bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Corn (Zea maysL.) Inbreds and Hybrids to Sulfonylurea Herbicides
Authors: Green Jerry M. , Ulrich Jim F.
Published: May 2019

Extensive field and greenhouse studies were done to characterize varietal response of three recently commercialized sulfonylurea corn herbicides: nicosulfuron, primisulfuron, and thifensulfuron. Most of the 94 varieties tested were highly tolerant to these herbicides. The 37 inbreds represented all major inbred families now used in hybrid seed production as well as several sensitive experimentals. Twenty-one defined hybrids from these inbreds as well as 36 commercially coded hybrids were also tested. Sensitive inbreds produced tolerant hybrids when crossed with tolerant inbreds. Sensitive hybrids occurred when both parents were sensitive. Genetic analysis of sensitive by tolerant crosses showed that sensitivity is controlled by a single recessive gene. Nicosulfuron had the widest corn safety margin and fewest sensitive varieties. Dose response analysis showed varieties can vary more than 40 000-fold in sensitivity. Only corn varieties with the AHAS-modified XA-17 gene showed any change in enzyme sensitivity. This gene overcame sensitivity to sulfonylureas, even when the organophosphate insecticide terbufos was present. Thus, breeders have three options to eliminate sulfonylurea sensitivity: backcross sensitive inbreds with tolerant, always use at least one tolerant hybrid parent, or use the XA-17 gene.
In Vitro Selection of Imazethapyr-Tolerant Tomato (Lycopersicon esculentumMill.)
Authors: Iler Susan E. , Swanton Clarence J. , Pauls K. Peter
Published: May 2019

Effectiveness of cyclical in vitro selection for imazethapyr tolerance in tomato was studied. Cotyledons and leaf explants from shoots regenerated on media containing imazethapyr were used to initiate three successive cycles of selection. Increases in tissue viability, callus initiation, and callus proliferation were observed following three cycles of selection on 10−7M imazethapyr. Dry matter accumulation of unselected tomato seedlings was reduced by 50% when imazethapyr was applied postemergence at a rate of 28 g ae ha−1. Progeny of eight tomato lines selected after one cycle of selection had greater tolerance to imazethapyr than control plants (60 to 70% dry matter accumulation versus 50%, respectively). Variability was also generated for imazethapyr tolerance among progeny of the same tomato line.
Herbicide Comparisons on Quackgrass (Elytrigia repens) Within Different Crop Competition and Tillage Conditions
Authors: Harker K. Neil , O'Sullivan P. A.
Published: May 2019

Five herbicides (cloproxydim, fluazifop, haloxyfop, quizalofop, and sethoxydim) were compared from 1984 to 1988 at 250 and 400 g ha−1for controlling quackgrass within different crop competition and tillage conditions at the Lacombe Research Station. Crop competition usually augmented quackgrass control with the herbicides in conventional-tillage plots although direct statistical comparisons were not made. Without crop competition, haloxyfop and quizalofop at 250 g ha−1were more effective than the other herbicides in conventional tillage 1 mo after treatment (MAT). In a conventional-tillage situation on a unit active ingredient basis, the herbicides ranked in order of decreasing activity as follows: quizalofop ≥ haloxyfop > fluazifop > cloproxydim > sethoxydim. In a zero-tillage situation, none of the herbicides reduced quackgrass shoot weights by 50% 3 MAT. However, haloxyfop and quizalofop were more effective in suppressing quackgrass shoot weight than the other herbicides in the zero-tillage experiments 3 MAT.
Volatile Monoterpenes as Potential Parent Structures for New Herbicides
Authors: Vaughn Steven F. , Spencer Gayland F.
Published: May 2019

Eighteen volatile monoterpenes, which are among the major constituents of essential oils from plants, were screened for phytotoxicity to several crop and weed species. Several monoterpenes containing an oxygen function severely inhibited germination of four different annual weeds while concurrently displaying little effect on soybean germination. Soybeans varied in their sensitivity to various monoterpenes (measured by seedling growth), with α-terpineol and geraniol selectivity inhibiting weed seed germination while having little or no effect on soybeans. All of the monoterpenes tested exhibited relatively high germination and growth inhibition to corn and wheat.
An Automated System for Large-Scale Recovery of Germination Stimulants and Other Root Exudates
Authors: Müller Sigrid , Van Der Merwe Andre , Schildknecht Hermann , Visser Johann H.
Published: May 2019

A large-scale continuous system for recovery of root exudates from millet and cowpea was developed and tested extensively. Large quantities of germination stimulants were exuded into the medium flowing through the plant trays, which could be demonstrated by germination of seeds of three species of angiospermous parasitic plants,Alectra vogelii, Striga gesneriodes, and witchweed. Recovery of root exudates was affected by adsorption on the macroreticular polymer resin XAD-4 followed by desorption with methanol. Furthermore, indications were found that germination inhibitors are released into the medium. Subsequent testing confirmed the quantitative release of the germination stimulants as well as a large number of other compounds.
Absorption and Activity of Nicosulfuron and Primisulfuron in Quackgrass (Elytrigia repens) as Affected by Adjuvants
Authors: Bruce Joseph A. , Penner Donald , Kells James J.
Published: May 2019

Greenhouse and field experiments were conducted to examine foliar absorption and activity of nicosulfuron and primisulfuron by quackgrass with various adjuvants. Foliar absorption of14C-nicosulfuron and14C-primisulfuron plus petroleum oil adjuvant (POA) was completed by 4 h after application. Absorption of nicosulfuron plus POA and primisulfuron plus POA increased from 11 and 2% of applied, respectively, to 51 and 12% with the addition of urea-ammonium nitrate liquid fertilizer (UAN). At least 83% of the absorbed14C from either herbicide penetrated the leaf epicuticular waxes. Absorption of14C-labeled herbicides was greatest with the following adjuvants: POA + UAN > nonionic surfactant (NIS) + UAN = methylated seed oil. The addition of UAN to either NIS or POA significantly increased14C-herbicide uptake. In greenhouse studies, nicosulfuron and primisulfuron applied with POA plus UAN provided greater quackgrass control than with POA alone. Despite the differences in foliar uptake in the greenhouse, few differences were observed between these adjuvants in 1989 or 1990 field efficacy trials. Quackgrass control was reduced by the addition of atrazine to nicosulfuron plus POA in 1989 and to primisulfuron plus POA in 1990. Combinations with atrazine did not reduce14C-nicosulfuron or14C-primisulfuron uptake by quackgrass.
Leaching of Dichlorprop, Bentazon, and36Cl in Undisturbed Field Lysimeters of Different Agricultural Soils
Authors: Bergström Lars F. , Jarvis Nicholas J.
Published: May 2019

A leaching test conducted in field lysimeters for the purpose of pesticide registration is evaluated, particularly in terms of factors such as the effects of soil type, variability in leaching between replicate lysimeters, and simulation of worst-case scenarios. Two herbicides, dichlorprop and bentazon, were chosen as test compounds due to their documented high mobility in laboratory tests. Four different soil types (sand, loam, clay, peat) and two irrigation treatments were included. Both herbicides were applied at rates representing normal doses (1.6 and 0.6 kg ai ha−1of dichlorprop and bentazon, respectively).36Cl was also applied to sand and clay lysimeters to follow the pattern of water movement. Leaching of dichlorprop for the varying soil type/treatment combinations ranged from 0.02 to 1.8% of the amount applied. Leaching losses of bentazon reached up to 0.07% of that applied. Leaching of both herbicides was greater mostly in clay monoliths than in sand monoliths, which was explained in terms of macropore flow. A more effective macropore flow was also suggested to be the main reason why more dichlorprop leached in clay and peat monoliths treated with a small water input. Detectable, and in some cases large, concentrations of dichlorprop were found in the first drainage water in early autumn in all soil/treatment combinations, indicating the occurrence of preferential flow in all soils tested, including sand. A rapid breakthrough of36Cl was also found in clay and low-irrigation input sand, providing additional confirmation of the role of preferential flow processes in these soils. It is concluded that field mobility tests for pesticide registration are a necessary complement to measurements of physical/chemical properties of a compound and that these should be performed in a range of soil types, including at least one structured soil. Other factors identified to be of importance when evaluating lysimeter studies such as this were the analytical detection limits of the pesticides and the need for replication.
Seed Separation and Enumeration from Soil Using K2Co3-Centrifugation and Image Analysis
Authors: Buhler Douglas D. , Maxwell Bruce D.
Published: May 2019

This research presents a modified floatation method to extract weed seed from soil samples and an automated imaging technique to enumerate seed following extraction. Rapid floatation of weed seed from soil in a K2CO3solution was facilitated by centrifugation. High recovery of seed from soil samples was accomplished in a relatively short time. Recovery of seed of giant foxtail and velvetleaf from a silt loam soil was near 100% and recovery of redroot pigweed was 86%. Germination of common lambsquarters, giant foxtail, and velvetleaf seed was reduced by exposure to K2CO3under certain conditions. However, these reductions do not appear to reduce the utility of this extraction technique. The automated image capture technique for counting seed showed similar limitations as with manual counting. Seed count accuracy generally decreased with increased number of seed and smaller seed sizes. In general, the image capture technique compared favorably with manual seed counting and has the potential to further improve seedbank assessment methods.
Wild Proso Millet (Panicum miliaceum) Interference in Dry Beans (Phaseolus vulgaris)
Authors: Wilson Robert G.
Published: May 2019

Effects of proso millet interference with irrigated dry beans were evaluated in Nebraska over a 2-yr period. Dry bean yield reduction ranged from 12 to 31% from a wild proso millet density of 10 plants m-2. As density increased, dry bean yield reduction could be predicted with a rectangular hyperbola regression model. Ten wild proso millet plants m-2growing with dry beans produced 14 780 to 21 420 seed m-2. Dry bean yields were reduced 41 and 11% in 1990 and 1991, respectively, when wild proso millet removal was delayed 6 wk after dry bean planting. Four weeks of weed-free maintenance were sufficient to provide dry bean yields comparable to plots kept weed free all season.
Hysteretic Characteristics of Atrazine Adsorption-Desorption by a Sharkey Soil
Authors: Ma Liwang , Southwick Lloyd M. , Willis Guye H. , Selim H. Magdi
Published: May 2019

The purpose of this study was to quantify hysteresis during adsorption and desorption of atrazine as a function of incubation time for a Sharkey clay soil. Adsorption was carried out using one day batch equilibration and was followed by incubation periods ranging from 1 to 24 d. Incubation was subsequently followed by six consecutive desorption steps where each step represented 1 d. The Freundlich equation (S = K CNwhere S is the amount of atrazine retained, μg g-1; C is concentration, μg ml-1; K is the distribution coefficient, cm3g-1; and N is a dimensionless parameter) was used to describe batch results. Both adsorption and desorption isotherms were well described by the Freundlich model. Fitted K parameter values for desorption isotherms were consistently higher than those associated with adsorption. The opposite trend was observed for the exponential parameter N. The results revealed that desorption deviated significantly from adsorption data. The deviation, which is commonly referred to as hysteresis, was more pronounced as incubation time increased. Batch equilibration results also indicated that the extent of hysteresis was not influenced by soil sterilization. Attempts to quantify the extent of hysteresis using a simplified approach are presented. We found that, for a given batch data set, hysteresis can be quantified provided that Freundlich N from adsorption and desorption isotherms is known.
Relative Foliar Uptake of a Tank Mixture of 2,4-D and Dicamba by Wheat
Authors: Cessna Allan J.
Published: May 2019

Leaf washing was used to determine relative rates of uptake of 2,4-D and dicamba dimethylamine salts by wheat following field application of a postemergence tank mixture (3:1) of 476 g ae ha-1at the 4- to 5-leaf growth stage. Foliar herbicide deposits and total acid residues in the crop were determined the day of spraying as well as 2 and 7 d after spraying. Leaf washing of foliage samples collected on the day of spraying indicated that the crop/weed canopy intercepted 51% of the application, and that dicamba was taken up more quickly than 2,4-D. Within a few hours of spraying, approximately 80% of the deposited dicamba and 65% of 2,4-D were taken up by the crop. A 35-mm rain during the first 48 h after application reduced plant surface deposits of both herbicides by more than 98%. During this 2-d period, dicamba residues within the crop were metabolized more quickly than those of 2,4-D. There was little difference in effectiveness among water, 10% methanol, 25% methanol, or 90% methanol in removing plant surface deposits of 2,4-D and dicamba from wheat.
Canola (Brassica rapa) Plant Density Influences Tartary Buckwheat (Fagopyrum tataricum) Interference, Biomass, and Seed Yield
Authors: O'Donovan John T.
Published: May 2019

Field experiments were conducted at Vegreville, Alberta, in 1990, 1991, and 1992 to investigate the influence of canola plant density and row spacing (1991 and 1992 only) on interference from Tartary buckwheat. Nonlinear regression equations incorporating both canola and Tartary buckwheat density provided good descriptions of the data. Parameter estimates for both weed and crop density were significant (P < 0.05) but did not differ between row spacings. Where no Tartary buckwheat plants were present, canola yield was little affected by canola plant density. At a given Tartary buckwheat density, canola seed yield increased as canola plant density increased, while Tartary buckwheat shoot weight and seed yield decreased. None of the factors significantly affected canola 1000-seed weight, or oil or protein levels in the canola seed. The results suggest that seeding canola to achieve a density of approximately 200 plants m–2will significantly reduce the impact of weeds on canola yield, as well as reduce weed biomass and seed yield.
Simulated Environments Influence Primisulfuron Efficacy
Authors: Morton Cathy A. , Harvey R. Gordon
Published: May 2019

The influence of hot-dry and cool-moist environments on primisulfuron efficacy on giant foxtail and quackgrass was compared at the University of Wisconsin Biotron. Primisulfuron was applied POST at 20 and 40 g ai ha-1with nonionic surfactant (NIS) or crop oil concentrate (COC) and with or without 28% nitrogen fertilizer (28% N). Giant foxtail control 3 wk after treatment was not affected by primisulfuron rates or adjuvants. Adding 28% N tended to improve quackgrass control with primisulfuron plus NIS or COC. Primisulfuron was more injurious to both giant foxtail and quackgrass in the cool-moist than the hot-dry environment. Absorption of14C-primisulfuron into giant foxtail tissue 3 days after treatment (DAT) was greater in the cool-moist than the hot-dry environment Translocation of14C out of treated leaf of quackgrass 3 DAT was greater in the cool-moist than the hot-dry environment. More14C was absorbed and translocated in giant foxtail than quackgrass. Absorbed14C was translocated equally to underground and above treated leaf sections of quackgrass, whereas more14C was translocated above the treated leaf of giant foxtail.
Identification of Two Mechanisms of Sulfonylurea Resistance Within One Population of Rigid Ryegrass (Lolium rigidum) Using a Selective Germination Medium
Authors: Burnet Michael W. M. , Christopher John T. , Holtum Joseph A. M. , Powles Stephen B.
Published: May 2019

A biotype of rigid ryegrass (Lolium rigidumGaudin biotype VLR69) resistant to some ALS inhibitors was characterized to determine the mechanisms of resistance to the sulfonylurea herbicides. The biotype had a high level of resistance to chlorsulfuron (20×) and triasulfuron (25×), and an intermediate level of resistance to imazaquin (7×) and sulfometuron (7.5×) but exhibited a low level of resistance to imazapyr (2.5×). At 60 to 90 g ai ha-1sulfometuron, 4% of the population survived without apparent herbicidal effect The same response to sulfometuron was also observed when seeds of the resistant biotype VLR69 were germinated on agar containing sulfometuron. At 27 nM sulfometuron, 4% of the seeds germinated and grew normally while the growth of the bulk of the population was retarded. This differential response to sulfometuron at the seedling stage allowed selection of sulfometuron-resistant individuals from the population. Activity of ALS extracted from these sulfometuron-resistant plants was less sensitive to inhibition by chlorsulfuron than ALS extracted from plants considered sulfometuron susceptible in the same system. Unselected plants from the VLR69 population were able to detoxify chlorsulfuron more rapidly than susceptible VLR1 plants. It is apparent that there are at least two mechanisms of sulfonylurea resistance in the resistant biotype VLR69 which occur at different frequencies within the population. These data show that more than one mechanism or resistance may develop in response to herbicide selection pressure and that the resulting populations are not necessarily homogeneous.
A Method of Validating the Tetrazolium Assay for Testing Viability of Dormant Jointed Goatgrass (Aegilops cylindricalSeed
Authors: Donald William W.
Published: May 2019

Rapid biochemical tests developed for measuring viability of nondormant crop seed have been used for measuring dormant weed seed viability. The objective of this experiment was to propose and test a new method for validating one of these assays, the tetrazolium assay, for determining dormant weed seed viability. Subsamples of partially dormant jointed goatgrass seed from the same seed source were periodically subjected to sequential germination and tetrazolium assays as they afterripened until seed were completely nondormant. Changes in percent germinated, percent tetrazolium positive (presumably dormant), and percent tetrazolium negative (presumably dead) seed were graphed versus time, and compared with models of valid and invalid cases. The validation method showed that the tetrazolium assay accurately determined the viability of seed remaining after a 3-wk germination period for jointed goatgrass seed removed from joints at the start, but underestimated the viability for seed afterripened and germinated in joints. The validation method showed that additional research is needed to refine the tetrazolium assay for this latter purpose.
Effects of Phosphorus Fertility on Competition Between Lettuce (Lactuca sativa) and Spiny Amaranth (Amaranthus spinosus)
Authors: Shrefler James W. , Dusky Joan A. , Shilling Donn G. , Brecke Barry J. , Sanchez Charles A.
Published: May 2019

Field studies were conducted to determine the influence of phosphorus (P) fertility and method of application (banded versus broadcast) on the competitive interaction of lettuce and spiny amaranth. Weed density significantly affected lettuce head weight and spiny amaranth shoot biomass after 5 wk of interference. Weed density and duration of interference had little or no effect on P content of lettuce tissue. Duration of interference did affect P concentration of spiny amaranth; however, weed density did not Spiny amaranth competition reduced lettuce yield, but P was not the limiting factor. Duration of interference and method of P application interactively affected lettuce head weight; however, only duration of interference affected spiny amaranth biomass. Seven wk of interference caused a decrease in lettuce head weight of 20, 8, and 24% when P was broadcast, banded, or not applied, respectively. Banding of P reduced the negative impact of spiny amaranth on lettuce. Although method of P application influenced the interaction between lettuce and spiny amaranth, interspecific competition between the two species probably was not due to competition for P but some other factor.
Effect of BAS 145 138, CGA 154 281, and Naphthalic Anhydride Seed Treatments on Sweet Corn (Zea mays) Tolerance to Nicosulfuron
Authors: Robinson Darren K. , Monks David W. , Burton James D.
Published: May 2019

BAS 145 138, CGA 154 281, and 1,8 naphthalic anhydride were evaluated as seed treatments to safen 'Silver Xtra Sweet,’ ‘How Sweet It Is,’ ‘Zenith,’ and 'Sweetie 76’ sweet corn against nicosulfuron injury. Nicosulfuron POST injured sweet corn by causing slight leaf chlorosis and leaf base widening in Sweetie 76 and severe plant injury and total yield loss in Silver Xtra Sweet. Naphthalic anhydride or CGA 154 281 provided limited or no safening activity, respectively, and resulted in plant height reduction when applied alone. BAS 145 138 reduced nicosulfuron injury to Silver Xtra Sweet and prevented visible injury from nicosulfuron in How Sweet It Is, Zenith, and Sweetie 76.
Chloroacetamide Resistance in Rigid Ryegrass (Lolium rigidum)
Authors: Burnet Michael W. M. , Barr Andrew R. , Powles Stephen B.
Published: May 2019

Metolachlor has been evaluated both as a herbicide for use in cultivated oats (Avena sativaL.) and for its potential as an alternative herbicide for the control of herbicide-resistant rigid ryegrass. Eight herbicide-resistant and two susceptible biotypes of rigid ryegrass were tested for their susceptibility to metolachlor. Response to metolachlor was determined both in soil and an agar germination medium. The LD50for metolachlor in agar for a susceptible biotype (VLR1) was 0.13 μM. Five biotypes, SLR5 (6.9 fold), SLR31 (5.2 fold), SLR10 (2.5 fold), NLR12 (2.1 fold) and VLR69 (1.9 fold), were cross-resistant to metolachlor when compared with VLR1. Relative response of the biotypes was similar in both soil and agar, validating the use of an agar germination test to determine the susceptibility of rigid ryegrass biotypes to metolachlor. Biotypes cross-resistant to metolachlor also were cross-resistant to alachlor (SLR5 6.7 fold, SLR31 5.9 fold, SLR10 2.4 fold, and VLR69 1.6 fold with the LD50for VLR1 being 0.49 μM) and propachlor (SLR57.2 fold, SLR31 7.2 fold, SLR10 3.0 fold and VLR69 2.5 fold with the LD50for VLR1 being 0.47 μM) indicating that cross-resistance extends to other members of the chloroacetamide group. Cross-resistance to chloroacetamides was observed in biotypes that previously had been reported as cross-resistant to other herbicides. In contrast, biotypes with limited herbicide histories were generally not cross-resistant to metolachlor. These results indicate that there is a high probability of chloroacetamide cross-resistance in populations of herbicide-resistant rigid ryegrass.
Growth and Competitiveness of Sulfonyhirea-Resistant and -Susceptible Kochia (Kochia scoparia)
Authors: Thompson Curtis R. , Thill Donald C. , Shafii Bahman
Published: May 2019

Growth, competitiveness, and fecundity differences between resistant (R) and susceptible (S) biotypes affect management strategies. This greenhouse research examines growth, competitiveness, and fecundity of chlorsulfuron-resistant (R) and -susceptible (S) kochia collected from North Dakota and Kansas. In noncompetitive studies, sulfonylurea R and S kochia biotypes from Kansas and North Dakota had similar growth rates and seed production. All biotypes produced about 12000 seeds per plant. Competitiveness of R and S biotypes from Kansas was similar. Interbiotype competition reduced R and S plant biomass more than intrabiotype competition. The relative competitiveness of the R and S biotypes was 0.75 and 0.85, respectively. The resistance trait did not reduce growth, seed production, and competitiveness of R compared to S kochia in greenhouse studies.
Differential Tolerance of Morningglory Species (IpomoeaSp.) to DPX-PE350
Authors: Sunderland Shay L. , Coble Harold D.
Published: May 2019

Experiments were conducted in the greenhouse and field to investigate differential tolerance among tall, pitted, red, entireleaf, and ivyleaf morningglory species to DPX-PE350. Tall morningglory in the greenhouse was more tolerant of DPX-PE350 at 7 and 14 g ai ha-1applied POST than were other species of morningglory. Increased tolerance of tall morningglory also was observed under field conditions with DPX-PE350 applied PRE and POST. Adjuvants did not increase biomass reduction of tall morningglory by DPX-PE350 applied POST.
Use of Empirical Equations to Describe Dissipation of Metribuzin and Pendimethalin
Authors: Zimdahl Robert L. , Cranmer Brian K. , Stroup Walter W.
Published: May 2019

Four equations were evaluated as predictors of the rate of herbicide dissipation in soil. A biexponential equation was superior to the first-order equation for metribuzin and pendimethalin dissipation under five moisture levels and three temperatures in laboratory and field studies. The Hoerl function, adapted in the course of this work, is also a good descriptor. The first-order equation predicts slower initial and more rapid later dissipation than actually occurs and these deficiencies are not shared by the biexponential or Hoerl equations. The first-order equation ignores small residues remaining late in the dissipation process. These residues are important from an environmental point of view and the Hoerl and biexponential equations are more capable of dealing with them.
Influence of Temperature and Adjuvants on Thidiazuron Activity in Cotton Leaves
Authors: Snipes C. E. , Wills G. D.
Published: May 2019

A laboratory study was conducted to determine the effects of two adjuvants and temperatures at time of treatment on efficacy, absorption, and translocation of thidiazuron defoliant on cotton. Five days after treatment at 30/21 C day/night temperatures, leaf drop was 17% with no adjuvant, 37% with addition of crop oil concentrate, 40% with ammonium sulfate, and 75% with two adjuvants combined. At 21/13 C day/night temperatures, there was less than 10% leaf drop with all treatments. At 10 d after treatment, leaf drop was not different among treatments at the high or low temperatures. Shoot regrowth at high and low temperature was reduced 55 to 60% with addition of both adjuvants and 44 to 50% with each adjuvant or with no adjuvant when compared to plants defoliated by hand. Absorption of14C-thidiazuron was not affected by variations in temperature during the time of treatment but was affected by adjuvants. With no adjuvants, absorption was 7 to 10%. With 1.25% by vol crop oil concentrate, absorption was 33 to 46%. Addition of ammonium sulfate resulted in 18 to 19% absorption, and the combination of ammonium sulfate and crop oil concentrate increased absorption to 65 to 68%. There was no movement of radiolabel away from treated leaves as determined by autoradiographs of treated plants.
Pathogenic Interactions of Alternaria crassa and Phenolic Metabolism in Jimsonweed (Datura stramonium L.) Varieties
Authors: Hoagland Robert E. , Boyette C. Douglas
Published: May 2019

Alternaria crassa, a mycoherbicide for jimsonweed control, was tested for differential effects on growth, infectivity, and phenolic metabolism of two field-collected jimsonweed varieties. Seeds from field-grown red- and green-stemmed jimsonweed varieties were grown in the greenhouse and spores were applied in aqueous solutions. Infection studies showed no significant differences between the two weed varieties when tested at various growth stages from cotyledonary to 8–leaf stage at 2.5 × 104spores ml−1. Spore dose response tests with A. crassa spores (6.25 to 100 x103spores ml−1) showed no significant varietal differences in disease ratings. Extractable phenylalanine ammonia-lyase activity increased nearly equally (2- to 3-fold above control) in both varieties (8- to 9-leaf stage) 48 to 72 h after treatment with 5 × 104spores ml−1. The only significant differences between treated varieties occurred 72 h after treatment. Exposure to A. crassa lowered total ethanol-soluble phenolic levels in both varieties 72 h after treatment. Spectrophotometric scans (400 to 700 nm) of ethanol extracts (72 h after treatment) indicated that infection caused some absorbance increases, especially in red-stemmed jimsonweed. Anthocyanin content was about 11-fold higher in red-stemmed than green-stemmed jimsonweed, and A. crassa treatment slightly increased the anthocyanin absorption peak of the red-stemmed variety.
Germination Characteristics of Sulfonylurea-Resistant and -Susceptible Kochia (Kochia scoparia)
Authors: Thompson Curtis R. , Thill Donald C. , Shafii Bahman
Published: May 2019

Seed germination, one aspect of fitness, of chlorsulfuron-resistant (R) and -susceptible (S) kochia biotypes collected in North Dakota and Kansas was compared at 8, 18, and 28 C. Cumulative germination, characterized for each biotype using a Weibull function, was different at 8 and 18 C but not at 28 C. The Kansas R biotype reached 50% and maximum germination 70 and 300 h before Kansas S biotype at 8 C and 12 and 100 h before the S biotype at 18 C, respectively. The North Dakota R biotype reached 50% and maximum germination 12 and 100 h before the North Dakota S biotype at 8 C, respectively, and they were not different at 18 C. The resistance trait affects the cumulative germination process of kochia and may affect resistant-weed management strategies implemented early in the growing season when temperatures are lowest.
Effect of Drought Stress on Velvetleaf (Abutilon theophrasti) and Bentazon Efficacy
Authors: Hinz John R. , Owen Michael D. K.
Published: May 2019

Greenhouse experiments were conducted to determine the effects of drought stress length and relief on velvetleaf growth and bentazon efficacy with crop oil concentrate (COC) and 28% urea ammonium nitrate (UAN). Drought stress caused leaf water and osmotic potentials to decline linearly over time. Leaf water potential ΨL) declined 0.02 and 0.08 MPa day−1for velvetleaf subjected to −0.03 and −0.4 MPa soil water potential (ΨP), respectively. Osmotic potential (ΨO) declined 0.02 and 0.21 MPa day−1for velvetleaf subjected to −0.03 and −0.4 MPa ΨPrespectively. Bentazon did not reduce drought-stressed compared to non-drought-stressed velvetleaf dry weight 21 d after treatment with either COC or no adjuvant but did decrease dry weight with UAN. Reduced velvetleaf dry wights in drought-stressed velvetleaf compared to non-drought-stressed velvetleaf could not be accounted for by increased bentazon penetration in the drought-stressed plants. Rewatering velvetleaf subjected to 7 d of −0.4 MPA ΨPcaused them to be more sensitive to bentazon than velvetleaf subjected to −0.03 MPa ΨPexcept when UAN was the adjuvant.
Germination and Seedling Growth of Sorghum (Sorghum bicolor) Hybrids After Seed Storage with Safeners at Varying Humidities
Authors: Zhang Zujie , Coats G. Euel , Boyd Albert H.
Published: May 2019

Laboratory and growth room experiments were conducted to determine effects of CGA-133205, oxabetrinil, and flurazole on grain sorghum hybrids ‘DeKalb 46’ and ‘DeKalb 48’ after the seed were treated with the herbicide safeners and stored for up to 24 wk at various relative humidity levels. Each safener treatment had an adverse effect on grain sorghum seed as reflected by fewer normal seedlings at 4 d when averaged over storage time and relative humidity levels. Flurazole and oxabetrinil increased the number of ungerminated seed of both hybrids, and 0.4 and 0.8 g ai kg–1CGA-133205 increased ungerminated seed of DeKalb 46. At ≥ 8 wk after storage, a reduction in germination was observed for seed treated with flurazole or oxabetrinil compared to seed stored without safener. This reduction also occurred with 0.4 and 0.8 g kg–1CGA-133205, but only at 24 wk after storage. Each safener treatment minimized reduction in seedling shoot fresh weight by herbicides compared to the no-safener check through 24 wk after storage.
Effects of Clomazone on Biosynthesis of Geosmin by Streptomyces tendae and Penicillium expansion
Authors: Dionigi Christopher P.
Published: May 2019

Cultures of Streptomyces tendae grown on Actinomyces medium containing clomazone contained less geosmin 48 h after inoculation than untreated controls, suggesting a possible inhibition of reactions prior to sesquiterpenoid biosynthesis. However, exposure to clomazone increased geosmin accumulation in S. tendae cultures grown on Hickey-Tresner medium and in cultures of the fungus Penicillium expansum. Additionally, clomazone increased accumulation of a sesquiterpenoid tentatively identified as a eudesmol in S. tendae, indicating possible point(s) of inhibition subsequent to sesquiterpenoid biosynthesis. Geosmin biosynthesis was induced by transferring cultures of S. tendae inoculated on Actinomyces medium to Hickey-Tresner medium 24 h after inoculation. When harvested at 48 h, geosmin biosynthesis-induced-cultures exposed to clomazone contained more geosmin than untreated controls, indicating that response of a single taxon to clomazone can be rapidly altered by changing medium composition.
LE ELEZIONI NELLA CECOSLOVACCHIA DEMOCRATICA (1990-1992)
Authors: Campione Anna
Published: May 2019

Introduzione

Nei decenni precedenti l'instaurazione dei regimi comunisti nessuno dei sistemi politici dell'Europa centro-orientale, ad eccezione della Cecoslovacchia e della Germania, aveva sviluppato strutture partitiche relativamente forti, specie se confrontate con i sistemi democratici dell'Europa occidentale. Dopo la breve parentesi post-bellica di competizione «pluralistica» gli organi rappresentativi e le elezioni stesse erano stati trasformati in strumenti funzionali al dominio del partito unico. Benché il parlamento costituisse secondo le costituzioni di quei paesi l'organo più autorevole dello stato, le stesse avevano finito per recepire il principio (stabilito dalla costituzione sovietica del 1977) del partito comunista come «forza guida della società» (Ulc 1982)
LA GEOMETRIA DELLO SPAZIO ELETTORALE IN ITALIA
Authors: Ricolfi Luca
Published: May 2019

Introduzione

Quante dimensioni sono necessarie per rappresentare le posizioni dei partiti italiani nello spazio elettorale? La classica rappresentazione dei partiti lungo un unico continuum, il cosiddetto asse sinistra-destra, è ancora attuale? E se non lo è, quali sono le dimensioni oggi pertinenti?

Negli ultimi cinquant'anni il problema della unidimensionalità dello spazio elettorale ha sempre avuto un certo rilievo perché, dopo gli studi pionieristici di Black, Arrow e Coombs sul rapporto fra preferenze individuali e regole di scelta sociale, l'assunto di unidimensionalità è diventato, per così dire, il certificato di garanzia dei sistemi democratici. Solo assumendo uno spazio elettorale unidimensionale l'adozione della regola della maggioranza non incappa nel «paradosso del voto» su cui per primi, verso la fine del ‘700, avevano attirato l'attenzione Jean-Charles de Borda (1781) e il Marchese di Condorcet (1785).
L'ASCESA DELL'EUROPA MERIDIONALE: CENTRO E PERIFERIA NELLA COMUNITÀ EUROPEA
Authors: Leonardi Robert
Published: May 2019

Introduzione

La ratifica del Trattato di Maastricht tra i dodici paesi membri della Comunità europea mette in evidenza una contraddizione sottesa agli studi e alle riflessioni sull'Europa meridionale. In passato gli stati di questa area - Grecia, Spagna, Portogallo e anche l'Italia - sono stati descritti come paesi periferici o semi-periferici. Nelle analisi delle loro strutture politiche ed economiche si è sottolineata la difficoltà che questi paesi hanno incontrato nell'inserirsi nel flusso dello sviluppo economico europeo, nel partecipare attivamente alla determinazione delle politiche all'interno dell'Europa e alla definizione della posizione europea sulle problematiche mondiali. La gestione delle vicende europee continua ad essere vista come un processo dominato dai paesi settentrionali, cioè da quei paesi che hanno una più antica tradizione di istituzioni democratiche e di economie robuste.
Roman Tile
Authors: Rudling D.
Published: May 2019

Four small fragments of Roman tile were recovered from trench E. All of these are flat fragments, their approximate thicknesses being: 25 nm (context 1); 28 mm (context 35); 37 mm (context 1); and 40 mm (context 56). The two thinest fragments fall within the range of values known for tegulae, but could also possibly be from thin ‘Flat’ tiles. The two thicker fragments are from ‘Flat’ tiles/bricks.
Post-Medieval Pottery (16th/17th-18th century)
Authors: Rudling D.
Published: May 2019

Five sherds were submitted for study: three from trench A, context 1; and two from trench E, context 1. Those from trench A include: 1 sherd of orange ware with internal mottled green glaze; 1 sherd of orange ware with intelai orange-brown glaze; and 1 sherd of Staffordshire combed ware. Of the Merds from trench E, 1 is of pale orange/buff ware with internal mottled green glaze; and the other is of orange ware with partial external light green glaze and internal green glaze above applied, raised decoration in the form of pellets and lines.
The Metalwork
Authors: Oldham Brian
Published: May 2019

The excavation produced a total of 23 metal artefacts; five of copper alloy and eighteen of iron. This material was recovered from two trenches only (B and E). 7 ne relationship of types to trenches is given in table 2.

Copper alloy (fig, 9).

1. Terret ring. Oval in form and of circular cross-section, with a low ridge-moulding around the outer edge of the loop. The loop tapers gradually from 7.2 mm diameter at the terminals to 6.2 mm opposite them. The terminals are circular (12.8 mm diameter) and have a shallow groove incised around them close to their inner faces. The attachment bar is parallel-sided and of rectangular section (6.6 mm x 4.5 mm). External dimensions: 54 mm x 47.2 mm; weight 41.6 gm.
Slag Analysis
Authors: Brown K.
Published: May 2019

Excavation of trenches B and E produced a small quantity of metalworking residues which was subjected to a simple visual examination in order to determine the nature of the metalworking activity. Four basic types of ironworking slag were identified in addition to a small quantity of fired clay, ammounting to 1,44 kg of debris. Further metallographic analysis would be required to continue the following divisions.
The lithic industry: fieldwork and
surface collections in the Borwick
area
Authors: Clare T.
Published: May 2019

The area known as Dock Acres, almost
immediately due west of Manor Farm, Borwick, was
variously reputed to have been the site of a Roman
dock, Medieval castle and/or Medieval dock.
Initial field survey when the area was still
permanent pasture was carried out in advance of
gravel extraction by Mr B.J.N.Edwards. Subsequent
observation of the first stages of quarrying was
undertaken by the author (as a student) and led to
the recovery of some lithic material. It is
perhaps worth noting in passing that observation
of a later stage of mineral extraction by the
author and the newly formed Moorholme Local
History Society led to the recording of the
vestigial remains of the Medieval castle.

The lithic material was recovered from the top
and in the vicinity of the largest topographical
feature; a flat topped mound some 150 m by 50 m.
This ‘mound’ was separated from a similar more
extensive area to the south by a broad channel
whilst flat, low lying ground lay to east, north
west and north where there were two small
rectangular mounds.
Report on the buried
soil
Authors: Keeley Helen C.M.
Published: May 2019

Present-day soils in the Borwick area form the
Carnforth Association, i.e. freely drained
gravelly brown earths, some calcareous brown
earths and peaty gleys and peaty soils in hollows.
pH is normally 6 to 7, with some soil pH higher
than 7.

The buried soil beneath the cairn was a
truncated stagnopodzol with a pH of 7.35. The Eag,
Bf and Bs horizons were present but the lack of a
topsoil and relatively high pH suggested that
pollen analysis of the soil would be unproductive.
Similarly, detailed soil analysis was unlikely to
add to the interpretation of the site and was
therefore not pursued. The development of
podsolised soils on such gravels is not unusual
and may indicate that the vegetation at the time
the cairn was constructed was acid grassland or
moorland. The soil pH would have been on the acid
side at this stage, rising subsequently due to
downward leaching of the calcium carbonate from
the overlying limestone of the enclosure.
Geological Identification of Stone Artefacts and Samples from Hog Cliff Hill, Maiden Newton, Dorset
Authors: Ensom P.C.
Published: May 2019

Artefacts

D17 (pit, phase 4) Text D.5.

Chert form the Upper Greensand. Heavily battered - an effect unlikely to have been produced by natural causes. This type of chert is found in Dorset, and chert beds are reported to occur from the Maiden Newton area westwards. Lumps the size of this and D. 39 below are likely to have been imported. The chert beds of the Upper Greensand lie below the Chalk.
Balneaves: The Botanical Remains
Authors: Rushc Christine M
Published: May 2019

Samples were taken from the ditch and various pits within the enclosure and processed foi carbonised remains. All samples were wet sieved using mesh sizes of 1mm and 300ji and the material from the coarse flot (1mm) was sorted. Of the thirty six samples taken, twelve produced small amounts of carbonised plant material. The results from these seven ditch and five pit samples form the basis of this report.

A list of the species identified in each context is given below in Tables 6 and 7. Evidence for cereal grain is scant. Emmer (Triticum dicoccum) and barley (Hordeum sp.) are present. Both are known from the Bronze Age in Britain and in Scotland emmer appears to remain the commonest wheat into the Roman period and beyond (Jones 1981, 106). The evidence for emmer comes from a single grain and fragments of chaff from the ditch (context 1002A) near the entrance of the enclosure. A fragment of hulled barley was also found in the SW section of the ditch (context 1003). This fragment appeared to be twisted which suggests that the six-row variety is present. One other fragment of barley (possibly hulled) is present in context 1103A in Pit 10 (a large pit to the S of the enclosure).
Park of Tongland: Description of the Soil Thin Sections
Authors: Davidson Donald
Published: May 2019

Four samples were collected from a vertical sequence with No 1 at the base straddling contexts 0089 and 0066, No 2 straddling contexts 0066 and 0021, No 3 in the centre of context 0021, and uppemiost No 4 between contexts 0021 and 0065.

The four slides were described following the international system for thin section description (Bullock et al., 1985). Slides No 1 and 2 were virtually identical whilst slides 3 and 4 were variations on these. It thus seemed best to provide a full description of slide No 1 which is also applicable to No 2 and then only to describe the differences between these two pairs of slides which are of a particular interpretational value.
Park of Tongland: Analysis of Pottery Fabric Inclusions
Authors: Collins G
Published: May 2019

All three pots contain quartz (often milky), feldspar and small lumps of grey granite (Biotite Granite) which looks very similar to the Gatehouse-of-Fleet granite and Creetown Granite. This suggests that the source of this material lies to the west of Kirkcudbright rather than to the east. Hence the grits from all three pots, and therefore the manufacture, are likely to have been quite local to the site.
Underlying deficits in language-disordered children with central auditory processing difficulties
Authors: James Denita , van Steenbrugge Willem , Chiveralls Keith
Published: May 2019

Phonological working memory and auditory processing skills were investigated in a group of language-disordered children with central auditory processing (CAP) difficulties. Comparisons were made with two groups of control children, one group matched on chronological age and nonverbal intelligence and the other matched on language age. The CAP disordered children showed poorer abilities in nonword repetition and word recall. In agreement with earlier findings in language-disordered children (Gathercole & Baddeley, 1990), the CAP disordered children were sensitive to the phonological similarity and word length of the recall lists. However, contrary to earlier findings, the CAP disordered children in the present study also showed poorer phoneme discrimination skills. These findings may be inconsistent with the notion of one central deficit (poor phonological working memory) in CAP disordered children with a language deficit.
Out of the Shadow, into the Spotlights. The ‘Indigenous’ Aspects of Plantation Development; the Case of the Emergence of Syrian Christian Planters in Princely Travancore in the First Half of the Twentieth Century
Authors: Baak Paul E.
Published: May 2019

In the fascinating debate between Jan Breman and Vincent Houben following the former's publication Koelies, Planters en Koloniale Politiek, both authors seem to agree on at least one point: the great value of John R.W. Smai's approach to the writing of Asian history. The historian's perspective should be from within Asia. Although Smail's ideas became widely accepted among scholars, I would like to stress that his thoughts were hardly ever put into actual practice, especially with regard to plantation development. But let me elaborate on that a little further.
The Expiration of Morality
Authors: Matson Wallace I.
Published: May 2019

Has Alexander Pope's prediction, made a quarter of a millennium ago (1742), come true in our own day?

No one who has lived through the last thirty years is unaware of the spectacular alterations of behavior norms that have occurred in most Western societies. It is not merely that everywhere incivility and crime are on the increase, that there are more and more violations of moral standards which nevertheless continue to be acknowledged. Rather, we witness the relaxation or disappearance of the standards themselves. What was bad becomes permissible or even a positive good.
Common Sense and First Principles in Sidgwick'sMethods
Authors: Brink David O.
Published: May 2019

What role, if any, should our moral intuitions play in moral epistemology? We make, or are prepared to make, moral judgments about a variety of actual and hypothetical situations. Some of these moral judgments are more informed, reflective, and stable than others (call these ourconsideredmoral judgments); some we make more confidently than others; and some, though not all, are judgments about which there is substantial consensus. What bearing do our moral judgments have on philosophical ethics and the search for first principles in ethics? Should these judgments constrain, or be constrained by, philosophical theorizing about morality? On the one hand, we might expect first principles to conform to our moral intuitions or at least to our considered moral judgments. After all, we begin the reflection that may lead to first principles from particular moral convictions. And some of our moral intuitions (e.g., that genocide is wrong) are more fixed and compelling than any putative first principle. If so, we might expect common moral beliefs to have an important evidential role in the construction and assessment of first principles. On the other hand, common moral beliefs often rest on poor information, reflect bias, or are otherwise mistaken. We often appeal to moral principles to justify our particular moral convictions or to resolve our disagreements. Insofar as this is true, we may expect first principles to provide a foundation on the basis of which to test common moral beliefs and, where necessary, form new moral convictions.