bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Fertilizer, Oil, and Surfactant Adjuvants with Nicosulfuron
Authors: Nalewaja John D. , Praczyk Tadeusz , Matysiak Robert
Published: March 2018

Urea and ammonium nitrate are components of 28% nitrogen liquid fertilizer (UAN) that is often used as an adjuvant in addition to surfactants or oils with herbicides. Ammonium nitrate and/or UAN fertilizer enhancement of nicosulfuron phytotoxicity to large crabgrass or yellow foxtail depended upon the associated oil or surfactant adjuvant. Ammonium nitrate reduced the effectiveness of most block copolymers but not other surfactants with nicosulfuron for large crabgrass. Urea never enhanced and often reduced surfactant and oil adjuvant enhancement of nicosulfuron. Ammonium nitrate or UAN, but not urea, enhanced nicosulfuron phytotoxicity to yellow foxtail when the spray carrier contained sodium bicarbonate. These research results indicated that enhancement of nicosulfuron efficacy from UAN is mainly from the ammonium nitrate component. However, the benefit to nicosulfuron from UAN or ammonium nitrate depended upon the associated surfactant or oil adjuvants.
Postemergence Control of Foxtail Barley (Hordeum jubatum) Seedlings in Spring Wheat (Triticum aestivum) and Flax (Linum usitatissimum)
Authors: Blackshaw Robert E. , Semach Greg , Entz Toby
Published: March 2018

Field experiments were conducted to identify herbicides for selectively controlling foxtail barley seedlings in spring wheat and flax. ICIA0604, fenoxaprop-P/safener, CGA184927/safener, metribuzin, and MON37500 in wheat and sethoxydim, clethodim, quizalofop, fluazifop-P, and the mixture of fluazifop-P/fenoxaprop-P in flax were applied at the three- to four-leaf and one- to three-tiller stages of foxtail barley. MON37500 was the only herbicide tested in wheat that provided excellent control of foxtail barley and a high degree of crop tolerance. MON37500 at 13 to 19 g/ha applied at the early growth stage controlled foxtail barley but rates of 25 to 30 g/ha were needed at the later growth stage. In flax, quizalofop was the most efficacious herbicide on foxtail barley. Sethoxydim and clethodim sometimes provided weed control similar to that of quizalofop when applied at the three- to four-leaf stage, but quizalofop was always more effective at the one- to three-tiller stage of foxtail barley. Wheat and flax yields were greater when effective herbicides were applied at the early than at the late stage, indicating the need for early control of foxtail barley to minimize weed competition. MON37500 in wheat and quizalofop in flax provide growers with highly efficacious herbicide options for in-crop control of foxtail barley in conservation tillage systems.
Managing Melaleuca (Melaleuca quinquenervia) in the Everglades
Authors: Laroche François B.
Published: March 2018

Until recently melaleuca was spreading at a rate faster than it was being controlled throughout the boundaries of the South Florida Water Management District (District). Although melaleuca is a difficult species to eradicate, apparently District efforts, along with those of other governmental agencies and private groups, are containing its spread within the Everglades Water Conservation Areas (WCAs) and the marsh of Lake Okeechobee. Melaleuca has been completely cleared from WCA-2A, -3B, and -3A, south of Alligator Alley. These areas are now under “maintenance control.” Maintenance control means applying management techniques in a continuous basis to keep an invasive plant population at its lowest feasible level. Today, the melaleuca infestation is no longer increasing; in many areas, it is being reduced. Preliminary results from the latest District survey indicate melaleuca infestation has decreased considerably in South Florida, especially in public lands. The intent of this paper is to provide an assessment of progress made by the District's melaleuca control program over the past 7 yr.
Invasion of Tropical Soda Apple (Solanum viarum) into the U.S.: Lessons Learned
Authors: Mullahey J. Jeffrey , Shilling Donn G. , Mislevy P. , Akanda R. A.
Published: March 2018

Tropical soda apple (SOLVI) is an introduced, perennial broadleaf plant that has invaded Florida agricultural land and natural ecosystems and has spread to other states (Georgia, Alabama, South Carolina, Louisiana, North Carolina, Tennessee, and Pennsylvania). Tropical soda apple was first collected in Florida in 1988. In 1990, SOLVI-infested land was approximately 10,000 ha, in 1993, 162,000 ha, and in 1995, approximately 0.5 million ha were reported infested in Florida. Rapid spread of this invasive plant has occurred from seeds transported in cattle, hay, sod, grass seeds, water, and wildlife (deer, feral hogs, birds). Animals will not eat the foliage but will consume the fruits and spread the seeds in their feces. This exotic weed is an indeterminate plant with seed production averaging 50,000/plant/yr, seed germination of 70–90%, and seed longevity in soil of up to 1 yr. Integrated weed management strategies include prevention (avoidance of contaminated hay or grass seed, control of movement of cattle), control (mechanical, chemical), and monitoring. Seed production must be prevented and landowners should adopt a zero tolerance toward SOLVI. During the time (1990–1995) research (biology, ecology, control) was being conducted to control SOLVI from Florida, this weed had infested the entire state and escaped into other states. Risk assessment criteria for new plant introductions must be developed and implemented to prevent future biological pollution.
Bull Thistle,Cirsium vulgare
Authors: Mitich Larry W.
Published: March 2018

The rough burn-thistle spreading wide

Amang the bearded ear—

I turned the weeding heuk aside

An’ spared the emblem dear!

(Robert Burns [1759–1796], Scottish poet)
“Our” Weed Science Society of America: In Transition
Authors: Messersmith Calvin G.
Published: March 2018

Dr. Calvin G. Messersmith is Professor of Plant Sciences at North Dakota State University (NDSU), where he has been involved in teaching and research since 1966. He developed the undergraduate weed science option, the introductory weed science course, and the internship program for crop and weed science majors at NDSU. Dr. Messersmith introduced many teaching innovations into his undergraduate courses, including development of autotutorial laboratories, lecture and laboratory manuals, permanent plant mounts embedded in plastic resin, and educational films. Dr. Messersmith serves as coordinator of the departmental undergraduate teaching program, advisor for about 20 undergraduate students annually and assists in career placement. Dr. Messersmith has served as major professor for seven Ph.D. and eight M.S. graduates.

Dr. Messersmith has specialized in perennial weed control, especially leafy spurge. He is coordinator of a multidisciplinary leafy spurge control project at NDSU that includes biological, chemical, cultural, and physical control. The project includes cooperating scientists from the Departments of Agricultural Economics, Animal and Range Sciences, Botany, Plant Sciences, Entomology, and Plant Pathology.

Dr. Messersmith served the North Central Weed Science Society (NCWSS) as Editor of the Research Reports for 8 yr and was on the board of directors for about 16 yr, including 1 yr as President in 1985. Prior to becoming the WSSA Vice President in 1995, he served on the WSSA board of directors for 3 yr and was the first Editor who designed and launched Weed Technology from 1985 to 1990. Dr. Messersmith has been honored as an NCWSS Honorary Member and WSSA Fellow.

Dr. Messersmith received his B.S. and M.S. degrees from the University of Nebraska and his Ph.D. degree from NDSU. He has received several awards for contributions to education, including the American Society of Agronomy CIBA-Geigy Award, the first NDSU-wide Odney Award for Excellence in Teaching, the FarmHouse Fraternity Master Builder of Men Award, the WSSA Outstanding Teacher Award, the Burlington Northern Foundation Faculty Achievement Award at NDSU, and the NACTA (National Association of Colleges and Teachers of Agriculture) Teaching Award of Merit.
Effect of MON 12037 on the Growth and Tuber Viability of Purple Nutsedge (Cyperus rotundus)
Authors: Molin William T. , Maricic Alison A. , Khan Rehana A. , Mancino Charles F.
Published: March 2018

A field study was conducted in 1994 and 1995 to determine the efficacy of MON 12037 on purple nutsedge in a bermudagrass turf. The percentage of bermudagrass infested with purple nutsedge following a single application of MON 12037 decreased from 60 to 30% at 18 g ai/ha and to approximately 20% at 36, 54, and 72 g/ha. Regrowth of purple nutsedge occurred between 28 and 55 d after treatment (DAT) and was greatest at 18 g/ha. A second application of MON 12037 reduced purple nutsedge percent infestation similarly to one application. Tuber weight and number were not affected by either one or two applications of MON 12037; however, tuber viability decreased after two applications. These results suggest that when using MON 12037, a program of several years duration may be required to successfully manage purple nutsedge in a bermudagrass turf because viable tubers persist following two applications of MON 12037 in a season.
Limiting Green and Yellow Foxtail (Setaria viridisandS. glauca) Seed Production Following Spring Wheat (Triticum aestivum) Harvest
Authors: Kegode George O. , Forcella Frank , Durgan Beverly R.
Published: March 2018

Green and yellow foxtail seed production following harvest of spring wheat is a concern of producers in the northern Great Plains of the United States and the Prairie Provinces of Canada. Experiments were conducted in 1996 and 1997 in three tillage systems, no till (NT), chisel plow (CP), and moldboard plow (MP), at the University of Minnesota West Central Experiment Station, Morris, MN, to determine whether time of glyphosate application or tillage after spring wheat harvest could reduce postharvest foxtail seed production. In both years, hard red spring wheat was planted in late April and a packaged mixture of fenoxaprop and 2,4-D ester and MCPA ester was applied at a rate of 53 g and 81 g and 246 g ai/ha for grass and broadleaf weed control. Following spring wheat harvest, each main plot was subdivided into seven subplots, including an untreated control. One subplot was disked twice at 4 to 6 d after harvest (DAH) of spring wheat, and five other subplots had glyphosate (0.25 kg ai/ ha) applied on different days (1 to 31 DAH). Foxtail seeds were collected from the soil surface following first frost, and the number of green and yellow foxtail seeds were determined. Tillage immediately after spring wheat harvest eliminated foxtail plants, and no new foxtail seedlings emerged in either tilled or glyphosate-treated plots despite ideal postharvest conditions for foxtail germination and emergence in 1997. Most viable green foxtail seeds were consistently obtained in NT plots, whereas yellow foxtail seed production varied among tillage systems. Either tillage soon after spring wheat harvest or glyphosate application within 16 DAH reduced green and yellow foxtail seed production by greater than 70%.
SAN 582 Efficacy and Tolerance in Potato (Solanum tuberosum)
Authors: Tonks Dennis J. , Eberlein Charlotte V. , Guttieri Mary J. , Brinkman Bart A.
Published: March 2018

Field studies were conducted to examine weed control efficacy and crop injury with SAN 582 (proposed name, dimethenamid) in irrigated ‘Russet Burbank’ potato. SAN 582 applied preemergence (PRE) at 1.1 to 1.7 kg ai/ha controlled light to moderate infestations of redroot pigweed, common lambsquarters, and hairy nightshade > 90%. Season-long control of these species with mixtures of SAN 582 plus metribuzin or rimsulfuron was > 98% and was similar to or better than registered mixtures. Green foxtail control with SAN 582 alone ranged from 83 to 100%, depending on rate and year. SAN 582 mixtures with metribuzin or rimsulfuron usually controlled green foxtail > 90%. In weed-free plots, SAN 582 was applied alone PRE or early postemergence (EPOST) at rates up to 3.4 kg/ha. SAN 582 applied EPOST usually caused 10 to 30% more potato injury than when applied PRE, but U.S. No. 1 yield was not reduced by SAN 582 applied either PRE or EPOST. SAN 582 shows good potential for PRE use in irrigated potato.
Differential Control of Palmer Amaranth (Amaranthus palmeri) and Smooth Pigweed (Amaranthus hybridus) by Postemergence Herbicides in Soybean (Glycine max)
Authors: Gossett Billy J. , Toler Joe E.
Published: March 2018

Field studies were conducted in South Carolina to evaluate the herbicides acifluorfen, chlorimuron, and imazaquin for control of Palmer amaranth and smooth pigweed in soybean, when applied 3 wk after weed emergence. Palmer amaranth was more difficult to control than smooth pigweed. Compared to untreated controls, acifluorfen, chlorimuron, and imazaquin reduced Palmer amaranth and smooth pigweed biomass 78 and 96%, 80 and 98%, and 82 and 99% at 30 d after treatment (DAT), 60 DAT, and at soybean harvest, respectively. The high rate (140 g/ha) of imazaquin provided greater control of Palmer amaranth than other herbicide treatments at soybean harvest. Except for the 140 g/ha rate of imazaquin, inadequate control of Palmer amaranth resulted in lower soybean seed yields for all herbicide treatments than the weed-free control. However, all herbicides controlled smooth pigweed to provide soybean seed yields similar to the weed-free control.
Mature Goosegrass (Eleusine indica) Control in Bermudagrass (Cynodon dactylon) Turf with a Metribuzin–Diclofop Combination
Authors: Nishimoto Roy K. , Murdoch Charles L.
Published: March 2018

Field studies were conducted to determine if metribuzin–diclofop combinations could provide selective control of mature goosegrass in common bermudagrass turf. In two field trials, diclofop at 1.7 kg ai/ha provided 19% control of mature goosegrass at 7 wk after treatment (WAT), whereas metribuzin at 0.28 or 0.56 kg ai/ha controlled 30 and 53%, respectively. When diclofop at 1.7 kg/ha was combined with metribuzin at 0.28 or 0.56 kg/ha, goosegrass control increased to 68 and 90%, respectively. That degree of mature goosegrass control with a single application of metribuzin at 0.56 kg/ha plus diclofop at 1.7 kg/ha was equivalent to metribuzin at 0.56 kg/ha plus MSMA at 2.2 kg ae/ha followed by MSMA at 2.2 kg/ha 1 wk later. The metribuzin–diclofop combination injured common bermudagrass turf less than or equivalent to the metribuzin–MSMA combination. The injury was transitory; at 3 WAT, none of the treatments injured common bermudagrass.
Johnsongrass (Sorghum halepense) Control in Fallow Sugarcane (Saccharumspp. Hybrids) Fields
Authors: Richard Edward P.
Published: March 2018

Soil- and foliar-applied herbicide treatments were evaluated for the control of seedling johnsongrass in the interim between row formation and the planting of fallowed sugarcane fields approximately 90 d later. Soil-surface applications of metribuzin at 1,680 g ai/ha, pendimethalin plus atrazine each at 2,240 g ai/ha, terbacil at 1,680 g ai/ha, and sulfometuron at 35 and 70 g ai/ha and an incorporated application of trifluralin at 2,240 g ai/ha followed by a surface application of atrazine at 2,240 g/ha did not consistently control seedling johnsongrass until the crop was planted. Rhizome johnsongrass populations originating from seedling johnsongrass that escaped the fallow treatments were lowest in the newly planted crop when sulfometuron at 140 to 280 g/ha was applied to the soil surface and when glyphosate was applied POST at 2,240 g ai/ha, particularly as a sequential treatment alone or as a spot treatment at 2% by volume following applications of metribuzin, terbacil, and pendimethalin or trifluralin with atrazine. Sugarcane shoot populations in the fall after planting and sugar yields at the end of the crop's first growing season were highest where fallow treatments minimized johnsongrass development. These treatments also provided broad spectrum control of other seedling weeds, the residues of which influenced crop development.
Calibration of Greenhouse Spray Chambers—The Importance of Dynamic Nozzle Patternation
Authors: Wolf Thomas M. , Liu Shu Hua , Caldwell Brian C. , Hsiao Andrew I.
Published: March 2018

In an attempt to refine calibration procedures for greenhouse spray chambers, the effects of an herbicide adjuvant, operating pressure, and travel speed on the static and dynamic spray patterns of single flat-fan hydraulic nozzle tips were studied. The volume output in the central 15 cm of the spray pattern (where target plants would ordinarily be positioned) was used as an indicator of the relative dosages received from both a tapered flat-fan tip (8001 VS) and an even-spray tip (8001 EVS). All tested variables significantly altered the spray pattern. Specifically, dynamic spray patterns differed from static patterns, and speed of travel affected the dynamic pattern for both tapered and even flat-fan sprays. Increasing the travel speed from 0.375 to 0.75 m/s reduced spray deposit in the central 15 cm of the spray pattern by up to 19% for water, and by up to 34% for water containing 0.1% v/v nonionic surfactant. Increasing surfactant concentration to 1% decreased the magnitude of the speed effect. Higher pressure sprays tended to reduce the effect of increased travel speeds. These results show that changes in physicochemical properties of the spray solution as well as air turbulence introduced by nozzle movement can affect the pesticide dosage to which a target plant is exposed in a spray chamber. For proper treatment comparison, delivery systems for greenhouse spray experiments should be calibrated with end-use spray liquids, operating pressures, and nozzle travel speeds.
Common Bermudagrass (Cynodon dactylon) Management in Cool-Season Turfgrass
Authors: Cudney David W. , Elmore Clyde L. , Gibeault Victor A. , Reints John S.
Published: March 2018

Common bermudagrass is an invasive, perennial weed of cool-season turfgrass in California. Complete renovation of the infested area has been the only practical method of restoring desirable cool-season turfgrasses. In studies in southern and northern California, common bermudagrass was suppressed with sequential herbicide applications, allowing seedling establishment and regrowth of established cool-season turfgrass species. One application of fenoxaprop, triclopyr, or their combinations did not control common bermudagrass. Sequential applications of these herbicide treatments resulted in 99, 94, and 100% control of common bermudagrass, respectively, and resulted in establishment of seeded perennial ryegrass in Riverside, CA, over a 2-yr period. Similar results were obtained in the recovery of established tall fescue from a common bermudagrass/tall fescue turfgrass mixture in Willows, CA. Both fenoxaprop and triclopyr can reduce emergence and stunt seedling growth of perennial ryegrass and tall fescue. Greenhouse studies showed that stunting and stand loss of tall fescue and perennial ryegrass seedlings could be reduced by delaying applications from PRE to the two-leaf stage.
Glufosinate Efficacy on Annual Weeds Is Influenced by Rate and Growth Stage
Authors: Steckel Gregory J. , Wax Loyd M. , Simmons F. William , Phillips William H.
Published: March 2018

Field experiments were conducted in 1993, 1994, and 1995 to determine the effects of glufosinate rate and application timing on giant foxtail, common lambsquarters, common cocklebur, and Pennsylvania smartweed control in absence of a crop. Glufosinate at 140 g ai/ha controlled less than 80% of the weed species evaluated. When glufosinate rate was increased to 420 g/ha and applied to 10-cm giant foxtail, control was greater than 80% all 3 yr of the study. Applications made to 10-cm plants resulted in 80% or greater control for common cocklebur all 3 yr and Pennsylvania smartweed 2 of the 3 yr with 420 and 560 g/ha, respectively. Common lambsquarters was the most tolerant species evaluated and was not consistently controlled acceptably (> 80%), even with glufosinate at rates of 560 g/ha. Control with glufosinate at 420 or 560 g/ha was most effective when applied at the 10-cm weed height compared either to the 5- or 15-cm weed height.
Response of Triallate-Resistant and -Susceptible Wild Oat (Avena fatua) Populations to Difenzoquat and EPTC in a Seedling Bioassay
Authors: Rashid Abdur , O'Donovan John T. , Khan A. Aziz , Sharma M. Paul , Van Nguyen Hai
Published: March 2018

A seedling bioassay was used to determine the response of triallate-resistant (R) and -susceptible (S) wild oat populations to difenzoquat and EPTC. The bioassay, based on seedling shoot length at 10 d after treatment, provided a reliable and rapid means of determining if wild oat populations were resistant to difenzoquat. Using a bioassay concentration of 15 ppm difenzoquat, it was possible to identify populations that were resistant to the recommended foliar-applied rate (0.85 kg ai/ha). Expected herbicide dosages that reduced shoot length by 50% (ED50) derived from nonlinear regression analysis indicated three and two levels of response to difenzoquat among eight S and seven R populations, respectively, indicating within population variability in their response to difenzoquat. Of the populations tested, none was resistant to EPTC. On the contrary, some R populations had lower ED50values than did S populations, suggesting an increased sensitivity to EPTC.
Soil Temperature, Soil Moisture, Weed Control, and Tomato (Lycopersicon esculentum) Response to Mulching
Authors: Monks C. Dale , Monks David W. , Basden Tom , Selders Arthur , Poland Suzanne , Rayburn Edward
Published: March 2018

Shredded newspaper (2.5, 7.6, 12.7, and 17.8 cm depth), chopped newspaper (2.5 and 7.6 cm), wheat straw (15.2 cm), black plastic, and plastic landscape fabric were evaluated during 1993 and 1994 in West Virginia for their effect on soil temperature, soil moisture, weed control, and yield in tomato. Shredded newspaper and wheat straw applied at 0, 2, 4, or 6 weeks after transplanting (WAT) and napropamide (2.1 kg ai/ha) plus metribuzin (0.28 kg ai/ha) applied at transplanting were evaluated during 1992 and 1993 in North Carolina for effect on weed control and tomato yield. Results from West Virginia indicated that shredded (7.6 cm) and chopped (7.6 cm) newspaper conserved moisture similar to higher application rates of the shredded material. Higher newspaper mulching rates reduced soil temperature compared to black plastic and bare ground. Chopped newspaper controlled weeds more consistently than other treatments. At least 7.6 cm of chopped newspaper mulch was required to control weeds at least 90%. Wheat straw was not as effective in controlling weeds as 7.6 cm or greater of newspaper mulch. Chopped newspaper provided higher tomato yields than shredded newspaper applied at the same rates. Mulches applied at 0, 2, or 4 WAT resulted in weed control similar to the chemical treatment. In North Carolina, mulches applied 2 or 4 WAT resulted in tomato yields similar to the chemical treatment. Shredded and chopped newspaper have potential as a mulching material but may vary in effect in different environments and vegetable crops.
Weed Management in No-Till Cotton (Gossypium hirsutum) with Thiazopyr
Authors: Batts Roger B. , York Alan C.
Published: March 2018

Thiazopyr at 0.14, 0.28, and 0.42 kg ai/ha and pendimethalin at 1.1 kg ai/ha applied preemergence (PRE) were compared as components in weed management systems for no-till cotton. Mid- and late-season control of mixtures of large crabgrass, goosegrass, and fall panicum by thiazopyr at 0.28 kg/ha was 89 to 97% and 11 to 50%, respectively, compared with 11 to 38% midseason and 0 to 5% late-season control by pendimethalin. Thiazopyr at 0.42 kg/ha and pendimethalin controlled broadleaf signalgrass 44 and 0%, respectively, late in the season. Adding fluometuron PRE at 1.7 kg ai/ha had little to no effect on large crabgrass, goosegrass, and fall panicum control but increased broadleaf signalgrass control 47 to 79 percentage points compared with thiazopyr or pendimethalin alone. Late-season control of annual grasses by thiazopyr or pendimethalin plus fluometuron PRE followed by methazole plus MSMA early postemergence (POST)-directed and cyanazine plus MSMA late POST-directed was at least 95% at two locations and 80% at the third location. Common lambsquarters was controlled 54 and 95% in systems without and with fluometuron PRE, respectively. Acceptable control of ivyleaf, pitted, and tall morningglories at all locations and smooth pigweed at two of three locations was achieved only in systems with POST-directed herbicides. Adding POST-directed herbicides to systems with thiazopyr or pendimethalin plus fluometuron PRE increased cotton yield at two of three locations. Treatments had no effect on fiber quality.
English Daisy (Bellis perennis L.)
Authors: Mitich Larry W.
Published: March 2018

The English daisy, Bellis perennis L., is a widespread lawn weed and a bane to those who favor daisy-free lawns and golf courses. The genetic name Bellis, a designation used by Pliny, means “pretty”; perennis means “through the years,” “continuing,” or “perennial” (Gledhill 1985; Mabberley 1989). While pretty, the English daisy is a persistent weed that spreads by short stolons (Tutin et al. 1976). It is a member of the cosmopolitan family Compositae, which encompasses 1,100 genera and 25,000 species (Heywood 1993). The genus Bellis comprises about 15 European and Mediterranean species. Some of them are medicinal and some are cultivated ornamentals, especially forms of B. perennis. The signature of this species is a flower head that Closes at night and in wet weather (Tutin et al. 1976).
Uncertainties About Crop Protection
Authors: Abelson Philip H.
Published: March 2018

My remarks today will be largely devoted to assessing some of the effects of the Food Quality Protection Act of 1996. As introduced, the act had wide support among grower groups, the food industry, and the pesticide industry. Voting on the bill was unanimous in both House and Senate, and action was completed in 1 wk. The legislation was signed by the President on August 3, 1996. President Clinton wanted to be seen as a strong advocate of children's health. The Republican Congress wanted to show that it was pro-environment.
A New Soil Sampler and Elutriator for Collecting and Extracting Weed Seeds from Soil
Authors: Wiles Lori J. , Barlin Douglass H. , Schweizer Edward E. , Duke Harold R. , Whitt Douglas E.
Published: March 2018

A soil sampler, elutriator, and associated sample flushing device were designed and constructed for an intensive study of weed seedbanks. This equipment was used in 1993 to collect and process 4980 soil samples. The sampler was durable, core size was consistent, and sampling was efficient. Cores were approximately 200 cm3and two people could take 120 cores/h. The elutriator separated weed seeds from 36 of these cores at a time. Washing required 60 to 75 min depending on soil texture. Seeds as small as 0.3 mm in diam were recovered and almost 100% of the seeds were recovered from samples spiked with barnyardgrass, redroot pigweed, velvetleaf, and witchgrass. The flushing device was used to transfer sample contents from strainers of the elutriator to propyltex bags for drying and storing. Equipment like this, plus improved technology for identifying and counting seeds, is needed to make weed seedbank studies more feasible.
Similar Fitness Between Large Crabgrass (Digitaria sanguinalis) Accessions Resistant or Susceptible to Acetyl-Coenzyme A Carboxylase Inhibitors
Authors: Wiederholt Ronald J. , Stoltenberg David E.
Published: March 2018

Experiments were conducted to determine the productivity and the competitive ability of a large crabgrass accession (PW2) resistant to acetyl-coenzyme A carboxylase (ACCase) inhibitors relative to a susceptible accession (A310). Under noncompetitive conditions in the field, shoot dry biomass and plant height over time were similar for the two accessions. Leaf area was slightly greater for A310 than for PW2. The instantaneous relative growth rate was similar for the accessions. The instantaneous net assimilation rate was slightly greater for A310 than for PW2; however, the instantaneous leaf area ratio was slightly greater for PW2 than for A310. At maturity, the seed yield was similar for the accessions. The inter-accession competitive ability of PW2 and A310 plants in the field was similar, based on shoot dry biomass or seed yield. In the greenhouse, interspecific competitive ability of the accessions with corn was similar, based on shoot dry biomass or seed yield. These results suggest that resistance to ACCase inhibitors is not associated with reduced fitness of the PW2 accession.
Influence of Herbicides and Tillage on Weed Control, Yield, and Quality of Cabbage (Brassica oleraceaL. var. capitata)
Authors: Hoyt Greg D. , Bonanno A. Richard , Parker Glenn C.
Published: March 2018

Transplanted cabbage was grown in conventional-tillage (100% cultivated) and strip-tillage (25% cultivated and 75% residue) production systems with various herbicide treatments to evaluate weed control and cabbage yield. DCPA at 9 kg ai/ha, napropamide at 1.1 kg ai/ha, oxyfluorfen at 0.3 kg ai/ha, and oxyfluorfen at 0.2 kg ai/ha plus napropamide at 1.1 kg ai/ha provided commercially acceptable (> 80%) control of carpetweed, swinecress, large crabgrass, redroot pigweed, and common lambsquarters under both tillage systems. However, only oxyfluorfen plus napropamide provided control of eclipta. At a second location, all herbicides controlled common purslane and barnyardgrass and all but DCPA controlled hairy galinsoga. Overall, cabbage yields were the same between conventional and strip-tillage systems, and among herbicide treatments when average cabbage head weights across tillage method were pooled.
Grass Herbicide Efficacy as Influenced by Adjuvant, Spray Solution pH, and Ultraviolet Light
Authors: McMullan Patrick M.
Published: March 2018

Research was conducted at the Brandon Research Centre to determine the effect of spray solution pH or adjuvants on the efficacy of two cyclohexanedione (CHD) herbicides, clethodim and tralkoxydim, and two aryloxyphenoxypropionate (APP) herbicides, fenoxaprop-P and quizalofop, and if ultraviolet light is a factor influencing their activity. CHD herbicide efficacy decreased as spray solution pH increased above 7. APP herbicide efficacy was not affected by spray solution pH, probably due to their formulation as proherbicide esters. The choice of adjuvant affected CHD herbicide efficacy but not APP herbicide efficacy. Amigo®, Canplus-411® plus ammonium sulfate, and Merge® were usually the most effective adjuvants with the two CHD herbicides. Physical removal of ultraviolet light did not improve APP herbicide efficacy but did improve CHD herbicide efficacy.
Sugarcane (Saccharumspp. hybrids) Tolerance to Clomazone
Authors: Richard Edward P.
Published: March 2018

Field studies were conducted over four years to determine sugarcane response to clomazone applied POST at 1.1 and 2.2 kg ai/ha. Sugarcane leaves present when clomazone was applied were chlorotic 2 WAT. Injury 4 WAT ranged from 0 to 38% following single applications in March and April. Chlorosis 4 wk after the May application of a March plus May sequential treatment was only greater than for the single March application in 1992. The number of harvestable sugarcane stalks following treatments with clomazone was intermediate between those produced with standard applications of either metribuzin at 2.6 kg ai/ha (least injurious) or terbacil as a single treatment at 1.8 kg ai/ha in March and April or as a 1.8 plus 0.9 kg/ha March plus May sequential treatment. Sugar recovery as an average of all herbicide treatments was lower for the sequential applications than for the single applications. Averaged over single and sequential treatments, theoretically recoverable sugar levels with clomazone at both rates was intermediate between the recoveries obtained with standard applications of metribuzin (highest) and terbacil. Gross cane and sugar yields following all applications of clomazone at 1.1 kg/ha and following single applications of clomazone at 2.2 kg/ha in March and April were similar to the metribuzin standard. Sugar yields following the sequential treatment of clomazone at 2.2 kg/ha, although lower than the metribuzin standard, were similar to the standard terbacil sequential treatment.
Velvetleaf (Abutilon theophrasti) and Sugarbeet (Beta vulgaris) Response to Triflusulfuron and Desmedipham Plus Phenmedipham
Authors: Starke Robert J. , Renner Karen A.
Published: March 2018

Velvetleaf control and sugarbeet response to POST triflusulfuron applied alone and in combination with desmedipham plus phenmedipham, nonionic surfactant, and urea ammonium nitrate (50:50) were evaluated in the greenhouse (velvetleaf only) and field. In a second field study, the effect of POST applications of triflusulfuron, desmedipham plus phenmedipham, ethofumesate, endothall, or combinations of these herbicides on sugarbeet root yield and quality was determined in the absence of weeds. Triflusulfuron controlled velvetleaf only when nonionic surfactant (NIS) was added to the spray solution. Desmedipham plus phenmedipham plus triflusulfuron gave greater velvetleaf control than triflusulfuron in the absence of NIS in the field. However, adding desmedipham plus phenmedipham to triflusulfuron plus NIS decreased velvetleaf control in the greenhouse. Adding desmedipham plus phenmedipham to triflusulfuron plus NIS increased visible sugarbeet response compared to triflusulfuron plus nonionic surfactant or desmedipham plus phenmedipham 14 d after the last POST application in 1994. In the absence of weeds, POST herbicide applications that included triflusulfuron did not reduce sugarbeet root yield more than other POST herbicides.
Weed Management in Southeastern Peanut (Arachis hypogaea) with AC 263,222
Authors: Richburg John S. , Wilcut John W. , Colvin Daniel L. , Wiley Gerald R.
Published: March 2018

Field experiments conducted at four locations in Georgia and two locations in Florida during 1992 and 1993 evaluated AC 263,222 application rates and timings, systems, and mixtures for weed control, peanut injury, and yield. All rates of AC 263,222 applied early POST (EPOST) or POST controlledIpomoeamorningglories and smallflower morningglory at least 90%, and purple and yellow nutsedge at least 81%. Florida beggarweed and sicklepod control generally was highest when metolachlor was applied PPI followed by AC 263,222 applied EPOST at 71 g/ha, AC 263,222 at 27 or 36 g/ha plus bentazon plus paraquat applied POST, or with bentazon plus paraquat applied EPOST followed by AC 263,222 applied POST at 36 or 53 g/ha. Acifluorfen and acifluorfen plus bentazon reduced Florida beggarweed and sicklepod control at several locations when applied in mixture with AC 263,222. Common ragweed and hairy indigo control were 85 to 95% with bentazon plus paraquat applied EPOST followed by AC 263,222 applied POST at 36 or 53 g/ha. Highest peanut yields were obtained with treatments providing high levels of weed control.
A Review of Field Lysimeter Studies to Describe the Environmental Fate of Pesticides
Authors: Winton Kim , Weber Jerome B.
Published: March 2018

A brief review is presented for the use of soil lysimeters in studying transpiration, evapotranspiration, moisture, and nutrient movement in earlier times and pesticide dissipation and movement, and mass-balance of pesticide dissipation in more recent times. The important factors needed to understand research findings and to model pesticide dissipation such as key soil and site characteristics, climatic conditions, and the methods involved are discussed. Several case studies carried out by Ciba and North Carolina State University are discussed and current developments in soil column field lysimeters are presented.
Grazing Animals as Weed Control Agents
Authors: Popay Ian , Field Roger
Published: March 2018

Literature on the effectiveness of grazing animals (especially cattle, goats, and sheep) in controlling weeds is reviewed. Availability of animals and the ability to fence them onto or off weed infestations are essential. Weeds of pastures are the most suitable subjects for control, although weeds of arable crops, forestry, and waste places are sometimes amenable to control by grazing animals. Although grazing animals themselves often cause weed problems in pasture, adjusting grazing timing or intensity or both can sometimes redress the balance. Increasing sheep or cattle stocking rates prevents animals from grazing selectively and can help control some weeds. Adjusting grazing pressure can also improve the growth of desirable pasture species so that these are more competitive and able to resist invasion of annual or biennial weeds. Introducing a different class of stock, like sheep into a cattle system or goats into a sheep system can control many weeds. Goats are capable of browsing on and controlling spiny or poisonous brush weeds, including gorse and poison ivy, without suffering adverse effects. Examples are given of the use of grazing animals for weed control in crops and forestry.
Ragweeds (Ambrosiaspp.)—The Hay Fever Weeds
Authors: Mitich Larry W.
Published: March 2018

“Wither'd hogs … on ragweed nags, They skim the muirs [moors].”Address to the Diel, 1785, Scottish poet Robert Burns (1759–1796).
Diurnal Leaf Movement Effects on Spray Interception and Glyphosate Efficacy
Authors: Norsworthy Jason K. , Oliver Lawrence R. , Purcell Larry C.
Published: March 2018

Time of day at which a herbicide is applied can affect efficacy, and variability may be attributed to leaf angles at application. Spray interception by hemp sesbania (Sesbania exaltata), sicklepod (Senna obtusifolia), and prickly sida (Sida spinosa) under day and night conditions was quantified by measuring interception of a 2-M potassium nitrate solution. Following the night application, interception by prickly sida, hemp sesbania, and sicklepod was reduced 17, 67, and 70%, respectively. In a second study in the greenhouse, glyphosate was applied to hemp sesbania, pitted morningglory (Ipomoea lacunosa), prickly sida, and sicklepod at 6:00 and 11:00 A.M. and 4:00 and 9:00 P.M. Control of all species was dependent on the time of day treated, with night applications generally being less effective.
Response of Annual Weed Species to Glufosinate and Glyphosate
Authors: Tharp Brent E. , Schabenberger Oliver , Kells James J.
Published: March 2018

The recent introduction of glufosinate-resistant and glyphosate-resistant crops provides growers with new options for weed management. Information is needed to compare the effectiveness of glufosinate and glyphosate on annual weeds. Greenhouse trials were conducted to determine the response of barnyardgrass (Echinochloa crus-galli), common lambsquarters (Chenopodium album), common ragweed (Ambrosia artemisiifolia), fall panicum (Panicum dichotomiflorum), giant foxtail (Setaria faberi), large crabgrass (Digitaria sanguinalis), and velvetleaf (Abutilon theophrasti) to glufosinate and glyphosate. The response of velvetleaf and common lambsquarters was investigated at multiple stages of growth. Glufosinate and glyphosate were applied to each weed species at logarithmically incremented rates. The glufosinate and glyphosate rates that provided a 50% reduction in aboveground weed biomass, commonly referred to as GR50values, were compared using nonlinear regression techniques. Barnyardgrass, common ragweed, fall panicum, giant foxtail, and large crabgrass responded similarly to glufosinate and glyphosate. Common lambsquarters 4 to 8 cm in height was more sensitive to glufosinate than glyphosate. In contrast, 15- to 20-cm tall-velvetleaf was more sensitive to glyphosate than glufosinate.
Effects of Quinclorac on Following Rotational Crops
Authors: Moyer James R. , Esau Rudy , Boswall A. Lyle
Published: March 2018

Quinclorac was registered for weed control in wheat (Triticumspp.) for western Canada in 1997. Residues from quinclorac may persist in the soil and may damage following crops; therefore, field and growth chamber experiments were conducted to determine the tolerance of several following rotational crops. Cereals and bromegrass (Bromus biebersteinii) were sufficiently tolerant that they could be seeded within 16 d of quinclorac application without risk of injury. At the other extreme, marketable and total potato (Solanum tuberosum) yields were reduced by quinclorac on irrigated land 1 yr after application. Growth chamber experiments were used to rank crops in order of their tolerance of quinclorac residues and to compare the tolerance of crops that were grown in the field with additional crops. Quinclorac injured several legume and oilseed crops when the crops were seeded immediately after application, but quinclorac did not reduce the dry matter yield of two of the most sensitive legumes, faba bean (Vicia faba) and alfalfa (Medicago sativa), 1 yr after application on irrigated land. However, based on a previous study, one can conclude that injury to these crops may occur in the field under drought conditions in rain-fed agricultural systems.
The Effect of Ultraviolet Radiation on the Fresh Weight of Some Weeds and Crops
Authors: Andreasen Christian , Hansen Leif , Streibig Jens C.
Published: March 2018

Under greenhouse conditions, annual bluegrass (Poa annuaL.), common groundsel (Senecio vulgarisL.), shepherd's purse [Capsella bursa-pastoris(L.) Medicus], small nettle (Urtica urensL.), canola (Brassica napusL. ssp.napus), and pea (Pisum sativaL.) differed in sensitivity to ultraviolet (UV) radiation. Of the weed species, annual bluegrass was the least sensitive; whereas, among the crop species, canola was about sevenfold more sensitive than was pea. The sensitivity of a species to UV radiation was highly dependent upon its stage of development. The study indicates some potential for using UV radiation to control weeds, but the method needs further investigation to unravel the selectivity of the methods and potential health hazards.
Smutgrass (Sporobolus indicus) Control in Bahiagrass (Paspalum notatum) Pastures
Authors: Mislevy Paul , Shilling Donn G. , Martin Frank G. , Hatch Stephan L.
Published: March 2018

Field experiments were conducted in 1989 and 1990 to evaluate seasonal effects of herbicide application, smutgrass (Sporobolus indicus) growth stage, and herbicide rate on smutgrass control. The experimental design was a split–split plot, with season (late spring, midsummer, and fall) as the whole plot, physiological stage at application (uncut, 15-, and 30-cm regrowth) the subplot, and hexazinone rate (0.0, 0.56, 0.84, and 1.12 kg ai/ha) as the sub-subplot treatment. Whole plots were arranged in three randomized complete blocks. Smutgrass control for the mean of the hexazinone treatments (1989 and 1990) was 95%. Application of 0.56 kg/ha hexazinone during late spring, midsummer, and fall seasons provided 77, 92, and 92% smutgrass control, respectively. Generally, the influence of plant stage at time of hexazinone application had no effect (P > 0.05) on smutgrass control. At 20 d after treatment (DAT), hexazinone had injured bahiagrass (Paspalum notatum) plants by yellowing them, but the plants reverted to their usual dark green color by 40 DAT. Total nonstructural carbohydrates were lower for the 30-cm regrowth than for the uncut plants, regardless of season; however, 30-cm regrowth had little effect on smutgrass control.
Nature, Occurrence, and Cost of Herbicide-Resistant Wild Oat (Avena fatua) in Small-Grain Production Areas
Authors: Beckie Hugh J. , Thomas A. Gordon , Légère Anne , Kelner David J. , van Acker Rene C. , Meers Scott
Published: March 2018

Surveys were conducted across the northern Great Plains of Canada in 1996 and 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of wild oat (Avena fatua). The surveys indicated that resistance to acetyl-CoA carboxylase (ACCase) inhibitors (Group 1) occurred most frequently relative to other herbicide groups. Group 1-HR wild oat occurred in over one-half of fields surveyed in each of the three prairie provinces. Of particular concern was the relatively high incidence of multiple-group resistance in wild oat in Saskatchewan and Manitoba. In Saskatchewan, 18% of Group 1-HR populations were also resistant to acetolactate synthase inhibitors (imidazolinones), even though these herbicides were not frequently used. In Manitoba, 27% of fields surveyed had wild oat resistant to herbicides from more than one group. Four populations were resistant to all herbicides registered for use in wheat (Triticum aestivum). Depending on the nature of resistance in wild oat, alternative herbicides available for their control may substantially increase costs to the grower. The cost to growers of managing HR wild oat in Saskatchewan and Manitoba using alternative herbicides is estimated at over $4 million annually. For some HR biotypes, alternative herbicides either are not available or all have the same site of action, which restricts crop or herbicide rotation options and threatens the future sustainability of small-grain annual cropping systems where these infestations occur.
Medicine and Contextual Justice
Authors: RHODES ROSAMOND
Published: March 2018

This article provides a critique of the monolithic accounts that define justice in terms of a single and often inappropriate goal. By providing an array of real examples, I argue that there is no simple definition of justice, because allocations that express justice are governed by a variety of reasons that reasonable people endorse for their saliency. In making difficult choices about ranking priorities, different considerations have different importance in different kinds of situations. In this sense,justice is a conclusionabout whether an allocation reflects the human interests and priorities that are at stake. The article describes how several principles of justice have a legitimate place in medical allocations. To achieve justice within medical practice, professionals should focus on the human interests and compelling reasons for prioritizing specific principles within their specific medical domain.
The Effects of Closed-Loop Brain Implants on Autonomy and Deliberation: What are the Risks of Being Kept in the Loop?
Authors: GILBERT FREDERIC , O’BRIEN TERENCE , COOK MARK
Published: March 2018

A new generation of implantable brain–computer interfaces (BCI) devices have been tested for the first time in a human clinical trial, with significant success. These intelligent implants detect specific neuronal activity patterns, such as an epileptic seizure, and provide information to help patients to respond to the upcoming neuronal events. By forecasting a seizure, the technology keeps patients in the decisional loop; the device gives control to patients on how to respond and decide on a therapeutic course ahead of time. Being kept in the decisional loop can positively increase patients’ quality of life; however, doing so does not come free of ethical concerns. There is currently a lack of evidence concerning the various impacts of closed-loop system BCIs on patients’ decisionmaking processes, especially how being in the decisional loop impacts patients’ sense of autonomy. This article addresses these gaps by providing data that we obtained from a first-in-human clinical trial involving patients implanted with advisory brain devices. This article explores ethical issues related to the risks involved in being kept in the decisional loop.