bluuebunny/crossref_metadata_2025 huggingface dataset:
A Model for Combined GPS and BDS Real-Time Kinematic Positioning using one Common Reference Ambiguity
Authors: Tu Rui , Liu Jinhai , Zhang Rui , Zhang Pengfei , Lu Xiaochun
Published: March 2018

This paper proposes a model for combined Global Positioning System (GPS) and BeiDou Navigation Satellite System (BDS) Real-Time Kinematic (RTK) positioning. The approach uses only one common reference ambiguity, for example, that of GPS L1, and estimates the pseudo-range and carrier phase system and frequency biases. The validations show that these biases are stable during a continuous reference ambiguity period and can be easily estimated, and the other estimated double-differenced ambiguities, such as those of GPS L2, BDS L1, and BDS L2, are not affected. Therefore, our approach solves the problems of a frequently changing reference satellite. In addition, because all the carrier phase observations use the same reference ambiguity, a relationship is established between the different systems and frequencies, and the strength of the combined model is thus increased.
Teaching Seed Bank Ecology in an Undergraduate Laboratory Exercise
Authors: Regnier Emilie E.
Published: March 2018

The study of weed life cycles, reproductive strategies, and the soil seed bank is emphasized in the undergraduate weed science course at Ohio State University as central to an understanding of the survival of weeds in the environment. A laboratory exercise was conducted every spring and fall academic quarter from 1991 to 1993 to demonstrate the effects of long-term cropping and soil disturbance histories on weed seed banks and aboveground weed communities. Five sites with diverse histories of culture were sampled; these included a field cultivated in vegetables under continuous conventional tillage for 59 yr, a field cultivated in field corn under continuous no-tillage for 11 yr, a 24 yr-old turfgrass research farm, a 70 yr-old forest, and a section of the forest border. Students conducted a survey of the weeds growing at the sites and separated and identified seeds from soil samples over a 3-wk period in weekly 2-h laboratory periods. Students wrote reports interpreting the data based on their knowledge of the site histories, weed life cycles, and weed seed production and longevity characteristics. The data were consistent over academic quarters as well as with published research, indicating that the survey and soil sampling techniques provided a reasonably accurate representation of the weed flora and soil seed populations. Weeds found growing at the sites were primarily summer annuals at the vegetable site, and a mix of summer and winter annuals, biennials, and perennials at the remaining sites. Annual weeds dominated the seed banks of all sites with common lambsquarters, pigweed spp., and common purslane being the most commonly found seeds. The presence of most seeds in the soil could be explained by a combination of species seed production and seed longevity characteristics and species abundance in the standing community. Interpretation of the data required students to integrate and apply lecture material and provided an excellent thinking exercise.
Postemergence Green Foxtail (Setaria viridis) Control in Corn (Zea mays) in Western Canada
Authors: McMullan Patrick M. , Blackshaw Robert E.
Published: March 2018

Field research was conducted to determine the effectiveness of DPX-79406 (a 1:1 mixture of nicosulfuron and rimsulfuron) for green foxtail control in field corn. Green foxtail control was similar when DPX-79406 was applied postemergence compared to preplant incorporated EPTC/dichlormid or metolachlor. DPX-79406 gave similar green foxtail control to that of cyanazine and better control than inter-row cultivation following soil-applied herbicides. Green foxtail control was greatest when DPX-79406 was applied at the one- to two-tiller stage compared to the one- to two-leaf stage, suggesting that green foxtail is more susceptible to DPX-79406 at later growth stages. DPX-79406 injured ‘Pioneer 3995’ corn in all trials but injured ‘Pride K020’ corn in only one treatment. DPX-79406 between 15 and 25 g ai/ha gave 85% control of green foxtail with minimal corn injury. Adjuvants tended to increase both corn injury and green foxtail control with Scoil and Merge increasing DPX-79406 activity the most. DPX-79406 provides an effective postemergence alternative for green foxtail control in field corn, for either preplant incorporated herbicides or postemergence cyanazine.
Effect of Johnsongrass (Sorghum halepense) Control on the Severity of Virus Diseases of Corn (Zea mays)
Authors: Eberwine John W. , Hagood Edward S.
Published: March 2018

Field experiments were conducted to evaluate the hypothesis that johnsongrass control in corn causes increased maize dwarf mosaic virus (MDMV) and maize chlorotic dwarf virus (MCDV) disease severity because of increased movement of insect vectors from dying johnsongrass to the corn crop. Johnsongrass control treatments included 1) broadcast POST nicosulfuron, 2) directed POST imazethapyr, 3) mechanical control, and 4) no treatment. Disease severity in both a virus-susceptible and a virus-tolerant corn hybrid was evaluated. With the virus-susceptible hybrid, greater disease severity was observed where johnsongrass was controlled in the experimental area than where johnsongrass was not controlled. Increases in disease severity were independent of the method of johnsongrass control. Corollary studies conducted on the same site verified a double infection of corn with MDMV and MCDV and documented movement of blackfaced leafhoppers, the insect vector of MCDV, subsequent to treatment of johnsongrass.
Antagonism and Synergism Between Herbicides: Trends from Previous Studies
Authors: Zhang Jianhua , Hamill Allan S. , Weaver Susan E.
Published: March 2018

A synthetic data set was created by incorporating results from previously published papers on antagonistic and synergistic herbicide interactions between two herbicides applied as a tank mixture or sequentially, and then analyzed on the basis of various properties of the herbicides and target plants. Generally, interactions between herbicides were antagonistic more frequently than synergistic. This trend held no matter whether the interacting herbicides were absorbed by the same or different parts of the plant, had the same or different translocating abilities, had the same or different modes of action, and regardless of whether the target plants were annual or perennial plants, or crops or weeds. Antagonistic interactions occurred much more frequently when the target plants were monocot than dicot, and in the Compositae, Gramineae, or Leguminosae than in the Chenopodiaceae or Convolvulaceae families.
The Interaction of Insecticides with Herbicide Activity
Authors: Kwon Chae Soon , Penner Donald
Published: March 2018

The combination of certain herbicides with insecticides can inhibit crop growth. Greenhouse studies were conducted to evaluate interaction effects of herbicides and insecticides with/without protectant, on corn and weed species. ‘Northrup King 9283’ hybrid corn showed greater sensitivity to acetanilide herbicides than ‘Cargill 7567.’ Neither the insecticides terbufos nor isazofos appeared to enhance this sensitivity. Both hybrids were sensitive to the combination of chlorimuron, nicosulfuron, or primisulfuron with terbufos. Cargill 7567 was more tolerant than Northrup King 9283 to the growth inhibiting interaction of sulfonylurea herbicides with terbufos. Imazaquin at 70 g/ha reduced height of Northrup King 9283 corn, but there was no interaction with terbufos. The protectants CGA-154281 and NA reduced corn injury from metolachlor and the combination of nicosulfuron and primisulfuron with terbufos, respectively. Nicosulfuron and primisulfuron treatments combined with metolachlor showed less corn injury than metolachlor alone, but these herbicides increased corn injury when combined with terbufos. The inclusion of terbufos did not enhance primisulfuron activity on barnyardgrass, giant foxtail, or velvetleaf.
Susceptibility of Various Crop and Weed Species to AAL-Toxin, a Natural Herbicide
Authors: Abbas Hamed K. , Tanaka T. , Duke S. O. , Boyette C. D.
Published: March 2018

AAL-toxin, produced byAlternaria alternata, was investigated for its phytotoxic effects on 86 crop and weed species. On susceptible tomato leaf discs, AAL-toxin caused electrolyte leakage and chlorosis at 0.01 μM in 24 h. Plants tested exhibited a range of response. AAL-toxin damaged sensitive plants at 5 μM while other plants showed minimal damage at > 1000 μM. Cotton and the important weeds, Canada thistle, field bindweed, and velvetleaf were largely unaffected. Monocots tested were largely immune.
Broadleaf Weed Control with Clomazone in Pickling Cucumber (Cucumis sativus)
Authors: Al-Khatib Kassim , Kadir Sorkel , Libbey Carl
Published: March 2018

Broadleaf weed control ranged from 80% with clomazone at 0.14 kg/ha to 100% with clomazone at 1.12 kg/ha. Broadleaf weed control was higher with clomazone than naptalam or ethalfluralin. The combination of clomazone at 0.14 kg/ha and naptalam at 5 kg/ha or ethalfluralin at 1.25 kg/ha gave more than 90% broadleaf weed control. Clomazone caused chlorosis and bleaching on cucumber leaves but plants rapidly recovered. Cucumber yields were higher in plots treated with clomazone alone at 0.14 to 0.56 kg/ha than with ethalfluralin or naptalam alone. Clomazone dose response studies were conducted in weed-free plots with five cucumber varieties. The 0.28 kg/ha rate caused low levels of visible injury and did not decrease yields. Cultivar differences were more pronounced at higher clomazone rates. The five cucumber cultivars were, in order of increasing clomazone tolerance, ‘Sunre 3537,’ ‘Pioneer,’ ‘Quest,’ ‘Prince,’ and ‘Calypso.’ We concluded that clomazone is an effective and selective herbicide for broadleaf weed control in pickling cucumber.
Response of Selected Soybean (Glycine max) Cultivars to Dimethenamid and Metolachlor in Hydroponic Conditions
Authors: Osborne Bradley T. , Shaw David R. , Ratliff Randall L.
Published: March 2018

Soybean cultivars were grown in a hydroponic culture to evaluate tolerance to dimethenamid and metolachlor. Root length was reduced in 7 of the 32 cultivars with 50 ppb dimethenamid. ‘Asgrow 5403’ and ‘Bryan’ root lengths were reduced more than 20%. ‘Asgrow 6297’ was the only cultivar with greater than 12% root length reductions with 83 ppb metolachlor. The longest lateral root of all cultivars was shortened with dimethenamid. ‘NK-1460’ and Bryan expressed the most lateral root length reduction, at 73 and 62%, respectively. Asgrow 6297 was tolerant to dimethenamid, but lateral roots were reduced 16%. Metolachlor reduced the lateral root lengths of 12 cultivars, with Asgrow 5403, ‘Coker 6955,’ and Bryan reduced more than 20%. Bryan was the most sensitive cultivar to both herbicides, while ‘Brim’ was the most tolerant of cultivars evaluated.
Effect of Imazethapyr on Perennial Grasses
Authors: Wilson Robert G.
Published: March 2018

Experiments were conducted near Scottsbluff, NE in 1991 and 1992 to evaluate the selectivity of imazethapyr for weed control in blue grama, intermediate wheatgrass, little bluestem, Russian wildrye, switchgrass, and western wheatgrass. Imazethapyr reduced weed biomass in all seedings and injured all perennial grasses 12 days after treatment (DAT). Imazethapyr reduced the height of intermediate wheatgrass, Russian wildrye, and switchgrass 35 DAT. Russian wildrye, and switchgrass biomass 50 DAT was reduced by imazethapyr. Weed biomass in new seedings of intermediate wheatgrass and western wheatgrass were reduced more than that of the other grasses.
Biotypes of Palmer Amaranth (Amaranthus palmeri) and Common Waterhemp (Amaranthus rudis) are Resistant to Imazethapyr and Thifensulfuron
Authors: Horak Michael J. , Peterson Dallas E.
Published: March 2018

Seeds of suspected herbicide-resistant Palmer amaranth and common waterhemp were collected in Clay County and Douglas County, KS, respectively. An experiment was established in a greenhouse to determine if these species had developed resistance to imazethapyr and thifensulfuron. Imazethapyr was applied pre- (PRE) and postemergence (POST) at 1×, 2×, 4×, and 8× the suggested use rate (70 g/ha), and thifensulfuron was applied POST at 1×, 2×, 4×, and 8× the suggested use rate (4.5 g/ha). Both species had developed resistance to all rates of these herbicides. The occurrence of resistance at the Clay County site (Palmer amaranth) fit the typical pattern for the development of herbicide resistance, i.e., multiple applications of the same class of herbicide for several years. However, the Douglas County (common waterhemp) site had a limited history of use of ALS-inhibiting herbicides and did not follow typical models of resistance development.
Yellow Mignonette (Reseda lutea) in the United States
Authors: Harris Jerry D. , Davis Edward S. , Wichman David M.
Published: March 2018

Yellow mignonette (Reseda lutea (L.) # RESLU) is a broadleaf perennial weed that is native to the Mediterranean Basin and Asia Minor. It has been spread around the world and is widely recognized in Australia as a troublesome noxious weed in croplands. It is a problem in cropland and pastures because of its high seed output, extensive reproductive root system, ability to thrive under disturbed conditions, and high nitrate levels. While nitrate levels of 2.5 to 3.1% have been detected in plants during the rosette to early flower growth stages, when yellow mignonette is most palatable, no livestock injury or deaths have been reported. Yellow mignonette was first reported in Montana in 1958 but was not recognized as a weed problem until 1990. Since 1988 it has invaded several hundred hectares of small grains and alfalfa (Medicago sativa L.)-grass pastures in Central Montana and is spreading rapidly along gravel road shoulders.
Downy Brome (Bromus tectorum), Jointed Goatgrass (Aegilops cylindrica) and Horseweed (Conyza canadensis) Control in Fallow
Authors: Wiese Allen F. , Salisbury Clay D. , Bean Brent W.
Published: March 2018

Jointed goatgrass, downy brome, and horseweed are increasingly troublesome winter annual weeds during fallow periods in conservation-tillage systems in the southern Great Plains. These experiments determined the optimum weed size, vigor, and minimum herbicide rate required for 95% or better control of these weeds on fallow land. Jointed goatgrass and downy brome were controlled best when plants were 10 cm or less tall and growing vigorously at time of treatment. Horseweed was controlled best when plants were 30 cm tall and growing vigorously. Based on local retail and application costs and assuming optimum conditions for control, the two most economical herbicide treatments that controlled each weed 95% or better were: jointed goatgrass, clethodim at 250 g ai/ha and glyphosate + 2,4-D at 249 + 479 g ae/ha; downy brome, quizalofop at 18 g ai/ha and glyphosate + 2,4-D at 582 + 950 g ae/ha; and horseweed, 2,4-D at 560 g ae/ha and metsulfuron at 5 g ai/ha.
Jointed Goatgrass (Aegilops cylindrica) and Downy Brome (Bromus tectorum) Control in Perennial Grasses
Authors: Beck K. George , Sebastian James R. , Chapman Phillip L.
Published: March 2018

Glyphosate and package mixtures of glyphosate plus dicamba or 2,4-D were evaluated for the selective control of jointed goatgrass and downy brome in seeded perennial grasses. Glyphosate at 560, glyphosate plus dicamba at 550 + 220, and glyphosate plus 2,4-D at 420 + 350 and 570 + 470 g ai/ha controlled 90% or more jointed goatgrass in 1988 and 1991. Glyphosate plus 2,4-D at 150 + 120 and 280 + 240 g/ha were the only treatments that controlled less than 90% of jointed goatgrass in 1991. In 1988, glyphosate at 210 g/ha and glyphosate plus dicamba at 210 + 80 g/ha were the only treatments that controlled less than 90% of downy brome. Glyphosate at 210, 280, 420, and 560 g/ha, glyphosate plus dicamba at 210 + 80, 280 + 110, 420 + 170, and 550 + 220 g/ha, and glyphosate plus 2,4-D at 150 + 120, 280 + 240, 420 + 350, and 570 + 470 g/ha controlled 90% or more downy brome in 1990. Pubescent wheatgrass and crested wheatgrass were stunted or killed if they were growing when herbicides were applied.
Comparison of Spray Drift During Postemergence Herbicide Applications to Turfgrass
Authors: Hatterman-Valenti Harlene , Owen Micheal D. K. , Christians Nick E.
Published: March 2018

Field tests showed that the lawn spray-gun with a 4 gpm lawn tip reduced the percentage of application volume deposited 90 cm to 210 cm downwind from the spray swath edge when compared with XR8004 flat-fan or RA-6 wide angle hollow cone applications at wind speeds between 4.7 and 14.4 km/h. The percentage of applied volume collected at 210 cm downwind from the XR8004 flat-fan applications was 5 and 16 times greater than the percentage from the RA-6 Raindrop nozzle and lawn spray-gun applications, respectively. Visible injury alone with height increases and fresh weights from tomato plants located downwind from the applications concur with spray-drift data for all nozzle types. Triclopyr injury decreased as the distance from the swath edge increased. All tomato plants located downwind up to 210 cm from the XR8004 flat-fan applications were visibly injured (15 to 40%); whereas, only plants less than 150 cm downwind from the RA-6 Raindrop applications and less than 90 cm downwind from the lawn spray-gun applications were injured (2 to 8%).
Timing of Total Postemergence Herbicide Applications to Maximize Weed Control and Corn (Zea mays)Yield
Authors: Carey J. Boyd , Kells James J.
Published: March 2018

Grass and broadleaf herbicides are available for effective, single-application total postemergence weed control in corn. Field experiments were conducted in 1992 and 1993 on sites with dense natural weed infestations to determine the effects of weed interference prior to herbicide application on corn yield. Nicosulfuron plus bromoxynil was applied at 5-, 10-, 15-, or 20-cm weed canopy heights in plots with or without weed interference. Crop injury was more severe when herbicides were applied to smaller corn. Herbicide applications made to 5-, 10-, or 15-cm tall weeds provided nearly complete weed control. Weed interference did not reduce corn height or grain yield when postemergence applications were made to weeds 10 cm or less in height. Weed interference reduced corn height and grain yield in 1992 when applications were made to 15-cm tall weeds even though weed control was nearly complete. Weed control was incomplete and corn height and grain yield were reduced when applications were delayed until weeds were 20 cm tall.
Verification and Distribution of Propanil-Resistant Barnyardgrass (Echinochloa crus-galli)in Arkansas
Authors: Carey V. Frank , Hoagland Robert E. , Talbert Ronald E.
Published: March 2018

Propanil-resistant barnyardgrass was reported in Poinsett County, AR, in 1990. Greenhouse studies were initiated to determine the distribution of propanil-resistant barnyardgrass in the state and to characterize the resistance. Barnyardgrass seeds were obtained in 1991 and 1992 from fields in 19 of the 38 rice producing counties in Arkansas where propanil treatment at recommended rates gave unsatisfactory barnyardgrass control. Barnyardgrass seedlings from the various sources were treated with propanil at 4.5 kg ai/ha and seedling injury response was compared to the response of seedlings collected from known resistant and susceptible barnyardgrass populations. Propanil-resistance of varying levels was confirmed in 115 (16 counties) out of the 138 Arkansas barnyardgrass seed sources. Propanil I50values (rate of herbicide required to provide 50% injury/control) were determined to be 14, 20, and 39 kg/ha for slightly, moderately, and highly resistant barnyardgrass, respectively. A resistance factor of 20® was found in the highly resistant barnyardgrass category. Development of resistance was highly correlated with crop rotations where rice was grown one out of two, or two out of three years.
Tansy Ragwort
Authors: Mitich Larry W.
Published: March 2018

In 1753, Carolus Linnaeus described tansy ragwort, Senecio jacobaea, in Species Plantarum. This species is a member of the largest genus of the sunflower family (Asteraceae), which encompasses 1300 genera and 21 000 species worldwide. Taxa in the genus Senecio L. range from herbs to shrubs and occur globally. Comparatively few senecios are of economic importance and many of them are weeds, among them tansy ragwort, which can infest pastures, crowding out more desirable forage and poisoning grazing livestock.
Expanding the Weed Science Society of America Beyond Weed Science
Authors: Ogg Alex G.
Published: March 2018

The Weed Society of America (WSA) was organized in 1954. At that time, 114 scientists were identified as conducting research on weeds and their control, although only part of these scientists' time was devoted to weeds. Although “selective” herbicides were used in the late 1800s and the “sinox” or “dinitro” herbicides were fairly important from the 1930s, the discovery of the broadleaf selective phenoxy herbicides in the 1940s gave scientists and farmers an exciting new way to manage weeds and played a major role in advancing the notion that there was a need for a separate discipline of weed science. It was noted by C. J. Willard in 1954 at an address to the American Society of Agronomy (ASA) that there was an urgent need for research on weed biology and ecology and on the behavior of herbicides in plants and soils. WSA held its first meeting in January, 1956. There were 621 charter members of WSA.
Response of MSMA-Resistant and-Susceptible Common Cocklebur (Xanthium strumarium) Biotypes to Cotton (Gossypium hirsutum) Herbicides and Cross-Resistance to Arsenicals and Membrane Disrupters
Authors: Nimbal Chandrashekhar I. , Shaw David R. , Duke Stephen O. , Byrd John D.
Published: March 2018

Experiments were conducted to evaluate PRE and POST cotton herbicides for control of MSMA-resistant (R) and -susceptible (S) common cocklebur biotypes, and to determine potential cross-resistance of the R biotype to other arsenical and membrane disruptor herbicides. Cyanazine and clomazone applied PRE were the most effective herbicides for control of R populations. Lactofen or cyanazine in combination with MSMA controlled R and S biotypes better than fluometuron or pyrithiobac combined with MSMA. MSMA-resistant common cocklebur was not cross-resistant to other arsenical herbicides. Significant differences in cellular electrolyte leakage and chlorophyll content of the treated leaf between biotypes were not evident for paraquat, acifluorfen, and MSMA.
Absorption, Translocation, and Metabolism of Triclopyr in Rice (Oryza sativa)
Authors: Braverman Michael P.
Published: March 2018

Absorption, translocation, and metabolism of14C-triclopyr were compared in the rice cultivars ‘Lemont’ and ‘Tebonnet’ under flooded and non-flooded conditions. Radioactivity washed from14C-triclopyr-treated leaves was 26% at 6 h and decreased to about 11% of that applied at 96 h after treatment. Triclopyr was immobile with 98% of the recovered14C remaining in the treated rice leaf. An average of 19% of triclopyr was metabolized at 6 h and was similar among flooded and nonflooded rice cultivars. Absorption, translocation, and metabolism of triclopyr did not differ among rice cultivars or flooding treatments.
Effectiveness of Adjuvants with Nicosulfuron and Primisulfuron for Wirestem Muhly (Muhlenbergia frondosa) Control in No-Till Corn (Zea mays)
Authors: Nandula Vijay K. , Curran William S. , Roth Gregory W. , Hartwig Nathan L.
Published: March 2018

Greenhouse and field experiments were conducted to evaluate the effectiveness of nicosulfuron and primisulfuron with different adjuvants on wirestem muhly control. The adjuvants evaluated with the two herbicides included a nonionic surfactant, crop-oil concentrate, crop-oil concentrate plus urea-ammonium nitrate, methylated vegetable-oil concentrate, and organosilicone methylated vegetable-oil concentrate. In the greenhouse, nicosulfuron and primisulfuron performance was similar, although small differences occurred between adjuvants and herbicides. In the field, changing adjuvant affected nicosulfuron performance more than primisulfuron and in general, greater control was achieved with nicosulfuron than with primisulfuron. Among adjuvants, methylated vegetable-oil concentrate provided greater wirestem muhly control with nicosulfuron and sometimes primisulfuron compared to the others, while the nonionic surfactant was the least effective with both herbicides. Regardless of adjuvant, none of the field-applied treatments controlled wirestem muhly much beyond the 12 wk-evaluation period.
Effect of Nicosulfuron on Johnsongrass (Sorghum halepense) Control and Corn (Zea mays) Performance
Authors: Gubbiga Nagabhushana G. , Worsham A. Douglas , Coble Harold D. , Lemons Richard W.
Published: March 2018

Field experiments were conducted at two locations in North Carolina during the summer of 1992 to ascertain the reasons for stunted growth of corn noticed occasionally in fields treated POST with nicosulfuron to control dense infestations of johnsongrass. Treatments consisted of nicosulfuron at 35 g ai/ha sprayed POST, either over-top or post-directed only to johnsongrass in a single early application or in sequential applications of 17.5 g/ha. Checks included a hand-weeded, paraquat post-directed to johnsongrass, and non-weeded. Nicosulfuron provided satisfactory control of johnsongrass irrespective of whether applied once or sequentially. Corn yield in nicosulfuron-treated plots was as much as three times greater than in non-treated plots depending on hybrid and location. In the absence of johnsongrass interference, nicosulfuron caused a corn yield reduction of 6 to 9%. However, in the presence of johnsongrass interference, an additional 16 to 26% reduction in yield occurred with a POST application of nicosulfuron. Reductions in corn plant height and dry matter accumulation also were noticed for nicosulfuron treatments compared to post-directed application of paraquat and hand removal of johnsongrass.
Salts and Surfactants Influence Nicosulfuron Activity
Authors: Nalewaja John D. , Praczyk Tadeusz , Matysiak Robert
Published: March 2018

Experiments were conducted in the greenhouse to determine nicosulfuron activity on large crabgrass as influenced by surfactant, ammonium salt adjuvants, and various calcium, sodium, and magnesium salts in the spray carrier. Nicosulfuron activity varied with surfactant. Ammonium salt adjuvants at 0.2 M (ammonia) and sodium, calcium, or magnesium salts at 0.02 M (cation) increased or decreased nicosulfuron activity dependent on the specific salt and surfactant. Spray carrier surface tension or pH of the spray solution did not relate to nicosulfuron activity. The specific ammonium component influenced nicosulfuron activity differently depending on the surfactant. Increases in ammonium nitrate concentration decreased, nicosulfuron activity with Pluronic® P85 surfactant and increased activity with X-77® surfactant. The response to ammonium nitrate was less pronounced at high surfactant concentrations. Sodium bicarbonate antagonism of nicosulfuron activity was overcome by ammonium sulfate and 28% aqueous nitrogen fertilizer in the presence of several oil and surfactant adjuvants. The results indicate the importance of surfactant selection for use with nicosulfuron when applied with nitrogen salts.
Velvetleaf (Abutilon theophrasti) Effect on Corn (Zea mays) Growth and Yield in South Dakota
Authors: Scholes Chad , Clay Sharon A. , Brix-Davis Kalyn
Published: March 2018

Studies were conducted at two sites in South Dakota in 1992 and at one site in 1993 to measure the effect of velvetleaf on corn growth and yield. Velvetleaf was overseeded in corn rows and thinned to densities of 0, 1.3, 4, 12, and 24 plants/m2. Velvetleaf leaf area index and total biomass were positively correlated with velvetleaf density. Biomass per velvetleaf plant and corn biomass were correlated negatively with velvetleaf density. The percent corn yield reduction was similar for locations and years in spite of large yield differences. Maximum yield loss estimated by a hyperbolic yield reduction model was 37.2% with a loss of 4.4% per unit velvetleaf density.
Rapeseed (Brassica napus) Green Manure Crop Suppresses Weeds in Potato (Solanum tuberosum)
Authors: Boydston Rick A. , Hang Ann
Published: March 2018

Fall-planted rapeseed and sudangrass were evaluated for weed control in potato during a two-year study. Rapeseed incorporated in the spring in a loamy sand soil reduced weed density 85 and 73% in 1992 and 1993, respectively, and reduced weed biomass 96 and 50% in 1992 and 1993, respectively, in following potato crops compared to potato after fallow. Potato following rapeseed yielded 25% and 17% more total tuber weight than potato following sudangrass in 1992 and fallow in 1993, respectively. In greenhouse trials, rapeseed tissue added to a loamy sand soil at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and longspine sandbur by 90 and 83%, respectively. Similarly, white mustard tissue added at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and green foxtail by 83 and 70%, respectively.
Combined Effects of Acetolactate Synthase-Inhibiting Herbicides with Terbufos and Piperonyl Butoxide on Corn (Zea mays) and Soybean (Glycine max)
Authors: Kwon Chae Soon , Kells James J. , Penner Donald
Published: March 2018

Greenhouse studies were conducted to determine the response of six corn hybrids and two soybean varieties to acetolactate synthase (ALS) inhibitor herbicides applied with terbufos and/or piperonyl butoxide (PBO), a mixed function oxidase (MFO) inhibitor. Field experiments also were conducted to determine the response of six corn hybrids to the combination treatments, terbufos plus ALS inhibitor herbicides and/or PBO and/or antidote. PBO at 0.33 kg/ha tank-mixed with nicosulfuron and primisulfuron injured the Northrup King 9283 corn hybrid. Great Lakes 584 corn was less sensitive than Northrup King 9283 to these combination treatments. Pioneer 3377 IR corn hybrid was resistant to the combination of nicosulfuron or primisulfuron plus PBO at 2 kg/ha and also to the combination treatments of imazethapyr herbicide plus PBO even though terbufos was previously applied. ICI 8532 IT, ICI 8532, and Pioneer 3377 hybrids were injured by the combination of nicosulfuron or primisulfuron and/or terbufos and/or PBO at 2 kg/ha. ICI 8532 IT corn hybrid was not injured by the combination treatment of imazethapyr or thifensulfuron and terbufos. In the field studies, Pioneer 3377 IR and Ciba 4393 RSC hybrids were resistant to sulfonylurea and imidazolinone herbicides even when applied with PBO regardless of the presence of terbufos. All treatments of chlorimuron plus terbufos caused considerable injury to ICI 8532 IT, ICI 8532, Pioneer 3377, and Ciba 4393, but not Pioneer 3377 IR and Ciba 4393 RSC. The combination of thifensulfuron with PBO injured Elgin ‘87 soybean, but the W20 soybean was tolerant to this combination treatment. Combination of imazethapyr with PBO did not affect the growth of Elgin ‘87 soybean.
Reduced Preemergence Herbicide Rates for Large Crabgrass (Digitaria sanguinalis) Control in Six Tall Fescue (Festuca arundinacea) Cultivars
Authors: Johnson B. Jack , Carrow Robert N.
Published: March 2018

A field experiment was conducted over a 2-yr period to determine the effects of reduced PRE herbicide rates on large crabgrass infestation in six tall fescue cultivars. With the exception of oryzalin and benefin plus oryzalin in 1993, there was no cultivar by herbicide interaction for large crabgrass infestation when final ratings were made in 1993 and 1994. This interaction was caused by moderate to severe turfgrass injury that thinned the turf. When cultivars were disregarded, prodiamine was the only herbicide applied at one-third recommended rate in 1993 that effectively suppressed large crabgrass for the full season. Prodiamine and dithiopyr were the only PRE herbicides applied at one-third recommended rates for two consecutive years that effectively suppressed large crabgrass in 1994. Two-thirds recommended rate was needed for two consecutive years for oxadiazon, pendimethalin, oryzalin, benefin plus oryzalin, and benefin plus trifluralin to maintain optimum large crabgrass suppression in 1994.
Interactions of Fenoxaprop-ethyl with Bensulfuron and Bentazon in Dry-Seeded Rice (Oryza sativa)
Authors: Jordan David L.
Published: March 2018

Field experiments were conducted in 1993 and 1994 to evaluate barnyardgrass control with fenoxaprop-ethyl applied alone or in a mixture with bentazon or bensulfuron. Bensulfuron at 52 g ai/ha did not reduce barnyardgrass control with fenoxaprop-ethyl applied at rates of 56, 75, or 94 g ai/ha. In contrast, mixing bentazon at 1.1 kg ae/ha with fenoxaprop-ethyl reduced barnyardgrass control and rice yield compared with fenoxaprop-ethyl applied alone or mixed with bensulfuron.
Weed Management in Peanut (Arachis hypogaea) with Imazethapyr and Metolachlor
Authors: Richburg John S. , Wilcut John W. , Eastin E. Ford
Published: March 2018

Field studies at three sites in Georgia evaluated broadleaf weed and nutsedge management in peanut with PPI applications of imazethapyr and metolachlor and POST applications of paraquat in mixture with imazethapyr or bentazon. Imazethapyr at 36 g ai/ha applied PPI alone or in mixture with metolachlor at 2750 g ai/ha controlled coffee senna; entireleaf, ivyleaf, pitted, smallflower, and tall morningglories; bristly starbur; and prickly sida better than metolachlor applied PPI. Yellow nutsedge control was generally higher where metolachlor was applied PPI. Postemergence control of the aforementioned species and sicklepod was similar with paraquat plus imazethapyr and paraquat plus bentazon. Peanut yields with paraquat plus imazethapyr and paraquat plus bentazon were similar. With one exception, peanut yields from imazethapyr PPI systems were higher than metolachlor PPI systems when POST herbicides were not used. Inclusion of metolachlor with PPI application of imazethapyr increased yields only at one location.
Comparison of Imazethapyr and Paraquat-Based Weed Control Systems in Peanut (Arachis hypogaea)
Authors: Grey Timothy L. , Wehtje Glenn R. , Walker Robert H. , Paudel Krishna P.
Published: March 2018

Field studies were conducted from 1991 through 1993 to compare Weed control, peanut tolerance, yield, and net return from imazethapyr applied alone or in combination with paraquat. Sicklepod and Florida beggarweed were controlled with paraquat early POST followed by a POST application of either paraquat with 2,4-DB or paraquat with 2,4-DB and bentazon. Imazethapyr-based early POST treatments offered no improvement. An early POST application of paraquat with bentazon or imazethapyr was required for maximum control of bristly starbur. Imazethapyr applied alone early POST, with no further treatment, provided optimum yellow nutsedge control. Maximum yield and net return were associated with any paraquat-containing early POST-applied treatment followed by one of the tank mixed POST options.
Comparison of Postemergence Herbicides for Common Bermudagrass (Cynodon dactylon) Control in Peanut (Arachis hypogaea)
Authors: Grichar W. James
Published: March 2018

Field experiments conducted from 1990 through 1993 evaluated single and sequential applications of various postemergence graminicides for common bermudagrass control in peanut. UBI-1956 at 70 and 100 g/ha applied early POST (EP) or sequentially, controlled common bermudagrass equivalent to fluazifop-P applied EP or sequentially. Clethodim provided variable common bermudagrass control. Clethodim applied EP provided better control than sethoxydim while control from sequential clethodim applications were equivalent to fluazifop-P. Fenoxaprop-ethyl alone failed to control common bermudagrass while the addition of fluazifop-P to fenoxaprop-ethyl improved control at least 22% in two of three years. Quizalofop applied EP and fenoxaprop applied sequentially provided common bermudagrass control equivalent to fluazifop-P. Fenoxaprop-ethyl or sethoxydim applied once or twice controlled common bermudagrass similarly. Peanut yield increases from common bermudagrass control were erratic.
Influence of Capsule Age on Germination of Nondormant Jimsonweed (Datura stramonium) Seed
Authors: Pawlak John A. , Murray Don S. , Smith Brenda S.
Published: March 2018

Seed capsules of field-grown jimsonweed were harvested 2, 4, 6, and 10 weeks after anthesis. Degree day accumulation from anthesis and weeks after anthesis were equal in predicting the time required for nondormant jimsonweed seed production and seed dry weight. Seed germination increased as capsule age increased from 2 to 6 weeks. No additional increase in germination was observed in seed from capsules collected 10 weeks after anthesis. Maximum seed weight was obtained from capsules 6 and 10 weeks old in 1986 and 1987, respectively. Germination was correlated highly with seed weight.
Distance-of-Influence of Devil's-Claw (Proboscidea louisianica) on Cotton (Gossypium hirsutum)
Authors: Mercer Kay L. , Pawlak John A. , Murray Don S. , Verhalen Laval M. , Riffle Michael S. , McNew Ronald W.
Published: March 2018

The distance-of-influence of an individual devil's-claw plant to cotton leaf, stem, boll (reproductive parts), and combined aboveground plant parts was determined in two field experiments. The distance-of-influence could not be detected for the first 6 weeks after emergence; by 9 to 12 weeks, it extended up to 25 cm or more; and by the end of the season, up to 50 cm on each side of the weed. Cotton leaf and stem weights were less sensitive than cotton boll weights for measuring distance-of-influence from devil's-claw. At maturity, cotton boll weight was reduced 62 and 51% in 1983 and 45 and 29% in 1984 for sampling intervals of 0 to 25 and 25 to 50 cm, respectively. Interference from cotton reduced devil's-claw stem weight, seed capsule weight, and whole plant biomass by 6 weeks after emergence and reduced leaf biomass by 9 weeks in 1983. All except stem biomass were affected in 1984. Distance-of-influence and weed-density interference studies predicted lint yield loss similarly.
Response of Seed of 10 Weed Species to Fresnel-lens-concentrated Solar Radiation
Authors: Johnson David W. , Krall James M. , Delaney Ronald H. , Thiel David S.
Published: March 2018

A curved-linear Fresnel lens was investigated to test the effect of concentrated solar radiation on surface and buried weed seed. The lens produced a line focus 1 by 150 cm with a mean temperature of 309 C. A 20-s exposure to seed on the soil surface was 100% lethal to green foxtail, kochia, common lambsquarters, common purslane, and wild buckwheat. In a separate study, emergence from kochia and yellow foxtail seed was reduced 100% at 10 mm soil depth after 15 min in soil of 35 and 93 g/kg moisture and 20 to 40% at 178 g/kg moisture content. Concentrated solar radiation from a Fresnel lens has the greatest potential for affecting weed seed on the soil surface. A series of Fresnel lenses and/or larger lenses may be required for many practical field applications.
Effect of Postharvest Field Burning on Jointed Goatgrass (Aegilops cylindrica) Germination
Authors: Young Frank L. , Ogg Alex G. , Dotray Peter A.
Published: March 2018

In a kiln experiment, temperatures of 200 to 400 C for 120 sec reduced germination of jointed goatgrass seeds 50 to 100%. Postharvest field burning of wheat and jointed goatgrass stubble destroyed 43 to 64% of the jointed goatgrass spikelets located on the soil surface. Seeds contained in spikelets that were minimally burned (slightly browned) germinated 32 to 65%, while seeds contained in spikelets moderately (less than 50% charred) and severely burned (greater than 50% charred) germinated 5 and 0%, respectively. Field burning destroyed 90% or more of jointed goatgrass seeds in spikelets located on the soil surface. Burning may be a feasible method for controlling small infestations of this weed.
Identification of Sulfonylurea Herbicide-Resistant Prickly Lettuce (Lactuca serriola)
Authors: Mallory-Smith Carol A. , Thill Donald C. , Dial Michael J.
Published: March 2018

A naturally occurring prickly lettuce biotype resistant to a 5:1 formulated mixture of chlorsulfuron:metsulfuron (DPX-G8311) was identified in a no-till winter wheat field near Lewiston, ID, in April, 1987. Field and greenhouse studies were established to evaluate its resistance to other sulfonylureas, imidazolinones, and herbicides with alternate sites of action. The resistant biotype resisted eight sulfonylurea herbicides; resisted the imidazolinone herbicides, imazapyr and imazethypyr, but not imazaquin; and resisted no other herbicides included in the studies. The resistant biotype was identified in seven of nine fields on the farm where it was discovered.
Appearance and Spread of Triazine Resistance in Common Lambsquarters (Chenopodium album)
Authors: Darmency Henri , Gasquez Jacques
Published: March 2018

The first step in appearance of herbicide-resistant weed populations is the appearance of resistant plants or mutants. While efforts are underway to study and predict the spread of resistant plants within weed populations, knowledge of the conditions prevailing at the time of appearance of the first resistant plants is misunderstood. We try to shed some light on this phenomenon using the example of atrazine-resistant common lambsquarters. The population structure and variability, the presence of unusual genotypes that have a high mutation rate, the occurrence of a low-dose resistant phenotype that is the precursor of a high-dose resistant phenotype, and the potential for multiplication and spread are shown to be of major importance in the behavior of herbicide resistance.
Future Outlook for Herbicide-Resistance Research
Authors: Roush Mary Lynn , Radosevich Steven R. , Maxwell Bruce D.
Published: March 2018

Management of herbicide resistance will require interdisciplinary research to understand the mechanisms and dynamics of resistance. We believe that models are valuable tools. Models propose hypotheses about biological processes that influence the evolution of resistance and management tools that may reduce resistance in weed populations. Hypotheses help to direct research. For example, our model proposes that fitness and gene flow dramatically influence the evolution of and recovery from resistance in weed populations. Therefore, our research agenda should include ecological investigations of the life-history traits involved in fitness and gene flow. The model suggests thresholds of susceptible weed abundance to reduce selection pressure and to delay resistance. These thresholds will be related closely to economic weed thresholds. While the resistance issue emphasizes the need for basic biological and ecological research, resistance is only a part of the broader research agenda, which calls for holistic and interdisciplinary approaches to understanding and managing crop systems.
Bouncingbet – The Soap Weed
Authors: Mitich Larry W.
Published: March 2018

Known for thousands of years to produce a cleansing soaplike lather when crushed in water, bouncing-bet (Saponaria officinalis L. ♯3 SAWOF) is as pretty as its name. Though it has followed man around the world, it has always been an invited guest–until the 1900s, when our changing viewpoint redefined this millennial source of soap, fragrance, and beauty as a weed.
Immunoassays to Detect and Quantitate Herbicides in the Environment
Authors: Hall J. Christopher , Deschamps Raymond J. A. , McDermott Mark R.
Published: March 2018

Immunochemical techniques offer many advantages over chromatographic methods used for pesticide trace analysis of substrates such as soil, water, plants, urine, and blood. These advantages include speed of processing samples, high specificity for detecting a pesticide, reduced amount of preparation and cleanup of the sample before analysis, and a dramatic increase in the number of samples that can be analyzed. Immunoassays are based on the principle that antibodies to pesticides can be prepared, in animals, that can recognize and attach with exquisite specificity to certain chemical configurations displayed on the surface of a molecule. Small molecules such as herbicides usually are not immunogenic but can be made so by chemically bonding them to a large immunogenic protein such as bovine serum albumin before injection into an animal. Development of herbicide-specific antibodies and their use in direct and indirect enzyme-linked immunosorbent assays (EIA or ELISA) as well as radioimmunoassays (RIA) are discussed. The principles behind monoclonal antibody production are outlined, and immunoassays using polyclonal and monoclonal antibodies are compared. Specific reference is made to the development and use of indirect ELISA and RIA procedures for trace analysis of 2,4-D and picloram.
Ropewick Application of Picloram for Leafy Spurge (Euphorbia esula) Control
Authors: Moomaw Russell S. , Martin Alex R.
Published: March 2018

Picloram was applied to leafy spurge using flexible and rigid ropewick applicators for 3 yr at each of two upland pasture sites. The ropewick applicators were a cost-effective way to apply picloram to control leafy spurge compared to broadcast application, but minimal advantage was demonstrated for the segmented, flexible unit compared to the rigid applicator. Picloram applied as an 80 g ae/L solution through ropewick applicators controlled leafy spurge equal to broadcast picloram at 1.1 kg/ha while using 36% as much picloram.
Postemergence Weed Management Systems for Peanuts (Arachis hypogaea)
Authors: Wilcut John W. , Wehtje Glenn R. , Hicks T. Vint , Cole Tracy A.
Published: March 2018

Field studies were conducted from 1985 to 1987 to evaluate postemergence herbicide systems with preemergence systems to control Texas panicum, Florida beggarweed, sicklepod, and pitted morningglory in peanuts. Adding paraquat at 0.14 kg ai/ha to postemergence herbicide systems reduced fresh weight of Florida beggarweed 92% (18% increase over the same systems without paraquat), sicklepod 95% (21% increase), and pitted morningglory 95% (11% increase). Herbicide systems containing paraquat improved peanut yields by 230 kg/ha and net returns by $52/ha over herbicide systems not containing paraquat. Fluazifop-P and sethoxydim systems reduced Texas panicum fresh weight (at least 96%) more than a preemergence system (92% reduction) that used benefin applied preplant incorporated and alachlor plus naptalam and dinoseb applied at cracking (GC) or a postemergence system that used alachlor and naptalam plus dinoseb GC and paraquat applied early postemergence (86% reduction). Systems containing fluazifop-P provided greater yields (4190 kg/ha) and net returns ($383/ha) than systems containing sethoxydim (4010 kg/ha, $305/ha) when averaged across all rates of application.
Factors Influencing Fenoxaprop Efficacy in Cool-Season Turfgrass
Authors: Neal Joseph C. , Bhowmik Prasanta C. , Senesac Andrew F.
Published: March 2018

Experiments were conducted in Massachusetts and New York to evaluate the potential influence of plant growth stage, spray volume, nozzle type, additional surfactant, and herbicide formulation on smooth and large crabgrass control in turf with fenoxaprop. At a well-watered site, crabgrass control with fenoxaprop was equal to or greater than with MSMA. On an irrigated, fertilized site, crabgrass growth stage did not influence fenoxaprop efficacy. Excellent control of up to 5-tiller smooth crabgrass was obtained with 0.20 kg/ha of fenoxaprop. On nonirrigated turf, fenoxaprop was less effective on tillered crabgrass than on 2- to 5-leaf weeds. Under very dry conditions, fenoxaprop was ineffective regardless of growth stage. Control with MSMA was less affected by drought than was fenoxaprop. Spray volumes, between 140 and 1120 L/ha, did not affect fenoxaprop efficacy; however, high volume applications (1120 L/ha) with floodjet nozzles were less effective than flat fan nozzle treatments in two of three tests. Added surfactant did not improve efficacy except with floodjet nozzles on a droughty site. No differences were observed between the water-based and the emulsifiable concentrate formulations of fenoxaprop. Fenoxaprop caused temporary phytotoxicity (≤20% reduction in turf quality) to established Kentucky bluegrass and perennial ryegrass.