (≥ 39%) of radioactivity to the leaves. The three plant species had some capacity to metabolize14C-sulfentrazone. At 3 h after treatment, 7, 29, and 71% of the radioactivity in the shoots of peanut, prickly sida, and pitted morningglory, respectively, was sulfentrazone. Sulfentrazone levels in the shoots at 3 and 6 h after treatment correspond to reported tolerance levels, with peanut being the most tolerant of the three species, whereas prickly sida and pitted morningglory are moderately tolerant and completely susceptible to sulfentrazone, respectively. Levels of metabolites varied among species, plant part, and harvest timing. On the basis of these data, tolerance in peanut is largely due to its ability to rapidly metabolize sulfentrazone.}, number={4}, journal={WEED SCIENCE}, author={Thomas, WE and Troxler, SC and Smith, WD and Fisher, LR and Wilcut, JW}, year={2005}, pages={446–450} }
 @article{burke_thomas_pline-srnic_fisher_smith_wilcut_2005, title={Yield and physiological response of flue-cured tobacco to simulated glyphosate drift}, volume={19}, ISSN={["0890-037X"]}, DOI={10.1614/WT-03-219R}, abstractNote={Field trials were conducted in 2001 at the Tobacco Research Station near Oxford, NC, and in 2002 at the Lower Coastal Plains Research Station near Kinston, NC, to determine tobacco yield, injury, and shikimic acid accumulation in response to simulated glyphosate drift. Glyphosate was applied to 12- to 13-cm-high tobacco ‘K326’ early postemergence at 0, 9, 18, 35, 70, 140, 280, 560, and 1,120 (1×) g ai/ha. Crop injury was rated 7 and 35 d after treatment (DAT) and shikimic acid accumulation in leaves at 7 DAT, tobacco yield, and leaf grade index (whole-plant index of harvest interval leaf value) were also assessed. Shikimic acid accumulation and injury symptoms increased similarly as glyphosate rate increased. Glyphosate rates of 140 g/ha (0.125 of recommended rate) or higher resulted in significant crop injury, reduced tobacco yield, and decreased leaf grade index. Shikimic acid accumulation at 7 DAT was inversely related to tobacco yield. Shikimic acid accumulation was found to be an effective diagnostic tool to determine glyphosate drift in tobacco; however, in-season data are needed to correlate shikimic acid accumulation with yield loss.}, number={2}, journal={WEED TECHNOLOGY}, author={Burke, IC and Thomas, WE and Pline-Srnic, WA and Fisher, LR and Smith, WD and Wilcut, JW}, year={2005}, pages={255–260} }
 @article{thomas_burke_robinson_pline-srnic_edmisten_wells_wilcut_2005, title={Yield and physiological response of nontransgenic cotton to simulated glyphosate drift}, volume={19}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-194R}, abstractNote={Field studies were conducted in 2001 in Lewiston, NC, and in 2002 at Clayton and Lewiston, NC, to investigate the response of nontransgenic cotton to simulated glyphosate drift in a weed-free environment. Nontransgenic cotton variety ‘Fibermax 989’ was planted in a conventional seedbed at all locations. Glyphosate treatments were applied early postemergence (EPOST) at the four-leaf growth stage of cotton at 0, 8.7, 17.5, 35, 70, 140, 280, 560, and 1,120 g ai/ha and represent 0, 0.78, 1.55, 3.13, 6.25, 12.5, 25, 50, and 100% of the commercial use rate, respectively. Rates as low as 140 g/ha caused lint yield reductions depending on year and location. When averaged over all locations, lint yield reductions of 4, 49, 72, and 87% compared with nontreated cotton were observed with glyphosate rates of 140, 280, 560, and 1,120 g/ha, respectively. Visual injury and shikimic acid accumulation were evident at glyphosate rates greater or equal to 70 g/ha. Collectively, visual injury and shikimic acid accumulation at 7 d after EPOST treatment might be used as a diagnostic indicator to predict potential yield reductions from simulated glyphosate drift. Nomenclature: Glyphosate; cotton, Gossypium hirsutum L. ‘Fibermax 989’. Additional index words: Shikimic acid. Abbreviations: DAT, days after early postemergence treatment; DD, degree-day; EPOST, early postemergence; EPSPS, 5-enolpyruvylshikimate-3-phosphate synthase [EC 2.5.1.19]; HPLC, high-performance liquid chromatography; PDS, postemergence-directed; POST, postemergence; PRE, preemergence.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Burke, IC and Robinson, BL and Pline-Srnic, WA and Edmisten, KL and Wells, R and Wilcut, JW}, year={2005}, pages={35–42} }
 @article{thomas_pline_wilcut_edmisten_wells_viator_paulsgrove_2004, title={Glufosinate does not affect floral morphology and pollen viability in glufosinate-resistant cotton}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-032R1}, abstractNote={Studies were conducted to determine whether glufosinate treatments to glufosinate-resistant cotton caused changes in floral morphology, pollen viability, and seed set. Four glufosinate treatments were included: (1) glufosinate applied postemergence over the top (POST) at the four-leaf stage, (2) glufosinate applied POST at the eight-leaf stage, (3) the first two treatments sequentially, and (4) a POST application at the four-leaf stage followed by (fb) a postemergence-directed stem application (PDS) at the eight-leaf stage. Glufosinate was consistently applied at 0.49 kg ai/ha. A nontreated control was included. Glufosinate treatments did not affect stigma height, length of the staminal column, or pollen viability. However, the distance from the top anther to the tip of the stigma was less in plants treated with an eight-leaf POST treatment than in nontreated plants, although this difference is not likely to influence pollen deposition because in both cases anthers reached above the stigma tip. Plants receiving four-leaf POST fb eight-leaf PDS treatment with glufosinate had eight seeds per boll less than nontreated plants; however, the more rigorous four-leaf POST fb eight-leaf POST treatment did not differ from the nontreated in seeds per boll.}, number={2}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Pline, WA and Wilcut, JW and Edmisten, KL and Wells, R and Viator, RR and Paulsgrove, MD}, year={2004}, pages={258–262} }
 @article{thomas_pline-srnic_thomas_edmisten_wells_wilcut_2004, title={Glyphosate negatively affects pollen viability but not pollination and seed set in glyphosate-resistant corn}, volume={52}, ISSN={["1550-2759"]}, DOI={10.1614/WS-03-134R}, abstractNote={Abstract Experiments were conducted in the North Carolina State University Phytotron greenhouse and field locations in Clayton, Rocky Mount, and Lewiston-Woodville, NC, in 2002 to determine the effect of glyphosate on pollen viability and seed set in glyphosate-resistant (GR) corn. Varieties representing both currently commercial GR corn events, GA21 and NK603, were used in phytotron and field studies. All glyphosate treatments were applied at 1.12 kg ai ha−1 at various growth stages. Regardless of hybrid, pollen viability was reduced in phytotron and field studies with glyphosate treatments applied at the V6 stage or later. Scanning electron microscopy of pollen from affected treatments showed distinct morphological alterations correlating with reduced pollen viability as determined by Alexander stain. Transmission electron microscopy showed pollen anatomy alterations including large vacuoles and lower starch accumulation with these same glyphosate treatments. Although pollen viability and pollen production were reduced in glyphosate treatments after V6, no effect on kernel set or yield was found among any of the reciprocal crosses in the phytotron or field studies. There were also no yield differences among any of the hand self-pollinated (nontreated male × nontreated female, etc.) crosses. Using enzyme-linked immunosorbent assay to examine CP4-5-enolpyruvlshikimate-3-phosphate synthase expression in DKC 64-10RR (NK603) at anthesis, we found the highest expression in pollen with progressively less in brace roots, ear leaf, anthers, roots, ovaries, silks, stem, flag leaf, and husk. Nomenclature: Glyphosate; corn, Zea mays L.; ‘DK 662RR’; ‘DK 687RR’; ‘DKC 64-10RR/SIL’.}, number={5}, journal={WEED SCIENCE}, author={Thomas, WE and Pline-Srnic, WA and Thomas, JF and Edmisten, KL and Wells, R and Wilcut, JW}, year={2004}, pages={725–734} }
 @article{thomas_askew_wilcut_2004, title={Tropic croton interference in peanut}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-018R}, abstractNote={Studies were conducted to evaluate density-dependent effects of tropic croton on weed and peanut growth and peanut yield. Tropic croton remained taller than peanut throughout the growing season, yet tropic croton density did not affect peanut or tropic croton heights. Tropic croton biomass per plant decreased linearly with increasing plant density. Peanut pod weight decreased linearly 4.7 kg/ha with each gram of increase in tropic croton biomass per meter of crop row. The rectangular hyperbola model was used to describe effects of tropic croton density on percent peanut yield loss. Estimated coefficients for a (maximum yield loss) and i (yield loss per unit density as density approaches zero) were 81 and 26 in 1988, 41 and 33 in 1989, and 33 and 61 in 1998, respectively. Although a and i values varied between years, yield loss predictions were stable between years at weed densities below two plants per meter of crop row. Even though the results show that tropic croton is less competitive than many broadleaf weeds in peanut, it has potential to substantially reduce yields and subsequently reduce economic return. Nomenclature: Tropic croton, Croton glandulosus var. septentrionalis Muell.-Arg. #3 CVNGS; peanut, Arachis hypogaea L. ‘NC 10C’, ‘Florigiant’. Additional index words: Competition, economic threshold, models, plant height, weed biomass, weed density. Abbreviations: PRE, preemergence.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Askew, SD and Wilcut, JW}, year={2004}, pages={119–123} }
 @article{corbett_askew_thomas_wilcut_2004, title={Weed efficacy evaluations for bromoxynil, glufosinate, glyphosate, pyrithiobac, and sulfosate}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-139R}, abstractNote={Thirteen field trials were conducted in 1999 and 2000 to evaluate postemergence (POST) weed control with single applications of bromoxynil at 420 or 560 g ai/ha, glufosinate at 291 or 409 g ai/ha, glyphosate at 1,120 g ai/ha, pyrithiobac at 36 or 72 g ai/ha, or sulfosate at 1,120 g ai/ha. Additional treatments evaluated included two applications with glufosinate at both rates in all possible combinations, two applications of glyphosate, and two applications of sulfosate. Weeds were 2 to 5 cm or 8 to 10 cm tall for annual grass and broadleaf weeds whereas yellow nutsedge and glyphosate-resistant corn were 8 to 10 cm tall. All herbicide treatments controlled 2- to 5-cm common cocklebur, Florida beggarweed, jimsonweed, ladysthumb smartweed, Pennsylvania smartweed, pitted morningglory, prickly sida, redroot pigweed, smooth pigweed, and velvetleaf at least 90%. All herbicide treatments except pyrithiobac at either rate controlled 2- to 5-cm common lambsquarters, common ragweed, and tall morningglory at least 90%; pyrithiobac at the lower rate was the only treatment that failed to control entireleaf and ivyleaf morningglory at least 90%. Bromoxynil and pyrithiobac at either rate controlled 2- to 5-cm sicklepod 33 to 68% whereas glufosinate, glyphosate, and sulfostate controlled ≥99%. Glyphosate and sulfosate applied once or twice controlled hemp sesbania less than 70% and volunteer peanut less than 80%. Bromoxynil and pyrithiobac were the least effective treatments for control of annual grass species and bromoxynil controlled Palmer amaranth less than 80%. Glufosinate controlled broadleaf signalgrass, fall panicum, giant foxtail, green foxtail, large crabgrass, yellow foxtail, seedling johnsongrass, Texas panicum, and glyphosate-resistant corn at least 90% but controlled goosegrass less than 60%. Glyphosate and sulfosate controlled all grass species except glyphosate-resistant corn at least 90%. In greenhouse research, goosegrass could be controlled with glufosinate POST plus a late POST-directed treatment of prometryn plus monosodium salt of methylarsonic acid.}, number={2}, journal={WEED TECHNOLOGY}, author={Corbett, JL and Askew, SD and Thomas, WE and Wilcut, JW}, year={2004}, pages={443–453} }
 @article{thomas_burke_wilcut_2004, title={Weed management in glyphosate-resistant corn with glyphosate and halosulfuron}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-222R}, abstractNote={Three field studies were conducted at Lewiston Woodville, NC, in 2001 and 2002 to evaluate crop tolerance, weed control, grain yield, and net returns in glyphosate-resistant corn with various herbicide systems. Crop injury, weed control, and grain yield were not influenced by glyphosate formulation. Atrazine preemergence (PRE) and atrazine plus metolachlor PRE, averaged over postemergence (POST) systems, controlled Texas panicum at least 80 and 87%, respectively. Sequential glyphosate applications (early postemergence [EPOST] followed by [fb] POST) provided at least 99% control of Texas panicum compared with at least 86 and 88% control with glyphosate EPOST and glyphosate plus halosulfuron EPOST, respectively. Atrazine plus metolachlor PRE fb any glyphosate system controlled large crabgrass and goosegrass 89 to 100% and 94 to 100%, respectively. Sequential glyphosate treatments controlled large crabgrass and goosegrass at least 99 and 95%, respectively. Regardless of PRE system, glyphosate plus halosulfuron EPOST and sequential applications of glyphosate controlled common ragweed and common lambsquarters at least 99%, whereas glyphosate EPOST alone provided at least 88 and 96% control, respectively. Glyphosate plus halosulfuron EPOST and glyphosate sequentially controlled yellow nutsedge similarly and more consistently than glyphosate EPOST. Regardless of PRE treatment, sequential glyphosate applications provided at least 98% control of entireleaf and pitted morningglory, whereas glyphosate EPOST controlled at least 64 and 62%, respectively. Glyphosate EPOST and the sequential glyphosate EPOST fb POST systems yielded similarly at all three locations. Net returns were highest at all three locations with the glyphosate sequential system, with similar net returns obtained with glyphosate EPOST and glyphosate plus halosulfuron EPOST at two and one locations, respectively.}, number={4}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Burke, IC and Wilcut, JW}, year={2004}, pages={1049–1057} }
 @article{thomas_burke_wilcut_2004, title={Weed management in glyphosate-resistant corn with glyphosate, halosulfuron, and mesotrione}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-221R}, abstractNote={Four field studies were conducted at the Peanut Belt Research Station near Lewiston Woodville, NC, in 2000, 2001, and 2002 to evaluate crop tolerance, weed control, grain yield, and net returns in glyphosate-resistant corn with various herbicide systems. Preemergence (PRE) treatment options included no herbicide, atrazine at 1.12 kg ai/ha, or atrazine plus metolachlor at 1.68 kg ai/ha. Postemergence (POST) treatment options included glyphosate at 1.12 kg ai/ha as either the isopropylamine salt or the diammonium salt, either alone or in mixtures with mesotrione at 105 g ai/ha plus crop oil concentrate at 1% (v/v) or halosulfuron at 53 g ai/ha plus 0.25% (v/v) nonionic surfactant. All response variables were independent of glyphosate formulation. Addition of metolachlor to atrazine PRE improved large crabgrass and goosegrass control but did not always improve Texas panicum control. POST control of these annual grasses was similar with glyphosate alone or in mixture with halosulfuron or mesotrione. Glyphosate POST controlled common lambsquarters and common ragweed 89 and 93%, respectively. Glyphosate plus halosulfuron POST provided more effective yellow nutsedge control than glyphosate POST. Atrazine PRE or atrazine plus metolachlor PRE followed by any glyphosate POST treatment controlledIpomoeaspp. at least 93%. Glyphosate plus mesotrione in total POST systems always provided greater control ofIpomoeaspp. than glyphosate alone. The highest yielding treatments always included glyphosate POST, either with or without a PRE herbicide treatment. Similarly, systems that included any glyphosate POST treatment had the highest net returns.}, number={3}, journal={WEED TECHNOLOGY}, author={Thomas, WE and Burke, IC and Wilcut, JW}, year={2004}, pages={826–834} }
 @article{burke_thomas_spears_wilcut_2003, title={Influence of environmental factors on after-ripened crowfootgrass (Dactyloctenium aegyptium) seed germination}, volume={51}, ISSN={["0043-1745"]}, DOI={10.1614/0043-1745(2003)051[0342:IOEFOA]2.0.CO;2}, abstractNote={Abstract Laboratory and greenhouse studies were conducted to determine the effect of temperature, pH, water stress, and planting depth on crowfootgrass germination. When treated with constant temperature, crowfootgrass germinated over a range of 15 to 40 C, with the optimum germination occurring at 30 C (42%). Onset, rate, and total germination (94%) were greatest in an alternating 20 and 35 C temperature regime. Germination decreased as pH increased, with greatest germination occurring at pH 4 and 5. Germination was reduced when seed was subjected to water stress, and no germination occurred below −0.8 mPa. Emergence was similar when seed were placed on the soil surface or buried at depths of 0.5 or 1 cm. Germination decreased with burial depth, and no seed emerged from 10 cm. These data suggest that crowfootgrass may emerge later in the season with warmer temperatures and after a precipitation event, and may emerge rapidly. These attributes could contribute to poor control later in the season by soil-applied herbicides or allow crowfootgrass to emerge after final postemergence treatments are made. Nomenclature: Crowfootgrass, Dactyloctenium aegyptium (L.) Willd. DTTAE.}, number={3}, journal={WEED SCIENCE}, author={Burke, IC and Thomas, WE and Spears, JF and Wilcut, JW}, year={2003}, pages={342–347} }
 @article{burke_thomas_spears_wilcut_2003, title={Influence of environmental factors on broadleaf signalgrass (Brachiaria platyphylla) germination}, volume={51}, ISSN={["1550-2759"]}, DOI={10.1614/0043-1745(2003)051[0683:IOEFOB]2.0.CO;2}, abstractNote={Abstract Laboratory and greenhouse studies were conducted to determine the effect of temperature, solution pH, water stress, and planting depth on broadleaf signalgrass germination. Broadleaf signalgrass seed required removal of the husk for germination. When treated with constant temperature, broadleaf signalgrass germinated over a range of 20 to 35 C, with optimum germination occurring at 30 and 35 C. Onset, rate, and total germination (87%) was greatest in an alternating 20/30 C temperature regime. Germination decreased as solution pH increased, with greatest germination occurring at pH values of 4 and 5. Germination decreased with increasing water potential, and no germination occurred below − 0.8 mPa. Emergence was above 42% when seed were placed on the soil surface or buried 0.5 cm deep. Germination decreased with burial depth, but 10% of broadleaf signalgrass seed emerged from 6.0-cm depth. No seed emerged from 10-cm depth. These data suggest that broadleaf signalgrass may emerge later in the season, after rains, and could germinate rapidly and in high numbers. These attributes could contribute to poor control later in the season by soil-applied herbicides or allow broadleaf signalgrass to emerge after final postemergence treatments were made. Nomenclature: Broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash BRAPP.}, number={5}, journal={WEED SCIENCE}, author={Burke, IC and Thomas, WE and Spears, JF and Wilcut, JW}, year={2003}, pages={683–689} }