bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance of Four Seashore Paspalum (Paspalum vaginatum) Cultivars to Postemergence Herbicides
Authors: Johnson B. Jack , Duncan Ronny R.
Published: March 2018

A field study was conducted on tolerance of four seashore paspalum cultivars to postemergence (POST) herbicides in Georgia during 1995 and 1996. Quinclorac (0.8 kg/ha) and MON 12000 (0.07 kg/ha) at recommended rates were the only POST herbicides that did not affect the performance of any seashore paspalum cultivar (≥ 89%). When the rates were increased to three times recommended, the quality of ‘AP 10’ (≥ 96%) and ‘PI 28960’ (93%) cultivars was not affected, but the quality of ‘HI 25’ (≥ 84%) and ‘K-7’ (77%) was lower when compared with respective untreated plots. HI 25 recovered within 4 wk, but K-7 required 6 wk or longer. Dicamba at 1.7 kg/ha affected the quality of K-7 (69%) more at 2 wk than the other cultivars (85 to 92%). Diclofop, imazaquin, and 2,4-D plus mecoprop plus dicamba significantly reduced the quality of all cultivars 2 wk after treatment (WAT). The quality of all cultivars was similar at 2 WAT with diclofop at 1.1 kg/ha (79 to 84%). However, when treated with imazaquin at 0.4 kg/ha, the quality of K-7 (65%) was lower than AP 10 (85%), HI 25 (77%), and PI 28960 (81%), and when treated with 2,4-D plus mecoprop plus dicamba at 1.1 + 0.6 + 0.1 kg/ha, the quality of AP 10 (75%), PI 28960 (72%), and K-7 (57%) was lower than HI 25 (87%). POST applications of quinclorac, dicamba, and MON 12000 were safe to use for weed control in paspalum cultivars, whereas the safety of diclofop and imazaquin was marginal, and 2,4-D plus mecoprop plus dicamba was unacceptable.
Effect of Tillage and Soil-Applied Herbicides on Broadleaf Signalgrass (Brachiaria platyphylla) Control in Corn (Zea mays)
Authors: Mueller Thomas C. , Hayes Robert M.
Published: March 2018

Broadleaf signalgrass control from preemergence (PRE) herbicides was usually lower in no-till than in tilled plots. Broadleaf signalgrass control was most nearly complete in tilled plots treated with metolachlor in 1995, a year that favored an herbicide with more soil persistence. Broadleaf signalgrass control was most nearly complete in tilled plots treated with acetochlor in 1996, a year in which rainfall to activate the herbicides did not occur until 9 d after planting. The 1996 data indicated that acetochlor was more stable on the soil surface under the drier conditions. There was no difference in broadleaf signalgrass control between the two acetochlor formulations. Alachlor, metolachlor, and dimethenamid controlled broadleaf signalgrass > 80% for about 4 wk, acetochlor provided control for about 4 wk under no-till conditions and about 8 wk in tilled plots, and pendimethalin provided about 2 wk broadleaf signalgrass control. Acetochlor provided consistent control regardless of the rainfall pattern after application.
Influence of Herbicides and Timing of Application on Broadleaf Weed Control in Peanut (Arachis hypogaea)
Authors: Grichar W. James
Published: March 2018

Field studies were conducted from 1992 through 1994 to evaluate application timing of seven postemergence (POST) broadleaf herbicides alone and in mixtures for control of eclipta and pitted morningglory. Imazethapyr and 2,4-DB did not control eclipta while AC 263,222 applied early postemergence (EPOST) at 0.07 kg/ha provided greater than 90% control in 2 of 3 yr. EPOST applications of bentazon, acifluorfen + bentazon, and pyridate controlled eclipta at least 92% all 3 yr. Lactofen applied EPOST at 0.28 kg/ha provided similar levels of eclipta control in 2 of 3 yr. Imazethapyr controlled pitted morningglory > 70% when applied EPOST. AC 263,222 controlled pitted morningglory a minimum of 83% when applied EPOST at 0.04 or 0.07 kg/ha. Pitted morningglory control was at least 85% with 2,4-DB applied alone or in a mixture with AC 263,222, acifluorfen, imazethapyr, lactofen, or pyridate. Effective weed control increased peanut yields up to 98% over the untreated check.
Weed Management in Northeast China
Authors: Su Shao Q. , Ahrens William H.
Published: March 2018

Agricultural production in China occurs via three distinct organizational units: the countryside farmer, state farms, and military farms. The countryside farmer in northeast China carries out most production operations with hand tools, some animal and tractor power, and little additional mechanization. Most weeds in row crops are controlled by hand, although a high percentage of the rice crop is treated with herbicides as is about 20% of the wheat. Countryside farmers independently manage small plots of land. State and military farms, the majority of which are located in China's northeastern-most province of Heilongjiang, are highly mechanized and accomplish most weed control with herbicides. Military farms range from ~500–2,500 ha, and state farms generally occupy 50,000–100,000 ha, with some much larger. Primary crops on the military farms are soybeans, oilseed rape, and wheat. State farms generally have more diversity in crops. The need for herbicide adjuvants to increase postemergence (POST) herbicide efficacy and for reduced tillage practices to combat soil erosion are recognized concerns, as is the threat of herbicide resistance.
Grower Acceptance of Economic Thresholds for Weed Management in Illinois
Authors: Czapar George F. , Curry Marc P. , Wax Loyd M.
Published: March 2018

Although economic thresholds are often used to make insect control decisions, the use of thresholds for weed management has been limited. Surveys of growers, agricultural chemical dealers, and farm managers/rural appraisers helped identify limitations to grower acceptance of economic thresholds for weed management. Most growers were concerned about harvest problems due to weeds, with 64% identifying this factor as a major limitation. Landlord perception and weed seed production were identified by 38% of the growers as major limitations, while 36% of the growers listed general appearance of the field as reasons. In contrast, 75% of the agricultural chemical dealers and 63% of the farm managers surveyed listed field appearance as a major reason limiting grower acceptance of economic thresholds for weed management. Since grower concerns involve risk management and future profitability, economic weed thresholds that address long-term costs and benefits of weed control decisions may be more fully accepted.
Bromoxynil Antagonizes Johnsongrass (Sorghum halepense) Control with Graminicides
Authors: Corkern Chris B. , Reynolds Daniel B. , Vidrine P. Roy , Griffin James L. , Jordan David L.
Published: March 2018

Field studies were conducted over 2 yr to evaluate rhizome johnsongrass control with tank mixtures and sequential applications of bromoxynil at 1.7 kg ai/ha and the graminicides clethodim, fluazifop-P, and quizalofop-P. When compared with the graminicide alone, bromoxynil reduced johnsongrass control 28 days after treatment (DAT) 20, 36, and 55% when applied in combination with clethodim, fluazifop-P, and quizalofop-P, respectively. Application of bromoxynil 7, 3, and 1 d before or 1, 3, and 7 d after all graminicides reduced antagonism when compared with the bromoxynil plus graminicide mixtures. Based on johnsongrass control 28 DAT, antagonism was precluded when bromoxynil was applied 3 d before clethodim and 7 d before fluazifop-P and quizalofop-P. Application of bromoxynil 3 and 7 d after quizalofop-P and 7 d after clethodim also precluded antagonism. The antagonistic tank mixtures of bromoxynil and graminicides reduced cotton yield 17% because of reduced johnsongrass control compared with graminicides alone. A 3-d or greater application interval between bromoxynil and the graminicides was necessary to maximize cotton yield.
The Ecology and Control of Perennial Pepperweed (Lepidium latifoliumL.)
Authors: Young James A. , Palmquist Debra E. , Blank Robert R.
Published: March 2018

Field experiments were conducted for the control of perennial pepperweed with tillage and herbicides. Perennial pepperweed infests a wide range of soils and plant communities. These studies were conducted in native hay meadows, with wild-flooding irrigation and saline/alkaline soils. Such meadows are typical of livestock ranches throughout the Intermountain Area. Tillage with periodic disking over a 2-yr period resulted in no permanent reduction in perennial pepperweed cover. Applications of 2,4-D or glyphosate eliminated perennial pepperweed seed production and greatly reduced top growth but had no permanent influence on cover of the weed by the second season following application. Applications of chlorsulfuron in the spring at flowering, in late summer after hay harvesting, or in the autumn, were effective in suppressing perennial pepperweed for 2 yr or more following application.
Effect of Oil Adjuvants and Nitrogen Fertilizer on the Efficacy of Imazethapyr Applied at Conventional and Ultralow Spray Volumes
Authors: Wills Gene D. , Hanks James E. , Jones Elizabeth J. , Mack Robert E.
Published: March 2018

Field experiments evaluated pitted morningglory, velvetleaf, and barnyardgrass control in soybean with imazethapyr applied alone and with either crop oil concentrate at 1.0% v/v, a blend of methylated seed oil and organosilicone surfactant, or a blend of methylated seed oil, phosphate esters, and organosilicone surfactant at 0.5% v/v, each with and without a 28% N mixture of urea and ammonium nitrate (URAN) applied at 2.3 L/ha. Treatments were applied at spray volumes of 94 and 9.4 L/ha. Control of each species was often increased with the addition of both oil adjuvants and URAN. The blend of methylated seed oil, phosphate esters, and organosilicone surfactant and the blend of methylated seed oil and organosilicone surfactant were each more effective than crop oil concentrate on pitted morningglory and barnyardgrass, while each oil adjuvant was similar on velvetleaf. The URAN effectively increased imazethapyr control of all species. Control of all species was similar at the spray volume of 9.4 L/ha and at 94 L/ha.
Response of Cotton (Gossypium hirsutum) to Flame Cultivation
Authors: Seifert Simone , Snipes Charles E.
Published: March 2018

Field studies to evaluate the response of cotton to flame cultivation were conducted in 1994, 1995, and 1996. Flame cultivation at different liquid propane-gas (LP-gas) pressure settings (100 and 175 kPa) with or without watershield protection was applied to cotton at two stages of growth (20 to 25 cm and 40 to 45 cm tall). In 1994, younger cotton was more susceptible to flame cultivation than older cotton, and flaming at an LP-gas pressure of 175 kPa without watershield protection increased plant injury regardless of growth stage, whereas injury was not evident in 1995 and 1996. Injury caused by flame cultivation was a transient browning of lower leaf margins. The use of a watershield sprayed above the burner reduced injury. Flame cultivation applied to cotton 20 to 25 cm tall slightly elevated the first fruiting node, but no effects were noted on other vegetative and reproductive growth parameters or yield regardless of pressure setting or watershield protection. Flame cultivation applied to cotton 40 to 45 cm tall did not affect the position of the first fruiting node. Although flame cultivation caused some injury one year, total seed cotton and cotton lint yields were not reduced.
Ecological Characteristics of Three Winter Annual Grasses
Authors: Anderson R. L.
Published: March 2018

Producers rely on cultural practices to manage downy brome, jointed goatgrass, and feral rye in winter wheat because there are no effective herbicides for in-crop control. This study characterized seedling emergence, growth, and development of these winter annual grasses, with the goal of suggesting or improving cultural control strategies. Feral rye seedlings emerged within 4 wk, whereas downy brome and jointed goatgrass seedlings emerged over a 10-wk period. Emergence patterns of these grasses suggest that delay of winter wheat planting may be effective in reducing feral rye densities, but this strategy most likely will be ineffective with downy brome or jointed goatgrass. Downy brome began anthesis 1 to 2 wk earlier than the other two grasses and winter wheat. Both downy brome and jointed goatgrass were shorter than winter wheat during the growing season, whereas feral rye was at least as tall as wheat. Producers mow infested wheat to prevent weed seed production, but this practice may not be effective with jointed goatgrass and downy brome because of their short stature and downy brome's earlier development. Conversely, mowing has potential in preventing feral rye seed production. The grasses produced between 340 and 770 seeds/ plant.
Response of Downy Brome (Bromus tectorum) and Rotational Crops to MON 37500
Authors: Shinn Sandra L. , Thill Donald C. , Price William J. , Ball Daniel A.
Published: March 2018

Field experiments were conducted to determine the effect of different rates and application times of MON 37500 on downy brome control in winter wheat and on rotational crop injury. In southeastern Washington, MON 37500 applied postemergence at 36 to 72 g ai/ha in the fall and spring controlled downy brome 90 to 97% and 45 to 71%, respectively. MON 37500 was applied postemergence to winter wheat at 18, 36, and 72 g/ha during fall 1995 and spring 1996 near Moscow, ID; Pendleton, OR; and Endicott, WA, to determine its effect on rotational crops planted during spring 1997. At Pendleton, OR, fall applications of MON 37500 at 18, 36, and 72 g/ha applied to actively growing wheat reduced seed yield of spring barley and pea 13 to 59% and 26 to 29%, respectively, when these crops followed winter wheat in the rotation. At this site, spring applications of 36 and 72 g/ha reduced seed yield of spring barley 17 to 34%; when applied in the fall or spring, MON 37500 reduced canola yield 31 to 73%. MON 37500 at 18 g/ha in the spring reduced pea biomass 32% at Endicott. Aboveground biomass and seed yield of barley, pea, lentil, and mustard at Moscow were not affected by MON 37500 carryover. However, using a grain sorghum bioassay, predicted final concentrations of MON 37500 in soil at all three locations 360 d after treatment (DAT) was similar, ranging from 0.5 to 2 ng ai/g. In growth chamber herbicide dose–response studies, grain sorghum shoot height was reduced more at lower doses (0.025 to 5 ng/g) of MON 37500 in Pendleton soil than in soils from the other field locations. Perhaps the greater rotational crop injury observed at the Pendleton location was partly related to greater soil activity of the herbicide.
Interference and Control of Large Crabgrass (Digitaria sanguinalis) and Southern Sandbur (Cenchrus echinatus) in Forage Bermudagrass (Cynodon dactylon)
Authors: Walker Robert H. , Wehtje Glenn , Richburg John S.
Published: March 2018

Field experiments were conducted at two locations in central Alabama to evaluate competitiveness of large crabgrass and southern sandbur with ‘Tifton 78’ hybrid bermudagrass as influenced by diuron application and sprigging rate. Large crabgrass was the more competitive species. In late season, bermudagrass ground cover with no weed competition was 96% compared with 72 and 81% where large crabgrass and southern sandbur, respectively, were present. Similarly, large crabgrass and southern sandbur reduced the proportion of bermudagrass in the cumulative harvested forage by at least 59 and 38%, respectively. Application of diuron preemergence (PRE) at 1.1 kg ai/ha was more effective than postemergence (POST) application, both in terms of weed control and bermudagrass safety. With diuron applied PRE, large crabgrass and southern sandbur reduced the proportion of bermudagrass in the harvested forage only 32 and 25%, respectively. Increasing bermudagrass sprigging rate was beneficial for weed control but of relatively minor importance compared with diuron PRE.
Response of Nine Sugarbeet (Beta vulgaris) Cultivars to Postemergence Herbicide Applications
Authors: Wilson Robert G.
Published: March 2018

A field experiment was conducted for 2 yr near Scottsbluff, NE, to evaluate the growth and yield response of nine commercial sugarbeet cultivars to five postemergence herbicide mixtures applied two times. Sugarbeet cultivars varied in their response to herbicides. Three of the five postemergence herbicide mixtures reduced sugarbeet leaf area at 9 wk after planting (WAP), while two treatments had no significant effect. Root yield reductions from herbicide treatments ranged from 3 to 11% averaged over the nine cultivars. Two applications of desmedipham plus phenmedipham at 180 plus 180 g/ha reduced root yield 3% compared to untreated plots. Two applications of clopyralid at 100 g/ha, triflusulfuron at 18 g/ha, or ethofumesate at 160 g/ha plus desmedipham plus phenmedipham resulted in a 17, 29, and 22% reduction in leaf area at 9 WAR respectively, and a 6, 8, and 6% reduction in root yield, respectively, compared to untreated plots. Sethoxydim at 280 g/ha plus desmedipham plus phenmedipham did not cause additional sugarbeet injury.
Control of Propanil-Resistant Barnyardgrass (Echinochloa crus-galli) in Rice (Oryza sativa) with Carbaryl/Propanil Mixtures
Authors: Daou Hassane , Talbert Ronald E.
Published: March 2018

Propanil and carbaryl mixtures, propanil formulated with carbaryl, the package mixture of propanil plus molinate (alone and plus pendimethalin), propanil plus quinclorac, and propanil plus pendimethalin were evaluated in field experiments for control of propanil-resistant and -susceptible barnyardgrass in 1995 and 1996 in Arkansas. Propanil alone at 3.3 kg ai/ha did not control propanil-resistant barnyardgrass when applied to two-leaf and repeated at four-leaf barnyardgrass. Propanil at 3.3 kg/ha with carbaryl at 0.1 to 0.3 kg ai/ha controlled propanil-resistant barnyardgrass at least 90% when applied at the two-leaf stage with no rice yield reduction. Applications repeated at the four-leaf stage also controlled propanil-resistant barnyardgrass, but rice injury was 66% with 0.3 kg/ha carbaryl in 1 of 2 yr, and rice yield was reduced. Control of resistant barnyardgrass with the commercial formulation of propanil plus carbaryl and propanil plus molinate was lower with a single application than with repeat applications. Propanil plus quinclorac, propanil plus pendimethalin, and propanil plus molinate plus pendimethalin controlled resistant barnyardgrass with one application at the two-leaf stage.
Glyphosate Injury, Rainfastness, Absorption, and Translocation in Purple Nutsedge (Cyperus rotundus)
Authors: Bariuan Juanito V. , Reddy Krishna N. , Wills Gene D.
Published: March 2018

Greenhouse and laboratory experiments were conducted to study activity, rainfastness, absorption, and translocation of glyphosate with and without a nonionic organosilicone surfactant in purple nutsedge. Purple nutsedge responded differently to glyphosate depending on growth stage. Glyphosate at 2.24 kg ai/ha in 17-d-old and at 4.48 kg/ha in 10-wk-old plants controlled purple nutsedge at least 96%. Regrowth of plants and tuber resprouting were greatly reduced in these treatments. Organosilicone surfactant did not increase efficacy of glyphosate. A simulated rainfall of 2.5 cm (7.5 cm/h intensity) at 1 and 24 h after glyphosate application reduced efficacy by one-half and one-third, respectively, compared with no simulated rainfall. A rain-free period of 72 h prevented loss of glyphosate activity. Absorption of14C-glyphosate increased from 2.8% at 1 h after application to 21.4% at 168 h after application and translocation increased from 0.43% at 1 h after application to 5.18% at 168 h after application. Organosilicone surfactant did not affect absorption and translocation of glyphosate in purple nutsedge.
Response of Oat (Avena sativa) Varieties and Wild Radish (Raphanus raphanistrum) to Thifensulfuron plus Tribenuron
Authors: Fischer David W. , Harvey R. Gordon , Oplinger Edward S. , Maloney Timothy S.
Published: March 2018

Field studies evaluated wild radish control in oat with thifensulfuron plus tribenuron in 1995 and 1997. Thifensulfuron plus tribenuron at 16 or 21 g ai/ha controlled wild radish completely in both years. In tolerance studies conducted in 1995 and 1996, thifensulfuron plus tribenuron reduced vigor of ‘Bay,’ ‘Belle,’ ‘Dane,’ ‘Ensiler,’ ‘Gem,’ ‘Horicon,’ ‘Ogle,’ ‘Porter,’ and ‘Prairie’ oat varieties and Wisconsin test selection oat ‘X6396-1’ up to 25% 7 d after treatment (DAT), but all chlorotic symptoms had disappeared 28 DAT. Thifensulfuron plus tribenuron reduced oat height 13 to 19% in 1995 and 21 to 24% in 1996 7 DAT. Bay, Belle, Dane, Ensiler, Horicon, Prairie, and X6396-1 recovered from height reductions by 28 DAT in 1995; however, in 1996 only Horicon and Porter recovered. Thifensulfuron plus tribenuron did not reduce 1995 grain yields, but 1996 Bay and Porter grain yields were reduced 29 and 15%, respectively. Dane and Prairie seed weights were reduced 7 and 14%, respectively, in 1995, whereas no seed weight reduction occurred in 1996.
Absorption, Translocation, and Metabolism of Rimsulfuron in Black Nightshade (Solanum nigrum), Eastern Black Nightshade (Solanum ptycanthum), and Hairy Nightshade (Solanum sarrachoides)
Authors: Ackley John A. , Hatzios Kriton K. , Wilson Henry P.
Published: March 2018

Absorption, translocation, and metabolism of rimsulfuron were studied in three solanaceous weeds. Eastern black nightshade is sensitive (> 95% injury), hairy nightshade is moderately sensitive (50 to 99% injury), and black nightshade is tolerant to rimsulfuron postemergence (POST). Seedlings at the four- to six-leaf stage were treated with foliar-applied14C-labeled rimsulfuron for 3, 6, 24, and 48 h after treatment. Absorption of rimsulfuron by all weeds increased with time. Black and eastern black nightshade absorbed comparable amounts of radioactivity at each exposure time. Hairy nightshade absorbed less radiolabeled herbicide than the other two nightshades at any treatment time. Hairy nightshade absorbed 54% of the applied radioactivity at 48 h, compared to 74% absorbed by the other weeds. Translocation of rimsulfuron out of the treated leaf was rapid in all species. Black and eastern black nightshade translocated 50 to 70% of the absorbed radioactivity out of the treated leaf with 40 to 50% moving to the upper foliage. In hairy nightshade, about 40% of the absorbed radioactivity translocated out of the treated leaf with equal amounts moving to the upper and lower foliage. Metabolism of14C-rimsulfuron was rapid in the three nightshades with approximately 54% remaining as rimsulfuron at 3 h after treatment. The levels of the detected metabolites of rimsulfuron were similar in the three nightshade weeds. Differential early uptake and translocation may account for the differential sensitivity of these nightshade species to rimsulfuron.
Remediation of Herbicides in Runoff Water from Container Plant Nurseries Utilizing Grassed Waterways
Authors: Briggs Jeanne A. , Whitwell Ted , Riley Melissa B.
Published: March 2018

The ability of grassed waterways to remediate herbicide loads in runoff water was evaluated using simulated and on-site nursery research. Isoxaben plus oryzalin and isoxaben plus trifluralin were applied to model grassed (zoysiagrass or ‘Tifway 10’ hybrid bermudagrass) and nongrassed, metal and clay loam waterways, and runoff samples were collected. Grassed waterways reduced runoff volume an average of 47% and herbicide residues an average of 56% compared to nongrassed waterways. The smallest herbicide residues were from the clay/grass waterways. In a nursery study, isoxaben and trifluralin were applied to containerized landscape plant production beds. Overhead irrigation was applied and runoff water was channeled into either a clay/gravel waterway or a hybrid bermudagrass waterway. Samples were collected for 22 d following application. Isoxaben persisted through 15 d after application. Trifluralin was detected through 2 d after application. Total isoxaben recovered from the clay/gravel waterway was 32% of applied, and total trifluralin recovered was 0.9% of applied. The grass waterway reduced residues of isoxaben and trifluralin by 22 and 66%, respectively, compared to the clay/gravel waterway.
Long-Term Control of Perennial Broadleaf Weeds and Triazine-Resistant Common Lambsquarters (Chenopodium album) in No-Till Corn (Zea mays)
Authors: Glenn Scott , Phillips William H. , Kalnay Pablo
Published: March 2018

Control and regrowth of hemp dogbane, wild blackberry, and triazine-resistant common lambsquarters (TR-CHEAL) were studied in no-till corn from 1992 to 1994. Hemp dogbane, wild blackberry, and TR-CHEAL population increased 10, 123, and 177%, respectively, between 1992 and 1994 in plots treated with PRE applications of paraquat, atrazine, and metolachlor (weedy checks). POST applications of tank mixtures of 35 g ai/ha nicosulfuron or 20 g/ha primisulfuron with 280 g/ha 2,4-D or 140 g/ha dicamba, and 560 g/ha dicamba applied alone controlled hemp dogbane, wild blackberry, and TR-CHEAL 67 to 98%. These treatments reduced the population or prevented expansion of these weeds the year following treatment. In 1992, corn yield response to weed control was inconsistent. In 1993 and 1994, all plots treated with POST herbicides yielded higher than the weedy check. Corn yield of plots treated with combinations of nicosulfuron or primisulfuron with 2,4-D or dicamba and 560 g/ha dicamba applied alone were 102 to 149% and 124 to 153% higher than the weedy check in 1993 and 1994, respectively.
The Effect of Trifluralin Applied Preplant on Grass Weed Control and Establishment and Yield of Barley (Hordeum vulgare)
Authors: Scursoni Julio A. , Satorre Emilio H.
Published: March 2018

The objective of this paper was to evaluate the effect of preplant applications of trifluralin on barley stand and yield, and control of grass weeds in field experiments during 1992 and 1993. Factors examined were: (1) crop planting patterns (conventional drill with rows 15 cm apart and deep-seeder drill with rows 25 cm apart), (2) herbicide application times (22 d before sowing and immediately before sowing), and (3) herbicide application. During 1993, hand-weeded plots also were established. Trifluralin applied preplant at 528 g ai/ha reduced weed density and biomass. Weed control was higher under conventional planting than under the deep planting pattern, and there was no effect of the time of application on herbicide efficacy. There was no herbicide injury to the crop, and grain yield was higher in treated than in untreated plots due to successful weed control.
Controlling Kochia (Kochia scoparia) in Soybean (Glycine max) with Postemergence Herbicides
Authors: Wicks Gail A. , Martin Alex R. , Hanson Gordon E.
Published: March 2018

POST herbicides were applied at four soybean growth stages to evaluate their effect on triazine-resistant (TR) kochia in 1991, 1992, and 1993. Applying imazethapyr at 70 g ai/ha or bentazon plus imazethapyr at 1,120 plus 70 g ai/ha controlled 75 to 100% of 1- to 13-cm-tall TR kochia consistently across growth stages and years. Acifluorfen at 560 g ai/ha, chlorimuron at 13 g ai/ha, or chlorimuron plus thifensulfuron at 4 plus 4 g ai/ha controlled 68 to 96% of 1- to 2-cm-tall TR kochia at soybean growth stage VC to V1, and control was inconsistent at later growth stages. In most instances, soybean seed yield was greater with herbicides applied at the V1 or V2 growth stage of soybean compared with the V4 and V5 growth stage because of better weed control. No wheat yield reduction occurred because of herbicide carryover in 1992 and 1994. However, in 1993, imazethapyr and bentazon plus imazethapyr treatments applied in 1992 caused 22% injury and reduced winter wheat yield 10% when wheat was planted after soybean harvest.
Cultural Systems Can Reduce Reproductive Potential of Winter Annual Grasses
Authors: Anderson R. L.
Published: March 2018

Feral rye and jointed goatgrass are winter annual grasses that infest winter wheat in the western United States. Currently, no herbicides are available that selectively control these weeds in wheat. Because of this constraint, producers need cultural practices that reduce the seed densities of these two grasses in the soil seedbank. This research shows that applying nitrogen 5 mo before wheat planting and increasing the seeding rate with a tall wheat cultivar reduces seed production per plant of either species by > 40%. However, tall wheat cultivars usually yield less grain than semidwarf cultivars. Producers can avoid this yield loss by combining narrow rows with time of N application and increased seeding rate of semidwarf cultivars. This combination reduces weed seed production similarly to cultural systems with tall cultivars.
Effect ofSclerotinia sclerotiorumon the Interference between Bluebunch Wheatgrass (Agropyron spicatum) and Spotted Knapweed (Centaurea maculosa)
Authors: Jacobs James S. , Sheley Roger L. , Maxwell Bruce D.
Published: March 2018

Effectiveness of the common soil fungusSclerotinia sclerotiorumas a biological control for spotted knapweed and its effect on competitive interactions between spotted knapweed and bluebunch wheatgrass were evaluated in a growth chamber study using addition series methods. Total seeding densities ranged from 2000 to 60 000 seeds/m2. Mean bluebunch wheatgrass plant weight was 3.5 times greater than spotted knapweed weight per plant, respectively. Coefficient ratios estimating species interaction showed bluebunch wheatgrass density had a greater influence than spotted knapweed density on both bluebunch wheatgrass and spotted knapweed weights (2.11 and 0.51, respectively) when not under the influence ofS. sclerotiorum. Niche differentiation ratios indicated a lack of resource partitioning between species (1.11).S. sclerotiorumreduced spotted knapweed density by 68 to 80% without reducing bluebunch wheatgrass density. Spotted knapweed weight per plant also was reduced by the addition of 5.sclerotiorum(1.4 to 1.2 mg) but there was not a corresponding increase in bluebunch wheatgrass weight.S. sclerotiorumdecreased competition between spotted knapweed and bluebunch wheatgrass. This study provides evidence that establishment of bluebunch wheatgrass on spotted knapweed infested rangeland may be improved by combiningS. sclerotiorumwith high grass seeding rates.
Mobility Assessment of Agrichemicals: Current Laboratory Methodology and Suggestions for Future Directions
Authors: Cleveland Cheryl B.
Published: March 2018

The current state of registration requirements for mobility assessments of pesticides is described and the various uses for mobility estimates are outlined. A survey of recent literature on mobility assessments is presented along with a suggestion for a refocus on Kdrather than KF. A proposal for a different, yet standard, more efficient approach as a replacement for the current requirements is outlined. The suggested approach could fit well within a registration package or a limited research budget as well as provide more information for model input.
Cross-Resistance of Imazethapyr-Resistant Common Sunflower (Helianthus annuus) to Selected Imidazolinone, Sulfonylurea, and Triazolopyrimidine Herbicides
Authors: Baumgartner Jolene R. , Al-Khatib Kassim , Currie Randall S.
Published: March 2018

The study was conducted to determine the cross-resistance of imazethapyr-resistant common sunflower (Helianthus annuus) to selected imidazolinone, sulfonylurea, and triazolopyrimidine herbicides. Whole-plant herbicide dose–response curves and in vitro enzyme studies showed that imazethapyr-resistant common sunflower was highly resistant to imazamox, slightly resistant to thifensulfuron and chlorimuron, and not resistant to cloransulam. Resistance ratios of herbicide concentrations required to inhibit growth by 25% were 310, 3.3, 2.0, and 1.4 times greater in the resistant biotype than in the susceptible biotype for imazamox, thifensulfuron, chlorimuron, and cloransulam, respectively. Similarly, herbicide concentrations required to inhibit ALS activity in vitro by 25% were 332.0, 18.6, 8.3, and 1.2 times greater in the resistant biotype than in the sensitive biotype for imazamox, chlorimuron, thifensulfuron, and cloransulam, respectively.
Response of Various Weed Species and Corn (Zea mays) to RPA 201772
Authors: Bhowmik Prasanta C. , Kushwaha Sanjay , Mitra Sowmya
Published: March 2018

Greenhouse and field experiments were conducted to determine the response of corn (Zea mays), barnyardgrass (Echinochloa crus-galli), common lambsquarters (Chenopodium album), large crabgrass (Digitaria sanguinalis), velvetleaf (Abutilon theophrasti), and yellow foxtail (Setaria lutescence) to RPA 201772. Barnyardgrass, large crabgrass, velvetleaf, and common lambsquarters were more susceptible than yellow foxtail to RPA 201772. Velvetleaf was the most susceptible species and rates above 18 g ai/ha of RPA 201772 controlled 100% of the population 4 wk after treatment (WAT). Percent control of all the weed species increased with increased RPA 201772 rates. In the field, the dry weights of yellow foxtail decreased as the rate of RPA 201772 increased from 0 to 210 g/ha. However, a 60% reduction of dry weight of yellow foxtail was recorded at 140 g/ha of RPA 201772 compared to the untreated check 6 WAT, whereas at 12 WAT the dry weight of yellow foxtail was reduced to only 15% because of intraspecific competition. Yellow foxtail was moderately susceptible to RPA 201772. Corn was tolerant to RPA 201772; the GR80 value was 435 g/ha in the greenhouse. The bleaching injury to corn in the field was less than 10%, and it was found only with the 210 g/ha rate of RPA 201772. This injury was temporary and the plants recovered within 2 to 3 wk. Based on the GR80 values, velvetleaf was the most susceptible, followed by common lambsquarters, large crabgrass, barnyardgrass, and yellow foxtail.
Discovery of a Common Purslane (Portulaca oleracea) Biotype Resistant to Linuron
Authors: Masabni Joseph G. , Zandstra Bernard H.
Published: March 2018

Greenhouse and field experiments were conducted to confirm and quantify linuron resistance in common purslane (Portulaca oleracea) collected from a carrot (Daucus carota) field in Imlay City, MI. Preliminary evaluation was made using a flotation test kit to identify resistance to linuron and atrazine. Subsequent greenhouse experiments indicated that this common purslane was resistant to 11.2 kg/ha linuron and 179 kg/ha atrazine. The resistance ratio for linuron was > 300 and was > 400 for atrazine. The resistant common purslane was also highly resistant to diuron, cyanazine, and prometryn but had a low level of negative cross-resistance to bromoxynil. Both resistant and susceptible biotypes of common purslane were sensitive to hexazinone and bentazon.
Nature, Occurrence, and Cost of Herbicide-Resistant Green Foxtail (Setaria viridis) Across Saskatchewan Ecoregions
Authors: Beckie Hugh J. , Thomas A. Gordon , Légère Anne
Published: March 2018

In Saskatchewan, a field survey was conducted in 1996 and a grain elevator survey in 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of green foxtail (Setaria viridis). Based on results of the field survey, one in every 20 fields (1 million ha) in Saskatchewan is estimated to have acetyl-CoA carboxylase (ACCase) inhibitor (Group 1)-HR green foxtail. Of the samples received from 30 grain elevators, 83% had Group 1 resistance. Similar to the field survey, incidence of aryloxyphenoxy propionate (AOPP) resistance was much higher than cyclohexanedione (CHD) resistance. Both surveys indicated relatively low incidence of dinitroaniline (Group 3) resistance or cross-resistance (Groups 1 and 3). Most alternative herbicides to control Group 1-HR green foxtail in broadleaf crops and cross-HR biotypes in cereal and broadleaf crops increase costs to the grower.
Cultural Practices for Weed Resistance Management
Authors: Nalewaja John D.
Published: March 2018

Cultural practices, such as delayed crop seeding, tillage, black fallow, crop rotation, hand weeding, and competitive crops, when used to replace herbicides, provide an opportunity to reduce the selection pressure that causes weeds to become resistant to herbicides. Herbicides on the other hand reduce the selection pressure that causes weeds to resist cultural practices. Rotation of the two systems should then delay resistance to both systems. Growers consider many factors in addition to weed resistance in selecting herbicide or cultural weed control, from associated convenience to economic potential. Rotation of different types of weed control practices would delay resistance, compared to a continuous single practice. The extent of the delay depends upon genetics of resistance, weed reproduction characteristics, weed seed survival, and fitness of resistant weed plants. An understanding of the basic aspects of weeds and herbicides, as well as their interaction with the environment, would help in predicting the delay in resistance to an herbicide from use of cultural practices in the rotation. A grower's final choice of a weed control practice will involve available equipment, time, markets, and soil erosion in addition to potential weed resistance. Weeds that develop resistance to a control practice still allow for reversion to preresistance practices, an important component of a grower's decision. The rate of resistance development is dependent upon the removal of susceptible genes from the population and fitness of the resistant plants. Resistance might be delayed for many years or be manageable when the resistance is genetically recessive or resistant weeds are poorly fit. Growers may not want to accept alternative cultural practices as long as there is the potential for development of another herbicide or reversion to cultural control after resistance occurs.
The Effect of Labeling Herbicides with Their Site of Action: A Canadian Perspective
Authors: Beckie Hugh J. , Chang Fa-Yan , Stevenson F. Craig
Published: March 2018

Industry, public-sector researchers and extension agents, and growers were surveyed in 1998 to determine their perspectives on how labeling herbicides with their site of action (group number) would affect the herbicide use practices of growers. The crop protection industry in Canada represented by the Crop Protection Institute (CPI) generally supports herbicide resistance labeling but has some concerns regarding the wording of the labels, including the identification symbol. Most researchers and extension agents believe that labeling herbicides with their site of action will facilitate herbicide group rotation by growers who frequently use herbicides from the same group. Of the two-thirds of the 126 surveyed growers who were familiar with herbicide groupings, 58% practiced herbicide group rotation. Those who did not tended to lack understanding of the basis and purpose of herbicide classification. Grower responses were similar to those from the research and extension community, although only 29% of the growers who currently do not rotate herbicides from different groups believed that resistance management labeling would influence them.
Anarchism and Health
Authors: SCOTT NIALL
Published: March 2018

This article looks at what anarchism has to offer in debates concerning health and healthcare. I present the case that anarchism’s interest in supporting the poor, sick, and marginalized, and rejection of state and corporate power, places it in a good position to offer creative ways to address health problems. I maintain that anarchistic values of autonomy, responsibility, solidarity, and community are central to this endeavor. Rather than presenting a case that follows one particular anarchist theory, my main goal is to raise issues and initiate debate in this underresearched field in mainstream bioethics.
Can Theories of Global Justice Be Useful in Humanitarian Response?
Authors: SIMM KADRI
Published: March 2018

Why is it that humanitarianism and theories of global justice seem to have relatively little engagement with each other? This article discusses some of the reasons for this being the case, and argues that instead of seeing these two fields as separate or adversarial they should be viewed as complementary. The article begins with a brief overview of humanitarianism, in order to argue for the relevance of justice in humanitarianism. The second section focuses on analyzing selected theories of justice— those of Peter Singer, John Kekes, and Thomas Pogge—through a particular lens, that of the question of responsibility for global well-being. The article concludes by arguing that theories of global justice can be beneficial for humanitarian causes, not in a comprehensive and consistent “all-or-nothing” manner, but rather on a case-by-case basis and through selective application of particular arguments.
Ethics of Virtual Reality in Medical Education and Licensure
Authors: ISERSON KENNETH V.
Published: March 2018

The aim of this section is to expand and accelerate advances in curriculum developments and in methods of teaching bioethics.
Gender Bias in Student Evaluations
Authors: Mitchell Kristina M. W. , Martin Jonathan
Published: March 2018

Many universities use student evaluations of teachers (SETs) as part of consideration for tenure, compensation, and other employment decisions. However, in doing so, they may be engaging in discriminatory practices against female academics. This study further explores the relationship between gender and SETs described by MacNell, Driscoll, and Hunt (2015) by using both content analysis in student-evaluation comments and quantitative analysis of students’ ordinal scoring of their instructors. The authors show that the language students use in evaluations regarding male professors is significantly different than language used in evaluating female professors. They also show that a male instructor administering an identical online course as a female instructor receives higher ordinal scores in teaching evaluations, even when questions are not instructor-specific. Findings suggest that the relationship between gender and teaching evaluations may indicate that the use of evaluations in employment decisions is discriminatory against women.
Blood Eosinophil Count and Metabolic, Cardiac and Pulmonary Outcomes: A Mendelian Randomization Study
Authors: Amini Marzyeh , Vonk Judith M. , Abbasi Ali , Prins Bram P. , Bruinenberg Marcel , Franke Lude , van der Harst Pim , Navis Gerjan , Koppelman Gerard H. , Wolffenbuttel Bruce H. R. , Boezen H. Marike , Snieder Harold , Chasman Daniel I. , Alizadeh Behrooz Z.
Published: March 2018

Blood eosinophil count is associated with a variety of common complex outcomes in epidemiological observation. The aim of this study was to explore the causal association between determined blood eosinophil count and 20 common complex outcomes (10 metabolic, 6 cardiac, and 4 pulmonary). Through Mendelian randomization, we investigated genetic evidence for the genetically determined eosinophil in association with each outcomes using individual-level LifeLines cohort data (n = 13,301), where a weighted eosinophil genetic risk score comprising five eosinophil associated variants was created. We further examined the associations of the genetically determined eosinophil with those outcomes using summary statistics obtained from genome-wide association study consortia (6 consortia and 14 outcomes). Blood eosinophil count, by a 1-SD genetically increased, was not statistically associated with common complex outcomes in the LifeLines. Using the summary statistics, we showed that a higher genetically determined eosinophil count had a significant association with lower odds of obesity (odds ratio (OR) 0.81, 95% confidence interval (CI) [0.74, 0.89]) but not with the other traits and diseases. To conclude, an elevated eosinophil count is unlikely to be causally associated to higher risk of metabolic, cardiac, and pulmonary outcomes. Further studies with a stronger genetic risk score for eosinophil count may support these results.
Rb is required for retinal angiogenesis and lamination
Authors: Zhou Yi , Wei Ran , Zhang Liu , Chen Yongjiang , Lu Suying , Liang Chen , Wang Yujiao , Xiao Lirong , Zhang Junjun , Bremner Rod , Chen Danian
Published: March 2018

Retinoblastoma tumor suppressor (Rb) promotes cell cycle exit, survival, differentiation, and tumor suppression in the retina. Here, we show it is also essential for vascularization and lamination. Despite minimal effects on Hif1a target expression, intraretinal vascular plexi did not form in the Rb
−/−
murine retina. Deleting adenovirus E2 promoter binding factor 3 (E2f3), which rescues starburst amacrine cell differentiation, or E2f2, had no effect, but deleting E2f1, which promotes neuronal cell cycle exit and survival, restored retinal vasculature. We specifically linked cell loss to the defect because removing Bax rescued rod and bipolar neurons and the vasculature, but not cell cycle exit. Despite rescuing Rb
−/−
neurons, Bax deletion exacerbated a delay in outer retina lamination, and exposed a requirement for Rb in inner retina lamination. The latter resembled Sem5 or FAT atypical cadherin 3 (Fat3) mutants, but expression of Sem5/Fat3 pathway components, or that of Neogenin, which perturbs migration in the Rb
−/−
cortex, was unchanged. Instead, lamination defects correlated with ectopic division, and were E2f1-dependent, implicating the cell cycle machinery. These in vivo studies expose new developmental roles for Rb, pinpoint aberrant E2f1 and Bax activity in neuronal death and vascular loss, and further implicate E2f1 in defective lamination. Links between Rb, angiogenesis and lamination have implications for the treatment of neovascularization, neurodegeneration and cancer.
Divergent T-cell receptor recognition modes of a HLA-I restricted extended tumour-associated peptide
Authors: Chan Kok Fei , Gully Benjamin S. , Gras Stephanie , Beringer Dennis X. , Kjer-Nielsen Lars , Cebon Jonathan , McCluskey James , Chen Weisan , Rossjohn Jamie
Published: March 2018

Human leukocyte antigen (HLA)-I molecules generally bind short peptides (8–10 amino acids), although extended HLA-I restricted peptides (>10 amino acids) can be presented to T cells. However, the function of such extended HLA-I epitopes in tumour immunity, and how they would be recognised by T-cell receptors (TCR) remains unclear. Here we show that the structures of two distinct TCRs (TRAV4+TRAJ21+-TRBV28+TRBJ2-3+ and TRAV4
+
TRAJ8+-TRBV9+TRBJ2-1+), originating from a polyclonal T-cell repertoire, bind to HLA-B*07:02, presenting a 13-amino-acid-long tumour-associated peptide, NY-ESO-160–72. Comparison of the structures reveals that the two TCRs differentially binds NY-ESO-160–72–HLA-B*07:02 complex, and induces differing extent of conformational change of the NY-ESO-160–72 epitope. Accordingly, polyclonal TCR usage towards an extended HLA-I restricted tumour epitope translates to differing TCR recognition modes, whereby extensive flexibility at the TCR–pHLA-I interface engenders recognition.
A systematic approach to the development of a safe live attenuated Zika vaccine
Authors: Kwek Swee Sen , Watanabe Satoru , Chan Kuan Rong , Ong Eugenia Z. , Tan Hwee Cheng , Ng Wy Ching , Nguyen Mien T. X. , Gan Esther S. , Zhang Summer L. , Chan Kitti W. K. , Tan Jun Hao , Sessions October M. , Manuel Menchie , Pompon Julien , Chua Camillus , Hazirah Sharifah , Tryggvason Karl , Vasudevan Subhash G. , Ooi Eng Eong
Published: March 2018

Zika virus (ZIKV) is a flavivirus that can cause congenital disease and requires development of an effective long-term preventative strategy. A replicative ZIKV vaccine with properties similar to the yellow fever 17D (YF17D) live-attenuated vaccine (LAV) would be advantageous, as a single dose of YF17D produces lifelong immunity. However, a replicative ZIKV vaccine must also be safe from causing persistent organ infections. Here we report an approach to ZIKV LAV development. We identify a ZIKV variant that produces small plaques due to interferon (IFN)-restricted viral propagation and displays attenuated infection of endothelial cells. We show that these properties collectively reduce the risk of organ infections and vertical transmission in a mouse model but remain sufficiently immunogenic to prevent wild-type ZIKV infection. Our findings suggest a strategy for the development of a safe but efficacious ZIKV LAV.