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Comparing fitness of herbicide-resistant and herbicide-susceptible weed biotypes is important for managing herbicide resistance. Previous research suggests there is little to no fitness penalty from amplification of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene (a mechanism of glyphosate resistance) in Palmer amaranth (Amaranthus palmeri S. Watson) in controlled studies in the greenhouse or growth chamber. A field study was conducted in North Carolina at three locations naturally infested with A. palmeri to determine vegetative, reproductive, and germination fitness of plants with and without EPSPS amplification grown season-long with cotton (Gossypium hirsutum L.). Seed number was not correlated with EPSPS copy number. However, when plants were binned into two groups, those having an EPSPS copy number ≥2 (relative to reference genes) and those having an EPSPS copy number <2, plant fresh weight and seed number were 1.4 and 1.6 times greater, respectively, for plants with fewer than 2 EPSPS copies. Amaranthus palmeri height and seed germination, and yield of cotton, did not differ when comparing the two binned groups. These data suggest that A. palmeri plants with EPSPS amplification are relatively less fit in the absence of glyphosate, but this reduced fitness does not translate into differences in interference with cotton.
Poor diet quality (DQ) is associated with poor cognition and increased neurodegeneration, including Alzheimer’s disease (AD). We are interested in the role of DQ on cognitive functioning (by sex and increasing genetic risk for AD), in a sample of African American (AA) middle-aged adults. We analysed a sub-group of participants (about 55 % women; mean follow-up time of about 4·7 years) from the Healthy Aging in Neighborhoods of Diversity across the Life Span study with a genetic risk score for AD (hAlzScore). The Healthy Eating Index-2010, Dietary Approaches to Stop Hypertension and the mean adequacy ratio computed at baseline (2004–2009) and follow-up visits (2009–2013) were used to assess initial DQ and change over time. Linear mixed-effects regression models were utilised, adjusting for select covariates, selection bias and multiple testing. DQ change (ΔDQ) was associated with California Verbal Learning Test-List A – overall (0·15 (se 0·06), P = 0·008) and in women (0·21 (se 0·08), P = 0·006), at highest AD risk, indicating protective effects over time. Greater AD risk was longitudinally associated with poorer Clock Command Test scores in men. Poor DQ was positively and cross-sectionally associated with Trails B scores, but in women only. Better-quality diet was associated with a slower decline in verbal memory among AA women, with greater AD risk. Insufficient clinical evidence and/or mixed findings dictate that more studies are needed to investigate brain morphology and volume changes in relation to DQ in an at-risk population for AD, over time.
Glyphosate-resistant (GR) Palmer amaranth continues to be challenging to control across the U.S. cotton belt. Timely application of POST herbicides and herbicides applied at planting or during the season with residual activity are utilized routinely to control this weed. Although glyphosate controls large Palmer amaranth that is not GR, herbicides such as glufosinate used in resistance management programs for GR Palmer amaranth must be applied when weeds are small. Dicamba can complement both glyphosate and glufosinate in controlling GR and glyphosate-susceptible (GS) biotypes in resistant cultivars. Two studies were conducted to determine Palmer amaranth control, weed biomass, and cotton yield, as well as to estimate economic net return when herbicides were applied 2, 3, 4, and 5 wk after planting (WAP). In one experiment POST-only applications were made. In the second experiment PRE herbicides were included. In general, Palmer amaranth was controlled at least 98% by herbicides applied at least three times regardless of timing of application or herbicide sequence. Glyphosate plus dicamba applied at 4 and 5 WAP controlled Palmer amaranth similarly compared to three applications by 8 WAP; however, yield was reduced 23% because of early-season interference. The inclusion of PRE herbicides benefited treatments that did not include herbicides applied 2 or 3 WAP. Glyphosate plus dicamba applied as the only herbicides 5 WAP provided 69% control of Palmer amaranth. PRE herbicides increased control to 96% for this POST treatment. Economic returns were similar when three or more POST applications were applied, with or without PRE herbicides.
The experiments reported in this research paper aimed to track the microbiological load of milk throughout a low-heat skim milk powder (SMP) manufacturing process, from farm bulk tanks to final powder, during mid- and late-lactation (spring and winter, respectively). In the milk powder processing plant studied, low-heat SMP was produced using only the milk supplied by the farms involved in this study. Samples of milk were collected from farm bulk tanks (mid-lactation: 67 farms; late-lactation: 150 farms), collection tankers (CTs), whole milk silo (WMS), skim milk silo (SMS), cream silo (CS) and final SMP. During mid-lactation, the raw milk produced on-farm and transported by the CTs had better microbiological quality than the late-lactation raw milk (e.g., total bacterial count (TBC): 3.60 ± 0.55 and 4.37 ± 0.62 log 10 cfu/ml, respectively). After pasteurisation, reductions in TBC, psychrotrophic (PBC) and proteolytic (PROT) bacterial counts were of lower magnitude in late-lactation than in mid-lactation milk, while thermoduric (LPC—laboratory pasteurisation count) and thermophilic (THERM) bacterial counts were not reduced in both periods. The microbiological quality of the SMP produced was better when using mid-lactation than late-lactation milk (e.g., TBC: 2.36 ± 0.09 and 3.55 ± 0.13 cfu/g, respectively), as mid-lactation raw milk had better quality than late-lactation milk. The bacterial counts of some CTs and of the WMS samples were higher than the upper confidence limit predicted using the bacterial counts measured in the farm milk samples, indicating that the transport conditions or cleaning protocols could have influenced the microbiological load. Therefore, during the different production seasons, appropriate cow management and hygiene practices (on-farm and within the factory) are necessary to control the numbers of different bacterial groups in milk, as those can influence the effectiveness of thermal treatments and consequently affect final product quality.
Palmer amaranth is the most economically damaging glyphosate-resistant (GR) weed in the southern United States. An understanding of the basic biology, including relative growth and competitiveness of GR and glyphosate-susceptible (GS) Palmer amaranth phenotypes from a segregating population collected from the same geographical location, may yield information helpful in the management of resistant populations. A segregating population of Palmer amaranth collected in North Carolina during 2010 was used as a plant source for both GR and GS traits. Research was conducted in the greenhouse to compare the following: level of resistance and shikimate accumulation in GR and GS phenotypes following glyphosate application; interference from GR and GS phenotypes on early-season vegetative growth of corn, cotton, and peanut; effect of various durations of imposed drought stress on GR and GS phenotypes; and response of GR and GS phenotypes to POST-applied herbicides. The GR50 (glyphosate rate providing 50% reduction in shoot dry biomass) was 17 times greater with the GR phenotype compared with the GS phenotype. Shikimate accumulated in both GR and GS phenotypes following glyphosate application, but greater concentrations were found in GS plants. The GR and GS phenotypes responded similarly when subjected to drought stress; grown with corn, cotton, and peanut; or treated with 2,4-D, atrazine, dicamba, fomesafen, glufosinate, paraquat, tembotrione, and thifensulfuron. These results indicate that in the absence of glyphosate selection pressure, resistance to glyphosate does not influence the growth and competitiveness of GR and GS Palmer amaranth phenotypes collected from the same geographical location.
Field experiments were conducted to determine effects of adding 2.8 kg/ha (NH4)2SO4 and/or substituting BCH 81508 S for crop oil with sethoxydim applied to large crabgrass, corn, johnsongrass, and common bermudagrass. Adding (NH4)2SO4 did not affect control of johnsongrass or common bermudagrass but did increase control of large crabgrass and corn by 6 and 15%, respectively. Cora control was enhanced more by (NH4)2SO4 at lower sethoxydim rates. Substituting BCH 81508 S for crop oil increased seedling johnsongrass, large crabgrass, common bermudagrass, rhizome johnsongrass, and corn control by 7, 9, 9, 10, and 15%, respectively. A sethoxydim rate by spray adjuvant interaction was observed with seedling johnsongrass, common bermudagrass, and corn where response to BCH 81508 S decreased as sethoxydim rates increased. The effects of substituting BCH 81508 S for crop oil and adding (NH4)2SO4 were independent.
The effect of nonionic surfactant, crop oil concentrate, organosilicone surfactant, methylated seed oil, and a blend of organosilicone surfactant and methylated seed oil on absorption of 14C-clethodim was evaluated in barnyardgrass (Echinochloa crus-galli). Absorption of 14C-label was greatest during the first 40 min after application when 14C-clethodim was applied with methylated seed oil or a blend of methylated seed oil and organosilicone surfactant. These adjuvants increased the rate of absorption more than crop oil concentrate, organosilicone surfactant, or nonionic surfactant. Crop oil concentrate was more effective than organosilicone or nonionic surfactant in increasing absorption, with nonionic surfactant being more effective than organosilicone surfactant. These results generally agreed with the order of increasing efficacy of clethodim on barnyardgrass as affected by adjuvants in field experiments. Another study was conducted to determine the effect of bromoxynil on absorption and translocation of 14C-clethodim in yellow foxtail (Setaria glauca). Bromoxynil reduced absorption of 14C–clethodim 4, 8, and 24 h after application and also reduced the amount of 14C-label translocated from the treated leaf. These data suggest that antagonism of clethodim control of yellow foxtail by bromoxynil observed in previous research can be attributed partially to decreased absorption and translocation of clethodim.
Field experiments were conducted from 1993 to 1995 to compare weed control by the isopropylamine salt of glyphosate at 0.21, 0.42, 0.63, and 0.84 kg ae/ha applied at three stages of weed growth. Weed control by glyphosate applied at these rates alone or with ammonium sulfate at 2.8 kg/ha was also evaluated. In other experiments, potential interactions between glyphosate and acifluorfen, chlorimuron, and 2,4-DB were evaluated. Velvetleaf, prickly sida, sicklepod, pitted morningglory, entireleaf morningglory, palmleaf morningglory, and hemp sesbania were controlled more easily when weeds had one to three leaves compared with control when weeds had four or more leaves. Glyphosate controlled redroot pigweed, velvetleaf, prickly sida, sicklepod, and barnyardgrass more effectively than pitted morningglory, entireleaf morningglory, palmleaf morningglory, or hemp sesbania. Increasing the rate of glyphosate increased control, especially when glyphosate was applied to larger weeds. Greater variation in control was noted for pitted morningglory, palmleaf morningglory, prickly sida, and velvetleaf than for redroot pigweed, sicklepod, entireleaf morningglory, or hemp sesbania. Ammonium sulfate increased prickly sida and entireleaf morningglory control but did not influence sicklepod, hemp sesbania, or barnyardgrass control. Acifluorfen applied 3 d before glyphosate or in a mixture with glyphosate reduced barnyardgrass control compared with glyphosate applied alone. Chlorimuron did not reduce efficacy. Mixtures of glyphosate and 2,4-DB controlled sicklepod, entireleaf morningglory, and barnyardgrass similar to glyphosate alone.
Field and greenhouse experiments were conducted to determine effects of adding (NH4)2SO4 or urea ammonium nitrate containing 30% N (UAN) and/or substituting BCH 81508 S for crop oil with sethoxydim and sethoxydim plus bentazon applied to corn and large crabgrass. Control was similar with sethoxydim plus crop oil and sethoxydim plus BCH 81508 S. Adding (NH4)2SO4 or UAN moderately improved control with sethoxydim in some experiments. Both (NH4)2SO4 and UAN increased control when added to sethoxydim plus bentazon, with UAN being the more effective ammonium fertilizer. Large crabgrass control with sethoxydim plus bentazon was enhanced more with 1.4 and 2.8 kg/ha (NH4)2SO4 than with 5.6 kg/ha. Substituting BCH 81508 S for crop oil with sethoxydim plus bentazon also increased corn and large crabgrass control. Adding ammonium fertilizers plus substituting BCH 81508 S for crop oil with sethoxydim plus bentazon eliminated antagonism on corn and partially alleviated antagonism on large crabgrass.
Field experiments were conducted to determine if aldicarb, disulfoton, or phorate applied in-furrow at 0.84 or 1.12 kg ai ha–1 affected cotton response to clomazone applied PPI or PRE at rates ranging from 0 to 1.12 kg ai ha–1. Disulfoton and phorate greatly reduced clomazone-induced chlorosis, stunting, and death of cotton seedlings. Compared with no insecticide or with dimethoate applied POST, aldicarb did not affect cotton response to clomazone. A clomazone rate by insecticide interaction was not observed for cotton yield. Clomazone reduced cotton yield at one of five locations. Insecticides affected yield at three locations, where highest yields were from cotton treated with aldicarb. In a separate experiment with 0.56, 1.12, and 2.24 kg ha–1 of phorate applied in-furrow and 1.12 kg ha–1 of clomazone applied PPI, phorate at all rates protected cotton from clomazone phytotoxicity.
Experiments conducted in North Carolina and Virginia compared weed control, peanut yield, and net returns with systems using imazethapyr applied at various times and the regional standard treatment of paraquat applied at the ground-cracking stage of peanut (GC) followed by acifluorfen plus bentazon applied POST. Imazethapyr was applied PPI, PRE, GC, or POST at 70 g ae ha−1. Imazethapyr also was applied sequentially PPI plus GC, PPI plus POST, and PRE plus POST at 35 + 35 and 70 + 70 g ha−1. Late-season control of common ragweed and a mixture of entireleaf, ivyleaf, and pitted morningglories by the standard treatment ranged from 85 to 100%. Spurred anoda was controlled 80%, and common lambsquarters and prickly sida were controlled completely. Control of common lambsquarters, prickly sida, and morningglory by imazethapyr applied one or more times was similar to control by the standard. Control by imazethapyr exceeded that by the standard only for spurred anoda. The most effective time for applying imazethapyr varied by species and locations. Imazethapyr was equally effective on common lambsquarters and spurred anoda when applied PPI, PRE, or GC. Prickly sida and morningglory were controlled best when imazethapyr was applied PPI or PRE and GC, respectively. Common ragweed was controlled poorly with single applications of imazethapyr. Applying imazethapyr sequentially improved consistency of control across the range of species. In most cases, imazethapyr applied sequentially at 35 + 35 g ha−1 controlled all weeds as well as or better than when applied once at 70 g ha−1. Overall, imazethapyr at the registered rate of 70 g ha−1 was most effective when applied PPI at 35 g ha−1 followed by 35 g ha−1 at GC. Except for common ragweed, weed control with this treatment was similar to that by the standard. Peanut yield and net returns with this treatment were similar to those with the standard at three of four locations.
Efficacy of herbicide programs containing clomazone PPI plus fluometuron PRE or clomazone plus pendimethalin PPI plus fluometuron PRE was compared with that of standard programs of pendimethalin PPI plus fluometuron PRE and norflurazon PPI plus norflurazon and fluometuron PRE. Cotton injury was less than 5% with all treatments when disulfoton or phorate was applied in the seed furrow. Control of fall panicum, goosegrass, large crabgrass, eclipta, entireleaf morningglory, ivyleaf morningglory, pitted morningglory, tall morningglory, prickly sida, redroot pigweed, smooth pigweed, hemp sesbania, spotted spurge, sicklepod, and velvetleaf and cotton yields with 0.8 kg ai ha−1 of clomazone plus fluometuron or 0.6 kg ha−1 of clomazone plus pendimethalin plus fluometuron equalled or exceeded that from the standard herbicide programs. POST-directed application of methazole at 0.8 kg ai ha−1 plus MSMA at 2.2 kg ae ha−1 increased sicklepod and morningglory control and cotton yield. Clomazone applied PRE at 0.6 kg ha−1 with fluometuron controlled broadleaf signalgrass, goosegrass, large crabgrass, prickly sida, and smooth pigweed equally with that of standard treatments of trifluralin or trifluralin plus norflurazon PPI and fluometuron PRE, whereas pitted morningglory control and cotton yield with clomazone plus fluometuron exceeded that with the standards.
The effect of ammonium sulfate on absorption of 14C-sethoxydim applied alone and with bentazon was studied in large crabgrass. Adding ammonium sulfate to 14C-sethoxydim increased 14C absorption 6-fold at 0.5 h after application but did not affect the amount of 14C absorbed 1 or 4 h after application. Applying bentazon with 14C-sethoxydim reduced 14C absorption 26%. When 14C-sethoxydim was applied with bentazon and ammonium sulfate, 14C absorption and translocation were similar to those with 14C-sethoxydim alone.
Antagonism of quizalofop-P efficacy on annual grasses by bromoxynil has been noted in both the field and greenhouse. Laboratory experiments were conducted on yellow foxtail (Setaria glauca) to determine the effect of mixing bromoxynil with the ethyl ester of quizalofop-P on absorption, translocation, and metabolism of 14C-quizalofop-P Applying bromoxynil in mixture with quizalofop-P reduced 14C-label absorption from 63 to 51%, 73 to 52%, 77 to 68%, and 90 to 80% at 4, 8, 24, and 96 h after treatment, respectively. Translocation of 14C-label from the treated leaf into the shoot above or shoot below was unaffected by bromoxynil. However, translocation into the roots was reduced from 0.9 to 0.4% and 1.0 to 0.5% at 4 and 8 h after treatment, respectively, but differences were not noted at 0.5, 1, 24, and 96 h after treatment. Bromoxynil increased deesterification of quizalofop-P-ethyl into quizalofop-P acid from 45 to 60% in the shoot above the treated leaf. However, bromoxynil did not affect metabolism of quizalofop-P in the treated leaf or shoot below the treated leaf. These results suggest that antagonism of quizalofop-P activity by bromoxynil is primarily due to decreased absorption of quizalofop-P, whereas effects on translocation and metabolism were minor.
An experiment was conducted at four locations during 1990 and 1991 to determine the response of cotton to 1.12 kg ai ha-1 of clomazone applied PPI in combination with in-furrow application of 0.50 kg ai ha-1 of aldicarb plus 0.14, 0.28, and 0.56 kg ai ha-1 of either disulfoton or phorate. Early-season cotton injury ranged from 15 to 63% with clomazone plus aldicarb. Stands were reduced 31 and 61% at two locations, and yield was reduced 50% at one location. Applied in combination with aldicarb, all three rates of disulfoton and 0.28 and 0.56 kg ha-1 of phorate protected cotton from clomazone injury. Phorate at 0.14 kg ha-1 partially protected cotton from clomazone injury.
Flumioxazin and fomesafen are commonly used to control glyphosate-resistant Palmer amaranth in cotton and other crops, thus increasing risk to select for Palmer amaranth biotypes resistant to protoporphyrinogen oxidase (PPO) inhibitors. A field experiment was conducted to determine the potential for fluridone and acetochlor to substitute for soil-applied PPO inhibitors in a Palmer amaranth management system with glufosinate applied twice POST and diuron plus MSMA POST-directed in conservation tillage cotton. Fluridone and flumioxazin applied preplant 23 to 34 d prior to planting were similarly effective. Fluridone and acetochlor plus diuron applied PRE controlled Palmer amaranth as well as fomesafen plus diuron PRE. All systems with preplant and PRE herbicides followed by glufosinate POST and diuron plus MSMA layby controlled Palmer amaranth well. Cotton yield did not differ among herbicide treatments. This research demonstrates that fluridone and acetochlor can substitute for soil-applied PPO-inhibiting herbicides in management systems for Palmer amaranth.
Glyphosate typically controls Palmer amaranth very well. However, glyphosate-resistant (GR) biotypes of this weed are present in several southern states, requiring the development of effective alternatives to glyphosate-only management strategies. Field experiments were conducted in seven North Carolina environments to evaluate control of glyphosate-susceptible (GS) and GR Palmer amaranth in narrow-row soybean by glyphosate and conventional herbicide systems. Conventional systems included either pendimethalin or S-metolachlor applied PRE alone or mixed with flumioxazin, fomesafen, or metribuzin plus chlorimuron followed by fomesafen or no herbicide POST. S-metolachlor was more effective at controlling GR and GS Palmer amaranth than pendimethalin; flumioxazin and fomesafen were generally more effective than metribuzin plus chlorimuron. Fomesafen applied POST following PRE herbicides increased Palmer amaranth control and soybean yield compared with PRE-only herbicide systems. Glyphosate alone applied once POST controlled GS Palmer amaranth 97% late in the season. Glyphosate was more effective than fomesafen plus clethodim applied POST. Control of GS Palmer amaranth when treated with pendimethalin or S-metolachlor plus flumioxazin, fomesafen, or metribuzin plus chlorimuron applied PRE followed by fomesafen POST was equivalent to control achieved by glyphosate applied once POST. In fields with GR Palmer amaranth, greater than 80% late-season control was obtained only with systems of pendimethalin or S-metolachlor plus flumioxazin, fomesafen, or metribuzin plus chlorimuron applied PRE followed by fomesafen POST. Systems of pendimethalin or S-metolachlor plus flumioxazin, fomesafen, or metribuzin plus chlorimuron applied PRE without fomesafen POST controlled GR Palmer amaranth less than 30% late in the season. Systems of pendimethalin or S-metolachlor PRE followed by fomesafen POST controlled GR Palmer amaranth less than 60% late in the season.
Residual herbicides are routinely recommended to aid in control of glyphosate-resistant (GR) Palmer amaranth in cotton. Acetochlor, a chloroacetamide herbicide, applied PRE, controls Palmer amaranth. A microencapsulated (ME) formulation of acetochlor is now registered for PRE application in cotton. Field research was conducted in North Carolina to evaluate cotton tolerance and Palmer amaranth control by acetochlor ME alone and in various combinations. Treatments, applied PRE, consisted of acetochlor ME, pendimethalin, or no herbicide arranged factorially with diuron, fluometuron, fomesafen, diuron plus fomesafen, and no herbicide. The PRE herbicides were followed by glufosinate applied twice POST and diuron plus MSMA directed at layby. Acetochlor ME was less injurious to cotton than pendimethalin. Acetochlor ME alone or in combination with other herbicides reduced early season cotton growth 5 to 8%, whereas pendimethalin alone or in combinations injured cotton 11 to 13%. Early season injury was transitory, and by 65 to 84 d after PRE treatment, injury was no longer noticeable. Before the first POST application of glufosinate, acetochlor ME and pendimethalin controlled Palmer amaranth 84 and 64%, respectively. Control by acetochlor ME was similar to control by diuron plus fomesafen and greater than control by diuron, fluometuron, or fomesafen alone. Greater than 90% control was obtained with acetochlor ME mixed with diuron or fomesafen. Palmer amaranth control was similar with acetochlor ME plus a full or reduced rate of fomesafen. Acetochlor ME controlled large crabgrass and goosegrass at 91 and 100% compared with control at 83 and 91%, respectively, by pendimethalin. Following glufosinate, applied twice POST, and diuron plus MSMA, at layby, 96 to 99% control was obtained late in the season by all treatments, and no differences among herbicide treatments were noted for cotton yield. This research demonstrated that acetochlor ME can be safely and effectively used in cotton weed management programs.
Cotton growers rely heavily upon glufosinate and various residual herbicides applied preplant, PRE, and POST to control Palmer amaranth resistant to glyphosate and acetolactate synthase-inhibiting herbicides. Recently deregulated in the United States, cotton resistant to dicamba, glufosinate, and glyphosate (B2XF cotton) offers a new platform for controlling herbicide-resistant Palmer amaranth. A field experiment was conducted in North Carolina and Georgia to determine B2XF cotton tolerance to dicamba, glufosinate, and glyphosate and to compare Palmer amaranth control by dicamba to a currently used, nondicamba program in both glufosinate- and glyphosate-based systems. Treatments consisted of glyphosate or glufosinate applied early POST (EPOST) and mid-POST (MPOST) in a factorial arrangement of treatments with seven dicamba options (no dicamba, PRE, EPOST, MPOST, PRE followed by [fb] EPOST, PRE fb MPOST, and EPOST fb MPOST) and a nondicamba standard. The nondicamba standard consisted of fomesafen PRE, pyrithiobac EPOST, and acetochlor MPOST. Dicamba caused no injury when applied PRE and only minor, transient injury when applied POST. At time of EPOST application, Palmer amaranth control by dicamba or fomesafen applied PRE, in combination with acetochlor, was similar and 13 to 17% greater than acetochlor alone. Dicamba was generally more effective on Palmer amaranth applied POST rather than PRE, and two applications were usually more effective than one. In glyphosate-based systems, greater Palmer amaranth control and cotton yield were obtained with dicamba applied EPOST, MPOST, or EPOST fb MPOST compared with the standard herbicides in North Carolina. In contrast, dicamba was no more effective than the standard herbicides in the glufosinate-based systems. In Georgia, dicamba was as effective as the standard herbicides in a glyphosate-based system only when dicamba was applied EPOST fb MPOST. In glufosinate-based systems in Georgia, dicamba was as effective as standard herbicides only when dicamba was applied twice.
Glyphosate-resistant (GR) Palmer amaranth has become a serious pest in parts of the Cotton Belt. Some GR cotton cultivars also contain the WideStrike™ insect resistance trait, which confers tolerance to glufosinate. Use of glufosinate-based management systems in such cultivars could be an option for managing GR Palmer amaranth. The objective of this study was to evaluate crop tolerance and weed control with glyphosate-based and glufosinate-based systems in PHY 485 WRF cotton. The North Carolina field experiment compared glyphosate and glufosinate alone and in mixtures applied twice before four- to six-leaf cotton. Additional treatments included glyphosate and glufosinate mixed with S-metolachlor or pyrithiobac applied to one- to two-leaf cotton followed by glyphosate or glufosinate alone on four- to six-leaf cotton. All treatments received a residual lay-by application. Excellent weed control was observed from all treatments on most weed species. Glyphosate was more effective than glufosinate on glyphosate-susceptible (GS) Palmer amaranth and annual grasses, while glufosinate was more effective on GR Palmer amaranth. Annual grass and GS Palmer amaranth control by glyphosate plus glufosinate was often less than control by glyphosate alone but similar to or greater than control by glufosinate alone, while mixtures were more effective than either herbicide alone on GR Palmer amaranth. Glufosinate caused minor and transient injury to the crop, but no differences in cotton yield or fiber quality were noted. This research demonstrates glufosinate can be applied early in the season to PHY 485 WRF cotton without concern for significant adverse effects on the crop. Although glufosinate is often less effective than glyphosate on GS Palmer amaranth, GR Palmer amaranth can be controlled with well-timed applications of glufosinate. Use of glufosinate in cultivars with the WideStrike trait could fill a significant void in current weed management programs for GR Palmer amaranth in cotton.