bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA Synthesis as the Basis for EPTC and 2,4-D Antagonism
Authors: Beste C. E. , Schreiber M. M.
Published: May 2019

Three-day-old soybean(Glycine max(L.) Merr., ‘Hawkeye 63′) hypocotyl segments (0.5 to 1.5 cm below the cotyledons) were utilized to evaluate the effects of the antagonistic interaction ofS-ethyl dipropylthiocarbamate (EPTC) and (2,4-dichlorophenoxy)acetic acid (2,4-D) on growth and nucleic acid synthesis. EPTC inhibited growth and RNA synthesis in soybean tissue. The addition of 2,4-D with EPTC was antagonistic to EPTC inhibition of growth and caused an increase in total RNA synthesis. Analysis of soybean tissue nucleic acids by methylated-albumin-kieselguhr(MAK) column chromatography showed that EPTC inhibited ribosomal-RNA (r-RNA), DNA like RNA (D-RNA), and tenaciously-bound-RNA (TB-RNA) synthesis. The combination of 2,4-D with EPTC caused an increase in D-RNA and TB-RNA synthesis compared to the EPTC treatment alone. The 2,4-D-enhanced synthesis of D-RNA and TB-RNA in the presence of EPTC appears to be the basis of the antagonism between EPTC and 2,4-D. Preliminary analysis of r-RNA indicated that EPTC preferentially inhibited the synthesis of 18S r-RNA more than 25S r-RNA and that 2,4-D had no effect on this selective inhibition.
Low-Volume Application of Propazine and Atrazine to Sorghum
Authors: Chamberlain E. W. , Wiese A. F. , Owen D. F. , Becton A. J. , Turner W. E.
Published: May 2019

Over a 3-year period, pigweed (Amaranthus sp.) was successfully controlled in grain sorghum (Sorghum bicolor (L.) Moench) with preemergence aerial application of 2-chloro-4, 6-bis(isopropylamino)-s-triazine (propazine) and postemergence application of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) in 4.7 to 47 L/ha of various carriers. Equally good pigweed control was obtained with ground application of the herbicides with as little as 37 L/ha carrier. Liquid formulations of the two herbicides gave results comparable to an 80% wettable powder formulation.
Tracer Studies by14C-labeled Herbicides, DMSO, and Surfactant
Authors: Jones D. W. , Foy C. L.
Published: May 2019

Primary leaves of 17-day-old-bean(Phaseolus vulgarisL. ‘Black Valentine’) were treated with14C-labeled dimethylsulfoxide (DMSO), 3,6-dichloro-o-anisic acid (dicamba), 1,1′-dimethyl-4,4′-dipyridinium salt (paraquat), and 2-chloro-4-(ethylamino)-6-(isopropylamino-s-triazine (atrazine). Each herbicide was tested alone, and in combination with 30% DMSO, 0.25% Tween 80 (nonionic surfactant containing polyoxyethylene sorbitan monooleate), or both. DMSO at concentrations of 25% or more caused varying degrees of acute toxicity. However, a small amount of radioactive carbon generally was distributed throughout the plant 5 days after application of DMSO-14C, as determined by autoradiography and counting. Tween 80 enhanced whereas DMSO had little effect on the absorption and translocation of dicamba, a phloem-mobile herbicide. The contact toxicity and apoplastic movement of paraquat was increased with DMSO. Tween 80 enhanced eight-fold and DMSO, two-fold, the foliar uptake and (apoplastic) movement of atrazine within the treated leaves.
Effects of Atrazine on Chlorophyll Retention in Corn Leaf Discs
Authors: Copping Leonard G. , Davis D. E.
Published: May 2019

Corn(Zea maysL. ‘Dixie 18′) leaf discs were incubated in light or darkness in dilute solutions of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) with and without 6-furfurylamino-purine (kinetin). Kinetin decreased chlorophyll loss in light whereas atrazine had no effect. In darkness atrazine at a concentration of 5 × 10−8M increased clorophyll a retention in the absence of exogenous kinetin; but in the presence of 1.5 μg/ml of kinetin, the herbicide increased loss of chlorophyll a. Increasing the kinetin concentration to 15 μg/ml relieved the effect of 5 × 10−8M atrazine, but 10−7M atrazine increased chlorophyll loss. Higher concentrations of kinetin (150 and 1500 μg/ml) prevented all effects of atrazine. Factorial analysis revealed a highly significant interaction between atrazine and kinetin.
Germination and Persistence of Achenes of Scotch Thistle
Authors: Young James A. , Evans Raymond A.
Published: May 2019

Achenes of Scotch thistle(Onopordum acanthiumL.) contain a water-soluble germination inhibitor and are sensitive to differences in light quality. Germination of these achenes can be enhanced by the addition of 0.14 mmole of gibberellic acid and 1.0 mmole of potassium nitrate to the substrate. Dissected embryos exhibit germination responses similar to those observed for achenes. Naturally-distributed achenes recovered from the soil in the field increased in germination under fluorescent light and after washing. Achenes will not germinate on the surface of a constant-moisture-supplying substrate when exposed to an unsaturated atmosphere. The physical environment of the seedbed apparently is paramount in controlling germination and persistence of achenes of Scotch thistle.
Response of Peach Trees to Herbicide and Mechanical Weed Control
Authors: Daniell Jeff W. , Hardcastle W. S.
Published: May 2019

Herbicides and mechanical methods of weed control were tested on 1 and 2-year-old peach trees(Prunus persica(L.) Batsch) on two soil types and locations. Several herbicide methods gave season-long weed control without detriment to growth or yield of peach trees. In general, a cultural system where herbicides were used in rows and 8-ft sodded strips maintained in row middles did not decrease the growth or yield of trees when compared to overall mechanical methods of weed control.
Trifluralin Vapor Emission from Soil
Authors: Swann Charles W. , Behrens Richard
Published: May 2019

Vapor ofa,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-loluidine (trifluralin) emitted from soils was collected in xylene and assayed by gas chromatography. Increasing the trifluralin application rate in soil surface treatments from 0.56 to 4.48 kg/ha resulted in substantial increases in vaporization from soils during the 2 hr immediately after treatment. Increasing the spray volume from 2.34 to 300 kl/ha with water reduced the rate of trifluralin vapor emission by approximately half. When trifluralin was applied as a spray (2.34 kl/ha) and then incorporated into soils of varying moisture contents, 4 to 10 times more trifluralin volatilized in 12 hr than when it was percolated into air-dry soils with sufficient water to yield equivalent soil moisture contents. The techniques employed were not sufficiently sensitive to detect trifluralin vapor loss occurring more than 12 hr after treatment. The amount of trifluralin lost during the first 12 hr was less than 5% of that applied to the soil, even under the most favorable conditions for volatilization.
Metabolism of Simazine and Atrazine by Wild Cane
Authors: Thompson Lafayette
Published: May 2019

Wild cane(Sorghum bicolor(L.) Moench) absorbed equal amounts of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) and 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine). The plants metabolized 70% of the atrazine and 30% of the simazine absorbed and translocated to the shoot during 24 hr. The major metabolites formed were hydroxyderivatives and very hydrophilic metabolites which were chromatographically identical to peptide conjugates of atrazine, e.g.,S-(4-ethylamino-6-isopropylamino-s-triazinyl-2)-glutathione andS-γ-L-glutamyl-(4-ethylamino-6-isopropylamino-s-triazinyl-2)-L-cysteine. Wild cane formed peptide conjugates of atrazine more rapidly than of simazine, but hydroxylation of theses-triazines occurred at approximately the same rate.
Hemp Dogbane Growth and Control
Authors: Robison Laren R. , Jeffery Larry S.
Published: May 2019

Hemp dogbane (Apocynum cannabinum L.) was investigated relative to seed germination, depth of seedling emergence, response to clipping, influence of soil type and fertility on vegetative growth, and herbicidal control. Seed germination in this study was influenced by light and scarification. Seedling emergence was influenced by the amount of soil cover. Soil type and fertility affected vegetative growth. In a greenhouse clipping study, hemp dogbane became perennial 41 days after emergence and by 65 days was producing more than one shoot per plant following clipping. Hemp dogbane was more completely controlled following September application of herbicide than from application made in June.
Effect of Two Methylcarbamates on Chlorpropham Toxicity to Safflower and Common Buckwheat
Authors: Kirkland K. , Appleby A. P.
Published: May 2019

Growth-chamber studies were conducted to determine the effect ofp-chlorophenyl-N-methylcarbamate (PPG-124) and 1-naphthylN-methyl carbamate (carbaryl) on the response of safflower(Carthamus tinctoriusL. ‘Gila’) and common buckwheat(Fagopyrum esculentumMoench.) to isopropylm-chlorocarbanilate (chlorpropham). Addition of PPG-124 or carbaryl did not increase the sensitivity of safflower, a resistant species, to chlorpropham and affected buckwheat, a susceptible species, only at the lowest dosage level.
Herbicidal Concentrations of Picloram in Cell Culture and Leaf Buds
Authors: Davis F. S. , Villarreal A. , Baur J. R. , Goldstein I. S.
Published: May 2019

Cell cultures of soybean(Glycine max(L.) Merrill ‘Acme’) were exposed to media containing 4-amino-3,5,6-trichloropicolinic acid (picloram) for 15 days. Picloram also was supplied once in droplets (water) to cotyledons of 10 to 13-day-old seedlings of cotton(Gossypium hirsutumL. ‘Champion’). The amounts of picloram necessary to reach and exceed the 50% tolerance limit (TL50) of the cell cultures (inhibition) and of the primary leaf buds (toxicity) were established, and internal picloram concentrations then were determined. Internal concentrations at the TL50were 0.17 nM/g fresh weight and 14.7 nM/g fresh weight for cell cultures and leaf buds, respectively. These values are approximately 10−7and 10−5molar. In leaf buds, concentrations increased rapidly for 36 hr after treatment and declined slowly thereafter. Primary leaf buds accumulated up to several times the lethal internal concentration of picloram when the dosage to the cotyledons was increased by one order of magnitude.
Yellow Nutsedge Control in Soybeans
Authors: Wax L. M. , Stoller E. W. , Slife F. W. , Andersen R. N.
Published: May 2019

A system for controlling yellow nutsedge(Cyperus esculentusL.) in soybeans [Glycine max(L.) Merr.] which involved preplanting tillage, late planting, herbicides, and cultivation was evaluated in 1969 and 1970. In Illinois on a Drummer silty clay loam,S-ethyl dipropylthiocarbamate (EPTC) andS-ethyl diisobutylthiocarbamate (butylate), incorporated in the soil before planting, gave good and fair control of yellow nutsedge, respectively, but both injured soybeans initially.S-propyl dipropylthiocarbamate (vernolate), also incorporated before planting, controlled yellow nutsedge as well as EPTC did, and resulted in less injury to soybeans. Soybean yields were not reduced by any of the thiocarbamate treatments. Incorporation of 2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide (alachlor) or 2-chloro-N-isopropylacetanilide (propachlor), just before planting, controlled at least 90% of the yellow nutsedge in both years, whereas preemergence applications were only moderately successful and dependent on rainfall. In field microplots, alachlor and vernolate provided only fair control of yellow nutsedge when applied to the soil surface, but they both controlled 95% of the yellow nutsedge when incorporated 7.6 cm. In greenhouse studies on selective control of yellow nutsedge in soybeans, alachlor exhibited a wider margin of safety to soybeans than did vernolate.
Common Purslane Competition in Table Beets and Snap Beans
Authors: Vengris Jonas , Stacewicz-Sapuncakis Maria
Published: May 2019

Competition studies in field trials were conducted between common purslane (Portulaca oleraceaL.) and table beets (Beta vulgarisL., var. Detroit Red) and between common purslane and snap beans (Phaseolus vulgarisL., var. Eastern Butter). Common purslane control was most critical during the first 2 weeks after beet and bean emergence. Common purslane control for longer than 2 weeks did not increase beet or bean yields. The longer common purslane was allowed to compete after beet or bean emergence, the more yields were decreased. Common purslane was a stronger competitor in beets than in beans. The faster and taller-growing bean plants provided more competition than did beets. Cultivation between rows until lay-by increased both beet and bean yields.
The Role of Phenolics and Abscisic Acid in Nutsedge Tuber Dormancy
Authors: Jangaard N. O. , Sckerl M. M. , Schieferstein R. H.
Published: May 2019

The phenolic content of purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (Cyperus esculentus L.) was determined. The major phenolic components were p-coumaric, ferulic, p-hydroxybenzoic, syringic, vanillic, salicylic, proto-catechuic, and caffeic acids, and eugenol. High concentrations of eugenol and salicylic acid inhibited the sprouting of nutsedge tubers. The lack of activity at lower concentrations argues against a major role for these compounds in maintaining nutsedge tuber dormancy. Exogenous abscisic acid inhibited nutsedge tuber sprouting and may be a natural dormancy factor in nutsedge.
Incorporation of Atrazine Side-Chain into Amino Acids of Corn
Authors: Schultz Donald P. , Tweedy B. G.
Published: May 2019

Seedlings of corn (Zea mays L., var. GT-112 RfRf and GT-112, resistant and susceptible, respectively) to 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) were grown 48 hr in sterile Hoagland's solution containing 14C-ethyl-labeled atrazine. More incorporation of the 14C-ethyl side-chain into free amino acids was found in the roots and shoots of GT-112 RfRf than GT-112, based on radioactivity. More radioactivity was found in roots of susceptible plants than in resistant plants; however, the trend was reversed in the shoots.
Absorption and Penetration of Picloram and 2,4,5-T into Detached Live Oak Leaves
Authors: Baur J. R. , Bovey R. W. , Baker R. D. , Riley Imogene
Published: May 2019

Detached live oak (Quercus virginianaMill.) leaves were immersed in aqueous solutions of 4-amino-3,5,6-trichloropicolinic acid (picloram) or (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) for periods up to 4 hr. Herbicide concentration ranged from 10−3to 10−6M; solutions were adjusted to either pH 4, 6, 7, or 8. Absorption of picloram in the presence of equimolar concentrations of 2,4,5-T exceeded that noted for picloram alone. The presence of picloram in the treating solutions had no effect on absorption of 2,4,5-T. This technique allows evaluation of absorption and penetration characteristics of mixtures of herbicides, solvents, and adjuvants.
Effects of Trifluralin on Growth, Nodulation, and Anatomy of Soybeans
Authors: Kust Cyril A. , Struckmeyer B. Esther
Published: May 2019

Effects ofα,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) rate and placement in soil on growth and anatomy of soybeans (Glycine max(L.) Merr.) were studied in greenhouses. In 7-week-old plants, trifluralin caused pronounced changes in number and organization of palisade cells in leaves. In fourth internodes, xylem elements of treated plants were less organized and walls of pericycle fibers were extremely thick compared to those of untreated plants. There was starch accumulation in nodules and in xylem elements of the upper root, and binucleate and trinucleate cells were present in tips of tap and lateral roots of treated plants. The effects were more pronounced as rate of trifluralin was increased from 0.36 to 0.74 and to 1.1 kg/ha and when trifluralin was incorporated into the 5 to 15-cm depth rather than the top 5 cm of soil. However, occlusions of xylem vessels in lateral and tap roots were most pronounced at 0.74 kg/ha. Plant topgrowth was reduced more when trifluralin was incorporated into the bottom 10 cm of soil, but root growth inhibition was not affected by trifluralin placement. Trifluralin reduced nodulation of soybeans and seemed to inhibit utilization of cotyledonary reserves and redistribution of organic and mineral constituents of unifoliolate leaves.
Shoot Zone Uptake and Translocation of Soil-Applied Herbicides
Authors: Nishimoto R. K. , Warren G. F.
Published: May 2019

Diphenamid (N,N-dimethyl-2,2-diphenylacetamide) severely inhibited adventitious roots in the shoot zone of sorghum (Sorghum bicolor(L.) Moench., var. RS 610) and corn (Zea maysL., var. WF9 X B37) without decreasing foliage growth. Using diphenamid to inhibit shoot zone roots, the presence of adventitious roots was shown to increase foliage injury to corn, sorghum, or both when exposed to 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron), 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryne), or 3-tert-butyl-5-chloro-6-methyluracil (terbacil) in the shoot zone. Inhibition of adventitious roots was associated with a decrease in uptake of14C-diuron and14C-ametryne in both corn and sorghum. Inhibition of the adventitious roots did not alter the response of corn or sorghum, as measured by top growth, when treated with dimethyl tetrachloroterephthalate (DCPA), isopropyl-m-chlorocarbanilate (chlorpropham),S-ethyl dipropylthiocarbamate (EPTC), andα,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin). The meristematic region of the sorghum shoot before emergence was more sensitive than other regions of the shoot to DCPA and chlorpropham. Injury from other application sites depended upon uptake from the treated area and movement to the meristematic region, where both herbicides appear to be acting.
Effects of a Dimethylpropynyl Benzamide Herbicide on Quackgrass Rhizomes
Authors: Smith L. W. , Peterson R. L. , Horton R. F.
Published: May 2019

The compound N-(l,l-dimethylpropynyl)-3,5-dichlorobenzamide affected the development of quackgrass (Agropyron repens (L.) Beauv.) by inhibiting the growth of meristematic regions. The nodes at the apex of treated rhizomes became swollen and necrotic and exhibited increases in DNA, RNA, and protein over untreated rhizomes. These changes in the terminal nodes were accompanied by a dramatic increase in the levels of cellulase and by several disruptive changes in the meristematic, nodal, and internodal tissue of quackgrass rhizomes.
Effect of Herbicides on Seedling Emergence Force
Authors: Burnside O. C.
Published: May 2019

A method is described to quantitatively record the upward force of an emerging seedling that exhibits epigeal germination. A soybean [Glycine max (L.) Merr.] seedling showed an average maximum emergence thrust of 434 g at 8 to 10 days after planting. Herbicides can be grouped into those that inhibit, have no effect, or stimulate the upward thrust exerted by an emerging soybean seedling. At the rates studied, the herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram) showed the greatest inhibition and 3-amino-2,5-dichlorobenzoic acid (chloramben) the greatest stimulation of emergence force of soybean seedlings.
Morphology and Photoperiodic Responses of Yellow Nutsedge
Authors: Jansen L. L.
Published: May 2019

Young vegetative clones of yellow nutsedge (Cyperus esculentusL.) were propagated by subdivision of older clones and then grown 6 months under photoperiods of 8 to 24 hr. Early stages of development of basal bulbs, tubers, and flowering structures were characterized in terms of apical meristem activity and differentiation of various foliar appendages: cladophylls, prophylls, leaf primordia, foliar tube development, and involucral leaves. Ramification of the axial stem system was interpreted as a repeating phylogenetic sequence:viz., undifferentiated axial meristem (from basal bulb) å primitive stem (rhizome) å advanced stem (new basal bulb). New photosynthetic leaves differentiated every 4.5 to 5 days, and each exhibited a sigmoid pattern of growth for 24 to 40 days. As photoperiods increased from 14 to 24 hr, certain active vegetative processes—total peripheral shoot development, rhizome proliferation, and rate of higher order shooting—were progressively promoted. The rate of differentiation of indeterminate rhizome tips into basal bulbs (new shoots) was maximum at 16 hr and into tubers at 8 to 12 hr. Delayed tuberization, however, occurred even at the longest photoperiod. Flowering occurred only at photoperiods of 12 and 14 hr. Active vegetative processes were competitive with tuberization, and flowering was competitive with both active and dormant vegetative development.
Ecology of Aquatic Vascular Plants in Southern Ontario Impoundments
Authors: McCombie A. M. , Wile Ivanka
Published: May 2019

Aquatic plants and physical-chemical data were collected during 1969 from 19 ponds and lakes. The fertility of these waters, as indicated by specific conductance, appeared to be a function of watershed area over the range 0 to 100 hectares. For watersheds greater than 100 hectares, differences in soil type and farming intensity were major causes of variability. Chara (Charaspp.) was found at specific conductances from 96 to 445 micromhos/sq cm (at 18 C) but was most abundant between 218 and 300. Chara also grew best in the upper half of the transparency range at Secchi disc readings varying from 2.4 to 5.8 m. Elodea (Elodea canadensisMichx.) flourished at specific conductances of 224 to 300 micromhos/sq cm and at transparencies from 2.7 to 5.8 m. Largeleaf pondweed (Potamogeton amplifoliusTuckerm.) was found only in the least fertile impoundment, whereas curlyleaf pondweed (P. crispusL.) occurred only in the most fertile impoundment. Sago pondweed (P. pectinatusL.) occurred at specific conductances of 200 to 349 micromhos/sq cm but was most prolific from 229 upward. This species also favored extensive shallow areas subject to a continuous summer flow.
Fate of Fluorodifen in Resistant Peanut Seedlings
Authors: Eastin E. F.
Published: May 2019

Rapid absorption and limited acropetal movement of 14C from p-nitrophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether (hereafter referred to as fluorodifen) labeled with 14C at either the 1 position of the p-nitrophenyl ring (fluorodifen-1′-14C) or the trifluoromethyl carbon (fluorodifen-14CF3) were observed in peanut (Arachis hypogaea L., var. Starr) seedlings after root treatment for 48 hr followed by 96 hr in nutrient solution. Major products of degradation of fluorodifen-1′-14C were p-nitrophenol and Unknown I (possibly a conjugate of p-nitrophenol). Some p-nitrophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether and several minor unknowns were detected. The major product of degradation of fluorodifen-14CF3 was Unknown II (possibly a conjugate of 2-amino-4-trifluoromethylphenol). Some 2-amino-4-trifluoromethylphenol and traces of p-nitrophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether, p-aminophenyl-α,α,α-trifluoro-2-nitro-p-tolyl ether, p-aminophenyl-α,α,α-trifluoro-2-amino-p-tolyl ether, and several minor unknowns also were detected. A major pathway of fluorodifen degradation in peanut seedlings is postulated whereby fluorodifen is reduced to the 2-amino derivative which is cleaved at the ether linkage to yield p-nitrophenol and 2-amino-4-trifluoromethylphenol. The respective phenols are then conjugated with natural plant substances to form water soluble conjugates.
Comparative Effects of Diuron and Chlorpropham on ATP Levels in Chlorella
Authors: St. John J. B.
Published: May 2019

The effect of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and isopropylm-chlorocarbanilate (chlorpropham) onin vivolevels of ATP inChlorella sorokinianaShihira and Krauss were compared. Diuron inhibited the photochemical, but not the oxidative, production of ATP, whereas chlorpropham inhibited both systems. Diuron equally inhibited growth and ATP synthesis, but chlorpropham had a stronger effect on ATP level than on growth.
Uptake of Copper by Parrotfeather
Authors: Sutton David L. , Blackburn R. D.
Published: May 2019

The copper content of emersed parrotfeather (Myriophyllum brasilienseCamb.) roots ranged from 52 to 6,505 ppmw after root applications of copper sulfate pentahydrate (hereinafter referred to as CSP) at 0.25 to 16.0 ppmw of copper, respectively, under greenhouse conditions. The coefficient of correlation for copper in the treatment solution to the copper content of the roots was 0.9502. A slight acropetal movement of copper occurred because of an increase of CSP in solution and an increase in treatment time. Concentrations of CSP at 2.0 ppmw of copper or higher inhibited growth of parrotfeather. Phosphorus levels in the roots of parrotfeather were reduced by root applications of CSP at 1.0 ppmw of copper or higher during a 2-week treatment period.
Soil Persistence of Repeated Annual Applications of Atrazine
Authors: Burnside O. C. , Fenster C. R. , Wicks G. A.
Published: May 2019

Dissipation of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) in sprinkler-irrigated fields was faster in a silty clay loam soil of eastern Nebraska than in loam soils of central or western Nebraska. Atrazine dissipated faster under fallow than under corn (Zea mays L.) culture in western Nebraska, but there was no difference in atrazine loss whether in corn or fallow in central or eastern Nebraska. In central and western Nebraska, atrazine persisted in the soil for longer than 1 year. In eastern Nebraska under sprinkler irrigation, most of the atrazine had dissipated before the following growing season. Sprinkler irrigation markedly reduced atrazine longevity in soils studied.
Cotton Response to Temperature and Organic Arsenicals
Authors: Keeley P. E. , Thullen R. J.
Published: May 2019

Nonradioactive and14C-organic arsenical herbicides were applied to foliage of young cotton (Gossypium hirsutumL., var. Acala SJ-1) at various temperatures. An application of 3.36 kg/ha of monosodium methanearsonate (MSMA), with and without 0.5% surfactant, severely injured plants exposed at 13 C. Similar injury resulted when plants were exposed and treated at 20 C with MSMA containing 0.5% surfactant. Applications of MSMA did not injure plants exposed at 31 C. Disodium methanearsonate (DSMA) was less injurious to cotton than MSMA. Only slight to moderate injury resulted when plants were exposed and treated at 13 C with 3.36 kg/ha of DSMA containing 0.5% surfactant. Applications at higher temperatures did not injure cotton. Cotyledons absorbed14C-methanearsonic acid (MAA) and14C-MSMA more readily than14C-DSMA. Contact injury from these herbicides was slight at 13 C but was pronounced at 20 and 29 C. Generally, translocation of herbicides into developing true leaves was slight. The exception resulted from applications of14C-MSMA to plants at 13 C when contact injury was negligible.
A Microradioautographic Study of 14C-Diuron Absorption by Cotton
Authors: Strang R. H. , Rogers R. L.
Published: May 2019

The techniques of cryostat sectioning, freeze-drying, and microradioautography were adapted to study the absorption and translocation of radio-labeled 3-(3,4-dichlorophenyl)-1,1-dimethylurea (14C-diuron) in root-treated cotton (Gossypium hirsutum L., var. Coker 201) plants. Diuron appeared to move primarily in the apoplast and to be transported acropetally and laterally in the transpiration stream. Radioactivity was observed to accumulate in striking concentrations in the lysigenous, or pigment, glands and the trichomes of the cotton plant. This accumulation is postulated to be a major factor in lowering the effective concentration of the herbicide in the leaves of cotton as compared to leaves of more susceptible plants, and thus may be a significant factor in the tolerance of cotton to diuron.
Response of Weeds and Soybeans to Vernolate and Other Herbicides
Authors: Johnson B. J.
Published: May 2019

Vernolate (S-propyl dipropylthiocarbamate) injected into a sandy loam soil controlled a higher percentage of early weeds in soybeans (Glycine max(L.) Merr.) in 2 years out of 3 when compared with incorporated vernolate at the same rate by conventional methods. Late season weed control was enhanced by split applications of herbicides applied postemergence in sequence with vernolate. Chloroxuron (3-[p-(p-chlorophenoxy)phenyl]-1,1-dimethylurea) applied early postemergence plus 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron) or 2,4-bis-(isopropylamino)-6-(methylthio)-s-triazine (prometryne) applied in split applications as late and layby treatments gave the best weed control. Prometryne caused chlorotic veination in the upper leaves of the plants each year. In 1970, when prometryne was applied in sequence with incorporated vernolate, soybean plants were injured 30% compared with only 8% injury when the same herbicide was applied in sequence with injected vernolate at the same rate. The average seed yields were higher from injected vernolate at 1.12 kg/ha than from incorporated vernolate at 2.24 kg/ha. There was no difference in yield when vernolate was incorporated or injected at the same rate. Seed yields from the 3-year average were lower from plots treated with prometryne than from plots treated with linuron or 2-sec-butyl-4,6-dinitrophenol (dinoseb). Generally, the soybean seed quality was lower and seed size smaller when herbicide treatments failed to control weeds throughout the growing season.
Influence of Incorporation Depth on Chloramben Activity
Authors: Sommerville Duane N. , Wax L. M.
Published: May 2019

Rates of 0, 1.7, and 3.4 kg/ha of 3-amino-2,5-dichlorobenzoic acid (chloramben) were incorporated to 0, 3.8, and 7.6-cm depths in 0.7 by 0.7-m microplots under low, moderate, and high rainfall conditions. Soybean [Glycine max(L.) Merr., var. Amsoy] injury increased with increasing depth of incorporation of 3.4 kg/ha chloramben. Chloramben incorporation under low rainfall conditions significantly improved control of giant foxtail (Setaria faberiiHerrm.), smooth pigweed (Amaranthus hybridusL.), and velvetleaf (Abutilon theophrastiMedic.) compared to surface treatments. Jimsonweed (Datura stramoniumL.) was not controlled well by chloramben regardless of rate or incorporation depth. In larger field plots over a 3-year period, 3.4 kg/ha chloramben incorporated with a disc produced slight but insignificant soybean injury. Giant foxtail, smooth pigweed, common ragweed (Ambrosia artemisiifoliaL.), and velvetleaf control with incorporated chloramben was equal to or better than the control obtained with surface-applied chloramben. Regardless of method of application, control of common cocklebur (Xanthium pensylvanicumWallr.), jimsonweed, and annual morningglory (Ipomoeaspp.) was poor.
Biologically Active Substances in Subterranean Parts of Purple Nutsedge
Authors: Friedman Theresa , Horowitz M.
Published: May 2019

The growth of barley (Hordeum distichum L., var. Esperanza) seedlings in nutrient solution was reduced by purple nutsedge (Cyperus rotundus L.) plants growing in connected vials and by addition of ethanolic extract of purple nutsedge. Aqueous and ethanolic extracts from subterranean parts of purple nutsedge reduced the germination and root elongation of barley; stimulations of barley root elongation were obtained with diluted aqueous extract. The germination of barley, mustard (Brassica nigra L., var. Alsace), and cotton (Gossypium hirsutum L., var. Acala 1517) was reduced in soil which had been infested previously with purple nutsedge. Radicle elongation of barley was inhibited by ethanolic extract of soil previously infested. Chromatographic studies indicated that the inhibitors are phenolic substances.
Metabolism of Atrazine by Fall Panicum and Large Crabgrass
Authors: Thompson Lafayette , Houghton J. M. , Slife F. W. , Butler H. S.
Published: May 2019

Compared to corn (Zea maysL.) (resistant), oats (Avena sativaL.) (susceptible), and giant foxtail (Setaria faberiiHerrm.) (susceptible), fall panicum (Panicum dichotomiflorumMichx.) and large crabgrass (Digitaria sanguinalis(L.) Scop.) metabolized 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) at an intermediate rate. The order of tolerance of these five species (corn > fall panicum and large crabgrass > giant foxtail > oats) is identical to the order of their ability to metabolize atrazine. In 6 hr, corn, fall panicum, large crabgrass, giant foxtail, and oats metabolized 96, 44, 50, 17, and 2%, respectively, of the14C-atrazine absorbed from a 10 ppm solution and translocated to the foliage, leaving concentrations of 2.2, 34.8, 30.1, 59.8, and 66.3 mμ moles, respectively, of atrazine per g of fresh weight of shoots. Hydroxyatrazine [2-hydroxy-4-(ethylamino)-6-(isopropylamino)-s-triazine] was found in the shoots of corn and giant foxtail. Corn shoots also contained a more hydrophilic metabolite, presumably a peptide conjugate. Hydrophilic metabolites found in the shoots of giant foxtail, fall panicum, and large crabgrass were chromatographically identical to the hydrophilic metabolite found in corn.
The Role of Weeds in Human Affairs
Authors: Holm LeRoy
Published: May 2019

I have chosen to begin with the proposition that more energy is expended for the weeding of man's crops than for any other single human task. Because it is one of man's principal occupations, the burden is intricately woven into the fabric of his family and community life and to lift it from the tangled skeins of his existence so that we may examine it, or judge it, is well nigh impossible. In the writings of Aristotle, there are these words which seem appropriate to the task ahead, “The search for Truth is in one way hard and in another easy, for it is evident that no one can master it fully nor miss it wholly.”
Mineral Nutrition and the Parasite-Host Relationship of Witchweed
Authors: Egley G. H.
Published: May 2019

The influence of mineral nutrition on the parasite-host relationship of witchweed (Striga luteaLour.) and sorghum (Sorghum vulgarePers. ‘Texas Bighead’) was investigated in greenhouse and growth chamber studies. Sorghum was grown in Eustis loamy sand, either infested or not infested with witchweed, and treated with one of three levels of mineral nutrients. Witchweed reduced host-shoot yields by about 70% at the low nutrient levels and by about 45% at the highest nutrient level. Witchweed produced seed at all nutrient levels, whereas the host produced seed at the highest level only. Increased nutrition also increased witchweed yields. Regardless of nutrient level, an early attack by witchweed was more destructive to the host than a late attack. Growth of witchweed in soil also was studied after the parasite was detached from the host or the host shoot was removed. When only the host shoot was removed, (a) witchweed growth was inhibited; (b) feeding of sucrose to witchweed did not restore parasite growth; (c) mineral nutrients were toxic to the parasite; and (d) high relative humidity around witchweed protected it from the nutrient toxicity. High relative humidity enhanced survival of the detached parasite but markedly inhibited growth of witchweed in the intact parasite-host relationship.
Effect of Weeds on Soybean Yield and Harvesting Efficiency
Authors: Nave W. R. , Wax L. M.
Published: May 2019

A reduction in soybean (Glycine max(L.) Merr.) yield of 25% (1968) to 30% (1969) resulted from one smooth pigweed (Amaranthus hybridusL.) per ft in 30-inch rows. A giant foxtail (Setaria faberiiHerrm.) infestation of one plant per ft in 30-inch rows reduced yield 13% in 1969. Harvesting before weeds were desiccated resulted in significant threshing and separating losses as speed was increased from 1 to 2 and 3 mph. Stubble, lodging, and stalk losses were more than double in the pigweed and foxtail plots when compared to the weed-free plots after weeds were desiccated by frost.
Disappearance of Triallate from Field Soils
Authors: Smith Allan E.
Published: May 2019

Small field plots, 18 by 18 cm in size, were treated with S-(2,3,3-trichloroallyl)diisopropylthiolcarbamate (triallate) at rates equivalent to 2.8 kg/ha at five sites in Saskatchewan. After one growing season (5 months) the residues remaining in the 0 to 5 and 5 to 10-cm levels of soil were determined by gas chromatographic analysis. At all locations 16 to 27% of the applied herbicide was found in the top 5 cm while negligible residues were detected at the 5 to 10-cm level.
Protecting Corn from Herbicide Injury by Seed Treatment
Authors: Burnside O. C. , Wicks G. A. , Fenster C. R.
Published: May 2019

The use of 1,8-naphthalic anhydride, at 0.5% by corn (Zea maysL. ‘501D’) seed weight, eliminated most of the corn yield loss caused byS-ethyl dipropylthiocarbamate (EPTC) at 3.4, 6.7, or 10.0 kg/ha. The seed protectant partially reduced the moderate corn yield loss fromS-ethyl diisobutylthiocarbamate (butylate) at 9.0 kg/ha. This seed protectant provides a new approach to increased weed control while maintaining selectivity in the production of corn.
Auger Soil Sampler for Herbicide Residues
Authors: Flynt T. O. , Riley T. E. , Bovey R. W. , Meyer R. E.
Published: May 2019

A soil sampler was constructed for moisture and pesticide residue determinations that will retrieve soils with rocky and heavy clay layers. The sampler consisted of a commercially constructed worm-gear driven auger mounted in a 3.7-m-tall vertical frame. Depth, speed, accuracy, and ease of sample retrieval were substantially increased, compared to manual sampling.
Selectivity of Dicamba in Wheat and Wild Buckwheat
Authors: Quimby P. C. , Nalewaja John D.
Published: May 2019

The uptake, translocation, and fate of14C-labeled 3,6-dichloro-o-anisic acid (14C-dicamba) were studied in wheat (Triticum aestivumL., 'Selkirk’) and wild buckwheat (Polygonum convolvulusL.) as resistant and susceptible species, respectively. Selectivity could not be explained by interspecific differences in uptake of14C-dicamba by leaf sections submerged in exogenous solutions.14C-dicamba accumulated in meristems of wild buckwheat but not in the youngest tillers of wheat. Moreover, wheat main culms conjugated or metabolized14C-dicamba more quickly than did wild buckwheat meristems. Therefore, selectivity of dicamba apparently was related to interspecific differences in translocation and metabolism.
Benefits of Agricultural Chemicals
Authors: Ennis W. B.
Published: May 2019

I am grateful for the opportunity to share with you some thoughts on the benefits of agricultural chemicals. I want to invite you to help examine some important aspects of this complex subject.
Root Absorption and Translocation of Picloram by Oats and Soybeans
Authors: Isensee A. R. , Jones G. E. , Turner B. C.
Published: May 2019

The effects of time, concentration, pH, temperature, and metabolic inhibitors on 4-amino-3,5,6-trichloropicolinic acid (picloram) uptake from nutrient solution by oats (Avena sativaL. ‘Markton’) and soybeans (Glycine maxL. ‘Lee’) were studied. Oats and soybeans had similar absorption patterns of rapid initial uptake. However, total accumulation patterns markedly differed in that accumulation was concentration-dependent for oats but not for soybeans. Initial uptake by oats and soybean roots increased as solution concentration increased. Picloram was redistributed in oats and soybeans and some egress from roots to solution occurred. Picloram uptake by both plant species was markedly diminished with an increase in pH from 3.5 to 4.5, but pH had little effect from 4.5 to 9.5. Less picloram was taken up by oats and soybean roots from solution maintained at 4 C than at 26 C. Translocation to tops followed a similar trend. Increasing concentrations of three metabolic inhibitors, 2,4-dinitrophenol (DNP), sodium azide, and sodium arsenite, reduced root uptake of picloram in both species. All inhibitors (except DNP for oats) at 10−6to 10−5molar concentrations stimulated translocation of picloram to oats and soybean tops while higher concentrations depressed translocation.
Molinate for Barnyardgrass Control in Rice
Authors: Smith Roy J.
Published: May 2019

In three field experiments at the University of Arkansas Rice Branch Experiment Station, Stuttgart,S-ethyl hexahydro-1H-azepine-1-carbothioate [molinate] at 2, 3, 4, and 6 lb/A was applied into the flood water 3, 6, 11, and 17 days after emergence of rice [Oryza sativaL.] and barnyardgrass [Echinochloa crusgalli(L.) Beauv.]. Molinate at 2 or 3 lb/A applied 3, 6, 11, or 17 days after emergence of rice and barnyardgrass, when weeds ranged from the one-leaf to tillering stages, provided acceptable weed control and rice tolerated these treatments satisfactorily. A rate of 3 lb/A frequently controlled barnyardgrass better than 2 lb/A, and usually was as effective as 4 or 6 lb/A. Sometimes, rates of 4 or 6 lb/A, applied 11 or 17 days after rice emergence, injured the crop moderately to severely and reduced grain yields.
Adsorption of Ametryne and Diuron by Soils
Authors: Liu L. C. , Cibes-Viadé H. , Koo F. K. S.
Published: May 2019

The adsorption of 2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine (ametryne) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) varied greatly among 34 Puerto Rican soils was studied using the agitated slurry technique. Adsorption was expressed as a distribution coefficient (Kd), which is the ratio of the amount of herbicide adsorbed to the amount in the equilibrium solution. In general, diuron was adsorbed to a greater degree than ametryne. Adsorption of ametryne was positively correlated with organic matter and silt content but negatively correlated with pH of the soil. The inclusion of soil pH in a multiple regression analysis contributed the highest increase in explanation for adsorption of ametryne. Adsorption of diuron was highly correlated with organic matter content and cation exchange capacity. A correlation was found between adsorption of diuron and content of magnesium, and soil texture. Cation exchange capacity was the only inclusion soil property which, in addition to organic matter, significantly contributed to the adsorption of diuron. Temperature appeared to have a greater effect on the adsorption of diuron than on the adsorption of ametryne. Conversely, the effect of pH on the adsorption of ametryne was significantly greater than that of diuron.
Antagonistic Interaction of EPTC and 2,4-D
Authors: Beste C. E. , Schreiber M. M.
Published: May 2019

An antagonistic interaction betweenS-ethyl dipropylthiocarbamate (EPTC) and (2,4-dichlorophenoxy)acetic acid (2,4-D) was observed on sorghum(Sorghum vulgarePers.) and corn(Zea maysL.) after 21 days growth in soil incorporated treatments. Increasing the 2,4-D concentration increased the antagonism to EPTC. The antagonistic interaction was alsoobserved onsorghum grown in solution culture. The antagonistic interaction occurred when the site of uptake was restricted to either the root or shoot zone of sorghum. Uptake studies with14C-EPTC indicated that 2,4-D does not interfere with uptake or subsequent movement of14C radioactivity within sorghum plants. Respiration of sorghum treated with the combination EPTC-2,4-D appeared to be normal. Respiration of EPTC-treated plants was inhibited.
Picloram and 2,4,5-T Influence on Honey Mesquite Morphology
Authors: Meyer R. E.
Published: May 2019

Seeds of honey mesquite(Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell) were germinated and grown in aqueous solutions of the sodium salt of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) or the potassium salt of 4-amino-3,5,6-trichloropicolinic acid (picloram). Elongation of germinating seedling hypocotyls and roots was progressively inhibited by increasing concn of each herbicide up to about 1 or 2 mg/L the first 2 days. After 5 and 10 days, progressively more inhibition occurred at 5 to 10 mg/L of 2,4,5-T and 1 to 2 mg/L of picloram. Four-month-old honey mesquite seedlings were treated with foliar sprays of the 2-ethylhexyl ester of 2,4,5-T or the potassium salt of picloram. Both herbicides caused curling of the stem tip, death of the growing point, cracking below the leaf, and increased numbers of lateral roots. Both herbicides caused phellem cells to enlarge radially, inner cortext and phloem parenchyma to proliferate, and xylem vessels to lignify without enlarging. Starch granules disappeared from treated plants within 8 days and re-occurred in treated plants only 53 days after spraying. Picloram was slightly more toxic to honey mesquite seedlings than 2,4,5-T.
IL METODO DELLA COMPARAZIONE
Authors: Lijphart Arend
Published: May 2019

Introduzione

Tra i vari settori o discipline particolari in cui la scienza politica è comunemente suddivisa, la politica comparata è l'unica ad avere un'etichetta metodologica anziché sostantiva. Il nome « politica comparata » indica ilcome, ma non specifica ilche cosadell'analisi. L'etichetta però è piuttosto ingannatrice, in quanto sia l'esplicito interesse metodologico sia l'implicita consapevolezza metodologica non sono stati in genere molto alti fra i cultori di politica comparata.
LA SCIENZA POLITICA AMERICANA ALL'INIZIO DEGLI ANNI '70
Authors: Giannotti Gianni
Published: May 2019

Introduzione

Il « bilancio » qui presentato intende fornire una rassegna accurata delle tendenze della scienza politica americana e si basa sull'esame di una bibliografia sufficientemente rappresentativa. Per la sua particolare natura di vera e propria indagine empirica il lavoro di Albert Somit e Joseph Tanenhaus, American Political Science: Profile of a Discipline è stato uno dei punti di partenza ed ha rappresentato un utile strumento di verifica.
CONFLITTO E ÉLITES NELLE SOCIETÀ INDUSTRIALI
Authors: Palma Giuseppe Di
Published: May 2019

Introduzione

Molte affermazioni sono state fatte circa cambiamenti che si manifestano nelle origini e negli sviluppi del conflitto politico nelle società occidentali, e nell'Europa occidentale in particolare. Tali cambiamenti sono stati chiamati, con un termine collettivo ora di moda rna inappropriato, la «fine delle ideologie». Le affermazioni possono essere cosí condensate: le tradizionali linee di divisione in classi economiche e forse anche sociali si sono venute sfumando con la rapida crescita di una «nuova classe media» e l'aumento del tenore di vita nelle nazioni dell'Europa occidentale.

I fattori locali, regionali, etnici e religiosi sono diminuiti d’importanza in quanto basi fondamentali di affiliazione politica in molti paesi, mentre ha luogo una « mobilitazione sociale » e le masse vengono sempre piú integrate nelle loro rispettive culture politiche nazionali. A ciò contribuiscono lo stesso sviluppo economico e sociale, il diffondersi dei mezzi di comunicazione, la proliferazione delle associazioni volontarie, e l’aumento dei poteri dell’esecutivo e delle sue responsabilità nella salute, nel benessere, nella sicurezza sociale nonché nelle attività economiche in generale.
CARRIERA PARLAMENTARE E PROFESSIONISMO POLITICO
Authors: Herzog Dietrich
Published: May 2019

Introduzione

Fin dai tempi dei padri fondatori della moderna teoria delle élites, Gaetano Mosca, Vilfredo Pareto, Roberto Michels, la ricerca sociologica si è interessata alla provenienza sociale dei decision-makers politici. Ogni volta che analizziamo le élites politiche, sociali e culturali, non solo vogliamo sapere che cosa queste persone facciano e pensino, ma anche da dove esse provengano ed in che modo siano ascese a posizioni d'influenza. Ciò è provatoda un numero ormai incalcolabile di studi sui leaders di partito, sui parlamenti, sui quadri della pubblica amministrazione, sui decision-makers di determinate comunit´, ecc. Piuttosto stranamente, peró, il processo dinamico di reclutamento delle èlites, le sue caratteristiche strutturali ed i suoi meccanismi di selezione, fino a non molto tempo fa, non sono stati trattati in maniera adeguata.