bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Four Herbicides on Four Early Maturing Soybean (Glycine max) Cultivars
Authors: Helms Theodore C. , Halvorson Mark A.
Published: March 2018

Tolerance of two metribuzin-tolerant and two metribuzin-sensitive early maturing soybean cultivars to two rates of acifluorfen, imazethapyr, metribuzin, and thifensulfuron was evaluated under weed-free conditions. Acifluorfen at 1120 g ai ha-1reduced plant height by 3 cm and thifensulfuron at 18 and 35 g ai ha-1delayed physiological maturity by 3 d. No herbicide treatment reduced soybean yield when compared with a weed-free check. Soybean yield of the two metribuzin-tolerant and the two metribuzin-sensitive cultivars did not change as metribuzin rate was increased from zero to 280 to 560 g ai ha-1.
Control of Annual Broadleaf Weeds in Pinto Beans (Phaseolus vulgaris)
Authors: Blackshaw Robert E. , Esau Rudy
Published: March 2018

Field studies were conducted to identify herbicides suitable for improved control of hairy nightshade, redroot pigweed, and common lambsquarters in pinto beans. Fomesafen at 0.25 kg ai ha-1did not adequately control these weeds. Clomazone at 0.5 kg ai ha-1controlled common lambsquarters but only suppressed the growth of redroot pigweed and hairy nightshade. Ethalfluralin at 0.84 to 1.1 kg ai ha-1gave excellent initial control of these weeds but did not control later flushes of hairy nightshade. Imazethapyr applied PPI or POST at 50 to 75 g ai ha-1controlled hairy nightshade, redroot pigweed, and common lambsquarters throughout the growing season. Imazethapyr combined with ethalfluralin gave superior weed control and resulted in greater yields than the most commonly used herbicides in pinto beans in western Canada.
Effect of Nitrogen, Sodium, and Potassium on Nitrate and Oxalate Concentration in Kikuyugrass
Authors: Williams M. Coburn , Smith Burton J. , Rafael Lopez V.
Published: March 2018

Kikuyugrass was analyzed for nitrate (expressed as KNO3) and soluble oxalate concentration after it was grown for 8 wk in nutrient solution supplemented with KCl, NaCl, or NH4NO3; fertilized in the greenhouse with urea and KNO3 at 112 kg N ha-1; and fertilized in the field in Hawaii and Panama with urea at 56 and 112 kg N ha-1. Both treated and untreated kikuyugrass grown in nutrient solution contained toxic levels of nitrates and soluble oxalates. Plants treated with urea in the greenhouse contained 0.4% nitrate (nontoxic) 72 h after treatment whereas those treated with KNO3 contained 2.36% nitrate (highly toxic). Fertilization of kikuyugrass with urea in Panama and Hawaii did not significantly affect soluble oxalate concentration, but nitrate concentration increased to potentially lethal levels (over 1.5% as KNO3, dry wt) in plants from Hawaii.
Carpetgrass Response to Postemergence Herbicides
Authors: McCarty Lambert B. , Colvin Daniel L.
Published: March 2018

Carpetgrass is a warm season grass used in the south as low maintenance turf, especially in wet areas where other turf species do not persist. The response of carpetgrass to postemergence (POST) herbicides currently available for turf producers has not been thoroughly investigated and was the objective of four experiments conducted over a 2-yr period. Slight reduction in turf quality followed application of atrazine (2.2 kg ai ha-1), bentazon (2.2 kg ai ha-1), imazaquin (0.4 and 0.6 kg ai ha-1), mecoprop (1.1 kg ai ha-1), triclopyr (0.6 kg ai ha-1), metsulfuron (0.2 kg ai ha-1), 2,4-D (1.1 kg ai ha-1), 2,4-D plus dicamba (0.8 + 0.3 kg ai ha-1), and 2,4-D plus dicamba plus mecoprop (0.9 + 0.1 + 0.5 kg ai ha-1). Marginally acceptable turf quality followed sulfometuron (0.2 kg ai ha-1), sethoxydim (0.3 and 0.6 kg ai ha-1), and diclofop (2.2 kg ai ha-1) treatments. Unacceptable turf quality resulted from asulam (2.2 kg ai ha-1) and MSMA (1.1 and 2.2 kg ai ha-1) treatments. Carpetgrass tolerated most POST broadleaf and sedge herbicides but was sensitive to most POST grass herbicides used in other turf species, with the exception of sethoxydim.
Dissipation of Imazaquin and Imazethapyr Under Conventional and No-tillage Soybean (Glycine max)
Authors: Mills J. Anthony , Witt William W.
Published: March 2018

Experiments were conducted to monitor the dissipation of imazaquin and imazethapyr applied to the soil surface under conventional and no-tillage conditions. Imazaquin or imazethapyr dissipation rate was similar in no-tillage in 1985 and 1986. Dissipation of the herbicides under conventional tillage conditions varied. Imazaquin dissipation occurred 2.4 times faster in 1986 than in 1985. Imazethapyr dissipation was 3.5 times faster in 1986 than in 1985. Corn planted without tillage (no-till) was injured in 1986 where 210 or 280 g ha-1of imazaquin or 105 g ha-1of imazethapyr had been applied the previous year to conventionally tilled soybeans, but injury was not evident where these herbicides had been applied to no-tillage soybeans. Corn injury was evident 2 wk after planting in 1987 but yields were not reduced.
BAS 514 and Dithiopyr for Weed Control in Cool-season Turfgrasses
Authors: Enache Adrian J. , Ilnicki Richard D.
Published: March 2018

Field experiments were conducted in 1986 to 1990 to determine the effect of different rates and application times of BAS 514 and dithiopyr alone and in combination on control of large crabgrass and dandelion in Kentucky bluegrass, tall fescue, and perennial ryegrass. Herbicides evaluated were applied PRE, early POST, and late POST. Results indicated that both herbicides provided excellent PRE control in all years. BAS 514 rates ranged from 0.84 to 0.56 kg ai ha-1. Rates of dithiopyr ranged from 0.43 to 0.56 kg ai ha-1. In addition to crabgrass control, both herbicides controlled dandelion, BAS 514 exhibiting slightly better activity than dithiopyr. BAS 514 at 0.84 to 1.12 kg ai ha-1 and dithiopyr at 0.26 to 0.56 kg ai ha-1 resulted in excellent early POST crabgrass control when applied at the one- to three-leaf stage of crabgrass. BAS 514 and dithiopyr applied late POST (2 to 3 tillers of crabgrass) resulted in 63 to 85% control of crabgrass and 29 to 85% control of dandelion at 10 wk after application. No weed control enhancement was evident from tank mixing the two herbicides. Excellent turf safety was demonstrated by both herbicides on all three turf species.
Effects of Mowing or SprayingCarduus thoermerionRhinocyllus conicus
Authors: Tipping Philip W.
Published: March 2018

In 1988, mowing C.thoermerionce at the bud stage, twice at the bud stage, or once at early bloom of the primary inflorescences, eliminated emergence ofRhinocyllus conicus, a weevil introduced as a biological control agent. Mowing at full bloom reduced weevil survival by 78.8%, whereas mowing at senescence had no effect. In 1989, mowing at full bloom or senescence did not affect weevil survival. Dicamba applied at the full bloom or senescence stage did not affectR. conicussurvival, whereas hexazinone reducedR. conicussurvival when applied at all growth stages.
EPTC Reduces Alfalfa (Medicago sativa) Tolerance to Bromoxynil
Authors: Hartzler Robert G.
Published: March 2018

EPTC applied at the time of ‘Saranac AR’ alfalfa establishment resulted in higher levels of crop injury from the octanoic acid ester of bromoxynil applied postemergence compared to alfalfa in areas not treated with EPTC. EPTC applied at 1.7 or 3.4 kg ai ha-1did not injure alfalfa. At Rock Springs, PA, 0.54 kg ai ha-1bromoxynil caused 28, 43, and 55% foliar injury in areas treated with 0, 1.7, and 3.4 kg ai ha-1EPTC, respectively. A similar interaction was observed at Landisville, PA, although the level of injury due to bromoxynil was less severe. EPTC also predisposed ‘WL 316’ alfalfa to bromoxynil injury in greenhouse experiments.
A Case Study of Herbicide Use
Authors: Pike David R. , McGlamery Marshal D. , Knake Ellery L.
Published: March 2018

The adoption of herbicide use within Illinois has passed through four stages characterized by methods of application. These stages include an initial stage of POST applications, the PRE stage, the PPI stage, and the most recent stage marked by diversification of application methods. Data from 19 pesticide use surveys conducted in Illinois since 1957 were used to determine trends in pesticide use. Herbicide use has increased from 33% of the corn and 1% of the soybean hectarage treated in 1957 to applications on approximately 97% of all the corn and soybeans in 1990. Total herbicide use in Illinois peaked at 3.0 × 107 kg ai annually in 1982 and declined to 2.1 × 107 kg in 1990. Total herbicide use in Illinois between 1950 and 1990 is estimated at 5.0 × 108 kg ai.
Effect of Spray Volume and Pressure on Postemergence Johnsongrass (Sorghum halepense) Control
Authors: McWhorter Chester G. , Hanks James E.
Published: March 2018

Fenoxaprop, fluazifop/fluazifop-P, haloxyfop, and quizalofop at 0.14 kg ai ha−1and sethoxydim at 0.28 kg ai ha−1were applied broadcast over-the-top in spray volumes of 94 and 374 L ha−1, each at 138 and 345 kPa, to control johnsongrass in soybeans over a 5-yr period. The two spray volumes provided equal control, but control was better when treatments were applied at 345 kPa than at 138 kPa. There were no significant interactions among herbicides, spray volumes, or spray pressures. Most of the spray was deposited on the upper surface of the plant canopy. Less than 10% of the herbicide spray applied penetrated into the canopy onto water-sensitive spray cards located 10, 20, 30, or 40 cm above the ground.
Weed Control in Soybean (Glycine max) with Lactofen Plus Chlorimuron
Authors: Vidrine P. Roy , Reynolds Daniel B. , Griffin James L.
Published: March 2018

Field experiments were conducted over a 3-yr period at three locations to evaluate lactofen at rates of 110 to 220 g ai ha−1applied POST in combination with chlorimuron at 9 g ae ha−1for weed control in soybean. At St. Joseph in 1989 and Baton Rouge in 1990, lactofen at 110, 150, and 170 g ha−1in combination with chlorimuron controlled prickly sida (3 to 5 cm) and entireleaf and pitted morningglory (5 to 13 cm) comparable with the full rate of lactofen at 220 g ha−1plus chlorimuron and the standard treatment of acifluorfen at 280 g ae ha−1plus bentazon at 560 g ae ha−1. Entireleaf morningglory and sicklepod control at Alexandria with lactofen at 110 to 170 g ha−1plus chlorimuron was comparable with that from the full rate of lactofen plus chlorimuron and better than with acifluorfen plus bentazon. Weed control was reduced when soil moisture was deficient at treatment time or when prickly sida height was more than 5 cm and entireleaf morningglory, pitted morningglory, and sicklepod more than 15 cm. In related studies at St. Joseph, a reduced rate of lactofen (170 g ha−1) in combination with chlorimuron controlled prickly sida 98%, pitted morningglory 93%, and entireleaf morningglory 90% in 1988, which was comparable with the control from the full rate of lactofen plus chlorimuron and with acifluorfen plus bentazon.
Differential Tolerance of Sweet Potato (Ipomoea batatas) Clones to Metribuzin
Authors: Motsenbocker Carl E. , Monaco Thomas J.
Published: March 2018

Sweet potato clones were evaluated for metribuzin tolerance in field and greenhouse studies. ‘Tinian’ was the most tolerant and ‘SC-1149-19’ and ‘J-2’ were the most susceptible clones. ‘Jewel’, a clone widely grown commercially, was sensitive to metribuzin in the field and greenhouse. ‘Sumor’ and ‘White Triumph’ exhibited intermediate metribuzin tolerance. All metribuzin application-by-rate treatments reduced plant stands, caused season-long crop injury, and reduced yields. Metribuzin applied 3 wk posttransplant at 1.1 kg ha−1did not reduce total yield of Tinian. Total yield of all the clones except Tinian were reduced by metribuzin regardless of timing or rate.
Weed Control in Pinto Beans (Phaseolus vulgaris) with Imazethapyr Combinations
Authors: Arnold Richard N. , Murray Martina W. , Gregory Eddie J. , Smeal Dan
Published: March 2018

Imazethapyr, alone and in combination with other herbicides, was applied PPI, PRE, and POST to pinto beans to determine weed control and selectivity to the crop. All of the herbicides improved pinto bean yield as compared with the unweeded control. Imazethapyr applied PPI and POST provided excellent control of black nightshade, kochia, Russian thistle, prostrate pigweed, and redroot pigweed. Barnyardgrass control with imazethapyr ranged from 58 to 96% and increased to 98% or greater when imazethapyr was combined with metolachlor, pendimethalin, trifluralin, or EPTC. Pinto bean yield was not reduced from any herbicide treatment compared to the handweeded control.
Triazine-Resistant Smooth Pigweed (Amaranthus hybridus) Control in Field Corn (Zea maysL.)
Authors: Birschbach Eric D. , Myers Mark G. , Harvey R. Gordon
Published: March 2018

Studies were conducted for 3 yr to evaluate herbicides and herbicide combinations for triazine-resistant smooth pigweed (TR-AMACH) control in field corn. Of the PRE treatments, combinations of atrazine plus acetochlor, metolachlor plus dicamba, and atrazine plus alachlor provided the most complete control of this weed (77 to 81%). The best early postemergence (EP) combination was pendimethalin plus atrazine plus dicamba (93% control). Pyridate plus atrazine applied POST provided a four-site average of 98% control. The most effective sequential herbicide treatments consisted of either metolachlor or pendimethalin PRE followed by POST treatments containing either pyridate, thifensulfuron, bromoxynil, or dicamba.
Soil Solarization for Weed Management in U.A.E.
Authors: Al-Masoom Ahmed A. , Saghir Abdur-Rahman , Itani Souheil
Published: March 2018

Field studies were conducted in 1991 and 1992 at the Faculty Farm of the U.A.E. Univ., Al-Ain, to evaluate the effectiveness of soil solarization for weed management in naturally infested plots of lettuce, and on subsequent planting of garlic. Solarization for 2 mo during the hottest summer period effectively suppressed weeds during the growing season of head lettuce. In subsequently-planted garlic, no significant effect was observed between solarized and nonsolarized treatments.
Soil Environment and Temperature Affect Germination and Seedling Growth of Mayweed Chamomile (Anthemis cotula)
Authors: Gealy David R. , Squier Sheila A. , Ogg Alex G.
Published: March 2018

Mayweed chamomile is an increasing weed problem in cropping systems of the Pacific Northwest. Modern farming practices that utilize conservation tillage systems and heavy application of nitrogen fertilizers have been associated with increased soil surface water potential and decreased soil pH. Therefore, soil water potential, soil pH, and temperature effects on germination and growth of mayweed chamomile were determined in controlled laboratory tests. Germination of mayweed chamomile in soil was greatest at 30 C and a soil water potential of –25 kPa. Germination and seedling growth were similar in soils with pH 4.7, 5.1, and 6.2. Total plant weight was greatest at 20 C and reduced at 10 and 30 C. Shoot dry weight, as a percent of total dry weight, ranged from a low of 54% at 10 C to 78% at 30 C. A soil moisture potential of –10 000 kPa reduced germination and total plant weight by as much as 95% and 80%, respectively.
Fluazifop-P Tank-Mixtures with Clethodim for Annual Grass Control in Flax (Linum usitatissimum)
Authors: Wall David A.
Published: March 2018

Field studies were undertaken in 1992 and 1993 to investigate the control of wild oat and green foxtail in flax with reduced rates of fluazifop-P and clethodim applied as tank-mixtures. Fluazifop-P plus clethodim at 50 + 18 g ai/ha controlled wild oat and green foxtail and was as effective as full rates of either herbicide applied alone. These rates represent a 20% reduction in total amount of active ingredient required to control wild oat and green foxtail. Application of fluazifop-P, and/or clethodim prior to the 3- to 4-leaf stage failed to control late emerging grass weeds. Application of graminicide mixtures at or after the 3- to 4-leaf stage controlled late emerging grass weeds and did not affect flax yield. When applied late, fluazifop-P at 175 g/ha tended to reduce flax yield, although weed control was acceptable and no foliar injury was observed following treatment. The efficacy of graminicide mixtures was reduced by addition of bromoxynil plus MCPA to the spray mix.
Effect of Nicosulfuron Rate, Adjuvant, and Weed Size on Annual Weed Control in Corn (Zea mays)
Authors: Kapusta George , Krausz Ronald F. , Khan Mustajab , Matthews Joseph L.
Published: March 2018

Field experiments were conducted in 1988 and 1989 to (i) evaluate annual weed control with nicosulfuron applied at rates of 17 to 70 g ai/ha with several additives and (ii) evaluate annual weed control with nicosulfuron applied at rates of 17 to 105 g/ha at three corn growth stages. In 1988, in the adjuvant study, giant foxtail control increased linearly with no additive or with urea ammonium nitrate as the rate of nicosulfuron increased. Petroleum oil concentrate, nonionic surfactant, and a combination of either petroleum oil concentrate or nonionic surfactant with urea ammonium nitrate applied with nicosulfuron increased giant foxtail control to 90% or greater regardless of rate both years. Nicosulfuron at all rates with no additive and in combination with all additives controlled 93% or more of redroot pigweed and Pennsylvania smartweed both years. Corn grain yield was related to the level of giant foxtail control. In the rate by corn growth stage study, giant foxtail, redroot pigweed, and Pennsylvania smartweed control was 90% or greater regardless of nicosulfuron rate or application stage both years. Corn grain yield was related more to the duration of weed competition than the level of weed control with grain yield 8 to 12% lower with nicosulfuron applied at the V7 growth stage compared with the V3 or V5 growth stage.
Spring Cereal Response to Imazamethabenz and Fenoxaprop-p-ethyl as Influenced by Environment
Authors: Xie Haisheng S. , Quick William A. , Hsiao Andrew I.
Published: March 2018

The influence of temperature, soil moisture, and light intensity on the tolerance of spring wheat, durum wheat, and spring barley to imazamethabenz and safened fenoxaprop-p-ethyl was determined in growth chamber experiments. Imazamethabenz at 500 g/ha reduced plant height and shoot fresh weight of durum and spring wheats grown under prolonged 70% shade. The height of durum and spring wheats was reduced by imazamethabenz under a low temperature regime. Compared to the plants grown under standard conditions, the shoot weight of spring and durum wheat plants was not reduced by imazamethabenz under drought, or high and low temperature conditions. Barley tolerance to imazamethabenz was not affected by environment. All three spring cereals were tolerant to fenoxaprop-p-ethyl plus a safener at 92 g/ha; and such tolerance was not greatly affected by various environments examined.
Rotation Affects Downy Brome (Bromus tectorum) in Winter Wheat (Triticum aestivum)
Authors: Blackshaw Robert E.
Published: March 2018

Downy brome control in winter wheat is often inadequate. The effects of three crop rotations and two tillage intensities on downy brome populations and associated crop yields were determined in an experiment at Lethbridge, Alberta from 1987 to 1993. Downy brome densities in continuous winter wheat increased from 24 to 970 plants/m2between 1988 and 1993; and were often higher with zero tillage. Inclusion of fallow or spring canola in rotation with winter wheat suppressed downy brome densities to less than 55 and 100 plants/m2, respectively, over the six years. In continuous winter wheat, yields decreased as downy brome densities increased progressively over years, indicating that monoculture winter wheat production will not be viable in regions where downy brome is prevalent unless effective herbicides are developed. In the more arid areas of the Canadian prairies, a winter wheat-fallow rotation may be most suitable but in higher precipitation areas, a winter wheat-canola rotation is a viable alternative. Crop rotation is a key component of an improved management system for control of downy brome.
Itchgrass (Rottboellia cochinchinensis) Interference in Soybean (Glycine max)
Authors: Lejeune Katherine R. , Griffin James L. , Reynolds Daniel B. , Saxton Arnold M.
Published: March 2018

Interference between itchgrass and soybean was evaluated over two years using area-of-influence procedures. Soybean seed weight within 20 cm of the weed was reduced 15 to 21%. In the first year, seed weight reduction of 9% was detected at a distance of 40 to 60 cm from the weed. Weight reductions were attributed to decreases in seed number of 12 to 22% within 40 cm of the weed compared with the 140 to 160 cm control area. Itchgrass interference increased soybean height within 40 cm of the weed, but soybean canopy width was generally unaffected. Soybean interference did not affect height of itchgrass plants, but did reduce weed stem numbers 89 to 94% when compared with weeds growing alone. With interference of 8 wk or less, both itchgrass green and dry weights were similar when weeds were growing alone or within the soybean row. Green and dry weights were reduced approximately 80% when itchgrass was in competition with soybean for 10 wk.
Control of Triazine-Resistant Kochia (Kochia scoparia) in Sorghum (Sorghum bicolor)
Authors: Wicks Gail A. , Martin Alex R. , Haack Alan E. , Mahnken Garold W.
Published: March 2018

Herbicidal control of triazine-resistant (TR) kochia was evaluated in no-till grain sorghum. Herbicides were applied early preplant (EPP) or POST. In EPP experiments, herbicides plus nonionic surfactant at 0.25% v/v were applied 7, 2, or 0 wk before planting (WBP). Fluorochloridone at 0.8 kg ai/ha applied 7 or 2 WBP, pyridate at 1.0 kg ai/ha applied 2 WBP, and paraquat at 0.4 kg ai/ha applied 0 WBP controlled 94 to 99% of TR kochia; a prepackaged mixture of glyphosate plus 2,4-D at 0.3 plus 0.6 kg ae/ha and paraquat at 0.4 kg/ha applied 7 or 2 WBP controlled 71 to 82% of TR kochia; and 2,4-D ester at 0.6 kg ae/ha applied 2 WBP controlled 75% of TR kochia. Linuron at 0.8 kg ai/ha and atrazine at 2.2 kg ai/ha were ineffective. In the POST herbicide experiments, where paraquat plus metolachlor at 0.6 plus 1.7 kg ai/ha were applied 17 d before planting, various combinations and rates of bentazon plus atrazine, bromoxynil, and dicamba with adjuvants provided good control of TR kochia that was less than 8 cm tall.
Common Ragweed (Ambrosia artemisiifolia) Control in Soybean (Glycine max) with Bentazon as Influenced by Imazethapyr or Thifensulfuron Tank-mixes
Authors: Hager Aaron , Renner Karen
Published: March 2018

Several herbicides control common ragweed postemergence in soybean. However, weed response may be altered if herbicides are tank-mixed and the choice of additive may also influence the degree of weed control. Imazethapyr and thifensulfuron could be tank-mixed with bentazon for broadleaf weed control and visual crop injury reduced compared to a bentazon plus acifluorfen tank-mix. Experiments determined common ragweed control with these herbicides and herbicide combinations when applied with various additives. In the greenhouse, bentazon at 560 g ai/ha reduced common ragweed dry weight 95 to 97%. Common ragweed control with imazethapyr at 35 g/ha increased by 13 and 7% when 28% urea ammonium nitrate was applied with nonionic surfactant or petroleum oil adjuvant, respectively. Tank-mixing imazethapyr with bentazon did not change dry weight of common ragweed compared with bentazon. Bentazon plus thifensulfuron plus nonionic surfactant required the addition of 28% urea ammonium nitrate to reduce dry weight of common ragweed comparable to that with bentazon. In field research, bentazon at 1120 g/ha reduced common ragweed dry weight 78 to 81%. Tank-mixing bentazon with thifensulfuron at 4.5 g/ha or imazethapyr at 71 or 35 g/ha reduced common ragweed dry weight at 14 d after treatment by 89 to 91%, thus enhancing control compared to each herbicide applied alone. Adding 28% urea ammonium nitrate to bentazon plus imazethapyr or bentazon plus thifensulfuron tank-mixes did not increase control compared to these treatments applied with either nonionic surfactant or petroleum oil adjuvant. By 28 d after treatment only imazethapyr at 35 or 71 g/ha plus 28% urea ammonium nitrate plus nonionic surfactant or petroleum oil adjuvant and bentazon plus imazethapyr tank-mixes provided 85% or more control of common ragweed in 1991, and only imazethapyr at 71 g/ha plus 28% urea ammonium nitrate plus petroleum oil adjuvant or imazethapyr at 71 g/ha plus bentazon provided greater than 78% common ragweed control in 1992. Soybean yield was not different from the handweeded control only where bentazon plus 71 g/ha of imazethapyr or acifluorfen at 560 g/ha was applied.
The Influence of a Hairy Vetch (Vicia villosa) Cover Crop on Weed Control and Corn (Zea mays) Growth and Yield
Authors: Curran William S. , Hoffman Lynn D. , Werner Edward L.
Published: March 2018

Influences of a hairy vetch cover crop and residual herbicides were examined in field corn in 1991 and 1992. Hairy vetch was seeded in mid-August and killed the following May with tillage, mowing, or glyphosate plus 2,4-D (no-till). These cover crop management systems were compared with a no-cover treatment. Residual herbicides including atrazine plus metolachlor applied PRE at three rates and nicosulfuron plus thifensulfuron applied POST at a single rate were compared within cover crop management systems. All cover crop management systems effectively controlled hairy vetch except mowing in 1992. The corn population was reduced in mow treatments containing uncontrolled vetch. Hairy vetch mulch suppressed some weeds in the no-till treatments in 1991, but more annual grass was noted late in the season with no-till into hairy vetch than with the no-cover treatments in 1992. Residual herbicide performance was similar across cover crop management systems, except for fall panicum control which decreased in some no-till systems. Unlike soil-applied herbicides, performance of POST herbicides was unaffected by cover crop management systems.
Tolerance of Five Annual Broadleaf Crops to Simulated Thifensulfuron:Tribenuron (2:1) Spray Drift
Authors: Wall David A.
Published: March 2018

Field experiments were conducted in 1992 and 1993 in southern Manitoba to investigate the tolerance of buckwheat, canola, field pea, lentil, and sunflower to simulated drift of 2:1 mixtures of thifensulfuron:tribenuron. Thifensulfuron:tribenuron at 0.23 to 3.6 g ai/ha was highly phytotoxic to all crops examined. Leaf area index 2 and 4 wk after treatment, seed yield, and seed weight were reduced for all crops at the rates examined. Predicted yield losses at 0.23 g/ha, averaged over two years, were 16% for sunflower, 20% for buckwheat, 22% for canola, 26% for lentil, and 37% for field pea. For each of the five crops, there was a strong linear relationship between percentage visual injury 2 wk after exposure and final yield. Simulated thifensulfuron:tribenuron drift reduced seed oil content of canola and sunflower. In one year, canola, field pea and lentil seed germination was reduced following exposure to simulated drift.
Smutgrass (Sporobolus Indicus) Control in Bermudagrass (Cynodon dactylon) Turf with Triazine-MSMA Applications
Authors: Nishimoto Roy K. , Murdoch Charles L.
Published: March 2018

Two or three applications of MSMA applied alone were ineffective in controlling smutgrass in common bermudagrass turf. Where atrazine at 2.2 kg ai/ha or simazine at 2.2 kg/ha was followed by two or three MSMA applications at 2.2 or 4.5 kg/ha, smutgrass control was increased. Metribuzin followed by two or three applications of MSMA was only slightly better than MSMA applied alone. Up to 35% injury to bermudagrass was observed 2 wk after the initial MSMA or the MSMA-triazine treatment, but complete recovery was evident 2 to 4 wk later, even with one or two follow-up MSMA applications at weekly intervals. Bermudagrass injury from the application of triazines followed with MSMA did not differ from MSMA applied alone in two of three experiments. In one experiment, atrazine or metribuzin followed with MSMA applications caused 10 to 25% more bermudagrass injury than MSMA applied alone.
Application Technology and Best Management Practices for Minimizing Herbicide Runoff
Authors: Baker James L. , Mickelson Steven K.
Published: March 2018

The fate of field-applied herbicides, including losses in surface runoff with water and sediment, is highly dependent on herbicide properties. The two most important properties are soil adsorption and persistence. Adsorption affects the potential for a herbicide to be lost primarily with sediment, runoff water, or possibly leaching water. Solubility, often though not always inversely correlated with adsorption, is of secondary importance, although low solubility can limit transport with water. Persistence affects the time available to be lost in runoff. Studies have shown that for soil-applied herbicides; extraction into runoff water or movement with sediment takes place from a thin soil layer at the surface. In addition, for herbicides studied, there is little interaction between surface crop residue and applied herbicides, and washoff from the residue readily occurs with small amounts of rainfall. Runoff loss equals the volume of carrier (water or sediment) times the concentration in that carrier; therefore, practices that reduce either, or both, can reduce losses. Rate of application has been directly related to concentration and therefore loss. Reducing rate, such as by banding, soil incorporation, and avoidance of application to crop residue reduce losses. The choice of herbicide and herbicide formulation, in conjunction with application technology, as they affect properties, rate, and placement, play a large role in determining runoff loss. Runoff losses of herbicides that are strongly adsorbed and therefore transported mainly with sediment can be reduced by erosion control; runoff volume reduction can reduce losses with water of moderately to weakly adsorbed herbicides. Conservation tillage has potential to reduce both runoff and erosion. Timing of application relative to expected intense storms, both in the short and long term, can reduce the potential for runoff. If possible to determine thresholds, herbicide use could be avoided if weed infestation is below the economic effect level. Buffer or filter strips have the potential to reduce transport of herbicides lost from fields to surface water resources.
Congress, Why Haven't You Heard of Weed Science?
Authors: Womach Jasper
Published: March 2018

Science shapes and is shaped by policy decisions. Yet scientists seem to have the greatest difficulty engaging in the policymaking process. When Congress makes public policy it does not work in a vacuum. It is responsive to public pressure. Interest groups that are effective at influencing policy know how Congress works, what are its rules, and who are the players. There is a need for scientists to engage in the process. Several important issues on the agenda involve weed science. There are a number of actions the weed science community can take to make itself available and helpful to policy makers.
Weed Control and Rotational Crop Response with AC 222,293
Authors: Miller Stephen D. , Alley Harold P.
Published: March 2018

In the field, eight barley (Hordeum vulgare L.) cultivars tolerated postemergence applications of AC 222,293 [a mixture of methyl 6 and 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) m- and p-toluate] at 0.4 to 1.4 kg/ha. AC 222,293 at 0.4 kg ai/ha applied at the 1.5- to 2-leaf stage controlled wild oats (Avena fatua L. # AVEFA) 96%, whereas 0.7 kg/ha applied at the 3.5- to 4-leaf stage controlled wild oats only 93%. Sugarbeets (Beta vulgaris L.) but not alfalfa (Medicago sativa L.), corn (Zea mays L.), pinto beans (Phaseolus vulgaris L.), or sunflower (Helianthus annus L.), were injured when planted 6 to 8 months after fall applications of AC 222,293 at 0.4 to 1.1 kg/ha.
Making Herbicide Rate Recommendations Based on Soil Tests
Authors: Weber Jerome B. , Tucker M. Ray , Isaac Robert A.
Published: March 2018

Percent soil organic matter content, as determined by standard chromic acid oxidations, was highly (r = 0.89) correlated with soil humic matter content, as determined by NaOH/DTPA (diethylenetriaminepenta-acetic acid)/alcohol extraction of 201 U.S. soils. Humic matter content of the soils was equally or better correlated (r = 0.89 to 0.97) with herbicide bioactivity, as measured in field experiments, than was percent organic matter content (r = 0.87 to 0.92). Regression equations provided allow herbicide rate recommendations for 80% weed control to be calculated based on soil humic matter or soil organic matter levels.
Yellow Nutsedge (Cyperus esculentus) Control with Herbicides
Authors: Keeley Paul E. , Carter Charles H. , Thullen Robert J.
Published: March 2018

The relatively new micro-encapsulated formulation of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] and diethatyl [N-(chloroacetyl)-N-(2,6-diethylphenyl)glycine] were soil-applied for yellow nutsedge (Cyperus esculentusL. #3CYPES) control in cotton (Gossypium hirsutumL. ‘Acala SF-2’). Both herbicides at rates of 1.68 to 3.36 kg ai/ha provided 60 to 80% control of yellow nutsedge for 6 weeks. Although control declined to 50 to 70% by cotton harvest, plots treated with herbicides usually yielded more seed cotton than cultivated control plots. Yields were similar from herbicide-treated and hand-weeded plots. Fewer tubers were counted in herbicide-treated than in cultivated-control plots in the fall. Based on yellow nutsedge control and seed cotton yields, alachlor and diethatyl could be helpful in controlling nutsedge and protecting cotton yields.
Mefluidide as an Enhancing Agent for Postemergence Broadleaf Herbicides in Soybeans (Glycine max)
Authors: Blumhorst Michael R. , Kapusta George
Published: March 2018

In field studies, mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} was most effective as an enhancing agent for bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] and/or acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} when applied as a tank mixture compared to sequential applications. The influence of mefluidide rate on weed control was not consistent. Additives improved the control of several weed species evaluated, but mefluidide generally was only equal to petroleum oil concentrate (phytobland petroleum oil plus emulsifiers in an 83:17 ratio) as an enhancing agent for bentazon and/or acifluorfen.
Imazaquin (Scepter)®: A New Soybean Herbicide
Authors: Congleton W. Franklin , Vancantfort Anne M. , Lignowski Edward M.
Published: March 2018

Imazaquin (Scepter) is a new, broad spectrum herbicide that is being marketed under the trademark Scepter® herbicide by American Cyanamid Co., Princeton, NJ. It can be applied preplant incorporated (PPI), preemergence (PE) or over-the-top postemergence (POST) in soybean. Crop tolerance is excellent with all methods of application. Imazaquin was tested in the United States in 1984 and 1985 under an Experimental Use Permit (EUP). Section 18 Emergency Exemptions also were granted by the Environmental Protection Agency (EPA) in 1985 for control of sicklepod (Cassia obtusifolia) in five southern states. Imazaquin was registered by the EPA for use in the United States on soybean, in March, 1986, and was sold in 23 states that year. Marketing in four additional states in 1987 was approved by the EPA in October, 1986.
Shattercane (Sorghum bicolor) Control with Alachlor where EPTC Failed
Authors: Moshier Loren J.
Published: March 2018

A location in east Central Kansas with a history of continuous corn (Zea maysL.), EPTC (S-ethyl dipropyl carbamothioate) plus dichlormid (2,2-dichloro-N,N-di-2-propenylacetamide) plus dietholate (O,O-diethylO-phenylphosphorothioate) application, and shattercane [Sorghum bicolor(L.) Moench. #3SORVU] was selected for herbicide efficacy investigations. Thiocarbamate herbicides applied before planting corn failed to control shattercane in 1 of 2 years. Adding dietholate did not improve EPTC efficacy in either year. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] applied preplant failed to control shattercane both years. Treatments which included applications of alachlor at 2.2 kg ai/ha 7 or 10 days after preplant herbicide applications were made provided significantly better shattercane control than did preplant treatments.
Understanding the Mode of Action of the Chloroacetamide and Thiocarbamate Herbicides
Authors: Fuerst E. Patrick
Published: March 2018

Chloroacetamide and thiocarbamate herbicides have many properties in common: both herbicide classes are effective only as preemergence herbicides; they inhibit early seedling growth and cause similar injury symptoms in susceptible species; they are detoxified in plants by glutathione conjugation; they have a similar spectrum of selectivity; they can be applied safely in certain susceptible grass crops when applied with antidotes; and they can inhibit the synthesis of lipids, isoprenoids, and other metabolic processes requiring coenzyme A. It can be hypothesized that these similarities are due to the ability of the chloroacetamides and the sulfoxide of thiocarbamates to bind covalently to enzymes, coenzymes, or metabolic intermediates containing sulfhydryl (-SH) groups.
Cattle Foraging Behavior in Leafy Spurge (Euphorbia esula)-Infested Rangeland
Authors: Lym Rodney G. , Kirby Donald R.
Published: March 2018

Leafy spurge causes economic loss by reducing both herbage production and use. Herbage use by grazing cattle in various densities of leafy spurge (Euphorbia esulaL. #3EPHES) was evaluated over a 3-yr period in North Dakota. Forage production and disappearance were estimated in four density classes of leafy spurge. Use of cool- and warm-season graminoids, forbs, and leafy spurge was estimated during the middle and the end of each grazing season. Cattle used 20 and 2% of the herbage in the zero and low density infestations, respectively, by mid-season. Moderate and high density infestations were avoided until the milky latex in leafy spurge disappeared in early fall, and herbage availability in zero and low density infestations declined. Herbage use in moderate and high density infestations increased to an average of 46% by the end of the grazing season compared to 61% in zero and low density infestations. An annual herbage loss of at least 35% occurred in pasture infested with 50% density or more of leafy spurge.
Research Priorities in Weed Science
Authors: Mcwhorter Chester G. , Barrentine William L.
Published: March 2018

Members from all four Weed Science Society of America (WSSA) regions in the United States ranked the research need to “develop new methods for controlling the movement of herbicides and their metabolites into ground water, surface water, and air” first of six major weed science research needs. Canadian members ranked the need to “devise more efficient and less costly weed control technology for conservation-tillage crop-production systems” first; but they also gave high ratings to “improve base knowledge of weed science, improve applicator training, and transfer of information to Extension Service personnel, farm producers, and administrators” and to “discover new ecological, biological, and non-chemical methods of weed control.” The needs to “develop improved methods of increasing the tolerance of crops to herbicides” and to “develop new technology for control of perennial weeds of crops and rangeland” were ranked low. The WSSA Research Committee, at the request of WSSA Presidents J. D. Riggleman (1985) and O. C. Burnside (1986), asked 977 members to rank weed science research needs. The members (ca 50% of the active membership in North America) were selected at random from every other state, federal, industry, and “other” member of each state or province from the up-to-date list of the WSSA business office. Within the highest ranked priority research need, the 422 U.S. and Canadian respondents consistently ranked the research areas (a) to “develop new application techniques that minimize or eliminate herbicides and their residues in air and water”, and (b) to “conduct research to regulate movement of herbicides through the soil profile to avoid contamination of ground water” high, regardless of the type of employment. They emphasized increasing research on the morningglory (Ipomoea spp. # IPOXX) complex, yellow nutsedge (Cyperus esculentus L. # CYPES), quackgrass [Agropyron repens (L.) Beauv. # AGREE], and several other weeds. More members, regardless of region or type of employment, ranked conservation tillage the most important crop or situation that needed new and improved weed control technology.
Chlorsulfuron and Metsulfuron Residues on Double-Cropped Soybeans (Glycine max)
Authors: Ritter Ronald L. , Harris Thomas C. , Kaufman Lisa M.
Published: March 2018

In field experiments in 1981, 36 g ai/ha of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} applied to winter wheat (Triticum aestivumL. ‘Arthur’) in early spring reduced seed yield in conventional and no-till plantings of double-cropped soybeans [Glycine max(L.) ‘Essex’]. From 1982 to 1984, three rates of chlorsulfuron (9, 18, and 36 g/ha) were applied at three different times (preemergence, early winter, and early spring) to study their residual effects on double-cropped soybeans. Chlorsulfuron at 36 g/ha applied preemergence or early spring reduced soybean seed yields when averaged over the 3-yr period. Metsulfuron {2-[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl)amino] carbonyl] amino] sulfonyl] benzoic acid} was tested at three rates (4.5, 9, and 18 g/ha) applied at three times (same as chlorsulfuron) in field studies in 1983 and 1984. Metsulfuron did not injure subsequently planted no-till soybeans.
Response of Spring Barley (Hordeum vulgare) to Herbicides
Authors: Clay Sharon A. , Thill Donald C. , Cochran Verlan L.
Published: March 2018

‘Karla’, ‘Klages', ‘Morex’, and ‘Steptoe’ cultivars of spring barley (Hordeum vulgareL.) differed in susceptibility to postemergence recommended application rates of diclofop {(±)-2-[4-(2,4-dichlorophenoxy) phenoxy] propanoic acid}, difenzoquat [1,2-dimethyl-3,5-diphenyl-1H-pyrazolium], chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide}, and metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] in 1981 and 1982. Metribuzin injured Morex, and difenzoquat injured all cultivars within 2 weeks after herbicide application. Metribuzin reduced height and crop biomass compared to the hand-weeded control. Herbicide treatments did not affect grain yield at Moscow, ID, in either year. However, metribuzin reduced yield of Karla and Morex, and diclofop reduced yield of Karla compared to the hand-weeded control at Pullman, WA, in 1982. Barley injury and grain yield loss depended on herbicide treatment and cultivar. Early season herbicide injury to barley did not indicate grain yield response at harvest.
Seasonal Emergence and Growth ofSorghum almum
Authors: Eberlein Charlotte V. , Miller Timothy L. , Lurvey Edith L.
Published: March 2018

Field studies on time of emergence, influence of planting date on growth and reproduction, and winter survival of rhizomes were conducted on sorghum-almum grown in corn and crop-free environments. In 1985, peak emergence of sorghum-almum occurred during early May in crop-free plots and mid-May in corn. In 1986, two peaks of emergence, one in early June and one in late June, were noted in both crop-free and corn plots. Emergence after mid-July was 4% or less of the total emerged in 1985, and no sorghum-almum emerged after mid-July in 1986. In planting date studies, sorghum-almum was seeded alone or in corn at 2-week intervals. Corn competition reduced sorghum-almum shoot, rhizome, and root growth at all planting dates. Maximum sorghum-almum seed production was 43 110 seed/plant when grown without competition but only 1050 seed/plant when grown with corn competition. When grown with corn competition, no seed developed on sorghum-almum seeded 6 or more weeks (mid-June or later) after corn planting. Shoot dry weight of sorghum-almum grown with corn competition was 3 g/plant or less for plants seeded 4 or more weeks (early June or later) after corn planting. Therefore, controlling sorghum-almum in corn through mid-June should prevent seed production and corn yield losses due to sorghum-almum competition. Rhizomes produced by sorghum-almum grown alone or with corn competition did not survive the winter; therefore, in Minnesota, sorghum-almum survival from one growing season to the next depends on seed production.
Comparison of Application Methods and Tillage Practices on Volatilization of Clomazone
Authors: Thelen Kurt D. , Kells James J. , Penner Donald
Published: March 2018

Field trials were conducted in 1985 and 1986 to determine the effect of incorporation on volatilization of clomazone from soil. Volatilization was detected up to 2 weeks after surface-applied or soil-incorporated treatments of clomazone at 1.1 kg ai/ha. The amount of volatilization detected was greatest following rainfall and varied between years. More clomazone volatilized after surface application than after incorporation, regardless of the climatic conditions present. Clomazone volatilization detected was in the order of no-tillage > minimum tillage > conventional tillage.
Herbicide Treatments for No-Till Alfalfa, Medicago sativa L., Establishment in Sod
Authors: Hagood Edward S.
Published: March 2018

Field experiments were established to evaluate the effect of herbicide treatments on control of tall fescue before spring or fall no-till alfalfa planting and to determine the effect of fescue control on alfalfa seedling establishment, forage yield, and forage quality. No treatment provided significantly greater tall fescue control than the standard two applications of paraquat at 13- to 21-day intervals. Fescue control values with this treatment ranged from 86 to 99% over experiments and were associated with maximum values for alfalfa ground-cover and alfalfa yield percentage parameters, 52 to 83% and 64 to 96%, respectively. Glyphosate and SC-0224 at 2.2 kg/ha and greater generally gave tall fescue control equivalent to the paraquat treatment in both spring and fall seedings as did sethoxydim at 0.6 kg/ha in spring seedings. Applications of fluazifop or HOE-0661 did not result in satisfactory tall fescue control or alfalfa establishment. Adding nonionic surfactant to glyphosate or SC-0224 did not increase tall fescue control. There was a direct linear relationship between tall fescue control and both alfalfa seedling establishment and yield percentage.
Soft Red Winter Wheat (Triticum aestivum) Response to Dicamba and Dicamba Plus 2,4-D
Authors: Schroeder Jill , Banks Philip A.
Published: March 2018

Soft red winter wheat cultivars were evaluated in field experiments in Georgia for tolerance to dicamba alone and mixed with 2,4-D. Treatments reduced ‘Florida 302’ yield more than ‘Florida 301’ or ‘Coker 983’ at Tifton in 1986. Mid-tillering Florida 302 wheat was more sensitive to treatment than fully tillered wheat. In 1987, dicamba plus 2,4-D applied at mid-tillering reduced yields of all cultivars in Watkinsville. Injury and yield reductions occurred primarily when mid-tiller treatments were applied to wheat that was planted 10 or 21 days later than recommended at Tifton or Watkinsville, respectively. When applied according to labeling, dicamba or dicamba plus 2,4-D use in Georgia soft red winter wheat can reduce grain yield.
Roadside Management of Annual Fleabane (Erigeron annuus) and Wild Carrot (Daucus carota)
Authors: Fleischer Shelby J. , Gaylor Michael J. , Dickens Ray , Turner David L.
Published: March 2018

Interstate rights-of-way may serve as weed host reservoirs for the tarnished plant bug, an insect pest of cotton. Management of these rights-of-way may have an impact upon cotton pest management. In a 3-yr study, time of mowing, frequency of mowing, and sulfometuron methyl applied against overwintering rosettes influenced the cover of annual fleabane and wild carrot, which harbor tarnished plant bugs.