bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of Bioerosion by Sphaerechinus Granularis on ‘Coralugène’ Concretions of the Western Mediterranean
Authors: Sartoretto Stephane , Francour Patrice
Published: May 2019

Sphaerechinus granularis (Echinodermata: Echinidea) is involved in the erosion of ‘coralligène’ concretions in the Mediterranean. In shallow water (10 m), a high abundance of this species (>20 ind 25 m−2) is associated with small diameter individuals (56·7 ±7·7 mm). In deep clean waters (>40 m), the abundance is lower (<1 ind 25 m−2) and the mean diameter is higher (86·0±9·3 mm). Daily erosion of Corallinaceae by this species is related to the urchin diameter (r=0.87). Local variations in urchin abundance and diameter influence the amount of CaCO3 eroded annually. In shallow waters, the eroded CaCO3 mass reaches 210 g m−2 y−1 vs 16 g m−2 y−1 in coralligène concretions in deep clean waters. Sphaerechinus granularis is an important biological agent which substantially erodes the Mediterranean coralligène concretions.
Promouvoir des normes visant à limiter la violence en situation de crise: un défi, une stratégie, des alliances
Authors: Harroff-Tavel Marion
Published: May 2019

En Somalie, un groupe de jeunes acteurs, musiciens et scénaristes composent une pièce de théâtre qui sera jouée, filmée et distribuée sous forme de vidéo dans le pays. Une scène met aux prises un jeune milicien qui se vante de semer la terreur et la femme qu'il aime, qui, elle, dépeint la souffrance engendrée par ces actes et se refuse à épouser un homme qui a oublié le code d'honneur de son clan. La création artistique adresse aux jeunes miliciens un message concernant l'effet d'une violence débridée sur la victime comme sur celui qui s'en rend coupable.
Création d'une cour criminelle internationale permanente: Conférence diplomatique de Rome: résultats escomptés par le CICR
Authors: Pfanner Toni
Published: May 2019

Les violations du droit international humanitaire ne sont pas un phénomène nouveau. L'idée de la création d'une cour criminelle internationale chargée de réprimer ces violations n'est pas non plus nouvelle. Le premier projet établissant un lien entre les violations d'un traité humanitaire—en l'occurrence, la Convention de Genève de 1864 pour l'amélioration du sort des militaires blessés dans les armées en campagne—et l'imposition de sanctions pénales par un organe judiciaire international permanent est dû à Gustave Moynier, l'un des fondateurs du CICR. Néanmoins, ce projet, comme bien d'autres, ne s'est pas concrétisé.
Première proposition de création d'une cour criminelle internationale permanente
Authors: Hall Christopher Keith
Published: May 2019

Le 15 juin 1998 s'ouvrira à Rome une Conférence diplomatique chargée de combler une des lacunes qui existe depuis longtemps dans le système de mise en œuvre du droit international humanitaire. Cette Conférence, qui durera cinq semaines, devrait aboutir à l'adoption d'une convention portant création d'une cour criminelle internationale permanente. Même si la volonté qui s'exprime actuellement au sein des Nations Unies en vue d'instaurer une cour permanente s'est manifestée pour la première fois il y a cinquante ans—il s'agit de la proposition présentée en 1947 par Henri Donnedieu de Vabres, juge français au Tribunal militaire international de Nuremberg—, on ignore encore souvent que la première proposition sérieuse en ce sens aurait été faite il y a plus de 125 ans par Gustave Moynier, un des fondateurs du Comité international de la Croix-Rouge, qu'il a longtemps présidé.
Carbon allocation and translocation in chlorsulfuron-treated canola (Brassica napus)
Authors: Kim Songmun , Born William H. Vanden
Published: May 2019

Our objective was to determine if the chlorsulfuron-induced reduction in assimilate export from leaves can be attributed to a shortage of carbohydrates. Treated canola leaves showed no reduction in carbon fixation or carbohydrate production during the first 24 h, but they exuded only 17 to 27% of the amount of sucrose exuded by corresponding control leaves. Exposure of the leaves to higher concentrations of CO2(500 vs. 350 μl L−1) resulted in greater net carbon exchange and higher starch content, but failed to overcome the reduction in sucrose export, presumably because of increased carbon allocation to starch.
Temperature- and moisture-dependent models of seed germination and shoot elongation in green and redroot pigweed (Amaranthus powellii, A. retroflexus)
Authors: Oryokot Joseph O. E. , Murphy Stephen D. , Thomas A. Gordon , Swanton Clarence J.
Published: May 2019

To predict weed emergence and help farmers make weed management decisions, we constructed a mathematical model of seed germination for green and redroot pigweed based on temperature and water potential (moisture) and expressing cumulative germination in terms of thermal time (degree days). Empirical observations indicated green pigweed germinated at a lower base temperature than redroot pigweed but the germination rate of redroot pigweed is much faster as mean temperature increases. Moisture limitation delayed seed germination until 23.8 C (green pigweed) or 27.9 (redroot pigweed); thereafter, germination was independent of water potential as mean temperatures approached germination optima. Our germination model, based on a cumulative normal distribution function, accounted for 80 to 95% of the variation in seed germination and accurately predicted that redroot pigweed would have a faster germination rate than green pigweed. However, the model predicted that redroot pigweed would germinate before green pigweed (in thermal time) and was generally less accurate during the early period of seed germination. The model also predicted that moisture limitation would increase, rather than delay, seed germination. These errors were related to the mathematical function chosen and analyses used, but an explicit interaction term for water potential and temperature is also needed to produce an accurate model. We also tested the effect of mean temperature on shoot elongation (emergence) and described the relationship by a linear model. Base temperatures for shoot elongation were higher than for seed germination. Shoot elongation began at 15.6 and 14.4 C for green and redroot pigweed, respectively; they increased linearly with temperature until the optimum of 27.9 C was reached. Elongation was dependent on completion of the rate-limiting step of radicle emergence and was sensitive to temperature but not moisture; hence, elongation was sensitive to a much smaller temperature range. Beyond mathematical changes, we are testing our model in the field and need to link it to ecophysiological, genetic, and spatially explicit population processes for it to be useful in decision support for weed management.
Effect of crop growth stage on tolerance to low doses of thifensulfuron:tribenuron
Authors: Wall David A.
Published: May 2019

Field studies were conducted at Morden, Manitoba, in 1994 and 1995 to investigate the effect of crop growth stages on canola and sunflower tolerance to sublethal doses of thifensulfuron:tribenuron (2:1). Thifensulfuron:tribenuron at doses of 0, 0.23, 0.45, 0.9, 1.8, and 3.6 g ai ha−1plus a nonionic surfactant at 0.5% v/v were applied to canola and sunflower at the two- to three-leaf, four- to five-leaf, and six- to seven-leaf stages. Crop leaf stage at the time of application affected tolerance of both crops to thifensulfuron:tribenuron. Crop injury was lowest, and flowering, seed yield, and seed oil content were least affected when low doses of thifensulfuron:tribenuron were applied at the two- to three-leaf stage. At the highest dose, there was little practical difference among growth stages since yield of both crops was severely reduced. Producers with drift-affected canola or sunflower can expect less effect on crop yield when thifensulfuron:tribenuron injury occurs during early crop growth.
Economic decision rules for postemergence herbicide control of barnyardgrass (Echinochloa crus-galli) in corn (Zea mays)
Authors: Bosnić Aca Č. , Swanton Clarence J.
Published: May 2019

Economic decision rules for postemergence herbicide control of barnyardgrass in corn were developed. Damage and control functions that formed the basis of an economic model were estimated. Barnyardgrass density and time of emergence relative to the crop were fundamental to calculate the damage function. The control function described barnyardgrass dry weight response to variable doses of two herbicides. Both the biologist's and economist's weed control decision rules, derived from the economic model, were influenced by time of weed emergence relative to the crop, corn yield, and price. Inclusion of time of weed emergence relative to the crop improved our interpretative ability of derived decision rules. The biologist's threshold weed density was more sensitive to changes in parameter values than the economist's optimal herbicide dose strategy. Herbicide use with recommended label dose was greater than either the economically optimal or the biologically effective doses. Use of the biologically effective dose for postemergence weed control decisions was cost efficient and could be of practical significance to corn growers.
Adsorption and relative mobility of flumetsulam
Authors: Shaw David R. , Murphy Glen P.
Published: May 2019

Laboratory studies were conducted to evaluate flumetsulam adsorption and mobility in seven Mississippi soils of different organic matter content, pH, and texture. Adsorption isotherms were determined for all soils using a 1:1 (soil: water) technique. In six of seven soils, Freundlichnconstants were close to unity, suggesting a partitioning-like adsorption mechanism for flumetsulam. Mobility was examined using packed soil columns.14C-flumetsulam recoveries in leachate ranged from 1 to 70% and were influenced by both organic matter content and soil pH. However, the effects of organic matter content and soil pH were not independent. Consequently, clear relationships between flumetsulam mobility and either organic matter content or soil pH were not established across all soils. However, among soils of similar pH (7.5 ± 0.3), mobility decreased linearly (R2= 0.75) as organic matter content increased from 0.7 to 3.6%. Across soils with similar organic matter content (3.9 ± 0.3%), mobility increased linearly (R2= 0.98) as soil pH increased from 5.3 to 7.2. Net adsorption constants (Kd) provided a more accurate assessment of flumetsulam mobility across all soils thanKoc.
Reproductive phenology in yellow starthistle (Centaurea solstitialis)
Authors: Roché Cindy Talbott , Thill Donald C. , Shafii Bahman
Published: May 2019

Exotic annual weeds on western U.S. rangelands, including yellow starthistle, owe at least part of their invasion success to prolific seed production. Occurrence of flowering in relation to soil moisture and development of competing vegetation heavily influences reproductive output. Yellow starthistle flowers much later than associated Mediterranean invaders, which avoid summer drought by early flowering and senescence. This study used successive planting dates and four densities to investigate the influence of temperature, photoperiod, and intraspecific competition on reproductive phenology in a population of yellow starthistle from Lewiston, ID. A base temperature for seed germination of 2 C was determined by experiments at constant temperatures. Under the conditions of this study, density, photoperiod, and vernalization did not regulate reproductive development, as measured by onset of bud, flowering, and achene dispersal stages. A thermal time model adequately predicted phenology in this population of yellow starthistle. Plants emerging between October and July required about 1,240 degree days for 50% of the plants to reach bud stage, and an additional 500 and 900 degree days to flowering and achene dispersal, respectively. The relatively long time from emergence to mature achenes in this species influences management options such as prescribed fire, livestock grazing, and management of competing vegetation. Insensitiviry to photoperiod and lack of a vernalization requirement allow late germinating plants to reproduce if moisture is adequate.
A stem cut and blade delivery method of herbicide application for weed control
Authors: Wahlers Richard L. , Burton James D. , Maness Eleanor P. , Skroch Walter A.
Published: May 2019

Greenhouse and field studies were conducted to investigate the responses of container-grown dogfennel, multiflora rose, and purple loosestrife to clopyralid or triclopyr applied to plants from a pruning shear blade. Clopyralid or triclopyr was diluted with water to various concentrations and placed on one side of a pruning shear blade in final volumes of either 1 or 5 μl. The shears were then used to sever and treat stems. Results indicated that 20% triclopyr concentrations in 5-μl total volume (360 μg active) gave ≥ 96% reductions of foliar regrowth in dogfennel, multiflora rose, and purple loosestrife 70, 42, and 56 days after treatment (DAT), respectively. The same delivery rate for clopyralid gave 96% dogfennel control 70 DAT. Subsequent visual ratings with multiflora rose (105 DAT) and purple loosestrife (260 DAT) confirmed that early reductions in biomass were good indicators of long-term control.
Atrazine dissipation and carryover from commercial and starch-encapsulated atrazine formulations
Authors: Vail Gordon D. , Hickman Michael V. , Schreiber Marvin M.
Published: May 2019

Field experiments were conducted in 1991, 1992, and 1993 to evaluate the dissipation and carryover potential of atrazine from starch-encapsulated (SE) and commercial formulations (CF). Formulation was not a significant factor in atrazine dissipation at any application rate. The dissipation time required to reach one-half of the original concentration (DT50) was measured for each formulation. The atrazine DT50 combined over all years (1991 to 1993) and rates (1.1 to 3.4 kg ai ha−1) was 7 wk for the CF, 10.3 wk for the SE large particles (0.85 to 1.4 mm), and 8.2 wk for the SE small (0.425 to 0.85 mm). Oat injury in the spring of 1992 from all rates of both SE formulations applied in 1991 was greater than that from the CF formulation. Increased oat injury from SE formulations was attributed to more atrazine present in the top 0 to 8 cm of soil compared to that for the CF. Despite significant oat injury from the 1991 application, no injury was observed on soybeans planted in 1992. Soybeans planted in 1993 and 1994 also showed no injury from the respective applications. These findings suggest that the potential for atrazine carryover from starch-encapsulated formulations was not greater than that from the commercial formulation.
The interaction of pyridate and 2,4-DB in peanut (Arachis hypogaea), Florida beggarweed (Desmodium tortuosum), and sicklepod (Senna obtusifolia)
Authors: Hicks T. Vint , Wehtje Glenn R. , Grey Timothy L.
Published: May 2019

Tank-mixed combinations of pyridate and 2,4-DB were synergistic with respect to sicklepod control and independent with respect to Florida beggarweed control and peanut tolerance in greenhouse studies. Leaf absorption of14C-pyridate was generally enhanced by the addition of 2,4-DB. Translocation of14C-pyridate out of the treated leaf did exceed 21% of the amount absorbed across all species, and14C-pyridate was not affected by the addition of 2,4-DB. Sensitivity of peanut, Florida beggarweed, and sicklepod to pyridate was independent of both adsorption and translocation. Metabolic detoxification of pyridate into a benign metabolite was highest in the tolerant peanut, lowest in highly susceptible Florida beggarweed, and intermediate in slightly susceptible sicklepod. Absorption of14C-2,4-DB by peanut was increased by approximately 10% with the addition of pyridate. No such increase was observed in either Florida beggarweed or sicklepod. Translocation of14C-2,4-DB out of the treated leaf was not affected by the addition of pyridate in any of the three species evaluated.
Critical periods for weed control in dry beans (Phaseolus vulgaris)
Authors: Burnside Orvin C. , Wiens Melvin J. , Holder Bobby J. , Weisbere Sanford , Ristau Eric A. , Johnson Michelle M. , Cameron James H.
Published: May 2019

Weed removal experiments in dry edible beans were conducted during 1992 and 1993 at Crookston and Staples, MN. Ten manual weed removal treatments were studied to determine when a natural infestation of weeds first reduced dry bean yield, and when weed removal could be discontinued without further loss of seed yield. Major weeds in order of average biomass production on weedy check plots at dry bean harvest over locations and years were wild mustard, foxtail spp., redroot pigweed, common ragweed, wild buckwheat, hairy nightshade, and common lambsquarters. Hairy nightshade also emerged late in the growing season and could negatively affect harvest efficiency and stain navy beans. Weed removal treatments had little effect on dry bean stands or 100-seed weights of harvested dry bean seed. The critical period for weed control in dry beans was 3 to 5 or 6 weeks after planting (WAP). Thus, weed control practices should begin no later than 3 WAP and continue until at least 5 or 6 WAP for maximum dry bean yields.
Phosphorus effects on competitive interactions of smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) with lettuce (Lactuca sativa)
Authors: Santos Bielinski M. , Dusky Joan A. , Stall William M. , Shilling Donn G. , Bewick Thomas A.
Published: May 2019

Replacement series studies were conducted under controlled conditions to determine the effect of phosphorus (P) rates and population densities on the competitiveness of smooth pigweed and common purslane with lettuce. Densities were 2, 4, and 8 plants per 113 cm2, whereas P rates were 0, 0.4, and 0.8 g PL−1soil. A P-deficient Histosol (0.3 mg water-extractable P L−1soil) was used. High P fertility enhanced the competitive ability of lettuce in smooth pigweed-lettuce mixtures. Smooth pigweed was not responsive to P rates. However, luxurious P consumption by smooth pigweed occurred, reducing the amount of the nutrient available for lettuce absorption. In common purslane-lettuce mixtures, the weed was responsive to P rates, increasing its competitive ability, whereas no increase in lettuce competitive ability was observed. Both weed species were more competitive than lettuce. Competition for P appears to be the main mechanism of common purslane interference on lettuce grown in low-P organic soils. Alternative fertilization strategies (i.e., banded applications) may reduce the effect of smooth pigweed on lettuce.
RAPD analysis of cultivated and wild yellow nutsedge (Cyperus esculentusL.)
Authors: Abad Paloma , Pascual Bernardo , Maroto José V. , López-Galarza Salvador , Vicente María J. , Alagarda José
Published: May 2019

Cultivated and weedy clones of yellow nutsedge were analyzed using random amplified polymorphic DNA (RAPD) markers to assess the polymorphism within the species and determine if this approach was suitable for identification of cultivar and wild populations. The RAPD markers unambiguously identified all studied clones. Nei-Li similarities were computed and used in an unweighted pair group method using arithmetic average (UPGMA) cluster analyses. Cultivated and weedy clones were clustered in two groups, but two cultivated clones were more closely related to weedy clones than to cultivated clones. The results showed a high level of genetic variability among the clones tested, particularly among the cultivated ones. Identification of yellow nutsedge cultivars and analysis of genetic diversity within and among weedy populations is possible by using only a small number of primers. In this study, seven selected primers discriminated among the 10 tested clones.
Influence of fluctuating temperatures on emergence of shattercane (Sorghum bicolor) and giant foxtail (Setaria faberi)
Authors: Kegode George O. , Pearce R. Brent , Bailey Ted B.
Published: May 2019

Understanding patterns of shattercane and giant foxtail field emergence during the spring and summer in the Midwest is important to determine the best weed management programs for crop production systems. The primary objective of this study was to determine percentage emergence of shattercane and giant foxtail under field conditions as influenced by soil temperature fluctuations, in 1992 and 1993. A secondary objective was to determine the difference in emergence percentage based on shattercane and giant foxtail seed lots harvested in different years (1985, 1991, and 1992). Soil temperature fluctuations were manipulated by artificially shading the soil surface with plastic netting that provided 30, 60, and 90% of incident sunlight in addition to the full sunlight control (0% shade). Giant foxtail and shattercane seed was planted at depths of 1.25, 2.5, 5, and 10 cm under each shade, and emergence was monitored for 45 d. Soil temperature fluctuations were reduced by increasing depth and amount of shade. Increasing depth of seed significantly reduced percentage emergence by 63 and 54% for shattercane, and 71 and 73% for giant foxtail in 1992 and 1993, respectively. Decreasing light intensity significantly reduced percentage emergence of shattercane by 72 and 73% in 1992 and 1993, respectively, but did not decrease giant foxtail emergence. Seed lots of both species were different from one another both years. These results were consistent over years, even though 1993 precipitation was three times that for 1992. Therefore, shattercane seed uses diurnal fluctuations in temperature to sense proximity to the soil surface and covering vegetation to avoid germination when conditions are unfavorable for growth. In contrast, giant foxtail seed can germinate readily and grow when environmental conditions are within an acceptable range and when seed is not buried too deeply. Differences in percentage emergence between seed lots could play a major role in emergence patterns of shattercane and giant foxtail observed in the field and may be influenced by environmental conditions during seed development on parent plants.
Production of herbicide-resistant jointed goatgrass (Aegilops cylindrica) × wheat (Triticum aestivum) hybrids in the field by natural hybridization
Authors: Seefeldt Steven S. , Zemetra Robert , Young Frank L. , Jones Stephen S.
Published: May 2019

Imazamox-resistant hybrids resulted from a cross between jointed goatgrass and an imazamox-resistant wheat (cv. FS-4 IR wheat). Two imazamox-resistant hybrids were discovered in a research plot where FS-4 IR wheat seed had been replanted from the harvest of an imazamox efficacy study conducted the year before at a different location. These hybrid plants survived imazamox applied at 0.053 and 0.069 kg ai ha−1in the field and produced seven viable seeds (BC1). This seed germinated, and chromosomes were counted from the roots (2N number ranged from 39 to 54). In the greenhouse, six of the seven plants survived an application of 0.072 kg ai ha−1imazamox, which confirmed that the resistance trait had been passed to these progeny. A large amount of phenotypic variation was observed in the mature BC1plants. A genetic description of the movement of the resistant gene is proposed based on the case of the gene being located on the D and the A or B genomes. Management strategies to reduce the occurrence of herbicide-resistant hybrids are presented.
The goals of agriculture and weed science
Authors: Aiken William
Published: May 2019

Five goals for agriculture are proposed: profitable production, sustainable production, environmentally safe production, satisfaction of human needs, and compatibility with a just social order. Four ways to view the origin of potentially conflicting values expressed in the five goals follow. In view of the five goals and differing value positions, the most pressing question for weed science is to what extent current methods of weed control are compatible with a more sustainable and environmentally sensitive agriculture.
Weed ecology and ethics
Authors: Radosevich Steven
Published: May 2019

Weed Scientists, like many other agricultural scientists and natural resource land managers, often engage in debate with other members of society about values and perceptions of food and fiber production. The focus of the debate is usually on the tools and tactics to grow crops, produce wood, or manage grazing land. Environmental ethical issues have dominated discussions among the membership of WSSA for decades. Examples include the decade-long debate over 2,4,5-T use in forestry and now water quality and human health concerns about atrazine use in agriculture. Ecology is a scientific discipline that seeks knowledge about the interactions of organism, their environments, and, more broadly, the effect of human activities on them. Because weeds are a consequence of how we grow food, the study of both ecological and human components of agroecosystems should allow weed scientists to construct management strategies that more fully address the production, environmental, and social implications of weeds and weeding.
Biochemical mechanism and molecular basis for ALS-inhibiting herbicide resistance in sugarbeet (Beta vulgaris) somatic cell selections
Authors: Wright Terry R. , Bascomb Newell F. , Sturner Stephen F. , Penner Donald
Published: May 2019

Three sugarbeet selections differing in cross-resistance to three classes of acetolactate synthase (ALS)-inhibiting herbicides have been developed using somatic cell selection. Sugarbeet selections resistant to imidazolinone herbicides,Sir-13and93R30B, do not metabolize [14C]-imazethapyr any faster or differently than sensitive, wild-type sugarbeets or a sulfonylurea-resistant/imidazolinone-sensitive selection, Sur. ALS specific activity from the three herbicide-resistant selections ranged from 73 to 93% of the wild-type enzyme extracts in the absence of herbicide, indicating enzyme overexpression was not a factor in resistance. Acetolactate synthase from Sir-13 plants showed a 40-fold resistance to imazethapyr but no resistance to chlorsulfuron or flumetsulam. Polymerase chain reaction amplification and sequencing of two regions of the ALS gene spanning all known sites for ALS-based herbicide resistance in plants indicated a single nucleotide change in theSir-13gene (G337to A337) resulting in a deduced substitution of threonine for alanine at position 113 in the sugarbeet amino acid sequence. Sur ALS was not significantly resistant to imazethapyr, but was 1,000- and 50-fold resistant to chlorsulfuron and flumetsulam, respectively.Surgene sequencing indicated a single nucleotide change(C562to T562) resulting in a serine for proline substitution at position 188 of the ALS primary structure. The93R30Bnucleotide sequence indicated two mutations resulting in two deduced amino acid substitutions: threonine for alanine at position 113 plus serine for proline at position 188. The93R30Bdouble mutant incorporated the changes observed in each of the single mutants above and correlated with higher resistance levels to imazethapyr (> 1,000-fold), chlorsulfuron (4,300-fold), and flumetsulam (200-fold) at the ALS level than observed in either of the single mutants.93R30Brepresents the first double mutant derived by a two-step selection process that incorporates two class-specific ALS-inhibitor resistance mutations to form a single broad cross-resistance trait. The interaction of the two altered amino acids is synergistic with respect to enzyme resistance vs. the resistance afforded by each of the individual mutations.
Influence of nitrogen on germination and early development of broomrape (Orobanchespp.)
Authors: Westwood James H. , Foy Chester L.
Published: May 2019

Broomrapes are parasitic angiosperms that live on the roots of many important crop plants. We have conducted a series of in vitro experiments to investigate the direct effects of nitrogen fertilizers on broomrape seed germination and early development. These experiments confirm that nitrogen in the ammonium form is more inhibitory than nitrate, but we conclude that it is the elongation of the seedling radicle that is primarily inhibited by ammonium, rather than the seed germination itself. Reductions in radicle length were observed when ammonium solutions were applied during either preconditioning or germination periods. For germinating seeds, exposures to ammonium sulfate of 4 to 8 h (depending on the species) reduced radicle elongation by half, indicating a relatively rapid inhibition. Broomrape species varied in sensitivity to ammonium, withOrobanche aegyptiacabeing the most tolerant, followed byO. crenata, O. ramosa, O. cernua, and finallyO. minoras compared in the presence of 5 mM ammonium. However, all broomrape species were much more sensitive to ammonium toxicity than were host crop species under similar treatment conditions.
A biochemical study of BAS 517 using excised corn and soybean root systems
Authors: Li Hwei-Yiing , Foy Chester L.
Published: May 2019

The mode of action of BAS 517 in a susceptible plant species, corn, was investigated using an excised root system and14C-tracer techniques. The root system of a tolerant species, soybean, was used for comparison. When UL-14C- glucose was used as a precursor,14C incorporation into lipids was reduced in BAS 517-treated corn roots, although14C incorporation from UL-14C-glucose into lipids was relatively low. Inhibition of14C incorporation into water-soluble compounds was not definite because of a high degree of variability. Using14C-acetate as a precursor, 49, 43, and 34% of the recovered radioactivity was found in the lipid fractions of root tips treated with 0, 1.0, and 10 μM BAS 517, respectively. In nontreated soybean root tips, 47% of the recovered radioactivity was found in the lipid fraction compared to 49% in root tips treated with 10 μM BAS 517. Further analysis of lipids showed that BAS 517 inhibited the incorporation of14C from14C-acetate into phosphatidylethanolamine, a phospholipid, whereas the labeling of sterols in treated corn roots was not adversely affected. Acetyl CoA carboxylase extracted from root systems of corn and soybean showed different sensitivity to BAS 517, suggesting its role as the herbicide target site and as a basis for the selectivity.
Absorption and translocation of MON 37500 in wheat and other grass species
Authors: Olson Brian L. S. , Al-Khatib Kassim , Stahlman Phillip , Parrish Scott , Moran Sharon
Published: May 2019

A growth chamber study was conducted to evaluate the effects of temperature and soil moisture on the absorption and translocation of the new sulfonylurea herbicide, MON 37500, in wheat, jointed goatgrass, wild oat, and downy brome. Treatment combinations of temperatures—25/23, 15/13, and 5/3 C—and soil moistures of one-third, two-thirds, and full field capacities were assigned to the germinated plants. Radiolabeled MON 37500 was applied to the second leaf of plants at the three-leaf stage. The plants were then harvested at 6, 24, and 96 h after application. The plants absorbed MON 37500 in the greatest quantity during the first 6 h; however, absorption did continue to increase over time. Absorption was highest in wheat and lowest in wild oat. Temperature influenced absorption, while soil moisture status appeared to have no effect. Translocation of radiolabeled material out of the treated leaf increased over time; however, 90 to 97% of absorbed radioactivity remained in the treated leaf 96 h after treatment. Temperature affected translocation differently in each species, but increasing soil moisture increased translocation.
Soybean response to weed interference and defoliation
Authors: Grymes Charles F. , Griffin James L. , Boethel David J. , Leonard B. Rogers , Jordan David L. , Russin John S.
Published: May 2019

Field experiments were conducted in Louisiana over 2 yr to evaluate the influence of full-season interference from johnsongrass, common cocklebur, or hemp sesbania at densities of 2.5, 0.5, and 2.0 plants m–1of row, respectively, and simulated insect defoliation of soybean on weed and soybean growth. Defoliation at R2 (full bloom) and R5 (beginning seed development) soybean growth stages was accomplished by removal of zero, one, or two leaflets per soybean trifoliate, which approximated 0, 33, and 66% defoliation, respectively. Height and dry weight of all weeds were not affected by soybean defoliation level or defoliation stage. Soybean height 3 wk after defoliation at R5 was not influenced by weed interference, soybean defoliation level, or defoliation stage in either year. Averaged across soybean defoliation levels and stages in 1994, johnsongrass, common cocklebur, and hemp sesbania reduced soybean yields 30, 15, and 14%, respectively. In 1995, johnsongrass reduced soybean yield 35%. As soybean defoliation level increased, a linear decrease in soybean yield was observed. Averaged across weeds and soybean defoliation stages, 33 and 66% defoliation reduced soybean yield 6 and 20% in 1994 and 12 and 33% in 1995, respectively. Defoliation at R5 resulted in 10% lower yield than defoliation at R2 in one of two years. Yield reduction due to combinations of weeds and soybean defoliation was additive.
Seasonal abundance and spatial pattern ofSetaria faberi, Chenopodium album, andAbutilon theophrastiin reduced-tillage soybeans
Authors: Mulugeta Dawit , Boerboom Chris M.
Published: May 2019

A better understanding of the influence of various crop and weed management practices on spatiotemporal dynamics of weeds could improve the design of integrated weed management systems. We examined the influence of 18- and 76-cm soybean row spacings on emergence pattern and spatial aggregation of giant foxtail, common lambsquarters, and velvetleaf seedling cohorts. In addition, we characterized the soil seedbank and determined the quantitative and spatial relationship between the seedbank and seedling populations. Viable seeds of about 10 weed species and twice as many species of seedlings were identified in the weed community. Giant foxtail and common lambsquarters were the predominant species in the seedling and seedbank population, respectively, each accounting for 60 to 70% of the total weed species density. Emergence of giant foxtail, common lambsquarters, and velvetleaf depleted 12 to 33%, < 2% and 12 to 49% of the seedbank in the upper 10 cm of the soil profile. Peak time and periodicity of weed emergence was not influenced by soybean row spacing, and peak time of emergence of giant foxtail, common lambsquarters, and velvetleaf occurred 3 to 4, 3 to 6, and 3 to 9 weeks after soybean planting (WAP), respectively. Magnitude of giant foxtail emergence 5, 6, and 9 WAP was 98, 96, and 76% greater in 76- than in 18-cm row soybeans only when the population of 76-cm row soybeans was 57% lower than the 18-cm soybeans in 1997. Giant foxtail and common lambsquarters seeds in the seedbank were aggregated in 1996 and 1997 according to the Taylor power law (TPL) and the negative binomial distribution (NBD). The TPL and the NBD were similar in describing the spatial aggregation of giant foxtail and common lambsquarters but not some velvetleaf seedling cohorts. The spatial aggregation of seedlings varied among cohorts for different weed species and was likely due to species-specific biological characteristics that influence seed dispersal, germination, and seedling emergence. Within a 1.5-ha area, aggregation declined with decreasing density. Within a 24-m2area, the level of aggregation of all weed species decreased as seedling densities increased. These results indicated that soybean row spacing influenced neither weed emergence pattern nor weed spatial aggregation; thus, several management decisions can be similar in 18- and 76-cm row soybeans.
Resistance to acetolactate synthase inhibitors and quinclorac in a biotype of false cleavers (Galium spurium)
Authors: Hall Linda M. , Stromme Kim M. , Horsman Geoff P. , Devine Malcolm D.
Published: May 2019

A false cleavers population that survived treatment with triasulfuron/bromoxynil in 1996 was identified in central Alberta, Canada, in a field that had been treated with acetolactate synthase (ALS) inhibitors in 3 of the previous 6 yr. In greenhouse studies, this biotype was highly resistant to the ALS inhibitors triasulfuron, thifensulfuron/tribenuron, and sulfometuron and moderately resistant to imazethapyr; GR50, values were > 16, > 5, > 1.0, and 9.9, respectively. In addition, cross-resistance was identified to the auxin-type herbicide quinclorac (GR50 value > 6.7) but not to fluroxypyr (GR50 value 1) or MCPA/mecoprop/dicamba. Quinclorac had not been used previously in this field. Analysis of ALS extracted from the resistant biotype and a susceptible biotype from a nearby location indicated that resistance to ALS inhibitors was due to an altered target site with reduced sensitivity to a broad range of ALS inhibitors. The ALS I50 values for triasulfuron, metsulfuron, chlorsulfuron, thifensulfuron, and imazethapyr were 36, 34, 92, 96, and 14 times higher, respectively, for the resistant compared to the susceptible biotype. The mechanism of resistance to quinclorac is unknown. This is the first report of high-level herbicide resistance in this weed species.
Optimizing foliar activity of isoxaflutole on giant foxtail (Setaria faberi) with various adjuvants
Authors: Young Bryan G. , Hart Stephen E.
Published: May 2019

Greenhouse, laboratory, and field studies were conducted to evaluate the potential of nonionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO), and 28% urea ammonium nitrate (UAN) to enhance whole plant efficacy, absorption, and spray retention of foliar applications of isoxaflutole to giant foxtail. In greenhouse studies, isoxaflutole at 10 g ai ha−1reduced giant foxtail growth 5%, whereas the addition of a spray adjuvant reduced giant foxtail growth at least 75%. The addition of UAN improved giant foxtail growth reduction when used in combination with isoxaflutole plus NIS. Isoxaflutole spray retention on the leaf surface was increased with an adjuvant and a further increase was observed with the addition of UAN. Isoxaflutole applied with NIS, COC, and MSO resulted in 42, 60, and 91%14C absorption, respectively, compared to 21% absorption from isoxaflutole applied alone 24 h after treatment (HAT). Increased14C absorption and entry into the cuticle when an adjuvant was utilized with isoxaflutole resulted in greater translocation of14C from isoxaflutole out of the treated leaf. Significant basipetal movement from foliar applications of14C-isoxaflutole suggests phloem mobility. In field studies, isoxaflutole applied with MSO provided greater giant foxtail growth reduction compared to isoxaflutole applied with NIS and in some cases COC. The addition of UAN to isoxaflutole did not increase whole plant efficacy in field studies. These studies indicate isoxaflutole has excellent potential to be used for control of existing giant foxtail present at the time of corn planting if an adequate adjuvant is utilized.
Interference between pigweed (Amaranthusspp.), barnyardgrass(Echinochloa crus-galli), and soybean (Glycine max)
Authors: Cowan Paul , Weaver Susan E. , Swanton Clarence J.
Published: May 2019

Field experiments were conducted to determine the influence of time of emergence and density of single and multispecies populations of pigweed and barnyardgrass on soybean yield and competitive abilities of pigweed and barnyardgrass. Pigweed and barnyardgrass were established at selected densities within 12.5 cm on either side of the soybean row. Pigweed and barnyardgrass seeds were sown concurrently with soybean and at the cotyledon stage of soybean growth. Time and density of pigweed and barnyardgrass seedling emergence relative to soybean influenced the magnitude of soybean yield loss. Maximum soybean yield loss ranged from 32 to 99%, depending upon time of emergence relative to soybean. Pigweed was more competitive than barnyardgrass across all locations, years, and time of weed emergence. When pigweed was assigned a competitive index of 1 on a scale from 0 to 1, the competitive ability of barnyardgrass ranged from 0.075 to 0.40 of pigweed, depending upon location and time of emergence. This is the first multiple weed species study to include time of weed emergence relative to the crop. Competitive index values for multiple weed species must be calculated from field experiments in which weeds are grown with the crop under differing environmental conditions.
Assessment of weed and crop fitness in cover crop residues for integrated weed management
Authors: Williams Martin M. , Mortensen David A. , Doran John W.
Published: May 2019

Cover crop residues are not widely used for weed control because, as a stand-alone tactic, they do not effectively suppress all weeds and their duration of weed control is too short. Field experiments were conducted in 1995 and 1996, under both irrigated and rainfed conditions, to quantifyAmaranthusspp.,Setariaspp., and soybean emergence and growth in residues of fall-planted, spring-killed barley, rye, triticale, wheat, and hairy vetch. For both weed species, seedling emergence was reduced 3 wk after soybean planting by rye and wheat residues (≥ 2, 170 kg ha−1) in 1996. In 1996,Amaranthusspp. canopy volume was reduced 38 to 71% by residues 3 wk after planting. Likewise,Setariaspp. canopy biomass was reduced 37 to 97% in residues 5 wk after planting over both years. The response comparison index was used to identify frequency by which weed growth was placed at a disadvantage relative to soybean growth.Amaranthusspp. andSetariaspp. growth suppressions 3 to 5 wk after planting indicate potential times for intervention with other integrated weed management tactics such as reduced postemergence herbicide rates and interrow cultivation.
Model of rice (Oryza sativa) yield reduction as a function of weed interference
Authors: VanDevender Karl W. , Costello Thomas A. , Smith Roy J.
Published: May 2019

Economic assessment of weed management strategies in rice is dependent upon a quantitative estimate of the yield impact of a given weed population. To assist rice producers in making such assessments, a mathematical model was developed to predict rice yield reduction as a function of weed density and duration of interference. The nonlinear empirical model was a unique 3-dimensional adaptation of the Richards equation with 4 parameters. Using published data, individual parameter values were fitted for each of 6 weed species interfering with either conventional or semi-dwarf statured rice cultivars. The functional form of the equation produced surfaces that were qualitatively consistent with available data and experience regarding rice-weed biology. Hence, predictions from the model should be useful and reliable in assessing the economic impact of weeds and in determining the feasibility of alternative weed control treatments for various field scenarios.
Herbicide-soil interactions in reduced tillage and plant residue management systems
Authors: Locke Martin A. , Bryson Charles T.
Published: May 2019

Recent changes in technology, governmental regulation and scrutiny, and public opinion have motivated the agricultural community to examine current management practices from the perspective of how they fit into a sustainable agricultural framework. One aspect which can be incorporated into many existing farming systems is plant residue management (e.g., reduced tillage, cover crops). Many residue management systems are designed to enhance accumulation of plant residue at the soil surface. The plant residue covering the soil surface provides many benefits, including protection from soil erosion, soil moisture conservation by acting as a barrier against evaporation, improved soil tilth, and inhibition of weed emergence. This review summarizes recent literature (ca. last 25 yr) concerning the effects of plant residue management on the soil environment and how those changes impact herbicide interactions.
Vancomycin Control Measures at a Tertiary-Care Hospital: Impact of Interventions on Volume and Patterns of use
Authors: Singer Mary V. , Haft Rachel , Barlam Tamar , Aronson Mark , Shafer Amy , Sands Kenneth E.
Published: May 2019

OBJECTIVE: Evaluate vancomycin prescribing patterns in a tertiary-care hospital before and after interventions to decrease vancomycin utilization.

DESIGN: Before/after analysis of interventions to limit vancomycin use.

SETTING: 420-bed academic tertiary-care center.

INTERVENTIONS: Educational efforts began August 10, 1994, and involved lectures to medical house staff followed by mailings to all physicians and posting of guidelines for vancomycin use on hospital information systems. Active interventions began November 15, 1994, and included automatic stop orders for vancomycin at 72 hours, alerts attached to the medical record, and, for 2 weeks only, computer alerts to physicians following each vancomycin order. Parenteral vancomycin use was estimated from the hospital pharmacy database of all medication orders. Records of a random sample of 344 patients receiving van-comycin between May 1, 1994, and April 30, 1995, were reviewed for an indication meeting published guidelines.

RESULTS: Vancomycin prescribing decreased by 22% following interventions, from 8.5 to 6.8 courses per 100 discharges (P<.05). The estimated proportion of van-comycin ordered for an indication meeting published guidelines was 36.6% overall, with no significant change following interventions. However, during the 2 weeks that computer alerts were in place, 60% of vancomycin use was for an approved indication.

CONCLUSIONS: Parenteral vancomycin prescribing decreased significantly following interventions, but the majority of orders still were not for an indication meeting published guidelines. Further improvement in the appropriateness of vancomycin prescribing potentially could be accomplished by more aggressive interventions, such as computer alerts, or by targeting specific aspects of prescribing patterns.
La cooperación como método necesario para la ejecución y el desarrollo de tareas por la Sociedad Nacional de la Cruz Roja Cubana
Authors: Dra. María de los Ángeles de Varona Hernández
Published: May 2019

La Sociedad Nacional de la Cruz Roja Cubana fundada el 10 de marzo de 1909, fue reconocida por el decreto presidencial 401 de ese mismo año como «Sociedad de socorros auxiliar del poder público». Durante más de 50 años, sus modestas funciones eran a la atención a la salud de los grupos de nuestra población de escasos recursos económicos; prestaba, por mediación de dispensarios, servicio médico y estomatológico, de forma gratuita o cobrando una mínima cuota.
Cooperación operacional entre las Sociedades Nacionales participantes y el Comité Internacional de la Cruz Roja
Authors: Lendorff Andreas , Lindner Andreas
Published: May 2019

«Lograr que las Sociedades Nacionales colaboren estrechamente en las actividades operacionales del CICR (asignando temporalmente personal o por mediación de la delegación de proyectos o proyectos bilaterales) para, por una parte, mejorar la capacidad operacional del Movimiento ante las nuevas necesidades y, por otra parte, para responder al deseo de las Sociedades Nacionales de intensificar sus actividades internacionales y hacer que se conozcan mejor«.
Cooperación entre la Cruz Roja Británica y el CICR: proyecto delegado para el abastecimiento de agua en Bosnia-Herzegovina
Authors: Hanley Teresa , Mitchell John
Published: May 2019

La cooperación entre el Comité International de la Cruz Roja y la Cruz Roja Briténica se ha limitado tradicionalmente a la asignación de fondos, puesta a disposición de delegados y contribuciones en especie de la Sociedad National a los programas del CICR. La participación efectiva en las operaciones del Comité se ha extendido, a lo sumo, a contribuciones específicas para un país o programa determinados. Esta Sociedad Nacional no interviene en las tareas de planificación, ejecución o estudio del CICR, aunque asigna con regularidad a la Institució al menos 25% de su presupuesto para las actividades internacionales y pone a disposición delegados sobre el terreno. Este porcentaje está aumentando y, en los últimos tres años, las contribuciones de la Cruz Roja Británica ascendieron al 50% de su presupuesto internacional, lo que supuso más de 15 millones de libras esterlinas en 1996. Además, actualmente el 12% de los delegados del CICR procede de esta Sociedad Nacional.