@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{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{price_pline_cranmer_danehower_2004, title={Physiological basis for cotton tolerance to flumioxazin applied postemergence directed}, volume={52}, ISSN={["1550-2759"]}, DOI={10.1614/ws-03-038r}, abstractNote={Previous research has shown that flumioxazin, a herbicide being developed as a postemergence-directed spray (PDS) in cotton, has the potential to injure cotton less than 30 cm tall if the herbicide contacts green stem tissue by rain splash or misapplication. In response to this concern, five-leaf cotton plants with chlorophyllous stems and older cotton, 16-leaf cotton plants, with bark on the lower stem were treated with a PDS containing flumioxazin plus crop oil concentrate (COC) or nonionic surfactant (NIS). Stems of treated plants and untreated plants at the respective growth stage were cross-sectioned and then magnified and photographed using bright-field microscopy techniques. More visible injury consisting of necrosis and desiccation was evident in younger cotton. Also, there was a decrease in treated-stem diameter and an increase in visible injury with COC compared with NIS in younger cotton. The effects of plant growth stage and harvest time on absorption, translocation, and metabolism of14C-flumioxazin in cotton were also investigated. Total14C absorbed at 72 h after treatment (HAT) was 77, 76, and 94% of applied at 4-, 8-, and 12-leaf growth stages, respectively. Cotton at the 12-leaf stage absorbed more14C within 48 HAT than was absorbed by four- or eight-leaf cotton by 72 HAT. A majority (31 to 57%) of applied14C remained in the treated stem for all growth stages and harvest times. Treated cotton stems at all growth stages and harvest times contained higher concentrations (Bq g−1) of14C than any other tissues. Flumioxazin metabolites made up less than 5% of the radioactivity found in the treated stem. Because of the undetectable levels of metabolites in other tissues when flumioxazin was applied PDS, flumioxazin was foliar applied to determine whether flumioxazin transported to the leaves may have been metabolized. In foliar-treated cotton, flumioxazin metabolites in the treated leaf of four-leaf cotton totaled 4% of the recovered14C 72 HAT. Flumioxazin metabolites in the treated leaf of 12-leaf cotton totaled 35% of the recovered14C 48 HAT. These data suggest that differential absorption, translocation, and metabolism at various growth stages, as well as the development of a bark layer, are the bases for differential tolerances of cotton to flumioxazin applied PDS.}, number={1}, journal={WEED SCIENCE}, author={Price, AJ and Pline, WA and Cranmer, JR and Danehower, D}, year={2004}, pages={1–7} }
 @article{pline_wells_little_edmisten_wilcut_2003, title={Glyphosate and water-stress effects on fruiting and carbohydrates in glyphosate-resistant cotton}, volume={43}, DOI={10.2135/cropsci2003.0879}, abstractNote={Crop ScienceVolume 43, Issue 3 p. 879-885 Crop Physiology & Metabolism Glyphosate and Water-Stress Effects on Fruiting and Carbohydrates in Glyphosate-Resistant Cotton Wendy A. Pline, Wendy A. Pline Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6ET U.K.Search for more papers by this authorRandy Wells, Randy Wells Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorGary Little, Gary Little Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorKeith L. Edmisten, Keith L. Edmisten Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorJohn W. Wilcut, Corresponding Author John W. Wilcut john_wilcut@ncsu.edu Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Corresponding author (john_wilcut@ncsu.edu)Search for more papers by this author Wendy A. Pline, Wendy A. Pline Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6ET U.K.Search for more papers by this authorRandy Wells, Randy Wells Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorGary Little, Gary Little Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorKeith L. Edmisten, Keith L. Edmisten Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Search for more papers by this authorJohn W. Wilcut, Corresponding Author John W. Wilcut john_wilcut@ncsu.edu Dep. of Crop Science, North Carolina State Univ., Raleigh, NC, 27695-7620Corresponding author (john_wilcut@ncsu.edu)Search for more papers by this author First published: 01 May 2003 https://doi.org/10.2135/cropsci2003.8790Citations: 9Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Water stress and glyphosate treatments to glyphosate-resistant (GR) cotton (Gossypium hirsutum L.) can cause abscission of young bolls although the interaction of these factors is not well defined. Studies were conducted to quantify the effects of water stress and glyphosate treatments on fruit retention, fruit placement, and carbohydrate partitioning in GR and conventional cotton varieties grown in a phytotron environment. Glyphosate-resistant plants treated with glyphosate at the four-leaf stage, postemergence (POST), and at the eight-leaf stage, POST-directed (PDIR), had fewer first-position bolls after 0 and 1 d of water stress than nontreated GR and conventional plants but did not differ after 2 and 3 d of water stress. Glyphosate-treated GR plants reached first bloom 3 to 4 d later than nontreated plants. Five-day-old bolls from plants of one genotype, SG 125RR, treated with glyphosate had lower fructose content than bolls from nontreated plants. Subtending leaf carbohydrates and boll sucrose, glucose, and starch content did not differ after glyphosate treatments. Increasing water stress caused reductions in subtending leaf glucose, sucrose, and starch content, as well as reductions in boll starch and sucrose content. Reductions in boll starch and sucrose content in response to water stress may indicate the potential for abscission. Water stress and glyphosate treatments to GR cotton do not alter carbohydrate profiles in boll or leaf tissues in a like manner. Differences in carbohydrate profiles of young bolls and leaves from glyphosate-treated and water-stressed cotton plants suggest that water stress and glyphosate treatments may promote fruit abscission in different manners. Citing Literature Volume43, Issue3May–June 2003Pages 879-885 RelatedInformation}, number={3}, journal={Crop Science}, author={Pline, W. A. and Wells, R. and Little, G. and Edmisten, K. L. and Wilcut, J. W.}, year={2003}, pages={879–885} }
 @article{pline_edmisten_wilcut_wells_thomas_2003, title={Glyphosate-induced reductions in pollen viability and seed set in glyphosate-resistant cotton and attempted remediation by gibberellic acid (GA(3))}, volume={51}, ISSN={["0043-1745"]}, DOI={10.1614/0043-1745(2003)051[0019:GIRIPV]2.0.CO;2}, abstractNote={Abstract Glyphosate treatments to glyphosate-resistant (GR) cotton can cause increased fruit loss compared with untreated plants, likely due to reductions in pollen viability and alterations in floral morphology that may reduce pollination efficiency. This study was conducted to determine whether both stamen and pistil are affected by glyphosate treatments by measuring seed set from reciprocal reproductive crosses made between glyphosate-treated GR, untreated GR, and conventional nontransgenic cotton. Pollen viability was 51 and 38% lower for the first and second week of flowering, respectively, in GR plants treated with a four-leaf postemergence (POST) treatment and an eight-leaf POST-directed treatment of glyphosate than in GR plants that were not treated. Seed set per boll was significantly reduced when the pollen donor parent was glyphosate treated vs. untreated for the first 2 wk of flowering. There were no significant differences between treatments applied to male parents as measured by seed set at Weeks 3 and 4 of flowering. Seed set was not influenced by glyphosate treatments applied to female parents at any time. Retention of bolls resulting from crosses was reduced by glyphosate treatment of male parents during the first and third week of flowering but was not affected by glyphosate treatment of female parents. The application of gibberellic acid (GA), which has been shown to reverse male sterility in tomato (Lycopersicon esculentum L.) and to enhance boll retention in cotton, was investigated for similar effects in glyphosate-treated GR cotton. The GA treatments to glyphosate-treated plants increased the anther–stigma distance 12-fold, stigma height, and pollen viability in the second week of flowering but decreased the number of seeds in second-position bolls on Fruiting branches 1 through 3, decreased the number of first-position bolls per plant, and increased the number of squares in comparison with glyphosate-treated GR plants not receiving GA. Although GA applications to glyphosate-treated GR cotton have some remedial effect on pollen viability, the GA-induced increase in the anther–stigma difference exacerbates the increase in anther–stigma distance caused by glyphosate, resulting in low pollination. Nomenclature: Glyphosate; cotton, Gossypium hirsutum L. ‘Delta Pine & Land 5415RR’, ‘Delta Pine & Land 5415’.}, number={1}, journal={WEED SCIENCE}, author={Pline, WA and Edmisten, KL and Wilcut, JW and Wells, R and Thomas, J}, year={2003}, pages={19–27} }
 @article{pline_wilcut_edmisten_wells_2002, title={Physiological and morphological response of glyphosate-resistant and non-glyphosate-resistant cotton seedlings to root-absorbed glyphosate}, volume={73}, ISSN={["1095-9939"]}, DOI={10.1016/S0048-3575(02)00014-7}, abstractNote={The level of tolerance in herbicide-resistant plants may vary among different tissues or growth stages. Studies were conducted to determine relative tissue sensitivity in glyphosate-resistant (GR) and non-GR cotton seedlings to the herbicide glyphosate. Glyphosate is often applied as a pre-plant treatment (burndown) in minimal tillage cotton production systems to remove any unwanted, emerged vegetation. Timing of these glyphosate applications may be in close proximity to the time of planting and seedling emergence. As glyphosate leaches from roots of nearby senescing weeds, it may be absorbed into the roots of cotton seedlings. Therefore, cotton seedlings were grown in hydroponic solutions containing technical grade glyphosate to ensure constant exposure to glyphosate. In all tissues, GR cotton required a greater concentration of glyphosate to reach 50% fresh weight reduction than non-GR cotton. Glyphosate inhibited the growth of non-GR cotton cotyledons, hypocotyls, and roots 50% at concentrations of 23, 69, and 27μM glyphosate, respectively. In contrast, growth of GR cotton cotyledons, hypocotyls, and roots was inhibited by 50% at 3.5-, 8-, and 5-fold greater glyphosate concentrations, respectively, than non-GR cotton tissues. Correspondingly, shikimic acid, an intermediate in the shikimic acid pathway, which accumulates upon 5-enolpyruvyl 3-shikimate phosphate synthase (EPSP synthase) inhibition, reached levels of 17.3, 21.6, and 8.8μMg−1 fresh weight at 1 mM glyphosate in non-GR cotyledons, hypocotyls, and roots, respectively. In contrast, shikimic acid levels in GR cotton were 4.2, 14.0, and 8.2μMg−1 fresh weight at 1 mM glyphosate for cotyledons, hypocotyls, and roots, respectively. Thus, roots of GR and non-GR cotton accumulate similar amounts of shikimic acid, whereas GR cotyledons and hypocotyls accumulated less shikimic acid than the corresponding non-GR tissues in response to glyphosate treatments. Additionally, glyphosate inhibited the development of lateral roots at concentrations of 0.01 or 0.1μM glyphosate greater, in GR and non-GR cotton, respectively. Lateral roots of GR and non-GR cotton inhibited by glyphosate appeared shorter and were surrounded by a thick layer of necrotic cells or root exudate which was not present in roots from plants grown in media not containing glyphosate. The quantity of GR CP4-EPSP synthase was 4.7 and 6.6 times greater in cotyledons than in hypocotyls and roots, respectively. Tissues from dark-grown GR cotton seedlings contained 1.2–2.1 times less CP4-EPSP synthase than their light-grown counterparts. Because lateral root development was inhibited, fresh weight was reduced, and shikimic acid accumulated following treatment with glyphosate in both GR and non-GR cotton, the potential exists for glyphosate to negatively affect cotton seedling establishment.}, number={1}, journal={PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY}, author={Pline, WA and Wilcut, JW and Edmisten, KL and Wells, R}, year={2002}, month={May}, pages={48–58} }
 @article{pline_wilcut_edmisten_2002, title={Postemergence weed control in soybean (Glycine max) with cloransulam-methyl and diphenyl ether tank-mixtures}, volume={16}, ISSN={["0890-037X"]}, DOI={10.1614/0890-037X(2002)016[0737:PWCISG]2.0.CO;2}, abstractNote={Abstract: Field studies were conducted in 1995 and 1996 at three locations in North Carolina to evaluate weed control and soybean injury with postemergence (POST) treatments of cloransulam-methyl alone or in tank-mixture with acifluorfen, fomesafen, or lactofen compared with a commercial standard of acifluorfen plus bentazon. Soybean injury was 2 to 3% 7 d after treatment with cloransulam-methyl applied alone and 11 to 46% when applied with fomesafen, lactofen, acifluorfen, or acifluorfen plus bentazon. Cloransulam-methyl applied alone controlled 95% of entireleaf morningglory and ivyleaf morningglory. Control was not increased by the addition of acifluorfen, fomesafen, or lactofen. Cloransulam-methyl improved the control of common lambsquarters to at least 81% compared with dimethenamid applied preemergence alone (69% control). All diphenyl ether herbicide treatments controlled common lambsquarters at least 91%. Prickly sida control by cloransulam-methyl ranged from 14 to 73% 8 wk after treatment. Control of prickly sida was varied by diphenyl ether herbicides (73 to 100% control). Tank-mixtures of cloransulam-methyl + fomesafen and cloransulam-methyl + acifluorfen increased the control of prickly sida over either herbicide applied alone. Soybean yield was greater for all tank-mixtures than for any diphenyl ether herbicide or for cloransulam-methyl treatment applied alone. But only the acifluorfen + cloransulam-methyl treatment had higher economic returns than the cloransulam-methyl treatment alone. All other POST systems, with the exception of lactofen applied alone, had similar economic returns. Tank-mixtures of cloransulam-methyl and diphenyl ether herbicides increased the spectrum of control and soybean yield compared with these herbicides applied alone. Nomenclature: Acifluorfen; bentazon; cloransulam-methyl; dimethenamid; fomesafen; lactofen; common lambsquarters, Chenopodium album L. #3 CHEAL; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray # IPOHG; ivyleaf morningglory, Ipomoea hederacea (L.) Jacq. # IPOHE; prickly sida, Sida spinosa L. # SIDSP; soybean, Glycine max (L.) Merr. Additional index words: Economic analysis, tank-mixtures. Abbreviations: ALS, acetolactate synthase (EC 4.1.3.18); fb, followed by; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; WAT, wk after POST treatment.}, number={4}, journal={WEED TECHNOLOGY}, author={Pline, WA and Wilcut, JW and Edmisten, KL}, year={2002}, pages={737–742} }
 @article{pline_viator_wilcut_edmisten_thomas_wells_2002, title={Reproductive abnormalities in glyphosate-resistant cotton caused by lower CP4-EPSPS levels in the male reproductive tissue}, volume={50}, ISSN={["0043-1745"]}, DOI={10.1614/0043-1745(2002)050[0438:RAIGRC]2.0.CO;2}, abstractNote={Abstract Glyphosate treatments to glyphosate-resistant (GR) cotton have been associated with poor pollination and increased boll abortion. Anatomical studies were conducted to characterize the effect of glyphosate treatments on the development of male and female reproductive organs of cotton flowers at anthesis. In comparison with nontreated plants, glyphosate applied at both the four-leaf stage postemergence (POST) and at the eight-leaf stage POST directed inhibited the elongation of the staminal column and filament, which increased the distance from the anthers to the receptive stigma tip by 4.9 to 5.7 mm during the first week of flowering. The increased distance from the anthers to the stigma resulted in 42% less pollen deposited on stigmas of glyphosate-treated plants than in nontreated plants. Moreover, pollen from glyphosate-treated plants showed numerous morphological abnormalities. Transmission electron microscopy showed the presence of large vacuoles, numerous starch grains, and less organized pockets of the endoplasmic reticulum containing fewer ribosomes in pollen from glyphosate-treated plants than from nontreated plants. Pollen development in glyphosate-treated plants is likely inhibited or aborted at the vacuolate microspore and vacuolate microgamete stages of microgametogenesis, resulting in immature pollen at anthesis. Although stigmas from glyphosate-treated plants were 1.2 to 1.4 mm longer than those from nontreated plants, no other anatomical differences in stigmas were visibly evident. The presence of the GR 5-enolpyruvylshikimate-3-phosphate synthase (CP4-EPSPS) enzyme from Agrobacterium sp. strain CP4 was quantified in reproductive and vegetative tissues using enzyme-linked immunosorbent assay. The content of CP4-EPSPS in the stigma, anther, preanthesis floral bud (square), and flower petals was significantly less than that in the vegetative leaf tissue. Glyphosate effects on the male reproductive development resulting in poor pollen deposition on the stigma, as well as production of aborted pollen with reduced viability, provide a likely explanation for reports of increased boll abortion and pollination problems in glyphosate-treated GR cotton. Nomenclature: Glyphosate; cotton, Gossypium hirsutum L. ‘Delta Pine & Land 5415RR’, ‘Delta Pine & Land 50’, ‘Delta Pine & Land 90’, ‘SureGrow 125RR’.}, number={4}, journal={WEED SCIENCE}, author={Pline, WA and Viator, R and Wilcut, JW and Edmisten, KL and Thomas, J and Wells, R}, year={2002}, pages={438–447} }
 @article{pline_edmisten_oliver_wilcut_wells_allen_2002, title={Use of digital image analysis, viability stains, and germination assays to estimate conventional and glyphosate-resistant cotton pollen viability}, volume={42}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2002.2193}, abstractNote={AbstractBecause the success of labor‐intensive hand crosses by breeders is dependent upon pollen viability, quick, simple, and inexpensive methods for viability assessment are of interest. Four such cotton pollen viability assays were compared to determine differences in viability estimates, and relative accuracy by correlation to seed set. The methods compared were Brewbaker & Kwack (B & K) medium, B & K medium plus aniline blue, a fluorochromatic reaction method (FCR), and Alexander's stain. Additionally, digital images of germinated pollen grains were analyzed by means of morphometry software to quantify pollen tube area per pollen grain, as a proposed additional method of assessing viability. Pollen from conventional, nontreated glyphosate‐resistant (GR) and glyphosate‐treated GR cotton (Gossypium hirsutum L.) plants was tested by each method. Glyphosate treatments to GR cotton reduced pollen viability and corresponding seed set in all methods tested. Pollen germination measured by the B & K method was most closely related to seed set per boll, while Alexander's stain gave the highest estimates of viability. The FCR method indicated that many pollen grains from glyphosate‐treated GR cotton were irregularly shaped and only partially flourescein diacetate (FD) stained. All methods tested showed similar high correlation (0.7–0.8) of pollen viability to seed set. Morphometric analysis of digital images of germinated pollen found the greatest pollen tube area to pollen grain ratio with B & K medium + 30 mM sucrose. Because the B & K method most closely predicted the linear magnitude of seed set reduction to reduced pollen viability, allowed the use of morphometry software analysis, and was one of the simplest and least equipment‐demanding methods, it may provide broad utility for those assessing cotton pollen viability.}, number={6}, journal={CROP SCIENCE}, author={Pline, WA and Edmisten, KL and Oliver, T and Wilcut, JW and Wells, R and Allen, NS}, year={2002}, pages={2193–2200} }
 @article{pline_price_wilcut_edmisten_wells_2001, title={Absorption and translocation of glyphosate in glyphosate-resistant cotton as influenced by application method and growth stage}, volume={49}, ISSN={["0043-1745"]}, DOI={10.1614/0043-1745(2001)049[0460:AATOGI]2.0.CO;2}, abstractNote={Abstract The influence of herbicide placement and plant growth stage on the absorption and translocation patterns of 14C-glyphosate in glyphosate-resistant cotton was investigated. Plants at four growth stages were treated with 14C-glyphosate on a 5-cm2 section of the stem, which simulated a postemergence-directed spray (PDS) application, or on the newest mature leaf, which simulated a postemergence (POST) application. Plants were harvested 3 and 7 d after treatment and divided into the treated leaf or treated stem, mature leaves, immature leaves and buds, stems, roots, fruiting branches (including the foliage on the fruiting branch), squares, and bolls. The PDS versus POST application main effect on absorption was significant. Absorption of 14C-glyphosate applied to stem tissue was higher in PDS applications than in POST applications. Plants receiving PDS applications absorbed 35% of applied 14C-glyphosate, whereas those receiving POST applications absorbed 26%, averaged over growth stages at application. Absorption increased from the four-leaf growth stage to the eight-leaf stage in POST applications but reached a plateau at the eight-leaf stage. Plants with PDS applications showed an increase in absorption from the four- to eight- to twelve-leaf stages and reached a plateau at the 12-leaf stage. Translocation of 14C-glyphosate to roots was greater at all growth stages with PDS treatments than with POST treatments. Herbicide placement did not affect translocation of 14C-glyphosate to squares and bolls. Squares and bolls retained 0.2 to 3.7% of applied 14C-glyphosate, depending on growth stage. Separate studies were conducted to investigate the fate of foliar-applied 14C-glyphosate at the four- or eight-leaf growth stages when harvested at 8- or 10-leaf, 12-leaf, midbloom (8 to 10 nodes above white bloom), and cutout (five nodes above white bloom, physiological maturity) stages. Thirty to 37% of applied 14C-glyphosate remained in the plant at cutout in four- and eight-leaf treatment stages, respectively. The concentration of 14C-glyphosate in tissue (Bq g−1 dry weight basis) was greatest in mature leaves and immature leaves and buds in plants treated at the four-leaf stage. Plants treated at the eight-leaf stage and harvested at all growth stages except cutout showed a higher concentration of 14C-glyphosate in squares than in other plant tissue. Accumulation of 14C-glyphosate in squares reached a maximum of 43 Bq g−1 dry weight at harvest at the 12-leaf stage. This concentration corresponds to 5.7 times greater accumulation of 14C-glyphosate in squares than in roots, which may also be metabolic sinks. These data suggest that reproductive tissues such as bolls and squares can accumulate 14C-glyphosate at higher concentrations than other tissues, especially when the herbicide treatment is applied either POST or PDS during reproductive stages (eight-leaf stage and beyond). Nomenclature: Glyphosate; cotton, Gossypium hirsutum L. ‘Delta Pine 5415RR’.}, number={4}, journal={WEED SCIENCE}, author={Pline, WA and Price, AJ and Wilcut, JW and Edmisten, KL and Wells, R}, year={2001}, pages={460–467} }
 @article{pline_lacy_stromberg_hatzios_2001, title={Antibacterial activity of the herbicide glufosinate on Pseudomonas syringae pathovar glycinea}, volume={71}, ISSN={["1095-9939"]}, DOI={10.1006/pest.2001.2556}, abstractNote={Abstract The antibacterial activity of the herbicide glufosinate on Pseudomonas syringae pathovar (pv.) glycinea (L-529), causal agent of soybean blight, was examined in culture and in planta. Bacteria were grown in medium containing either formulated or technical-grade glufosinate from 0.01 to 100 mM, and growth was monitored by turbidity measurements over time. Glufosinate inhibited bacterial growth at concentrations of 1 mM or greater and delayed growth at concentrations as low as 0.01 mM. Metabolism of [14C]glufosinate by P. syringae pv. glycinea grown in Davis minimal medium containing either a sublethal (1 mM) or a lethal (100 mM) glufosinate concentration was measured incrementally up to 45 h after inoculation. Thin-layer chromatography analysis revealed the presence of three glufosinate metabolites in addition to the parent compound. The rate of [14C]glufosinate metabolism by bacteria was greater in medium treated with 1 mM than in medium treated with 100 mM glufosinate. More 14C was recovered as 3-methylphosphinico-propionic acid and as an unidentified metabolite with an Rf value of 0.45 in medium treated with 1 mM than in medium treated with 100 mM glufosinate. These data suggest that P. syringae pv. glycinea can slowly metabolize glufosinate into less toxic metabolites, resulting in greater bacterial growth in medium treated with 1 mM glufosinate. Treatment of transgenic glufosinate-resistant (GR) soybeans with field rates of glufosinate reduced the number of live P. syringae pv. glycinea at 90 h after inoculation. Inoculated GR soybeans showed a 45;pc reduction of colony forming units after treatment with 0.5 kg/ha glufosinate and a 60;pc reduction after treatment with 1.0 kg/ha glufosinate. These results show that glufosinate exhibits some antibacterial activity against P. syringae pv. glycinea, but at concentrations greater than those of registered bactericides.}, number={1}, journal={PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY}, author={Pline, WA and Lacy, GH and Stromberg, V and Hatzios, KK}, year={2001}, month={Sep}, pages={48–55} }
 @article{pline_wilcut_duke_edmisten_wells_2002, title={Tolerance and accumulation of shikimic acid in response to glyphosate applications in glyphosate-resistant and nonglyphosate-resistant cotton (Gossypium hirsutum L.)}, volume={50}, ISSN={["0021-8561"]}, DOI={10.1021/jf0110699}, abstractNote={Measurement of shikimic acid accumulation in response to glyphosate inhibition of 5-enolpyruvylshikimate-3-phosphate synthase is a rapid and accurate assay to quantify glyphosate-induced damage in sensitive plants. Two methods of assaying shikimic acid, a spectrophotometric and a high-performance liquid chromatography (HPLC) method, were compared for their accuracy of recovering known amounts of shikimic acid spiked into plant samples. The HPLC method recovered essentially 100% of shikimic acid as compared with only 73% using the spectrophotometric method. Relative sensitivity to glyphosate was measured in glyphosate-resistant (GR) and non-GR cotton leaves, fruiting branches, and squares (floral buds) by assaying shikimic acid. Accumulation of shikimic acid was not observed in any tissue, either GR or non-GR, at rates of 5 mM glyphosate or less applied to leaves. All tissues of non-GR plants accumulated shikimic acid in response to glyphosate treatment; however, only fruiting branches and squares of GR plants accumulated a slight amount of shikimic acid. In non-GR cotton, fruiting branches and squares accumulated 18 and 11 times, respectively, more shikimic acid per micromolar of translocated glyphosate than leaf tissue, suggesting increased sensitivity to glyphosate of reproductive tissue over vegetative tissue. GR cotton leaves treated with 80 mM of glyphosate accumulated 57 times less shikimic acid per micromolar of translocated glyphosate than non-GR cotton but only 12.4- and 4-fold less in fruiting branches and squares, respectively. The increased sensitivity of reproductive structures to glyphosate inhibition may be due to a higher demand for shikimate pathway products and may provide an explanation for reports of fruit abortion from glyphosate-treated GR cotton.}, number={3}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Pline, WA and Wilcut, JW and Duke, SO and Edmisten, KL and Wells, R}, year={2002}, month={Jan}, pages={506–512} }