bluuebunny/crossref_metadata_2025 huggingface dataset:
Timing of Paraquat Applications for Weed Control in Virginia-type Peanuts (Arachis hypogaea)
Authors: Wilcut John W. , Swann Charles W.
Published: May 2019

Common ragweed was the most difficult to control of the species present and its control appeared to have the greatest effect on peanut yield. Preplant-incorporated (PPI) treatments provided no control of common ragweed but ethalfluralin plus vernolate PPI provided better than 90% control of yellow nutsedge and nearly 50% control of morningglory species. Single applications of paraquat at 0.14 kg ai ha−1following PPI applications of ethalfluralin or ethalfluralin plus vernolate provided less than 75% common ragweed control. Sequential applications of paraquat applied 1 and 3 weeks after peanut emergence (1 + 3 WAE) provided at least 81% common ragweed control. Peanut yield with ethalfluralin plus vernolate PPI followed by paraquat 1 WAE (4400 kg ha−1) was equivalent to the handweeded yield (4470 kg ha−1). Yields were not significantly less with the same PPI application followed by paraquat 1 + 3 WAE (3730 kg ha−1) or by acifluorfen plus bentazon 3 WAE (3730 kg ha−1), and ethalfluralin PPI followed by paraquat 1 + 3 WAE (3740 kg ha−1). Ethalfluralin plus vernolate PPI and paraquat 1 WAE provided the highest net returns of $1370 ha−1.
Differential Response of Corn Hybrids and Inbreds to Metolachlor
Authors: Rowe Loston , Rossman Elmer , Penner Donald
Published: May 2019

Greenhouse studies were conducted to determine the response of 200 corn hybrids and 29 inbreds to metolachlor applied at 4.5 kg ai ha−1. Both hybrids and inbreds varied in their response to the herbicide. The distribution of injury revealed a normal distribution curve with most of the hybrids having a midlevel of tolerance. Some hybrids were very tolerant, while others were quite sensitive. Laboratory studies were conducted to evaluate absorption and metabolism of14C-metolachlor for a subset of tolerant and sensitive hybrids. There was no observed difference in the product of metolachlor metabolism in the tolerant and sensitive hybrids. The observed variability in metolachlor tolerance among hybrids appeared due to differences in the amount of metolachlor absorption and metabolism and differences at the site of metolachlor action. The tolerant ‘Great Lakes 584’ hybrid absorbed significantly less14C-metolachlor than did the sensitive ‘Pioneer 3744’, while the tolerant ‘Cargill 7567’ metabolized significantly faster more14C-metolachlor than the other hybrids. The internal concentrations of available14C-metolachlor were the same for the tolerant Cargill 7567 and the sensitive ‘Northrup King 9283’ after 8 h, indicating differences at the site of action of metolachlor for these two hybrids.
Influence of Surfactants and Plant Species on Leaf Retention of Spray Solutions
Authors: De Ruiter Hans , Uffing André J.M. , Meinen Esther , Prins Albertus
Published: May 2019

Spray solutions containing a cationic or a nonionic surfactant were applied to six plant species at a broad range of concentrations. The species investigated were three weeds (black nightshade, chamomile, and quackgrass) and three crops (winter wheat, pea, and tomato). The microroughness of the leaf surface as revealed by scanning electron microscopy appeared to be a relevant retention-determining factor. Plant species with crystalline epicuticular waxes (winter wheat, pea, and quackgrass) retained much less spray solution than the other species, which are characterized by a smooth cuticular surface. The two surfactants enhanced retention on species with a reflective surface, whereas retention on black nightshade, chamomile, and tomato was hardly influenced by addition of surfactants. The two surfactants had a similar influence on the retention. Surfactant at 1% (wt/v) enhanced retention on pea, winter wheat, and quackgrass by factors of twenty, six, and four, respectively, compared with retention without surfactant. A linear relation between retention and logarithm of surfactant concentration was observed. Retention of spray drops was related not to equilibrium surface tension of the spray solution but rather to dynamic surface tension.
Surfactant-Altered Rates of Chlorimuron and Metsulfuron Photolysis in Sunlight
Authors: Thomas Sandra M. , Harrison S. Kent
Published: May 2019

Two nonionic surfactants altered photolysis rates of chlorimuron and metsulfuron in aqueous solutions and on glass slides exposed to sunlight. Photolysis of both herbicides followed first-order kinetics over an 8-day exposure period. Chlorimuron half-lives in solution were 5.8, 3.7, and 2.7 days in the presence of no surfactant, oxysorbic, and octoxynol, respectively. The extrapolated half-life of metsulfuron in solution with no surfactant was 15.7 days, compared to half-lives of 2.9 and 1.5 days in solutions containing oxysorbic or octoxynol, respectively. With the exception of metsulfuron in the absence of a surfactant, rates of chlorimuron and metsulfuron photolysis on glass slides were approximately two- to fourfold slower, and surfactants had little or no effect on herbicide photolysis rates compared to those in aqueous solution. Extrapolated half-lives on glass ranged from 9.9 to 12.5 days for chlorimuron and from 7.6 to 11.7 days for metsulfuron. Presence of oxysorbic or octoxynol did not greatly alter rates of riboflavin-sensitized herbicide photolysis on glass but did increase photolysis rates of metsulfuron in aqueous solution containing riboflavin.
Elaiosomes on Weed Seeds and the Potential for Myrmecochory in Naturalized Plants
Authors: Pemberton Robert W. , Irving Delilah W.
Published: May 2019

Seeds of plants naturalized in the United States were examined for the presence of elaiosomes. Seeds of 47 species belonging to 13 families (Asteraceae, Boraginaceae, Dipsacaceae, Euphorbiaceae, Fabaceae, Fumariaceae, Lamiaceae, Liliaceae, Poaceae, Polygonaceae, Resedaceae, Rosaceae, and Solanaceae) were found to have elaiosomes, indicating that these species are probably mymecochorous, i.e., dispersed by ants. These include important rangeland weeds such as bull thistle, Canada thistle, musk thistle, diffuse knapweed, spotted knapweed, and leafy spurge. Myrmecochory in naturalized species may enhance their weediness in areas where they are established and assist their colonization of new and relatively closed communities.
Interaction of Surfactants and Reaction Media on Photolysis of Chlorimuron and Metsulfuron
Authors: Harrison S. Kent , Thomas Sandra M.
Published: May 2019

Laboratory experiments were conducted to determine the effects of nonionic surfactants and reaction media (water, glass, and corn leaf residue) on photolysis and subsequent phytotoxicity of chlorimuron and metsulfuron residues. Oxysorbic and octoxynol enhanced rates of chlorimuron and metsulfuron photolysis in aqueous solution and on glass slides compared to controls with no surfactant. Enhanced photolysis of chlorimuron by surfactants was greatest on glass, where 93 and 89% loss occurred after 48 h exposure to ultraviolet light in the presence of oxysorbic and octoxynol, respectively, compared to 38% loss with no surfactant. Similarly, surfactant-enhanced metsulfuron photolysis was greatest on glass with 37 and 67% loss after 48 h exposure in the presence of oxysorbic and octoxynol, respectively, compared to 9% loss with no surfactant. Photolysis of herbicides deposited on corn leaf residue was significantly slower than that on glass or in aqueous media at all exposure times and metsulfuron photolysis on corn residue was enhanced by surfactants only after 144 h exposure. Bioassays confirmed that phytotoxicity of photolyzed herbicide residues was negatively correlated (r=-0.94 for chlorimuron and r=-0.92 for metsulfuron) with loss of parent herbicide as measured by liquid chromatography.
Measuring Herbicide Injury to Soybeans (Glycine max) Using a Radiometer
Authors: Adcock Timothy E. , Nutter Forrest W. , Banks Philip A.
Published: May 2019

Light reflectance from soybean foliage was compared to visual evaluations for assessing soybean injury caused by postemergence-applied paraquat and glyphosate. Coefficients of variation and of determination from multiple linear regressions for both herbicides indicated that reflectance was better correlated with injury measured by changes in leaf number, leaf weight, and stem weight than visual evaluations. Correlation coefficients among radiometer readings taken by different individuals were ≥0.98 for both herbicides. Correlation coefficients among visual evaluators ranged from 0.69 to 0.96 and from 0.74 to 0.94 for plots treated with paraquat and glyphosate, respectively. Light reflectance measured with a radiometer may be useful in evaluating injury from herbicides that cause chlorosis, necrosis, or defoliation of the target species.
Renovation of Endophyte (Acremonium coenophialum)-Infected Tall Fescue (Festuca arundinaceae) Pastures with Herbicides
Authors: Defelice Michael S. , Henning Jimmy C.
Published: May 2019

Fall, spring, or late-summer applications of glyphosate, paraquat, sethoxydim, and HOE-39866 were investigated in field trials for no-tillage renovation of endophyte fungus-infected tall fescue pastures. Only spring or late-summer applications of glyphosate at 1.68 and 2.52 kg ae ha−1 consistently provided greater than 80% visual tall fescue control. However, none of the herbicide treatments significantly reduced final percent endophyte fungus infection levels after the pasture was reestablished. High final infection levels were due to regrowth from underground rhizomes of old tall fescue sod that survived the herbicide treatments.
Interaction of Cupric Hydroxide, Paraquat, and Biotype of American Black Nightshade (Solanum americanum)
Authors: Bewick Thomas A. , Kostewicz Stephen R. , Stall William M. , Shilling Donn G. , Smith Kenneth
Published: May 2019

Experiments were conducted to determine the interaction between cupric hydroxide and paraquat on the control of American black nightshade. Three cupric hydroxide applications lowered paraquat toxicity with no further decrease in toxicity with six or nine cupric hydroxide applications when paraquat was applied 3 days after the last cupric hydroxide application. The interval between the last cupric hydroxide application and paraquat application was more important in decreasing paraquat toxicity than the number of cupric hydroxide applications. Three cupric hydroxide applications with a 10-day interval before paraquat application decreased paraquat toxicity less than three cupric hydroxide applications with a 3-day interval before paraquat application. Plants collected from three American black nightshade populations (Naples, Bradenton, and Gainesville) differed in their sensitivity to paraquat. I50values, based on dry weight, showed Naples plants to be 12 times more tolerant to paraquat than Gainesville plants without cupric hydroxide, and 14 times more tolerant when cupric hydroxide was applied. More plants of the Naples biotype regrew from apical buds after paraquat treatment following cupric hydroxide application, and from axillary buds with paraquat but not cupric hydroxide treatment, than did the Bradenton biotype. Plants of the Gainesville biotype did not regrow after paraquat application, regardless of cupric hydroxide treatment.
Response of Corn (Zea mays), Soybean (Glycine max), and Several Weed Species to Dark-Applied Photodynamic Herbicide Modulators
Authors: Mayasich Joseph M. , Mayasich Sally A. , Rebeiz Constantin A.
Published: May 2019

The photodynamic herbicidal performance of δ-aminolevulinic acid in combination with four chlorophyll biosynthesis modulators was evaluated under greenhouse conditions, using corn, soybean, and ten weed species. Treatments resulted in accumulation of various amounts of protoporphyrin IX and of monovinyl and divinyl Mg-protoporphyrin IX and protochlorophyllide. Accumulation of these tetrapyrroles was accompanied by various degrees of photodynamic injury, depending on treatment, plant species, and somewhat the modulator. The lower photodynamic susceptibility of dark monovinyl/light monovinyl and dark divinyl/light divinyl plants toward the accumulation of monovinyl and divinyl protochlotophyllide, respectively, was attributed to their greater abilities to metabolize these protochlorophyllides in the light. On the other hand, the higher photodynamic susceptibility of the dark monovinyl/light divinyl weed species toward the accumulation of monovinyl protochlorophyllide was attributed to their lower ability to metabolize the accumulated monovinyl protochlorophyllide in the light.
Effect of Planting Depth on Velvetleaf (Abutilon theophrasti) Seedling Development and Response to Cyanazine
Authors: Mester Thomas C. , Buhler Douglas D.
Published: May 2019

Experiments were conducted in a growth chamber to determine the effects of planting depth on the developmental sequence of velvetleaf seedlings and the effect of cyanazine placement relative to velvetleaf planting depth on cyanazine toxicity. Velvetleaf seedling emergence was delayed when seeds were planted 6 cm deep compared to the 2- and 4-cm planting depths. Lateral roots did not appear until after the cotyledons had emerged and expanded. This was followed by secondary root emergence from the primary root which occurred before adventitious roots appeared from the hypocotyl for the 2- and 4-cm planting depths. The first true leaf did not unfold until after the secondary root system was well developed. The quantity of adventitious roots on the hypocotyl increased with increasing planting depth. Velvetleaf adventitious roots appeared to be involved in cyanazine toxicity when cyanazine was placed above the seed. Increasing planting depth increased the proportion of seedling absorptive tissue above compared to below the seed. This resulted in increased cyanazine exposure for the deeper planted velvetleaf seeds when herbicide was placed above the seed.
Soil-Water Relations and Interference Between Devil's-Claw (Proboscidea louisianica) and Cotton (Gossypium hirsutum)
Authors: Riffle Michael S. , Murray Don S. , Stone John F. , Weeks David L.
Published: May 2019

Soil water from plots containing cotton, devil's-claw, cotton with devil's-claw, and bare soil was measured throughout the growing season using a neutron probe and related to weed interference with the crop. Volumetric water content throughout the soil profile to a depth of 180 cm did not differ among treatments before the 5th or 6th week after cotton emergence. Greater water depletion occurred early in the season in plots containing devil's-claw which corresponded to a period of rapid weed growth. In plots containing only cotton, the largest reduction in water content occurred later in the season during peak bloom and early boll formation. Soil water content at depths greater than 105 cm remained unchanged in all plots throughout the season. Interference from devil's-claw reduced cotton lint yield 96% in 1986 and 46% in 1987. Higher rainfall and reduced weed populations in 1987 reduced the impact of weed interference on cotton lint yield.
Effect of Application Timing on Rhizome Johnsongrass (Sorghum halepense) Control with DPX-V9360
Authors: Obrigawitch Timothy T. , Kenyon William H. , Kuratle Henry
Published: May 2019

Field, greenhouse, and laboratory studies were conducted to examine the effect of application timing on the activity of DPX-V9360 on rhizome johnsongrass. Field and greenhouse studies indicated that johnsongrass treated with postemergence applications of DPX-V9360 at late growth stages (>5 leaves) was controlled more effectively than when treated in early growth stages (<5 leaves). Johnsongrass control was optimized with split-postemergence applications (treatments applied at early and late growth stages) in field studies compared to a single postemergence application at either early or late growth stages. The pattern of translocation of 2-14C (pyrimidine)-labeled DPX-V9360 applied to a fully expanded johnsongrass leaf did not differ significantly between three different growth stages of 10-, 30-, and 60-cm height. Over 60% of the absorbed14C remained in the treated leaf. Most of the translocated14C moved out of the treated leaf within 3 days after application and distributed to the shoot in greater quantities than to the rhizomes. About 40% of14C-DPX-V9360 applied to the leaf surfaces of a tolerant species (corn) or susceptible species (johnsongrass) was absorbed into the leaf. Corn metabolized over 90% of absorbed DPX-V9360 within 20 h, while there was no perceptible metabolism of DPX-V9360 in johnsongrass leaves after 24 h. Late growth stage and split-postemergence applications appear to provide more effective control than early growth stage applications because of better control of regrowth (new shoot emergence from rhizomes after application) and because tillering and plant emergence are more nearly complete at application time.
Effect of Soil Type and pH on Adsorption, Mobility, and Efficacy of Imazaquin and Imazethapyr
Authors: Stougaard R. N. , Shea P. J. , Martin A. R.
Published: May 2019

Laboratory and greenhouse studies were conducted to determine imazaquin and imazethapyr adsorption, mobility, and efficacy in Sharpsburg silty clay loam, Holdrege silt loam, and Tripp sandy loam soils after adjusting pH to 5, 6, and 7. Both herbicides were more strongly absorbed, less mobile, and less efficacious at a lower pH. Observations were attributed to ionic bonding resulting from protonation of basic functional groups on the herbicide molecules as pH decreased. Adsorption was greatest in the silty clay loam and least in the sandy loam soil. Conversely, the herbicides were more efficacious and mobile in the more coarse-textured soils. Imazethapyr was less mobile, more highly adsorbed, and more phytotoxic than imazaquin. Greater adsorption of imazethapyr was attributed to a stronger basic pKaand steric factors.
Dissipation of Norflurazon and Other Persistent Herbicides in Soil
Authors: Hubbs Craig W. , Lavy Terry L.
Published: May 2019

Norflurazon applied for weed control in cotton, as well as some other herbicides, sometimes persists in soil from one growing season to the next at levels phytotoxic to the following crop. Dissipation modes of norflurazon were characterized by using14C-labeled herbicides for adsorption, mobility, photolysis, and volatility studies to aid in the prediction of conditions influencing herbicide carryover problems. A direct soil-counting technique modified for use in these studies yielded a norflurazon recovery as high as 83% of the applied radioactivity. Relative mobility of the herbicides on soil thin-layer chromatography plates was fluometuron ≥ atrazine > norflurazon. Norflurazon adsorption increased and mobility decreased as soil organic matter and clay content increased. Considerable upward movement of norflurazon and atrazine occurred in subirrigated columns containing herbicide-treated Hebert silt loam. Upward movement in excess of 5 cm occurred in 10 days and 8 weeks for atrazine and norflurazon, respectively. Photolysis and volatilization studies with norflurazon and atrazine revealed low volatilization but significant photolytic losses for norflurazon when herbicide-treated soil-coated slides were exposed to ultraviolet or sunlight. After 98 h atrazine volatilization was greater and photolysis in sunlight less than that observed for norflurazon. Laboratory studies showing upward movement of norflurazon and atrazine, in conjunction with dissipation losses occurring at the soil surface, suggested that losses of norflurazon and atrazine are facilitated by movement in capillary water referred to as the “wick” effect.
A Basis for the Antagonistic Effect of 2,4-D on Haloxyfop-Methyl Toxicity to Johnsongrass (Sorghum halepense)
Authors: Mueller Thomas C. , Barrett Michael , Witt William W.
Published: May 2019

Haloxyfop-methyl toxicity to johnsongrass was reduced when sprayed in combination with 2,4-D in greenhouse studies. The antagonism was not seen when 2,4-D application followed haloxyfop-methyl treatment by 72 h or preceded it by 24 h. The antagonism of haloxyfopmethyl activity was evident regardless of chemical form of 2,4-D used (DMA, BOE ester, IPA, or acid). Absorption of14C-haloxyfop-methyl into johnsongrass leaves was slowed by the presence of 2,4-D in the treatment solution but total absorption after 72 h was not affected. Translocation of14C was decreased when the14C-haloxyfop-methyl was applied in combination with 2,4-D. More haloxyfop-methyl, less haloxyfop, and more ether-soluble haloxyfop-methyl metabolites were found in treated leaves when haloxyfop-methyl was applied with 2,4-D compared to haloxyfop-methyl applied alone. The changes in haloxyfop-methyl translocation and metabolism caused by 2,4-D can quantitatively account for the antagonism observed.
Interference and Seed Production by Common Lambsquarters (Chenopodium album) in Soybeans (Glycine max)
Authors: Harrison S. Kent
Published: May 2019

Multiple regression and response surface plots were used to analyze the effects of common lambsquarters population density and interference duration on weed growth and soybean seed yield. Under favorable growing conditions in 1986, weed biomass production at all population densities and interference durations was four to five times that produced in 1987, under less favorable conditions. However, there was no significant treatment by year interaction for soybean seed yield reduction by common lambsquarters, and production of each kg/ha weed biomass resulted in an average soybean yield reduction of 0.26 kg/ha. Utilizing 5% yield loss as an arbitrary threshold level, the regression equation predicted a common lambsquarters density threshold of 2 plants/m of row for 5 weeks of interference after crop emergence and 1 plant/m of row for 7 weeks. Seed production by individual common lambsquarters plants was highly correlated (r=0.92) with weed dry weight, and seed production ranged from 30 000 to 176 000 seeds/plant.
Seed Viability and Dormancy of 17 Weed Species After Burial for 4.7 Years in Alaska
Authors: Conn Jeffery S.
Published: May 2019

Seed of 17 weed species that were buried at 2 and 15 cm at Fairbanks, AK, in 1984 were exhumed at 1-yr intervals and tested for germination and viability. Burial depth had a significant effect on seed viability of wild oats, bluejoint reedgrass, quackgrass, prostrate knotweed, and corn spurry with viability remaining higher at 15 than at 2 cm. The percent of viable foxtail barley and quackgrass seed that were dormant was greater at 15 than at 2 cm. Eleven of 17 species had greater than 6% seed viability 4.7 yr after burial. American dragonhead seed viability in 1989 was not significantly lower than in 1984. In contrast, viability of common hempnettle and quackgrass had dropped to zero by 2.7 and 3.7 years after burial, respectively. Foxtail barley and wild oats had less than 1% viable seed at the end of 4.7 yr. For most of the 17 species, a rectangular hyperbola model accounted for more of the variability in seed viability decline with time than did a negative logarithmic model.
Occurrence of Sesbanimide in Seeds of ToxicSesbaniaSpecies
Authors: Powell Richard G. , Plattner Ronald D. , Suffness Matthew
Published: May 2019

A tandem mass spectrometric procedure was developed to detect sesbanimide A and its isomers in plant materials. Analysis of seed extracts from 10Sesbaniaspecies using this procedure readily detected sesbanimides in Drummond rattlebush, rattlebush, and bagpod sesbania. The toxic sesbanimides were not detected in hemp sesbania or in other species with no known history of animal toxicity.
Cover Crop and Herbicide Influence on Row Crop Seedling Establishment in No-Tillage Culture
Authors: Weston Leslie A.
Published: May 2019

The establishment and management of nine cover crops in Kentucky production systems were evaluated in field experiments over a 2-yr period. ‘Wheeler’ rye, ‘Barsoy’ barley, and ‘Tyler’ wheat cereal grains produced greater biomass (180 to 260 g/m2) than the pasture species tall fescue, creeping red fescue, and white clover (55 to 110 g/m2). ‘Kentucky 31’ tall fescue, creeping red fescue, and white clover proved most difficult to control, and significant regrowth occurred regardless of herbicide or rate applied. HOE-39866 (1.7 kg ai/ha) was effective in rapidly controlling all cover crops except tall fescue by 30 days after application. Sethoxydim and fluazifop (0.4 and 0.3 kg ai/ha, respectively) effectively controlled the cereals and two ryegrass species. Glyphosate applied at 1.1 and 2.2 kg ai/ha was also effective, while 0.6 kg ai/ha controlled only cereal grain growth adequately. After chemical control, pasture grass plots contained fewest weeds/m2with some reductions likely due to density and regrowth of the sods. Cover crops were effective in suppressing weed growth at 45 days after chemical control. However, significant weed growth existed in all cover crop plots by 60 days after kill. Row crop establishment increased linearly with increasing glyphosate rate. Cereal grain covers provided the most compatible planting situations for greatest seedling establishment, with rye and wheat providing greatest weed suppression. Generally, increased weed suppression provided by a cover crop was accompanied by reduced row crop establishment, with greatest reductions observed in pasture grass plots. Cucumber was most easily established while snap pea was most difficult.
Involvement of Soil Microorganisms in the Accelerated Degradation of Diphenamid
Authors: Avidov Elana , Aharonson Nadav , Katan Jaacov
Published: May 2019

Degradation of diphenamid in soil with accelerated degradation and in nontreated control soil and the involvement of soil microorganisms in these processes were investigated. Soil with accelerated degradation and mixed bacterial cultures originating from the same soil degraded diphenamid and its monodemethylated metabolite (diphen M-1) much faster than the control. The bidemethylated derivative (diphen M-2) was degraded much more slowly than diphenamid or diphen M-1. The abundance of fungi capable of degrading diphenamid was similar in the soils with and without accelerated degradation. Degradation of diphenamid by mixed bacterial cultures from a soil with accelerated degradation was much faster than by a culture from nontreated soil and was suppressed by the fungicides thiram and fentin acetate. These two fungicides, as well as the bactericide chloramphenicol, suppressed diphenamid degradation in mixed bacterial cultures. The antifungal cycloheximide and the actinomycete suppressor PCNB did not affect the degradation of diphenamid. Metabolism of14C-diphenamid in a soil with accelerated degradation and in mixed bacterial cultures originating from the same soil showed similarities with regard to evolution of14CO2and production of certain metabolites, while the metabolism of diphenamid byFusarium, which rapidly degrades diphenamid in cultures, was different with regard to the above parameters. This study suggests that development of accelerated degradation in a soil involves a shift in population and/or in activity of microbial degraders in favor of bacteria. It appears that the accelerated degradation occurred by inducing oxidative reaction which involves demethylation of diphenamid.
Establishment, Dispersal, and Influence ofCeutorhynchus lituraon Canada Thistle (Cirsium arvense) in the Gallatin Valley of Montana
Authors: Rees Norman E.
Published: May 2019

Ceutorhynchus lituradispersed 9 km in 15 yr from its point of release in 1972 with incident of infestation of Canada thistle plants at one study site reaching 92% in 1987. Plants generally survived larval feeding in the spring, but holes created by departing larvae provided entrances for arthropods, nematodes, and diseases. Subsequent mortality rates were high for belowground Canada thistle shoots. However, the number of new shoots from underground roots the following spring usually offset the mortality that had been indirectly caused by C.litura.
Metabolic Detoxification of Phenmedipham in Leaf Tissue of Tolerant and Susceptible Species
Authors: Davies H. Maelor , Merydith Alexis , Mende-Mueller Liane , Aapola Alpo
Published: May 2019

Phenmedipham metabolism in leaf tissue of sugarbeet (tolerant) and rapeseed (sensitive) was compared. Sugarbeet leaf discs metabolized phenmedipham much more rapidly than rapeseed leaf discs, forming two metabolites of relatively low polarity. The less polar of these (metabolite 21) was a precursor to the other (metabolite 11), and its properties indicate derivation from phenmedipham by a single hydroxylation and monoglycosylation. Synthetic N-hydroxyphenmedipham was converted by both species into a compound that cochromatographs with metabolite 21. Purified metabolite 21 was much less inhibitory to light-driven oxygen evolution by isolated thylakoids of both species than was phenmedipham. Hydroxylation/glycosylation without prior carbamate hydrolysis appears to be a major factor in the tolerance of sugarbeet to phenmedipham.
Survival and Growth of Big Sagebrush (Artemisia tridentata) Plants in Reciprocal Gardens
Authors: Evans Raymond A. , Young James A.
Published: May 2019

Survival and growth of five collections of big sagebrush were compared in reciprocal transplant gardens. The study was designed to further the understanding of seedling ecology of this important rangeland plant. Survival of transplanted seedlings was not tied to their origin, but antagonism for collection site in survival was apparent for some collections. The site with the highest environmental potential as indexed by native plant community, soil development, and precipitation had the poorest seedling survival. The site with the lowest environmental potential produced seedlings that had the highest survival across all reciprocal gardens. The average mortality level after 3 yr was 11%, indicating that seedlings of big sagebrush can be transplanted successfully. In dry years, the collection from the driest location had the highest amount of juvenile biomass accumulation. However, during a season with much above-normal precipitation this was reversed and the amount of growth for this source was below levels observed for the dry years. The relation between subspecies of big sagebrush and survival or growth of the collections used in this study was not clear. Because collections were made on arid extremes of the subspecies they may reflect introgressive populations among subspecies.
Biodegradation of Butylate, EPTC, and Extenders in Previously Treated Soils
Authors: Harvey R. Gordon
Published: May 2019

Laboratory studies were conducted to determine the ability of the extenders dietholate and SC-0058 to prevent enhanced biodegradation of EPTC and butylate applied to Wisconsin soils with different histories of carbamothioate herbicide use. Enhanced EPTC and butylate biodegradation occurred in soils previously treated with those herbicides. Enhanced biodegradation of dietholate occurred on soils previously treated with that extender plus either EPTC or butylate. Enhanced dietholate biodegradation was observed when applied alone or in combination with butylate or EPTC. Application with dietholate prevented enhanced biodegradation of butylate but not EPTC even though enhanced biodegradation of dietholate was occurring. Enhanced biodegradation of SC-0058 did not occur. SC-0058 prevented enhanced EPTC and butylate biodegradation even in soils previously treated for three consecutive years with the respective herbicide plus SC-0058. Application of either 1.1 or 2.2 kg/ha SC-0058 plus 6.7 kg/ha EPTC provided equal or better wild proso millet control and sweet corn yields than applications of EPTC alone or EPTC plus dietholate.
Effect of Moisture on Chlorimuron Degradation in Soil
Authors: Fuesler Thomas P. , Hanafey Michael K.
Published: May 2019

The overall degradation of chlorimuron was very similar at −0.1 and −1.5 MPa and slightly less in air-dry soil. Degradation rates increased with increasing temperature. The primary 14C-labeled compounds observed in moist-soil extracts were desmethyl chlorimuron and saccharin, while the primary 14C-labeled compound observed in air-dry soil extracts was saccharin. Saccharin is formed quantitatively from ethyl 2-(aminosulfonyl)benzoate (phenylsulfonamide) during extraction and therefore represents phenylsulfonamide formed in the soil as a result of chemical hydrolysis of the sulfonylurea bridge. These degradation products suggest that chemical hydrolysis of the sulfonylurea bridge is the primary mode of degradation in air-dry soil, while microbial degradation and chemical hydrolysis both occur in moist soil. These laboratory results demonstrate that chlorimuron will degrade in air-dry soil at a temperature-dependent rate by chemical hydrolysis.
Adsorption and Desorption of Atrazine, Hydroxyatrazine, andS-Glutathione Atrazine on Two Soils
Authors: Clay Sharon A. , Koskinen William C.
Published: May 2019

Adsorption and desorption isotherms for atrazine and two metabolites, hydroxyatrazine (HA) andS-glutathione atrazine (GSHA), were determined by batch equilibration on Plano and Waukegan silt loam soils at two soil pH levels (Plano, 6.1 and 4.5; Waukegan, 6.1 and 4.0). Freundlich adsorption isotherms were not affected by soil type except for GSHA at pH 4.0 to 4.5. When averaged over both soils, the order of adsorption at pH 6.1 was atrazine (Kf= 3.7) < GSHA (Kf= 7.3) << HA (Kf= 25) and at pH 4.0–4.5 was atrazine (Kf= 6.1) << HA (Kf= 58) ≤ GSHA (Kf: Plano = 35; Waukegan = 78). The average slope of the adsorption isotherms (1/nads) was 0.81. The slopes of all desorption isotherms (1/ndes) were less than their respective 1/nads, indicating hysteresis. Atrazine desorbed into soil solution (1/ndes> 0.0). With the exception of GSHA which desorbed from the pH 6.1 Plano silt loam (1/ndes= 0.15), desorption of HA and GSHA from other treatments was negligible (1/ndes= 0.0). Consequently, leaching of HA and GSHA in these and similar soils is not likely, due to high adsorption and low desorption.
Influence of Simulated Rainfall and Soil Moisture on Herbicidal Activity of Cinmethylin
Authors: Russell Steven G. , Monaco Thomas J. , Weber Jerome B.
Published: May 2019

Field trials were conducted in 1986 and 1987 to determine the effects of moisture on herbicidal activity of cinmethylin applied preemergence at 0.0, 0.3, 0.6, and 0.9 kg ai ha to both dry and moist sandy loam soil. Herbicide application was followed by varying amounts of irrigation. Weed species included velvetleaf, prickly sida, green foxtail, and barnyardgrass. When cinmethylin was applied to a moist soil or when 2.5 cm of irrigation was applied 5 days after cinmethylin application to a dry soil, overall weed control was reduced. Optimum weed control resulted from cinmethylin application to dry soil followed either by a 2.5-cm irrigation within 8 h or a 7.6-cm irrigation within 36 h.
Remote Sensing of Chinese Tamarisk (Tamarix chinensis) and Associated Vegetation
Authors: Everitt J. H. , Deloach C. J.
Published: May 2019

Chinese tamarisk is an invader of riparian sites in the southwestern United States and northern Mexico. Plant canopy light reflectance measurements showed that Chinese tamarisk had higher visible (0.55- and 0.65-μm wavelengths and 0.63- to 0.69-μm waveband) reflectance than did associated woody and herbaceous plant species in the late fall-early winter period when its foliage turned a yellow-orange to orange-brown color prior to leaf drop. Chinese tamarisk had a yellow-orange color on conventional color (0.40- to 0.70-μm) aerial photographs during this phenological stage that made it distinguishable from other plant species. Computer analyses of conventional color film positive transparencies showed that Chinese tamarisk populations could be quantified from associated vegetation. This technique can permit area estimates of Chinese tamarisk infestations on wildland areas.
Physicochemical Aspects of Phloem Translocation of Herbicides
Authors: Bromilow Richard H. , Chamberlain Keith , Evans Avis A.
Published: May 2019

A physicochemical approach to understanding phloem transport of xenobiotics requires that similarities in transport processes in different plant species far outweigh any differences. There is now evidence that this is so, though additional factors such as rate of cuticular penetration, metabolism, and phytotoxicity may differ among plant species and thus may influence distribution patterns. Most herbicides that are translocated in phloem are weak acids, and their transport behavior can now be explained, at least in part, in terms of accumulation and retention in phloem. These processes can, in turn, be explained reasonably well by considering the polarity and acid strength of each compound. Specific carrier processes do not appear to be involved in the transport of most phloem-mobile herbicides. Phloem transport of herbicides has been assessed using the castor bean plant. For acids of pKa <4, intermediate lipophilicity is required for good phloem transport, while weaker acids of pKa >5 and nonionized compounds need to be more polar in order to move well.
LO STATO IN PROSPETTIVA STORICA
Authors: Finer Samuel E.
Published: May 2019

Introduzione

Nonostante l'opinione dei revisionisti, dal mio punto di vista l'Impero romano d'Occidente é veramente crollato; i secoli bui del Medio Evo sono stati veramente bui e iregnache da questo periodo sono faticosamente emersi non erano «stati» nel senso che noi oggi diamo a questo termine. Dopo la caduta dell'Impero romano dovevano passare un migliaio di anni prima che apparisse il «moderno stato europeo». Vorrei sottolineare come, contrariamente a quanto molti ritengono, l'Europa non abbia ‘inventato’ lo Stato. L'Europa lo hareinventatodopo un lungo periodo in cui al crollo era seguita una condizione di quasi anarchia e successivamente il feudalesimo.
PARLAMENTI E PARLAMENTARI NEGLI ANNI OTTANTA
Authors: Mastropaolo Alfio
Published: May 2019

Introduzione

All'interno di quello che si suole ormai definire il mercato politico, il successo degli interessi organizzati ha da qualche decennio a questa parte finito, com'é noto, per cancellare del tutto la tradizionale rappresentazione del parlamento quale baricentro del sistema politico. Superata la fase in cui l'insidia piò grave alle prerogative delle assemblee legislative veniva dai partiti politici, i grandi gruppi d'interesse funzionali hanno addirittura dato luogo ad un secondo circuito rappresentativo in pieno regola, postosi decisamente in concorrenza rispetto a quello della rappresentanza politica democratica, che ha nel parlamento il suo principale punto di transito.
OPINIONE PUBBLICA E COMPETIZIONE PRESIDENZIALE NEGLI STATI UNITI
Authors: Mattei Franco
Published: May 2019

Introduzione

Nel corso degli ultimi vent'anni, il processo di selezione dei candidati alla presidenza americana ha prodotto frequenti sorprese politiche ed alcuni vincitori inattesi. Il rapido declino di Muskie e la nomina di McGovern nel 1972, la scelta di Jimmy«Who?»Carter nel 1976, i successi di piò breve periodo di Bush e di Anderson nel 1980, la meteorica ascesa di Hart e le impreviste difficoltá di Mondale nel 1984 sono i casi piò noti offerti dalle recenti campagne elettorali pre-congressuali del partito democratico e repubblicano. L'analisi dei modi e dei tempi con i quali diversi candidati alla Casa Bianca hanno visto mutare radicalmente la propria posizione nella competizione intrapartitica é centrata sulla nozione dimomentum; in essa sono state condensate l'instabilitá e l'incertezza ricorrenti nell'attuale sistema di nomina dei candidati alla presidenza.
SCIENZA POLITICA E RELAZIONI INDUSTRIALI
Authors: Lanzalaco Luca
Published: May 2019

Introduzione

«Nello studio delle relazioni industriali nessuna disciplina, tra le scienze sociali, ha avuto un ruolo meno rilevante della scienza politica»: questa affermazione fatta da Peter Gourevitch, Peter Lange e Andrew Martin in un saggio purtroppo poco conosciuto (Gourevitch, Lange, Martin 1981, 401) induce, da un lato, a domandarsi se effettivamente la latitanza di questa disciplina sia stata grave e, dall'altro, a tentare di colmare parzialmente questa lacuna.
GENESI E SVILUPPI DELLA COMPARAZIONE: UNO, NESSUNO O CENTOMILA METODI?
Authors: Gangemi Giuseppe
Published: May 2019

Introduzione

Per molto tempo, con il termine comparazione si individua il momento centrale dell'argomentazione razionale e soprattutto si afferma la direzione della riflessione logica sulla pratica di ricerca. Di conseguenza, si sostiene che i ricercatori dipendono dai logici, e sono questi che definiscono preventivamente le regole del corretto metodo di ricerca. Tale metodo consiste, per i razionalisti, nel piò e nel meno (cioè nella quantificazione). I logici cartesiani, infatti, usavano chiamare comparazione il confronto per appurare se qualcosa sia maggiore o minore, migliore o peggiore, di un'altra. Nella Logique de Port Royal, viene chiamato comparativo il giudizio per valutare se una cosa è piò o meno di un'altra (1662, II, X; 1969, 199). Questa definizione di comparazione non è dissimile dal «giudizio di confronto» della scolastica tomistica. Tuttavia, la differenza è nella maggiore enfasi posta sul concetto di quantità (il piò o il meno). Una simile definizione è strettamente connessa al tentativo di Cartesio (condiviso dai cartesiani di Port-Royal) di sviluppare la matematica come modello metodologico e come significato ultimo della natura. A proposito della metodologia cartesiana, essa ritiene indispensabile, all'esattezza di ogni raffronto, che ambedue i termini considerati consentano un piò o un meno, e quindi rientrino nel concetto generale di grandezza
COMPARAZIONE E CONTROLLO LOGICO
Authors: Bruschi Alessandro
Published: May 2019

Introduzione

All'espressione «comparazione» vengono attribuiti molti e differenti significati: quasi in ciascuno di essi è previsto l'uso del cosiddetto «metodo logico» (definito nei canoni di Mill) per operare controlli sulle ipotesi. L'importanza accordata al metodo è tale che spesso la stessa comparazione viene ridotta al metodo logico, e il metodo comparato (logico) contrapposto ad altri, quali quello statistico o sperimentale (Smelser 1966, Lijphart 1971).
IL METODO COMPARATO: DUE DECENNI DI MUTAMENTI
Authors: Collier David
Published: May 2019

Introduzione

L'idea che la comparazione sia una «buona cosa» nasce direttamente dal nostro modo intuitivo di comprendere il mondo. La comparazione acuisce la nostra capacità di descrizione e può costituire un prezioso stimolo per la formazione dei concetti. Essa ci fornisce dei criteri per sottoporre a verifica le ipotesi, contribuisce alla scoperta per via induttiva di nuove ipotesi e alla costruzione di teorie. Harold Lasswell, nell'articolo di apertura del primo numero della rivista «Comparative Politics», affermava che il rilievo assunto dalla comparazione in una buona analisi è tale che il metodo scientifico è inevitabilmente comparato (Lasswell 1968, 3).
COMPARAZIONE E SPIEGAZIONE IN SCIENZA POLITICA
Authors: Panebianco Angelo
Published: May 2019

Introduzione

Oltre alle domande su «come» e «perché» comparare, una domanda che vale la pena di porsi in tema di comparazione è: «perché si compara così poco nella scienza politica contemporanea?». A differenza delle domande sul come e sul perché, che sono di carattere metodologico, essa riguarda una questione di fatto. Tuttavia, come nel caso delle altre due, è impossibile rispondere a questa domanda senza mettere in conto le divisioni di fondo che attraversano la comunità internazionale degli scienziati politici (come tutte le altre comunità di scienziati sociali) e che riguardano natura e scopi delle scienze sociali. Come cercherò di dimostrare, partire da questa domanda su un problema di fatto può aiutare anche a meglio definire le questioni del come e, soprattutto, del perché.
TEMPO E RICERCA COMPARATA
Authors: Bartolini Stefano
Published: May 2019

Introduzione

Questo articolo raccoglie una serie di riflessioni metodologiche attinenti al disegno della ricerca preferito dall'autore: una ricerca comparata che combina dimensione di variazione spazialeetemporale. Nel corso del lavoro si cercherà di giustificare tale preferenza. Tuttavia, l'obiettivo principale rimane quello di confrontare questa strategia di ricerca con altre e di porre in rilievo alcune questioni di metodo che le sono specifiche.
Accounting for the Importance of Nonfarm Income on Farm Family Income Inequality in New York
Authors: Boisvert Richard N. , Ranney Christine
Published: May 2019

As the proportion of farm family income due to nonfarm sources continues to grow nationally, it is important to understand how farm families in various regions or states are affected. This paper develops a better understanding of the contribution of income from nonfarm sources to the level and distribution of income among farm families in New York. In analyzing income distribution, the Gini ratio is decomposed to determine the effects of marginal changes in income by source to overall inequality. The results are compared with the simulated changes in income inequality due to changes in income by source as measured by an “adjusted” Gini ratio which accounts specifically for negative farm incomes. Differences in the policy implications from both procedures are compared. The relationships among sources of income and policy implications can be brought into sharper focus by examining both measures.
Information Value in Weed Management
Authors: Gillmeister William J. , Moffitt L. Joe , Bhowmik Prasanta C. , Allen P. Geoffrey
Published: May 2019

Use of the economic threshold to improve the efficiency of preemergent-herbicide treatment decisions is limited by a lack of weed information. An economic model for assessing the expected value of weed information needed to implement a threshold decision rule is developed. Empirical results suggest that early season weed information can have value in cabbage weed management in Massachusetts.
An Economic Analysis of the U.S. Generic Dairy Advertising Program Using an Industry Model
Authors: Liu Donald J. , Kaiser Harry M. , Forker Olan D. , Mount Timothy D.
Published: May 2019

The market impacts of generic dairy advertising are assessed using an industry model which encompasses supply and demand conditions at the retail, wholesale, and farm levels, and government intervention under the dairy price support program. The estimated model is used to simulate price and quantity values for four advertising scenarios: (1) no advertising, (2) historical fluid advertising, (3) historical manufactured advertising, and (4) historical fluid and manufactured advertising. Compared to previous studies, the dairy-industry model provides additional insights into the way generic dairy advertising influences prices and quantities at the retail, wholesale, and farm levels.
A Conjoint/Logit Analysis of Nursery Stock Purchases
Authors: Gineo Wayne M.
Published: May 2019

Product attributes that determine nursery-stock sales from wholesalers to retail garden centers and landscapers were studied. Conjoint analysis was used to obtain data on buyer preferences. The data were analyzed using ordinary least squares and logit procedures to determine the attributes that are preferred by buyers. It was determined that good- to excellent-quality stock, offerings with a full line of additional plants, taller plants, and cash discounts are desirable attributes. Quality is the dominant attribute affecting preferences. Packaging the preferred attributes together significantly increases the probability of a plant being purchased by buyers.
Food Safety Issues in Canada
Authors: Sutherland Ian R.
Published: May 2019

Canadians enjoy the highest possible level of food safety. Despite this fact, there is a public perception and concern about the potential presence of chemical residues in foods and the possible presence of bacteria, such as salmonella and listeria.
The U.S.-Canada Free Trade Agreement and Agriculture: One Year Later
Authors: Goodloe Carol
Published: May 2019

On January 1, 1989, the much-heralded—or much-maligned, depending on which side of the border you sit—U.S.-Canada Free Trade Agreement (FTA) went into effect. With only a year and a half under its belt, the FTA continues to generate discussion and debate in Canada, as it has ever since Prime Minister Mulroney proposed the idea at the “Shamrock Summit” in 1985. The FTA is actually generating some columns in the U.S. press as well. Agricultural and natural-resource topics remain prominent in U.S.-Canadian trade issues.