bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial Degradation of Flurtamone in Three Georgia Soils
Authors: Mueller Thomas C. , Banks Philip A. , Steen William C.
Published: May 2019

Degradation of flurtamone in a Greenville sandy clay loam, a Cecil loam, and a Dothan loamy sand with 0, 1, or 2 yr of previous flurtamone field use was evaluated under controlled conditions. Soil sterilization by autoclaving significantly reduced flurtamone dissipation rate in all soils. Enhanced degradation of flurtamone was observed in a Greenville sandy clay loam after 1 yr of previous flurtamone field use and in a Cecil loam after 2 yr of previous flurtamone field use. No enhancement of flurtamone degradation was observed in a Dothan loamy sand. Flurtamone degradation kinetics in these studies was described as a first-order process. Microbial populations in each soil showed no major changes in total bacterial numbers due to preexposure to flurtamone in the field.
Flurtamone Adsorption and Mobility in Three Georgia Soils
Authors: Mueller Thomas C. , Banks Philip A.
Published: May 2019

Flurtamone and atrazine adsorption to soil was examined using a batch equilibrium method. Flurtamone mobility in packed soil columns under saturated flow conditions was also evaluated. Adsorption was greater for flurtamone than atrazine in the three soils, and the order of adsorption to soil for both herbicides was Greenville sandy clay loam > Cecil loam > Dothan loamy sand. Greater adsorption of each herbicide corresponded to soils with greater organic matter and clay content. The14C–flurtamone movement under saturated flow conditions in 28–cm soil–packed columns was limited to 16 cm, with no flurtamone leaching from any soil column after the addition of two pore volumes of water. Seventy–five percent of the applied14C–flurtamone remained in the 0– to 4–cm soil depth in the Greenville sandy clay loam, with less than 5 percent moving to a depth > 4 cm. Flurtamone movement was greater in the Cecil loam and the Dothan loamy sand, with movement in each soil to a depth of 16 and 12 cm, respectively.
Influence of Repeated Applications of 2,4-D on Yield and Juice Quality of Concord Grapes (Vitis labruscana)
Authors: Ogg Alex G. , Ahmedullah M. Ahmed , Wright Gale M.
Published: May 2019

In two field experiments over a 4-yr period, 2,4-D amine applied up to four times per year from late April to early June at 2.5, 10, and 25 ppmw produced a wide range of symptoms on ‘Concord’ grapes. When 2,4-D symptoms in July were severe, yields were reduced by as much as 85%. However, when 2,4-D symptoms in July were slight (less than 2 on a 0 to 6 visual scale), grape yields were not reduced. A second-order polynomial described well (R2= 0.92) the relationship between symptoms and grape yield. Symptoms of 2,4-D on grape leaves did not persist beyond the year of treatment, although grape yields did not recover fully until the second year after the last 2,4-D treatment In the first year of 2,4-D treatments, low grape yields were correlated with reduced weight and number of berries per cluster. In the second and third year of treatment, low grape yields were correlated with fewer clusters per shoot in addition to lower cluster weight and fewer berries per cluster. When 2,4-D was applied one year only, soluble solids in the grape juice were reduced as much as 9%, although reductions were not related to severity of foliar symptoms. When 2,4-D was applied for three consecutive years, soluble solids in the juice were consistently higher in grapes with moderate to severe 2,4-D symptoms. There were no consistent effects of 2,4-D on juice color or titratable acidity. The pH of fresh juice was increased slightly by 2,4-D with the maximum being 10% after 3 yr of consecutive treatments. In the first subsequent non-treatment year after 3 yr of 2,4-D treatments, juice quality was similar to the quality of nontreated grapes. At a detection limit of 0.05 ppmw, 2,4-D was not detected in the harvested grapes. Based on the results of these experiments, grapes with slight 2,4-D symptoms would not be expected to have reduced yields or reduced juice quality.
Evidence That Sweet Potato (Ipomoea batatas) is Allelopathic to Yellow Nutsedge (Cyperus esculentus)
Authors: Harrison Howard F. , Peterson Joseph K.
Published: May 2019

In field studies, ‘Regal’ sweet potato greatly reduced yellow nutsedge growth when the two species were grown together using standard cultural practices. At the end of the growing season, yellow nutsedge shoot dry weight per m2in plots where the two species were planted together was less than 10% of shoot weight in plots where nutsedge was grown alone. Presence of yellow nutsedge did not markedly affect sweet potato growth. When grown together in a greenhouse experiment designed to minimize the competitive effects of sweet potato on yellow nutsedge, yellow nutsedge growth was reduced more than 50% by sweet potato 8 and 12 weeks after planting. The most polar fraction of serially extracted sweet potato periderm tissue was highly inhibitory to yellow nutsedge root growth. These results indicate that sweet potato interference with yellow nutsedge under field conditions is partially due to allelopathy.
Clomazone Causes Accumulation of Sesquiterpenoids in Cotton (Gossypium hirsutumL.)
Authors: Duke Stephen O. , Paul Rex N. , Becerril Josea M. , Schmidt John H.
Published: May 2019

The herbicide clomazone caused ultrastructural damage to etioplasts of cotton cotyledons. Etioplast envelopes were irregular, prothylakoids were absent or irregular, stroma density was low, and there were abnormal stromal vesicles. Further damage occurred upon exposure to light. Clomazone greatly slowed the conversion of chlorophyllide to chlorophyll in cotton, suggesting that phytol synthesis was affected. Neither synthesis of protochlorophyllide nor phototransformation of protochlorophyllide to chlorophyllide was affected by clomazone. Clomazone completely inhibited carotenoid synthesis without an accumulation of phytoene. However, the sesquiterpenoids hemigossypol and the dimeric sesquiterpenoid gossypol accumulated in greater amounts in clomazone-treated than in control tissues. These results indicate that this herbicide inhibits synthesis of terpenoids after the formation of farnesyl pyrophosphate.
Interference Durations of Red Rice (Oryza sativa) in Rice (O. sativa)
Authors: Kwon Sam L. , Smith Roy J. , Talbert Ronald E.
Published: May 2019

Red rice at 20 plants m−2was grown with two rice cultivars for 0, 40, 60, 80, 100, or 120 days after emergence. Red rice interference for 120 days after rice emergence reduced straw dry weights of Lemont and Newbonnet 58 and 34%, respectively. Grain yield of Lemont and Newbonnet was reduced 86 and 52%, respectively, by red rice interference for 120 days after emergence. Regression analyses indicated that red rice interference reduced straw dry weights of Newbonnet and Lemont 25 and 50 kg ha−1day−1, respectively, for interference durations of 40 to 120 days after emergence. Grain yield of Newbonnet and Lemont was reduced 60 and 93 kg ha−1day−1, respectively, for interference durations of 60 to 120 days. Negative linear relationships occurred between interference durations of red rice and plant height, panicles m−2, spikelets panicle−1, filled grains panicle−1, or panicle length of both cultivars. However, all parameters were reduced more for Lemont than for Newbonnet as interference duration increased. Head rice (whole kernels) and total milled rice yields of both cultivars were reduced by season-long red rice interference. Red rice straw dry weight and number of culms m−2were greater when red rice was grown with Lemont than when grown with Newbonnet.
False Chamomile Seed Germination Requirements and its Enhancement by Ethephon and Nitrate
Authors: Mekki Mounir , Leroux Gilles D.
Published: May 2019

Dormant weed seeds are difficult to kill and, with the exception of soil sterilization methods, current weed control techniques are not effective against dormant weed seeds. This study was conducted to investigate the effects of temperature, light, soil moisture, burial depth, ethephon, and potassium nitrate (KNO3), and their interactions on the germination of false chamomile seeds under controlled conditions. False chamomile was photoblastic and thermophilic and germinated rapidly within the first 4 days of incubation under all conditions. Regression analysis indicated that ethephon and KNO3had quadratic effects on false chamomile germination. Ethephon enhanced germination more than KNO3. There was a linear reduction in germination with increased storage time, and it is projected that zero germination should occur after 9 yr of storage at room temperature. Soil moisture had a positive linear effect and a positive interaction with ethephon on false chamomile germination. Very little germination occurred when seeds were buried 5 cm deep even with high soil moisture.
Quackgrass (Elytrigia repens) Interference in Canola (Brassica campestris)
Authors: O'Donovan John T.
Published: May 2019

The effects of quackgrass shoot populations shortly after emergence, and dry weight at harvest on yield of canola were determined in four field experiments conducted near Vegreville, Alberta in 1986 and 1988. A hyperbolic model described the data well in most cases and indicated little intraspecific quackgrass interference among quackgrass shoots until populations exceeded 200 shoots m−2. Magnitudes of predicted canola yield losses among experiments were close, even though quackgrass-free yields varied. A pooled hyperbolic equation, based on shoot density, predicted that an intermediate quackgrass infestation of 50 to 100 shoots m−2would reduce canola yield by 18 to 32%. An economic threshold model based on the hyperbolic model provides a means of estimating when control of quackgrass with herbicides is economical.
Influence of Ammonium Sulfate, Imazapyr, Temperature, and Relative Humidity on the Absorption and Translocation of Imazethapyr
Authors: Kent Lisa M. , Wills Gene D. , Shaw David R.
Published: May 2019

The effects of 1.24 kg ha−1ammonium sulfate, 5 g ae ha−1of the isopropylamine salt of imazapyr, and air temperatures of 18, 27, or 35 C at 40 or 100% relative humidity (RH) on the absorption and translocation of the ammonium salt of14C-imazethapyr applied postemergence to pitted morningglory were evaluated. Absorption of14C-imazethapyr was greater at 100 than at 40% RH (88 vs. 47%). At 40% RH, absorption was increased to 79% by the addition of ammonium sulfate. At 100% RH absorption was similar with all treatments. Translocation of14C-imazethapyr applied alone was greater at 100 than at 40% RH (34 vs. 17%). Addition of ammonium sulfate increased translocation at 40% RH but not at 100%. Addition of imazapyr did not affect14C translocation. Distribution of14C throughout the plant was more acropetal than basipetal with the greatest distribution at 35 C.
Adsorption of Chloridazon by Soils and their Components
Authors: Sánchez-Martín Maria J. , Sáanchez-Camazano Maria
Published: May 2019

The effect of soil composition on adsorption of chloridazon by 18 samples of natural soils, with different chemical and textural characteristics, obtained from west-central Spain, was investigated. The effect of removal of organic matter on adsorption and adsorption of the herbicide by the active components of the soils (montmorillonite and humic acid) was also studied. A highly significant correlation was found between the distribution coefficient (Kd) and organic matter content when all the soils or the soils with organic matter content >2% were considered. According to the determination coefficients (r2), organic matter content accounted for 72% of the variance in adsorption in the former case and 92% in the latter. In soils with an organic matter content <2%, there was no correlation between Kd and organic matter content. A significant correlation was observed between Kd and smectite content for soils containing smectite in their clay fraction. Both simple and multiple correlations showed that clay content, excluding the smectite fraction, had a relatively small effect on adsorption of the herbicide. Adsorption of chloridazon by oxidized soils, montmorillonite, and humic acid confirms the effect of organic matter and smectite on adsorption in natural soils.
Applications of Physiological Ecology to Weed Science
Authors: Holt Jodie S.
Published: May 2019

Weed scientists are trained broadly in agronomy, botany, chemistry, soils, and other agricultural disciplines. The study of weeds, rather than the techniques used or the questions asked, unifies weed scientists around a common focus. It is often difficult for weed scientists to identify closely with any one scientific discipline, since the techniques and questions of many disciplines are needed to address problems posed by weeds. One discipline with relevance and potential for addressing weed science problems is physiological ecology. The study of the functioning or adaptation of plants in relation to environmental influences has its roots in both classical ecology and experimental physiology. Application of this discipline to weed science may take an environmental approach (e.g., studying limiting factors in the environment), a physiological approach (e.g., studying the responses of critical plant processes to environmental stress), or a more autecological approach (e.g., studying the physiological basis for the adaptation of a particular weed to a particular habitat). Many methodologies and technologies are available for both field and laboratory investigations. For example, photosynthesis, a major determinant of plant growth, can be investigated in the field at the leaf, plant, or canopy level using plant growth analysis or a portable infrared gas analyzer (IRGA) and appropriate assimilation chambers. Investigations of photosynthesis in the laboratory can focus on the plant, leaf, chloroplast, or thylakoid level using an IRGA or the techniques of polarography (measurement of evolved oxygen) or fluorometry. Application of such approaches to weed science should improve our understanding of the basis for particular weed problems and thus broaden our options for management.
Techniques for Detecting Grass Tolerance to Sethoxydim and Fenoxaprop-Ethyl Herbicides
Authors: Hubbard Joanna , Whitwell Ted
Published: May 2019

Measurements of net photosynthesis, chlorophyllafluorescence and solute leakage were evaluated as techniques for rapid detection of grass tolerance to fenoxaprop-ethyl and sethoxydim. Net photosynthesis measured as net CO2uptake of the youngest fully expanded leaf ofCalamagrostis arundinacea‘Karl Foerster’ (Feather Reed Grass) detected tolerance to fenoxaprop-ethyl and susceptibility to sethoxydim 4 days after treatment and prior to the observation of visual injury. Sethoxydim reduced photosynthesis compared to untreated controls but fenoxaprop-ethyl did not. Measurements of older leaf (second most recently fully expanded leaf) photosynthesis were less consistent than those of the younger leaf. Chlorophyllafluorescence ofCalamagrostisleaf segments following treatment with fenoxaprop-ethyl and sethoxydim was ineffective for detecting grass tolerance. Solute leakage from leaf discs treated with 50 to 500 μg ml−1fenoxaprop–ethyl and 10 to 100 μg ml−1sethoxydim indicated differential tolerance ofCalamagrostisand johnsongrass to fenoxaprop–ethyl and centipedegrass and johnsongrass to sethoxydim. Fenoxaprop–ethyl increased solute leakage from susceptible johnsongrass at 100 μg ml−1while the 500 μg ml−1concentration was required to cause substantial solute leakage from tolerantCalamagrostis. Sethoxydim caused greater leakage from johnsongrass than from centipedegrass at 50 and 100 μg ml−1. The best potential rapid screening technique was solute leakage measurements.
Chlorsulfuron Tolerance and Acetolactate Synthase Activity in Corn (Zea maysL.) Inbred Lines
Authors: Forlani Giuseppe , Nielsen Erik , Landi Pierangelo , Tuberosa Roberto
Published: May 2019

Seven corn inbred lines previously shown to differ in response to soil residues of chlorsulfuron were characterized as to the target-enzyme acetolactate synthase (ALS) specific activity and to its susceptibility to the herbicide. ALS from plantlets at the five-leaf stage of growth was similarly susceptible to chlorsulfuron in all lines and its specific activity in the shoots was not significantly correlated with in vivo tolerance to the herbicide. By contrast, differences in ALS specific activity in roots of plants both at the five- and three-leaf stages of growth were significantly correlated (r = 0.96∗∗and r = 0.93∗∗, respectively) with in vivo tolerance. Correlation was also noted in extracts from cultured excised root tips (r = 0.94∗∗). Callus tissue of a chlorsulfuron-tolerant line was less affected by the herbicide and had a significantly higher ALS specific activity than callus from a chlorsulfuron susceptible line, whereas inhibition of ALS by the herbicide was similar in both lines. These results indicate that the naturally occurring differences in ALS levels in the roots of the investigated inbred lines contribute largely to the differential in vivo response observed to chlorsulfuron.
Competitive Ability of Wild Oats (Avena fatua) and Barley (Hordeum vulgare)
Authors: Dunan Claudio M. , Zimdahl Robert L.
Published: May 2019

Replacement series and growth analysis experiments under greenhouse and field conditions quantified and explained the competitive ability of wild oats and barley. Barley was a stronger competitor than wild oats under greenhouse and field conditions. The reciprocal yield approach showed that barley's intraspecific competition was 7.3 times greater than its interspecific competition with wild oats when calculated on a dry weight per plant basis. When leaf area per plant was the yield variable, barley's intraspecific competition was only 2.4 times greater than its interspecific competition. The difference was explained by wild oats' higher leaf area ratio. Barley had a greater leaf area, root and shoot biomass, absolute growth rate, and shoot-root ratio than wild oats, but wild oats' leaf area ratio was always higher. No differences were detected in relative growth rate and net assimilation rate.
Growth and Interaction of Bermudagrass (Cynodon dactylon) by Cotton (Gossypium hirsutum)
Authors: Keeley Paul E. , Thullen Robert J.
Published: May 2019

Several weed-free and bermudagrass competition periods were established and maintained in cotton to evaluate their influence on cotton yields and reproduction of bermudagrass. Cotton sprayed with fluazifop for bermudagrass control 4 or 8 weeks after emergence yielded 93 and 90% as much as weed-free cotton. This compared to losses of 16 and 26% when bermudagrass was permitted to compete with cotton for 12 and 25 weeks, respectively. Cotton handweeded for 8 to 12 weeks yielded the same as weed-free cotton and 9% more than cotton weed free for only 4 weeks. Bermudagrass seed production was prevented and rhizome production was negligible when weed competition did not exceed 8 weeks and weed-free periods exceeded 4 weeks. Bermudagrass produced significant amounts of seeds (45 to 88% of weedy checks) and rhizomes (9 to 31% of weedy checks) in plots weed free for 4 weeks and in plots where control was delayed for 12 weeks. Cotton grades were reduced because the cotton lint was contaminated with grass in plots weed free for only 4 weeks, and in plots where bermudagrass competed for 25 weeks.
Functional Relationships of Growth and Competitiveness in Perennial Weeds and Cotton (Gossypium hirsutum)
Authors: Holt Jodie S. , Orcutt Deborah R.
Published: May 2019

Growth characteristics and competitive relationships of cotton and three perennial weeds (johnsongrass, purple nutsedge, and yellow nutsedge) were investigated at the USDA Cotton Research Station in Shafter, CA. In growth analysis experiments, yellow nutsedge and johnsongrass had highest values for height, biomass, leaf area production, growth rate, and photosynthetic efficiency. The weeds exhibited greater overall resource use and production efficiency than cotton, while cotton attained greater leafiness and canopy closure than weeds over the 10-wk experiment. Linear correlation indicated that most growth variables were significantly correlated with aggressivity (competitiveness); however, all correlation coefficients were less than 0.80. Stepwise multiple regression, using aggressivity as the dependent variable, defined 4 growth variables out of 12 that best described competitiveness. These were unit leaf rate (ULR), height, relative growth rate (RGR), and initial propagule weight (PWT). Thus, parameters of light utilization (ULR, height) and early establishment (RGR, PWT) were best predictors of competitive success in this system.
Emergence Periodicity of Six Summer Annual Weed Species
Authors: Egley Grant H. , Williams Robert D.
Published: May 2019

Emergence periodicity of common purslane, hemp sesbania, horse purslane, prickly sida, spurred anoda, and velvetleaf was determined from March to October during 5 yr at Stoneville, MS, in the absence of reseeding. In early March of each year prior to emergence determinations, plots were not tilled or tilled to depths of 0, 5, 10, or 15 cm. Yearly emergence periodicity of the six weed species was not affected by tillage. In each year, weeds of all species emerged in identifiable flushes and very few emerged at other times during the growing season. Velvetleaf emerged mainly during the early growing season from March through May. Peak periods of emergence for the other species varied slightly over the 5 yr, but conformed generally to the early or the midseason peak period (June, July, and August) or both. In most years, common purslane, horse purslane, hemp sesbania, prickly sida, and spurred anoda emerged during the midseason period. Annual patterns of temperature fluctuations were similar during the 5 yr, but relatively warm soil temperatures during the early growing season of 1977 may have caused earlier emergence of velvetleaf, prickly sida, and hemp sesbania. Weekly water balance (rainfall minus open-pan evaporation) varied during March through May of each year but was negative during each June, July, and August. Apparently the main effect of a positive water balance during most of the year was to cause merger of the early and midseason peak emergence periods in 1979. Early and midseason emergence peaks were possibly due to different populations of seeds able to germinate in cooler soil temperatures of the early season and warmer soil temperatures of the midseason, respectively.
Factors Influencing Germination of Field Violet (Viola arvensis)
Authors: Doohan Douglas J. , Monaco Thomas J. , Sheets Thomas J.
Published: May 2019

Field violet germination occurred during May to early July and again during September to November in Nova Scotia (N.S.), Canada. Germination occurred from October until early April in the North Carolina (NC) piedmont. Germination was stimulated by tillage. Seed collected in N.S. and in NC germinated optimally in the dark under a temperature regime of 15/5 C, on an 8/16 h thermoperiod. Germination at constant temperatures decreased with increasing temperatures, from 5 to 25 C. Seed collected in NC was capable of germinating at a higher constant temperature of 25 C than seed collected in N.S. Germination of seed collected in NC was partially inhibited by constant irradiance with a photosynthetic photon flux density of 100 μM m−2 s−1 (400 to 700 nm). Seed did not germinate when exposed to constant red or far-red irradiance.
Effect of Herbicide Rotations on Enhanced Herbicide Biodegradation and Wild-Proso Millet (Panicum miliaceum) Control
Authors: Harvey R. Gordon
Published: May 2019

A 6-yr field study was conducted to determine the effect of herbicide rotations on enhanced biodegradation of EPTC applied with and without dietholate, and on long-term control of wild-proso millet in sweet corn. Alachlor plus pendimethalin plus cyanazine or cycloate plus cyanazine for 1 yr following previous EPTC plus cyanazine applications reduced enhanced EPTC biodegradation in 3 of 4 and 2 of 3 yr, respectively. Enhanced biodegradation of EPTC applied with dietholate was reduced in 1 of 2 yr when EPTC plus dietholate plus cyanazine treatments were followed for 1 yr by alachlor plus cyanazine, pendimethalin plus cyanazine, or cycloate plus cyanazine, but was not reduced in 2 of 3 yr when EPTC plus dietholate plus cyanazine treatments were followed for 1 yr by alachlor plus pendimethalin plus cyanazine. Dietholate biodegradation was enhanced in soils treated 1, 2, or 3 yr previously with one application of EPTC plus dietholate plus cyanazine. After 3 yr of repeated use, cycloate biodegradation was also enhanced. Continuous use of EPTC plus cyanazine and EPTC plus dietholate plus cyanazine over 6 yr provided an average of only 46 and 64% wild-proso millet control, respectively. When applied once every second, third, or fourth year in rotation with alachlor plus pendimethalin plus cyanazine or cycloate plus cyanazine, EPTC plus cyanazine provided 83, 86, and 95% wild-proso millet control, respectively. EPTC plus dietholate plus cyanazine applied every second, third, or fourth year in rotation with cycloate plus cyanazine, alachlor plus cyanazine, pendimethalin plus cyanazine, or alachlor plus by pendimethalin plus cyanazine provided 88, 91, and 95% wild-proso millet control, respectively.
Salt Antagonism of Glyphosate
Authors: Nalewaja John D. , Matysiak Robert
Published: May 2019

Glyphosate is often applied with diammonium sulfate to increase weed control. However, many other salts in the spray carrier have antagonized glyphosate phytotoxicity. Research was conducted with wheat as a bioassay species to further determine the influence of various salts on glyphosate phytotoxicity. Cation antagonism of glyphosate occurred with iron > zinc > calcium ≥ magnesium > sodium > potassium. Ammonium cation with hydroxide or most other anions was not antagonistic. Anions of ammonium compounds were of primary importance in overcoming glyphosate antagonistic salts, while the ammonium cation was neutral or slightly stimulatory with certain anions. Sulfate, phosphate, citrate, and acetate anions were not antagonistic, but nitrate and chloride anions were slightly antagonistic when applied as ammonium salts or acids. Antagonism of glyphosate action by sodium bicarbonate and calcium chloride was overcome by phosphoric, sulfuric, and citric acid and phosphate, sulfate, and citrate ammonium salts. Acid and ammonium salts of nitrate and chloride were more effective in overcoming sodium bicarbonate than calcium chloride antagonists of glyphosate. Ferric sulfate antagonism was overcome only by citric, partly by phosphoric and sulfuric but not by nitric and hydrochloric acids or their ammonium salts. Acetic acid, ammonium acetate, and ammonium hydroxide did not overcome any salt antagonism of glyphosate. Glyphosate response to salts was independent of spray carrier pH.
Reducing Imazethapyr Injury to Field Corn (Zea mays) with Naphthalic Anhydride
Authors: Boldt Laura D. , Barrett Michael
Published: May 2019

A field trial was conducted in 1988 and 1989 to confirm the efficacy of naphthalic anhydride (NA) for providing full-season protection of corn from imazethapyr applied at various times and rates. NA applied as a 1% by weight dust to corn seed caused 6% injury 2 weeks after treatment (WAT) in 1989; however, plants recovered within 6 WAT and grain yield was not affected. Imazethapyr applied to corn untreated with NA resulted in greater than 30% injury for all treatments in both years except PRE in 1988. NA reduced phytotoxicity from all imazethapyr applications in 1989 and from PPI, early POST, and 4- to 5-leaf stage (mid-POST) applications in 1988. Despite the safening effect, corn injury was still observed 6 WAT in NA-treated corn for all imazethapyr applications in both years except early POST in 1988. Higher yields were produced from NA-treated than untreated corn with imazethapyr applied PPI in both years, PRE in 1989, early POST in both years, and mid-POST in 1988. Safened corn treated PPI and early POST yielded the same as the safened corn in the control in both years. Imazethapyr applied at the 8- to 10-leaf stage caused total yield loss regardless of NA treatment. Drought conditions may have caused the lower corn injury and yield loss from imazethapyr observed in 1988 compared to 1989.
Influence of Growth Stage and Broadleaf Herbicides on Tralkoxydim Activity
Authors: Harker K. Neil , Blackshaw Robert E.
Published: May 2019

Experiments were conducted at the Lacombe and Lethbridge Research Stations to determine tralkoxydim activity at two leaf stages of green foxtail and wild oat and to determine tralkoxydim activity in tank mixtures with bromoxynil and thifensulfuron. Green foxtail and wild oat control was usually better when tralkoxydim was applied at the 2- to 3-leaf stage. However, tralkoxydim applied at the 4- to 5-leaf stage of the weeds often led to less weed topgrowth at harvest because later flushes of green foxtail and wild oat often occurred after the early applications. Nevertheless, wheat and barley yields usually indicated the importance of early weed removal. In greenhouse and field tank mixture studies, thifensulfuron antagonized tralkoxydim activity on green foxtail more than wild oat. Bromoxynil was less antagonistic than thifensulfuron, but significant reductions in green foxtail and wild oat control were detected in tralkoxydim tank mixtures with bromoxynil. In field studies, control of false cleavers with thifensulfuron or bromoxynil was not reduced in tank mixtures with tralkoxydim.
Interactions of Herbicides with Water-Soluble Soil Organic Matter
Authors: Pennington Karrie L. , Harper Sidney S. , Koskinen William C.
Published: May 2019

Interactions of water-soluble soil organic matter (WSSOM) with the herbicides bromacil, metribuzin, alachlor, diquat, and paraquat were examined to determine if these interactions can improve predictions of herbicide leaching potential. A high-performance liquid chromatography gel filtration column was used to separate WSSOM extracts from four mineral agricultural soils into fractions with approximate log molecular weights of 4.96 to 6.82. WSSOM fractions were predominantly anionic in nature with some hydrophobic character. The amount of paraquat bound by WSSOM ranged from 1.1 to 2.1 mmol g−1DOC−1 with KDOC (partition coefficient for dissolved organic carbon) values from 0.050 to 0.187 L kg−1. Diquat was bound at 0.9 to 1.5 mmol g−1DOC−1 by the extracts with KDOC values from 0.044 to 0.143 L kg−1. Bromacil, metribuzin, and alachlor did not bind to the extracts tested. WSSOM did not increase paraquat solubility in the presence of soil. Binding of these herbicides to WSSOM in the soils used in this study would not be a significant mechanism for increased mobility and groundwater contamination potential.
Biological Control of Jimsonweed (Datura stramonium) withAlternaria crassa
Authors: Boyette C. Douglas , Weidemann Gregory J. , Beest D. O. Te , Quimby P. C.
Published: May 2019

In field experiments conducted from 1985 to 1987 in Mississippi and Arkansas, jimsonweed was successfully controlled with the fungusAlternaria crassa(Sacc.) Rands. Conidial applications of the fungus provided an average of 96% control in Mississippi, and 87% control in Arkansas. Mycelial formulations were less effective than conidial applications overall, but during periods of favorable environmental conditions, weed control provided by the mycelial formulations was similar to that provided by conidial preparations. These results indicate thatAlternaria crassahas potential as a mycoherbicide for controlling jimsonweed.
VALORI E DOMANDA POLITICA LATENTE
Authors: Calvi Gabriele
Published: May 2019

Introduzione

I risultati di numerosi sondaggi consentono di identificare la struttura del consenso ai valori, che mostra una sorprendente analogia con la struttura sociale e rispecchia la tensione culturale piò rilevante del nostro tempo. Mi propongo, ora, di riferire sommariamente tali risultati e di interpretarli secondo l'ipotesi che piò mi convince, ancorchè non sia l'unica possibile.
AUSTERITÀ CONSERVATRICE E RIGORE SOCIALISTA: CHE DIFFERENZA? I
Authors: Pappalardo Adriano
Published: May 2019

Introduzione

I partiti socialisti dell'Europa meridionale sono gli attori politici sui quali piò si è concentrata l'attenzione della comunità scientifica negli anni ottanta. Tre ragioni, piò o meno connesse, spiegano questo fenomeno, che rappresenta una svolta rispetto all'indifferenza, o all'interesse marginale, a lungo prodotti dal tema. La prima — ovvia — è la rapida scalata al potere dei partiti in questione, sull'onda di maggioranze elettorali senza precedenti nei paesi interessati. Quali caratteristiche avrebbe assunto la loro azione di governo, gli obiettivi ai quali si sarebbe rivolta e le probabilità di successo nel conseguirli, sono stati gli interrogativi inizialmente trattati dai commentatori, piò o meno suggestionati dalle ambizioni programmatiche del socialismo francese (Wright 1984; Beaud 1983), o dal piò cauto, ma pur sempre significativo, «cambio» annunciato da quelli spagnoli (Psoe 1982) o portoghesi.
SCIENZA POLITICA E DIRITTO: COMMENTO
Authors: Bartole Sergio
Published: May 2019

Introduzione

L'invito a intervenire sull'importante contributo di Leonardo Morlino (1989) mi consente di ritornare su un argomento — quello dei rapporti fra la scienza politica e la scienza del diritto costituzionale — cui ho già dedicato in altre occasioni una qualche riflessione (1985, 1986). Debbo confessare di guardare con un po’ di invidia all'iniziativa che Morlino ha preso di tracciare una sorta di bilancio dello stato della sua disciplina. Sono, in effetti, convinto che molto spesso gli studi di diritto costituzionale stiano procedendo senza una precisa consapevolezza della direzione da prendere, delle manchevolezza che li connotano e delle risposte di ordine scientifico che da essi si attendono: mancano adeguate meditazioni di ordine teorico e metodologico, e troppo spesso contributi monografici e saggistici nascono in obbedienza a quella che Morlino chiama una «logica esterna», e quindi senza una seria attenzione alla «logica interna» alla disciplina ed alle connesse preoccupazioni di ordine sistematico. Né vale rispondere che le preoccupazioni metodologiche e teoriche rappresentano fughe in avanti rispetto all'analisi e considerazione dei problemi concreti, di fronte ai quali soltanto ha senso proporre questioni di teoria e metodo, che, se formulate in astratto, restano nel limbo delle pie dichiarazioni di intenti, senza trovare adeguato riscontro nella attività pratica di ricerca. La mancanza di un bagaglio metodologico e teorico solo in apparenza allevia le fatiche del viaggiatore e, in realtà, lo obbliga a rifare il punto astronomico ad ogni giro di strada, anche al di là delle normali e corrette esigenze di una responsabile autocritica e di un doveroso autocontrollo.
RISPOSTA
Authors: Sartori Giovanni
Published: May 2019

Introduzione

Come Panebianco spiega benissimo, tutto è fermo anche perché i politici al potere si aggrappano come colla al potere che hanno. Gli studiosi non li debbono aiutare (nel bloccare tutto) con i loro dissensi. Se, dunque, rispondo sia a lui come a Passigli, è a fini di chiarimento costruttivo. Il mio intento è di cercare convergenze, accantonando dissensi secondari, innecessari o comunque superabili.
‘My Favorite Song’: understanding a music learning ecology of children from interaction among media, family and school contexts
Authors: Ocaña-Fernández Almudena , Reyes-López Mª Luisa
Published: May 2019

In the present case study, we used observation and interviews to investigate the musical experience of a group of children of 3–4 years old. We look into the uniqueness of music in the child’s environment which belongs to the media, family and school contexts. The present study allows us to understand some implications of musical experiences for building social identity and the need to link formal music learning processes with those taking place in non-formal and informal spaces. Through this paper, we provide a vicarious experience that will enable the reader to understand our findings and raise new questions and interpretations.
Towards an informed public
Authors: Ingram D. S.
Published: May 2019

Synopsis

The successful utilisation of recent advances in plant biotechnology for the benefit of mankind, with the avoidance of fundamental mistakes that could lead to environmental disaster, requires wise and balanced legislation. In addition, the conservation of the habitats and germplasm so essential to plant breeding requires carefully planned management of resources. These, however, depend upon an informed public with a sensitivity to, and knowledge and understanding of, the issues at stake. It is the people, after all, who influence decision making by governments, through the ballot box or through the pressure of public opinion. Botanic Gardens have a vital role to play in public education, and have the capacity to become the shop windows for the whole of plant science.

Four examples of public education in plant biology being developed at the Royal Botanic Garden Edinburgh are considered, as follows:

(i) Public information, as exemplified by the provision of information about plants, lectures about plants and the development of ecological plantings and displays relating to agriculture, plant breeding and conservation.

(ii) Contact through art, as exemplified by the Andy Goldsworthy retrospective exhibition of 1990 and the 1991 exhibitions of the work of Redouté and Margaret Stones, in which the media of sculpture and painting inspired by the natural world have been used to build bridges between plant science and the wider public.

(iii) Education in primary schools, as exemplified by the ‘Living in a Rainforest’ project, in which young people and their teachers spend periods of time in a replica of a Bornean longhouse and through this experience develop an understanding of the importance of the balance between people and the complex ecosystem of the rainforest.

(iv) Education in secondary schools, as exemplified by the Science and Plants for Schools project in which rapid cycling Brassica rapa and other materials are used in the development of new and exciting approaches to the teaching of experimental plant science, genetics and breeding.

The ways in which projects such as these can be designed to convey important messages concerning plant breeding, genetic engineering, germplasm and habitat conservation and the role of plants in the world economy are discussed, and ideas for other approaches to public education in the Royal Botanic Garden Edinburgh are outlined.
RELATIONSHIPS BETWEEN IMPORTANCE MEASURES AND REDUNDANCY IN SYSTEMS WITH DEPENDENT COMPONENTS
Authors: Navarro Jorge , Fernández-Martínez Pedro , Fernández-Sánchez Juan , Arriaza Antonio
Published: May 2019

The paper shows the connections between some importance indices for the components in an engineering coherent system and the performance of the system obtained when a redundancy mechanism is applied to a specific component. A copula approach is used to model the dependency among the components. This approach includes the popular case of independent components. Under some assumptions, it is proved that if component i is more important than component j, then the system obtained by applying a redundancy procedure to the ith component is better, under different stochastic criteria, than that obtained with the jth component. These results can be applied to several redundancy mechanisms. A new importance index is defined to study active redundancies. Some illustrative examples are provided.
A Comparison of CT Contrast Enhancement and BUDR Labeling Indices in Moderately and Highly Anaplastic Astrocytomas of the Cerebral Hemispheres
Authors: McDermott Michael W. , Krouwer Hendrikus G.J. , Asai Akio , Ito Satoyuki , Hoshino Takao , Prados Michael D.
Published: May 2019

Contrast enhancement on computerized tomography (CT) scans has been used in directing therapy for presumed intracranial gliomas. However, for moderately anaplastic astrocytomas (MOAAS) and highly anaplastic astrocytomas (HAAS), it provides no information about proliferative potential. The bromodeoxyuridine (BUDR) labeling index (LI), however, indicates proliferative potential, correlating with histologic malignancy and survival. An LI < 1% is a favorable indicator; LI > 5% suggests more aggressiveness. To determine the correlation, if any, between BUDR LI and contrast enhancement, CT scans of 71 patients with cerebral hemisphere tumors labeled with BUDR were retrospectively reviewed. Among 36 MOAAS, the BUDR LI was < 1% in 77% of enhanced tumors and 61% of unenhanced tumors. Among 35 HAAS, it was < 5% in 56% of enhanced tumors and 90% of unenhanced tumors. Therefore, contrast enhancement on CT scans does not always correctly predict proliferative potential in these tumors, and biopsy and labeling studies are recommended before therapy.
Is Cerebral Arteritis the Cause of the Landau-Kleffner Syndrome? Four Cases in Childhood with Angiographic Study
Authors: Pascual-Castroviejo Ignacio , Martín V. López , Bermejo A. Martínez , Higueras A. Pérez
Published: May 2019

Four children with Landau-Kleffner syndrome were studied over a six year period. They presented with acquired aphasia, epilepsy, and focal or generalized EEG discharges which were exacerbated during sleep. In addition, cerebral angiography demonstrated isolated arteritis of some branches of the carotid arteries in all cases. Computed tomographic and magnetic resonance images were normal. Nicardipine in a dose of 1 to 2 mg/kg/day, added to conventional anticonvulsant drugs provided effective supplementary control of seizures, of paroxysmal EEG discharges, and of language and behavioural disturbances, even several years after the onset of the disorder and in patients whose response to other medications, including steroids, had been poor. Interruption of nicardipine administration was followed by relapse of the language disorder. Repeat angiography was performed in all four patients and showed recanal-ization of obstructed vessels in two cases. Focal cerebral vasculitis may be the pathogenesis of the Landau-Kleffner syndrome and calcium channel blockers such as nicardipine may be effective and specific therapy.
A Comparison of Methods to Assess the Excitability of Lower Motoneurones
Authors: Milanov Ivan G.
Published: May 2019

The purpose of this investigation was to compare three methods of assessing the excitability of lower motoneurones—TA-reflex, H-reflex and F-wave—in 120 patients with spastic hemiparesis following a stroke. The H-reflex was recorded from the soleus muscle after submaximal electrostimulation of the tibial nerve. The T-Achilles (TA) reflex was recorded from the soleus muscle after percussion of the Achilles tendon. The F-wave was recorded in the distal limb muscles after supramaximal electrostimulation of the median, ulnar, fibular and tibial nerves. The patient’s healthy side was used as a control. The TA-reflex, H-reflex and F-wave showed increased amplitudes on the spastic side. All amplitude ratios: TA/M, H/M, Fmax/M and Fmean/M were increased. The H-reflex thresholds were decreased. The F-wave duration, persistence and number of phases were also increased on the spastic side. Despite clinically decreased muscle tone, there were no changes in TA or H-reflex parameters after treatment. On the other hand, F-wave parameters tended to normalize after treatment in all groups. In conclusion, the F-wave is a more sensitive method than the TA and H-reflexes in assessing the excitability of the lower motoneurone.
Neurodevelopmental Criteria in the Classification of Congenital Motor Nystagmus
Authors: Jan J.E. , Carruthers J.D.A. , Tillson G.
Published: May 2019

Congenital motor nystagmus (CMN) can be familial or non-familial. The expressivity of CMN is so variable that in one affected member of the family the oscillations are obvious, while in the others the nystagmus could be overlooked even by the patients themselves. In spontaneous cases the proof of heredity might be discovered by an ophthalmological examination or eye movement recordings of other family members. Our multidisciplinary studies of 27 children with CMN suggests that a neurodevelopmental assessment can also be valuable in establishing a diagnosis of heredity. Our studies suggest that the hereditary form of CMN is free from neurodevelopmental problems, while the non-familial form is not. Therefore, children with spontaneous CMN could be referred for neurodevelopmental evaluation in order to establish a more accurate diagnosis.
Beta-Adrenoceptor Modulation in a Case of Pure Autonomic Failure
Authors: Perna Sergio , Leone Rocco , Farace Maria Jussie , Brescia-Morra Vincenzo , Campanella Giuseppe , Brevetti Gregorio
Published: May 2019

In a patient with pure autonomic failure, exercise did not modify beta-adrenoceptor density, probably due to an insufficient increase in plasma catecholamines. Isoproterenol infusion increased the number of beta-adrenoceptor by only 17%. Since in control subjects an increased beta-adrenoceptor level was found, following both physical stress and isoproterenol infusion, we suggest that the lack of increased beta-adrenoceptor levels may contribute to the poor circulatory adjustments observed in autonomic dysfunction during activities involving the sympathetic nervous system.
Myasthenia Gravis in a Child with Sequelae of Opsoclonus-Myoclonus Syndrome
Authors: Wilfong Angus A. , Fernandez Fabio
Published: May 2019

Immune-mediated myasthenia gravis occurred in a 13-month-old girl who had sequelae of an opsoclonus-myoclonus syndrome. She had an abnormal Raji cell assay along with elevated antiacetylcholine receptor and antithyroglobulin antibodies. No evidence of an associated malignancy was found with either condition. Clearly, the co-occurrence of two diseases within a single patient does not establish a common pathogenesis. Nevertheless, this is a provocative association and may point to an immunologically mediated process in the opsoclonus-myoclonus syndrome.
The Returns to Agricultural Research in Maine: The Case of a Small Northeastern Experiment Station
Authors: Leiby James D. , Adams Gregory D.
Published: May 2019

Estimates of the marginal internal rate of return to expenditures for research by the Maine Agricultural Experiment Station are presented. Estimates are performed using ridge regression under an array of specifications, including alternative functional forms, lag structures, costs of public funds, and variable specifications. The results are consistent with many previous results that imply an underinvestment in agricultural research.
Physical and Economic Model Integration for Measurement of the Environmental Impacts of Agricultural Chemical Use
Authors: Antle John M. , Capalbo Susan M.
Published: May 2019

Chemical use in agriculture has, over the last fifty years, been the good, the bad, and the uncertain. By all accounts, agricultural productivity increased significantly in the last half century due in part to the introduction and expanded use of agricultural chemicals. More recently, however, some agricultural practices, including increased chemical use, are viewed as having a major impact on the larger ecosystem and as being an important source of environmental nonpoint pollution. Recent groundwater-monitoring programs in the United States sponsored by the U.S. Environmental Protection Agency (EPA) have revealed contamination of underground water supplies by pesticides, nitrates, and other industrial organic chemicals. It has also been questioned whether the high rates of productivity growth that have characterized modern agriculture can be sustained with technologies that disrupt the ecosystem. While there is no doubt that production agriculture does affect the ecosystem, it is not obvious that these effects are necessarily widespread and deleterious to the environment or to long-run productivity, or, if they are, how they should be valued and traded-off with other social objectives.