bluuebunny/crossref_metadata_2025 huggingface dataset:
Fall Panicum Interference in Peanuts
Authors: York A.C. , Coble H.D.
Published: May 2019

Peanut (Arachis hypogaeaL. ‘Florigiant’) seed yield was reduced 25% by a fall panicum (Panicum dichotomiflorumMichx.) density of one weed per 4.9 m of row. Greater weed densities resulted in greater yield losses. Peanut seed yield was reduced by fall panicum interference for 2 weeks or more after peanut emergence. Peanuts kept weed-free for 8 weeks after emergence failed to yield as well as those kept weed-free all season. However, control for the first 2 weeks appeared to be the most critical.
Weed Control in Narrow and Wide-Row Soybeans
Authors: Wax L.M. , Nave W.R. , Cooper R.L.
Published: May 2019

Field studies were conducted over a 3-yr period to evaluate weed control systems for soybeans [Glycine max(L.) Merr.] grown in 18- and 76-cm rows. Combinations of herbicides satisfactorily controlled a broad spectrum of annual grass and broadleaf weeds in soybeans grown in 76-cm rows with cultivation and in 18-cm rows without cultivation. Where a single herbicide treatment was used to control only annual grasses, the 76-cm rows (which were cultivated once) yielded from essentially the same as 18-cm rows up to almost 50% more than the 18-cm rows, which received no cultivation, depending on the year and broadleaf weed infestation. However, where herbicide combinations were used to effectively control all weeds, soybeans in 18-cm rows averaged up to 9% higher yields than those in the 76-cm rows.
The Physiology and Mode of Action of the Dinitroaniline Herbicides
Authors: Parka S. J. , Soper O. F.
Published: May 2019

The substituted 2,6-dinitroanilines were first reported as herbicides in 1960. At the present time, there are 14 2,6-dinitroaniline herbicides in various stages of product development. Literature on absorption, translocation, and mode of action of the dinitroaniline herbicides refers almost entirely to trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline]. These herbicides do not directly inhibit the germination of seed. Inhibition of lateral root development is the most characteristic growth response. Swelling of the root tip is a universally recognized morphological effect caused by these compounds. The cells in this region are multinucleate, indicating that the mitotic process has been disrupted. Examination of these cells shows an increase in the percentage of cells in arrested metaphase due to the disruption of spindle microtubules. Inference is made that the dinitroaniline herbicides affect chromosomes in a manner similar to colchicine, but research with pig brain (Sus scrofa) microtubules has shown that effects of the herbicide on microtubular protein is different.

Injury to the top of plants is recognized by stunting, development of dark green color, and swelling and brittleness of the stem or hypocotyl. The major sites of uptake are the shoot of monocots and the hypocotyl or hypocotyl hook for dicots. Exposure of seedling roots to the dinitroaniline herbicides does not kill the plant, but exposure of the young shoot will result in death. Available data indicate that the dinitroaniline herbicides are either absorbed or adsorbed by the roots due to the proximity of the roots to the herbicide, but that translocation from the root to the top is minimal. When a dinitroaniline was found in the plant, the parent compound was the major product present with metabolites equal to 5% or less.

Insufficient information is available to accurately describe effects of these herbicides on plant carbohydrates, lipids, and nitrogenous compounds. The effect of trifluralin on RNA and DNA varies with the plant species, treatment time, concentration of herbicide, and plant part investigated, but differences observed do not correlate with dinitroaniline-susceptible and resistant species. Enzyme activity does not appear to be greatly inhibited by the dinitroaniline herbicides. However, the dinitroaniline herbicides interfere with photosynthesis and respiration in vivo and in vitro.

The phytotoxic action of trifluralin can be antidoted with the organophosphorus insecticides, phorate [0,0-diethyl-S-(ethylthiomethyl)-phosphorodithioate], disulfoton [0,0-diethyl-S-2-(ethylthioethyl)-phosphorodithioate], and externally applied lipids such as D-α-tocopherol. There is a strong correlation that seeds with a high lipid content are resistant to trifluralin and those with a low lipid content are susceptible. Despite all the work that has been conducted, the mode of action of the dinitroaniline herbicides is still unclear.
Nitrite Accumulation Within Herbicide-Treated Leaves
Authors: Klepper Lowell A.
Published: May 2019

Six herbicides including DNP (2,4-dinitrophenol) were tested for their effects upon nitrate metabolism in green leaves. It was found that these herbicides which are not classified as “photosynthetic inhibitors” permitted nitrite to accumulate within green leaves in darkness but not in light. It is postulated that these herbicides have an uncoupling effect, similar to that of DNP, which indirectly affects the process of nitrate reduction. A new technique which demonstrates this effect is presented and discussed.
Triallate Mobility in Soils
Authors: Beestman G. B. , Deming J. M.
Published: May 2019

Laboratory studies were conducted to measure the relative volatility of triallate [S-(2,3,3-trichloroallyl) diisopropylthiocarbamate] from soils and to determine the effect of surfactants on triallate mobility. Significant volatilization occurred from continuously moist soils under constant air exposure but triallate did not volatilize more rapidly than herbicides which do not respond to incorporation. Volatilization rates from Ray silt soil fell in the order of propachlor (2-chloro-N-isopropylacetanilide) > triallate > alachlor [2-chloro-2′, 6′-diethyl-N-(methoxymethyl)acetanilide] and from Drummer silty clay loam were propachlor > alachlor > triallate. In suspension studies soils reversibly adsorbed 93 to 98% of the triallate in aqueous solution. With soil at field moisture capacity, the concentration of triallate in soil solution was 13 ppbw without surfactant and 14 ppbw with 3 parts emulsifier blend to 1 part of triallate (w/w). With this level of emulsifier 92% of triallate applied to the soil surface remained in the upper 3 cm of soil following a 15.2-cm simulated rainfall. Without surfactant 99% remained in the upper 3 cm of soil. Lower triallate mobility in moist soils observed in this study coupled with the strong dependence of triallate bioactivity as reported by others strongly suggests that deactivation by dry surface soils rather than volatility is primarily responsible for the triallate response to incorporation.
The Light Requirement for Herbicidal Activity of Diphenyl Ethers
Authors: Fadayomi Omosuyi , Warren G.F.
Published: May 2019

Light after treatment was found to be required for the herbicidal activity of nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] following postemergence applications of both herbicides to greenbean (Phaseolus vulgarisL. ‘Spartan Arrow’). The effect of photosynthate and/or light before treatment was investigated. A 24-hr dark period prior to postemergence treatment of the bean seedlings had no effect on herbicidal activity when light followed treatment. The effect of plant pigments on the activity of both herbicides was studied using mutants of corn (Zea maysL.) and soybean [Glycine max(L.) Merr.]. A white mutant of corn was much more resistant to the herbicides than a greenish-yellow mutant or the normal plant. A yellow mutant of soybean was equally as susceptible as the normal type. Studies with radiolabeled foliar applications of both herbicides showed no significant difference in translocation in the light or dark.
Soil Persistence of Atrazine and Cyanazine
Authors: Libik A.W. , Romanowski R.R.
Published: May 2019

The persistence of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile} both applied at 2.24 and 4.48 kg/ha was studied in the field on two soils. A greenhouse bioassay using cucumber (Cucumis sativusL. ‘Wisconsin SMR-18′) showed no reduction in growth when plants were grown in soil taken from cyanazine and atrazine treatments at the end of the season. Similarly, fall-sown rye (Secale cerealeL.) was not injured. The yields of transplanted tomatoes (Lycopersicum esculentumL. ‘Campbell 28′) and transplanted watermelons (Citrullus vulgaris‘Crimson Sweet’) were not significantly reduced when grown 1 yr after the initial application of either herbicide.
Control of Winter Annual Weeds in White Clover Raised for Seed
Authors: Lee W. O.
Published: May 2019

Winter applications of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or combinations of paraquat with diquat [6,7-dihydrodipydrido (1,2-α: 2′,1′-c) pyrazinediium ion], propham (isopropyl carbanilate), or pronamide [3,5-dichloro-N-(1,1-dimethyl-2-propynyl)benzamide], usually controlled both winter annual grass and broadleaf weeds in established white clover (Trifolium repensL. ‘New Zealand,’ ‘Louisiana S-1,’ and ‘Tillman’). Diquat controlled broadleaf weeds, but was less effective than paraquat or combinations of paraquat with diquat, propham, or pronamide for grass control. Dichlobenil (2,6-dichlorobenzonitrile) controlled weeds in some experiments. Pronamide and propham usually controlled grass weeds but not broadleaf weeds. In experiments in which clover seed production differed significantly, paraquat or combinations of paraquat with propham or pronamide usually resulted in higher yields than the check. Yields increased more often where treatments included paraquat.
Cytokinin Effects Induced in Purple Nutsedge by Perfluidone
Authors: Bendixen Leo E.
Published: May 2019

Cytokinins break bud dormancy and apical dominance, induce basal bulb formation, and dwarf shoot growth in purple nutsedge (Cyperus rotundusL.). Perfluidone (MBR 8251) [1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl) phenyl] methanesulfonamide] in addition to being phytotoxic, mimics the cytokinins in these aspects. This and other herbicides which have demonstrated effectiveness in nutsedge control may derive their potency from the preconditioning effects of their cytokinin activity combined with their phytotoxicity.
Napropamide Adsorption, Desorption, and Movement in Soils
Authors: Wu Chu-Huang , Buehring Normie , Davidson J. M. , Santelmann P. W.
Published: May 2019

Soil columns and soil thin-layer chromatography were used to evaluate the mobility of napropamide [2-(α-naphthoxy)-N,N,-diethylpropionamide] in various soils. The surface-applied herbicide did not move deeper than approximately 6 cm in a Teller sandy loam soil after a water application of 10.2 cm. The Rfvalues for napropamide and two reference herbicides were in the order of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] > napropamide > terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine]. The mobility of each herbicide was reduced with an increase in clay and organic matter content. Carbon-14 ring labeled napropamide was used to determine the adsorption and desorption characteristics of the herbicide in various soils. The Rfvalues obtained with napropamide and each soil agreed with the adsorptive characteristics. Small applications of a muck soil to a sand (2%, w/w) significantly increased herbicide adsorption and decreased herbicide desorption.
Response of Weeds to Soil pH
Authors: Buchanan G. A. , Hoveland C. S. , Harris M. C.
Published: May 2019

Ten warm-season and six cool-season weed species were grown in the glasshouse on Hartsells fine sandy loam soil and Lucedale sandy loam soil at pH levels from 4.7 to 6.3. Growth of species varied widely in response to soil pH as measured by herbage yield. Showy crotalaria (Crotalaria spectabilis Roth), coffee senna (Cassia occidentalis L.), and large crabgrass (Digitaria sanguinalis (L.) Scop.] were highly tolerant to low pH soils. Sicklepod (Cassia obtusifolia L.), annual bluegrass (Poa annua L.), Carolina geranium (Geranium carolinianum L.), and buckhorn plantain (Plantago lanceolata L.), were medium to high in tolerance. Jimsonweed (Datura stramonium L.), tall morningglory [Ipomoea purpurea (L.) Roth], crowfootgrass [Dactyloctenium aegyptium (L.) Richter], and prickly sida (Sida spinosa L.) were medium to low in tolerance to low soil pH. Growth of Florida beggarweed [Desmodium tortuosum (Sw.) DC], redroot pigweed (Amaranthus retroflexus L.), chickweed [Stellaria media (L.) Cyrillo], common dandelion (Taraxacum officinale (Weber), and wild mustard [Brassica kaber (DC.) L.C. Wheeler var. pinnatifida (Stokes) L.C. Wheeler] was severely reduced in soils with low pH.
Phytotoxic Action of Desmedipham: Influence of Temperature and Light Intensity
Authors: Bethlenfalvay Gabor , Norris R. F.
Published: May 2019

Inhibition of growth and photosynthesis in sugarbeet (Beta vulgarisL. var. ‘USH10’) treated with desmedipham [ethylm-hydroxycarbanilate carbanilate (ester)] was most severe between 25 and 30 C and decreased with higher or lower temperatures. Transfer of sugarbeet plants grown at temperatures from 10 to 35 C to higher temperatures after treatment increased injury and photosynthetic inhibition. Higher temperatures prior to treatment reduced injury at all posttreatment temperatures. When the temperature was changed from 25 to 40 C, inhibition was most severe immediately after treatment. Two days after treatment this 15 C temperature change did not cause additional injury. High posttreatment light intensities caused greater inhibition of photosynthesis than low light intensities.
The Interaction of Atrazine and EPTC on Navy Bean
Authors: Wyse Donald L. , Meggitt William F. , Penner Donald
Published: May 2019

Navy bean (Phaseolus vulgarisL.) treated with the combination of EPTC (S-ethyl dipropylthiocarbamate) and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] developed more chlorosis of the leaves than beans treated with atrazine alone. Navy bean yields in field studies in 1972, were reduced 39% when grown in the presence of 0.55 kg/ha of atrazine and 3.4 kg/ha of EPTC, whereas the single application of either herbicide reduced yields 0 to 14%, respectively. In 1973, atrazine at 0.28 kg/ha did not significantly reduce yields, but combinations of 0.28 kg/ha of atrazine plus 2.2, 3.4, and 4.5 kg/ha of EPTC, reduced yields 40, 30, and 62% respectively. The combination of atrazine and EPTC also reduced plant weight and delayed flower and pod development. EPTC was found to increase wind blast damage under conditions of low relative humidity, high winds, and limited soil moisture. EPTC at 2.2, 3.4, and 4.5 kg/ha reduced the chloroform-soluble leaf extract from the surface of leaves and scanning electron micrographs confirmed that EPTC at 10-6M altered leaf surface waxes. EPTC at 10-5and 10-6M increased the transpiration rate of plants. Increased uptake of14C-atrazine from solution was associated with increased transpiration.
Effect of Herbicides on the Development of Root Rot on Navy Bean
Authors: Wyse Donald L. , Meggitt William F. , Penner Donald
Published: May 2019

Application of EPTC (S-ethyl dipropylthiocarbamate) at 3.4 and 4.5 kg/ha in 1972 increased root rot severity and reduced navy bean (Phaseolus vulgaris L.) yields in soil with an artificial root rot [Fusarium solani (Mart.) Appel and Wr. f. Phaseoli (Burk.) Snyd. and Hans.] inoculum level. EPTC at 3.4 kg/ha and chloroamben (3-amino-2,5-dichlorobenzoic acid) at 3.4 kg/ha in 1973 caused the greatest root rot severity and greatest decrease in yield. Dinoseb (2-sec-butyl-4,6-dinitrophenol) and fluorodifen (p-nitrophenyl α,α,α-trifluoro-2-nitro-p-tolyl ether) at 5 kg/ha interacted with root rot less than the other herbicides assayed. In the growth chamber at 23 C, EPTC at 3.4 kg/ha and alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide] at 2.8 kg/ha applied to navy bean grown in soil infested with F. solani reduced plant growth. Root rot injury was most severe in plants treated with EPTC at 20 C ambient temperature. Navy bean growth was reduced as the level of F. solani chlamydospore inoculum increased in the presence of EPTC.
Yield and Height of Cotton as Affected by Weed Density and Nitrogen Level
Authors: Robinson E. L.
Published: May 2019

Cotton (Gossypium hirsutumL. ‘Stoneville 7A’) grown for 3 yr in competition with various weed densities and nitrogen levels showed annual weeds could reduce cotton heights as much as 75% and cotton yields as much as 88%. Cotton yields were increased by 18 to 30% by adding nitrogen to plots with no weeds. In 1973, cotton supplied with 224 kg/ha of nitrogen could tolerate up to 50% weeds without loss of yield. Weeds left to grow and reseed with no control resulted in increasingly greater competition with each succeeding year.
Competition Between Upland Rice and Purple Nutsedge for Nitrogen, Moisture, and Light
Authors: Okafor L. I. , De Datta S. K.
Published: May 2019

Field experiments were conducted on clay and clay loam soils at the International Rice Research Institute to investigate the effects of competition between upland rice (Oryza sativa L.) and varying populations of purple nutsedge (Cyperus rotundus L.) for nitrogen, moisture, and light on the grain yield of upland rice. ‘IR5’ was used in 1972, while the experimental line ‘IR442-2-58’ was used in 1973. Grain yields of ‘IR5’ and ‘IR442-2-58’ increased with 60 kg/ha of nitrogen, and decreased with increased purple nutsedge population. The application of nitrogen to weedy upland rice fields benefited the purple nutsedge more than the rice. Purple nutsedge and upland rice competed extensively for moisture and the competition was much more serious with increased nitrogen fertilization. Purple nutsedge competition reduced the light transmission ratio (LTR). The reduction was proportional to the increase in purple nutsedge population density. Reductions in the LTR were greater at higher nitrogen levels during the three seasons.
Phytotoxicity of Herbicides to a Tifgreen Bermudagrass Green
Authors: Callahan L. M.
Published: May 2019

A ‘tifgreen’ bermudagrass [Cynodon dactylon(L.) Pers.] golf-type green was treated with seven preemergence and one postemergence type herbicides at two rates each for three consecutive years to assess their phytotoxicity. A few herbicides were applied on a second, third, and fourth treatment date during the year with applications made in separate plots. Severe foliage injury occurred the first year with siduron [1-(2-methylcyclohexyl)-3-phenylurea] while moderate injury occurred with bromacil (5-bromo-3-sec-butyl-6-methyluracil) and DCPA (dimethyl tetrachloroterephthalate); and slight injury occurred with benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine), bensulide [0,0-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide], and terbutol (2,6-di-tert-butyl-p-tolyl methylcarbamate). No injury was observed with bandane (polychlorodicyclopentadiene isomers) and tri-calcium arsenate. Injury to the bermudagrass in the second year following renewal treatments was severe with siduron and bromacil; moderate with benefin, bandane, DCPA, and terbutol; and slight with bensulide and tri-calcium arsenate. Injury in the third year following repeat applications was severe with siduron, terbutol, bandane, bromacil, benefin, and DCPA; slight to moderate with bensulide, and slight with tri-calcium arsenate. Injury observed the fourth year resulting from residues was moderate with bandane; slight with terbutol, benefin, bensulide, and DCPA; and none with siduron, bromacil, and tri-calcium arsenate.
UV and IR Spectral Characteristics of Chloramben in Selected Environments
Authors: Berkheiser V. E. , Ahlrichs J. L.
Published: May 2019

Ultraviolet (UV) absorption spectra were recorded of chloramben (3-amino-2,5-dichlorobenzoic acid) and selected relatives in solutions of different pH's. From these spectra, the Broensted acid-base properties of chloramben were deduced. Interpretations of solution spectra were applied to UV absorption spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Infrared (IR) transmittance spectra were recorded of chloramben and selected derivatives in KBr pellets and band assignments were made. Interpretations of these spectra were also applied to IR spectra of chloramben adsorbed onto Ca-montmorillonite at low water content. Both UV and IR measurements indicated that protonation of the amino group occurs and that the carboxyl group of chloramben is strongly hydrogen-bonded to the hydration water of the interlayer cations.
Phytotoxicity of Triallate Vapors to Wild Oat
Authors: Miller Stephen D. , Nalewaja John D.
Published: May 2019

Wild oat (Avena fatuaL.) seedlings were exposed to vapors arising from soil treated with triallate [S-(2,3,3-trichloroallyl)diisopropylthiocarbamate]. Vapor from the liquid triallate formulation inhibited seedling growth more than vapor from the granular formulation, and the degree of inhibition was least in Fargo clay, intermediate in Hecla sandy loam and greatest in washed sand. Growth inhibition from vapors of soil-applied liquid or granular triallate increased as soil moisture content and soil temperature increased. The site of effective vapor action on wild oat seedlings was below the soil surface.
Germination of Seeds of Turfgrasses as Affected by Glyphosate and Paraquat
Authors: Klingman Dayton L. , Murray J. J.
Published: May 2019

Effects of glyphosate [N-(phosphonomethyl)glycine] and paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) on turfgrass seed germination were evaluated in the greenhouse. Glyphosate caused little effect on germination of Kentucky bluegrass (Poa pratensis L.), red fescue (Festuca rubra L.), and tall fescue (F. arundinacea Schreb.) when applied to the soil immediately before seeding or when applied directly over the seed on the soil surface. Paraquat sprayed directly over the seed on the soil surface prevented germination of most of the seeds of the three grass species. Covering seeds on the soil surface with clippings from grass turf sprayed with paraquat greatly reduced germination. About half of those that germinated either died later or were severely chlorotic. Covering seeds on the surface of the soil with clippings from turf that had been sprayed with glyphosate did not significantly reduce the number of seedlings established.
Field Growth of Fall Panicum and Witchgrass
Authors: Vengris Jonas , Damon R.A.
Published: May 2019

Fall panicum (Panicum dichotomiflorum Michx.) and witchgrass (Panicum capillare L.) emerged in naturally infested fields as early as April 30 and May 14, respectively. The shortest period between seeding and emergence was during the warmest period of the growing season. The number of days from emergence to heading decreased progressively for later seedings. After emergence witchgrass formed seedheads about 7 days earlier than fall panicum. Fall panicum emerging in the middle of July and witchgrass seedlings emerging July 25 produced mature seeds in the fall, shaded or not. Plant height, tiller number, and yield of both grasses were highest for plants emerging in May and June. Decreased light intensity delayed seed emergence, heading, and maturity of both grasses. Plant height, yields, number of tillers, and number of panicles also were decreased by shading. Fall panicum was a coarser plant than witchgrass and produced more tillers and panicles than witchgrass. Fall panicum and witchgrass seedlings emerging between June 23 and July 7 produced the most vigorous fast growing plants.
EPTC Altered Beet Disc Betacyanin Efflux and Fatty Acid Synthesis
Authors: Wilkinson R. E. , Smith A. E.
Published: May 2019

Betacyanin efflux from “aged” red beet (Beta vulgarisL.) root tissue, measured spectrophotometrically, was increased as temperature and EPTC (S-ethyl dipropylthiocarbamate) concentration increased. Acetate-2-14C (∗Ac) incorporation into the total fatty acid content was inhibited by EPTC. EPTC inhibited the incorporation of∗Ac into the dienoic fatty acids and NA (1,8-naphthalic anhydride) reversed the EPTC induced inhibition of the incorporation of ∗Ac into dienoic fatty acids.
Biology of the Waterhyacinth Mite in Argentina
Authors: Cordo Hugo A. , Deloach C. J.
Published: May 2019

Populations of the waterhyacinth mite (Orthogalumna terebrantis Wallwork) of ca 200,000 galleries/m2 (or 10,000 per plant) caused serious damage to waterhyacinth [Eichhornia crassipes (Mart.) Solms.] in the field, but such damage was sporadic and confined to small areas of plants in midsummer. Two or three generations a year occurred in the field. Adults emerged in late December, March, and May and adults were found on waterlettuce (Pistia stratiotes L.) throughout the winter. Development, appearance of the different stages, behavior of immatures and adults, and manner of attacking waterhyacinth is described. Only small differences were found between the biology of the mites studied in Argentina and of that reported in Uruguay and the United States.
Control of Volunteer Corn and Giant Foxtail in Soybeans
Authors: Andersen Robert N.
Published: May 2019

In field studies, HOE 22870 [4-(4′-chlorophenoxy)-phenoxy-α-propionic-isobutylester] and HOE 23408 methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate at 0.84 to 3.36 kg/ha were sprayed over the top of soybeans [Glycine max(L.) Merr.], corn (Zea maysL.), and giant foxtail (Setaria faberiHerrm.). Rates of 0.84 or 1.68 kg/ha of either herbicide controlled corn and giant foxtail. Soybeans tolerated 3.36 kg/ha (the highest rate used) of either herbicide. Both herbicides performed quite similarly, but HOE 22870 was generally more effective on giant foxtail and less effective on corn than was HOE 23408. The optimum time of application, in terms of soybean development, was the first trifoliolate stage. At this stage, corn had four to five leaves and giant foxtail had three to five leaves. HOE 23408 was applied to 32 inbred lines of corn in a greenhouse study. Several inbreds had considerable tolerance. When HOE 23408 at 0.56 kg/ha was applied to these 32 inbreds in a field study, control ranged from 100% for the most susceptible inbred to 22% for the most resistant inbred. At 1.12 kg/ha, control of corn ranged from 100% to 42%.
Comparative Morphological Development of Six Johnsongrass Ecotypes
Authors: Mcwhorter C. G. , Jordan T. N.
Published: May 2019

The comparative morphological development of six johnsongrass [Sorghum halepense(L.) Pers.] ecotypes was studied over a 10-week period. Three of the ecotypes were previously shown to be susceptible to dalapon (2,2-dichloropropionic acid) while others were resistant to the herbicide. The production of primary culms varied from 5.0 to 9.3 per plant system, and secondary culms ranged from 7 to 24 per plant system. Plant heights varied nearly two-fold, and the number of individual rhizomes produced by different ecotypes varied three-fold. Susceptible ecotypes from Georgia, Washington, and Illinois produced more rhizome nodes and higher dry and wet weights of culms and rhizomes than resistant ecotypes from Mississippi, Louisiana, and California. Ecotypes most resistant to dalapon had longer rhizome internodes and higher water content in culms and rhizomes than susceptible strains. Differences in anatomy and growth support the hypothesis of the existence of johnsongrass ecotypes, but the results were not consistent with the susceptibility of ecotypes to dalapon.
Development of Isocitric Lyase Activity in Germinating Prickly Sida Seed
Authors: Reger Bonnie J. , Smith E. Wayne
Published: May 2019

Maximum activity of isocitric lyase (EC 4.1.3.1) was reached at 24 hr incubation of afterripened (nondormant) prickly sida (Sida spinosaL.) seed. Enzyme activity declined gradually with incubation times in excess of 24 hr. Actinomycin D (Act D) at 5 μg/ml had essentially no effect on 24-hr germination but inhibited development of isocitric lyase activity 83%. Cycloheximide (CH) at 10 μg/ml inhibited 24-hr germination of punctured seed only 7% but inhibited development of isocitric lyase activity 76%. Seed incubated in water 12 hr before being transferred to Act D at 5 μg/ml for an additional 12 hr did not escape sensitivity to the antibiotic. Isocitric lyase activity was inhibited when assayed at 24 hr total incubation. In the reverse experiment, seed incubated in Act D 12 hr before being transferred to water, isocitric lyase activity at 24 hr was not affected. Apparently prickly sida seed lacked a performed mRNA for isocitric lyase and transcription and translation of the mRNA occurred shortly after initiation of radicle protrusion (~8 hr).
Numerical and Chemotaxonomy of the Green Foxtail Complex
Authors: Williams R. D. , Schreiber M. M.
Published: May 2019

The phenetic relationships of green foxtail [Setaria viridisvar.viridis(L.) Beauv.] and its allies were examined by numerical and chemotaxonomic methods. Correlation coefficients and taxonomic distances based on quantitative data from 31 characters displayed close phenetic similarities among green foxtail, its varieties and foxtail millet [S. italica(L.) Beauv.]. Isolation and separation of 35 alcohol-soluble compounds by two dimensional paper chromatography supported the numerical comparisons. By combining all characters examined, the resulting cluster analysis displayed the closest similarity between robust white (S. viridisvar.robusta-albaSchreiber), robust purple (S. viridisvar.robusta-purpureaSchreiber) and giant green foxtail [S. viridisvar.major(Gaudin.) Posp.] indicating that the robust foxtails may be subvarieties of giant green foxtail rather than of green foxtail. The numerical, morphological and chemical comparisons support the proposed phylogeny of the Old World foxtails and indicate green foxtail as the probable center of ancestorial origin.
Effect of Dinitroanaline Herbicides in a Soil Medium on Snap Bean and Soybean
Authors: Struckmeyer B. Esther , Binning L. K. , Harvey R. G.
Published: May 2019

Anatomical studies determined the effect of 0.8, 1.7, and 3.4 kg/ha of penoxalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine]; AC-92390 (N-sec-butyl-3-4-dimethyl-2,6-dinitrobenzenamine); oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide); and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) on the cell structure of snap bean (Phaseolus vulgarisL. ‘Tenderette’) and soybean[Glycine max(L.) Merr. ‘Corsoy’]. Cellular abnormalities in the swollen and brittle area of the stem of treated plants included thinnerwalled cells, elongated xylem elements, hypertrophy and hyperplasia of cells, and anomalous rings of vascular tissue in the cortical region. Injury caused by the four herbicides was similar in snap bean and soybean.
Seed Dormancy of Nodding Beggarticks (Bidens cernua L.)
Authors: Hogue E. J.
Published: May 2019

For prompt germination, the achenes of the nodding beggarticks (Bidens cernua L.) required 6 to 12 weeks of afterripening at 2 C and exposure to light. Without cold afterripening, a slow but complete germination was obtained after 2 weeks when the achene and seed inside, or the seed excised from the achene, were clipped at the distal end and germinated in light at 24 C. The embryo behaved like a clipped seed. Complete germination within 7 days, in light or dark, of the clipped seed was obtained by treating with gibberellic acid (GA) or N-6-benzyladenine (BA). The barriers to germination in the non-after-ripened seed appear to be first in the achene, the coverings of the seed itself and in a metabolic factor.
Penetration, Translocation, and Metabolism of14C-Difenzoquat in Wild Oat and Barley
Authors: Sharma M. P. , Vanden Born W. H. , Friesen H. A. , McBeath D. K.
Published: May 2019

Foliar penetration of14C-difenzoquat (1,2-dimethyl-3,5-diphenyl-1-H-pyrazolium), in the presence of a surfactant, into both wild oat (Avena fatuaL.) and barley (Hordeum vulgareL. ‘Conquest’), was rapid and continued at a nearly constant rate for 72 hr, the maximum time period studied; 93 and 84% of the applied dose was absorbed by the leaves of wild oat and barley, respectively. Added surfactants at 0.01% to 0.3% and high relative. humidity (RH) greatly enhanced the penetration of the herbicide into wild oat. An increase in temperature from 10 to 30 C resulted in a large increase in penetration. Commercial formulations of bromoxynil (3,5-dibromo-4-hydroxy-benzonitrile) + MCPA {[(4-chloro-O-tolyl)oxy] acetic acid} (1:1, w/w), 2,4-D[(2,4-dichlorophenoxy)acetic acid] ester and barban (4-chloro-2-butynylm-chlorocarbanilate) markedly increased the penetration of14C-difenzoquat into wild oat. Amine formulation of 2,4-D, on the other hand, had no effect on penetration. Foliarly-applied14C-difenzoquat rapidly translocated mainly in the acropetal direction. Most of the absorbed14C, however, was accumulated in the treated area and a few centimeters above the treated area. There was some basipetal movement, and 24 hr after treatment14C was detectable in the roots. Root uptake of14C-difenzoquat was very rapid, but upward movement of14C was slight, and even 24 hr after treatment most of it was retained by the roots. Chromatographic analysis of plant extracts up to 15 days after treatment with14C-difenzoquat revealed no evidence of difenzoquat metabolism by wild oat, barley, and wheat (Triticum vulgareL. ‘Thatcher’). The selective action of difenzoquat in wild oat and barley cannot be accounted for by differences in its foliar penetration, translocation, or metabolism in these species.
Chemical Control of Field Horsetail
Authors: Ryan G. F.
Published: May 2019

Soil-incorporated treatments of dichlobenil (2,6-dichlorobenzonitrile) at 4.5 or 9 kg/ha completely controlled field horsetail (Equisetum arvense L.) for 2 yr and at 9 kg/ha, control was 90 to 99% in the third year. Mulching with sawdust after surface application of dichlobenil gave similar results. In an area treated at 9 kg/ha and isolated from emerged field horsetail, there was no reappearance of field horsetail until 5.5 yr after treatment. Japanese holly (Ilex crenata Thunb.) and azalea (Rhododendron X ‘Rosebud’) planted a year after treatment made as much growth in treated as in adjacent untreated soil. Douglas fir seedlings [Pseudotsuga menziesii (Mirb.) Franco] made as much growth in treated as in untreated soil only when planted 2 yr after treatment. Strawberry (Fragaria X ‘Northwest’) plants made approximately 80% as much top growth in treated as in untreated soil when planted 2 yr after herbicide application.
Soil Persistence of Isopropalin and Oryzalin
Authors: Gingerich L. L. , Zimdahl R. L.
Published: May 2019

The aerobic rate of disappearance of isopropalin (2,6-dinitro-N,N-dipropyl-cumidine) was slower than that of oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) in soil. The aerobic half-lives for isopropalin were 3.5 months and 13.3 months and for oryzalin 1.40 months and 4.35 months at 30 and 15 C respectively. A simple system was devised to create anaerobiosis in soil at 80% of field capacity. Both herbicides dissipated more rapidly under anaerobic conditions. The first order half-lives at 30 C in anaerobic soil were 0.17 months for isopropalin and 0.34 months for oryzalin. Neither first, second, nor half order kinetics were clearly superior in describing the degradation processes. Arrhenius activation energies suggested that the degradation processes were non-biological.
Field Competition Between Tall Morningglory and Soybean. II. Development and Distribution of Root Systems
Authors: Scott H. D. , Oliver L. R.
Published: May 2019

Studies of the development and distribution of root systems of intraspecific and interspecific competition were conducted between soybean [Glycine max.(L.) Merr. ‘Lee 68′] and tall morningglory [Ipomoea purpurea(L.) Roth]. Tall morningglory at three plant densities and soybean were grown for 2 yr on a Taloka silt loam. The greatest density of soybean and tall morningglory roots grown under intraspecific competition was in the surface 12 cm and in the center of the row. Greater values of root length and density were during the dryer season. The largest fraction of total root length at a given date also was in the surface 12 cm and decreased with depth. The fraction at a given depth was a dynamic property of the root system during the growing season. When compared with the soybean root system, tall morningglory roots were found at deeper depths and had greater root densities. Little expansion of the soybean root system was found after initiation of the soybean reproductive phase. During this phase, the tall morningglory root system was increasing at a faster rate of growth than the soybean root system. The greatest density of roots grown under interspecific competition also was in the surface 12 cm and at the center of the row. These values were less than those found under intraspecific competition. Root distribution and development are dynamic functions of growth stage, planting density, and plant species.
Field Competition Between Tall Morningglory and Soybean. I. Growth Analysis
Authors: Oliver L. R. , Frans R. E. , Talbert R. E.
Published: May 2019

The intraspecific (competition between same species) and interspecific (competition between different species) competitiveness of tall morningglory [Ipomoea purpurea(L.) Roth] in soybeans [Glycine max(L.) Merr.] was evaluated for 3 yr at Fayetteville, Arkansas. Tall morningglory was planted at densities of one plant per 61, 30, and 15 cm of row, and competition duration ranged from 2 weeks to full-season. Soybeans were more competitive than tall morningglory for the first 6 to 8 weeks after emergence. The competitiveness of tall morningglory was dependent upon a rapid increase in photosynthetic area which occurred 4 to 6 weeks after emergence. Reductions in leaf area index (LAI) or plant dry weight and crop growth rate (CGR) of soybeans were closely correlated to percent soybean yield reduction. Tall morningglory could remain in soybeans for 12, 10, and 6 weeks without significantly reducing soybean yield at one plant per 61, 30, and 15 cm of row, respectively. Tall morningglory was three to four times more competitive during the soybean reproductive stage than during the vegetative stage.
REQUISITI PER LA STABILITÀ DELLE COALIZIONI
Authors: Pappalardo Adriano
Published: May 2019

Introduzione

Negli ultimi cinquanta anni, almeno una mezza dozzina di sistemi politici europei sono stati contemporaneamente retti da governi di coalizione. Ciononostante, la riflessione politologica sulle cause che ne determinano la stabilità e la dissoluzione è ancor oggi assai embrionale e frammentaria. Nella letteratura sull'argomento, per lo piú costituita da studi monografici e descrittivi sulla Terza e sulla Quarta Repubblica e sulla Germania di Weimar, la relativa stabilità di certe coalizioni è generalmente attribuita alla abilità degli attori nel sottrarsi alle decisioni controverse. Nessuno dei tentativi di sistemazione teorica finora compiuti in chiave comparata si è rivelato soddisfacente, cosicché, mentre alcuni continuano a parlare di «intrinseca instabilità» dei governi di coalizione, per altri questi non sono meno stabili dei monocolore e, in alcuni casi, «figurano fra i piú stabili governi democratici del mondo».
L'ORIZZONTE TEMPORALE DEI REGIMI DEMOCRATICI
Authors: Zannoni Paolo
Published: May 2019

Introduzione

Uno dei temi piú problematici ed importanti dibattuti oggi nella scienza politica è l'orizzonte temporale dei regimi democratici. La sua problematicità consiste nel fatto che non si sa con certezza se l'esistenza di una forma democratica di governo influenzi l'orizzonte temporale dei regimi politici. È ipotesi assai frequente nella letteratura politologica degli ultimi venti anni, da Lippmann a Rawls, che i sistemi politici democratici siano affetti da miopia nel prendere le decisioni politiche, in quanto legati alle preferenze immediate dei cittadini. Questa ipotesi, per quanto interessante, non è però stata fino ad ora suffragata da sufficienti dati empirici.
LA SCIENZA POLITICA NELLA REPUBBLICA FEDERALE TEDESCA
Authors: Caciagli Mario
Published: May 2019

Introduzione

Dopo un primo periodo di avvio incerto e pieno di ostacoli di varia natura, da una decina d'anni a questa parte la scienza politica — tanto come disciplina di insegnamento universitario, quanto come settore specialistico di studi — ha conosciuto nella Repubblica federale tedesca (e a Berlino Ovest) una improvvisa e rigogliosa espansione. La crescita quantitativa in istituti, cattedre, numero di studenti, pubblicazioni e produzione scientifica è stata in quest'ultimo periodo a dir poco imponente. Nel 1974 è stato possibile constatare, da parte di chi ne è direttamente interessato, che « la scienza politica in Germania è, sulla base del numero dei posti di insegnamento, la piú sviluppata in Europa ». C'è parso questo uno dei motivi piú validi per redigere questa rassegna e render conto di una situazione che può essere di un qualche interesse per chi si occupa nel nostro paese di studi politologici e della loro organizzazione.
IL PLURALISMO RIVISITATO
Authors: Dahl Robert A.
Published: May 2019

Introduzione

La lotta di singoli e di gruppi per ottenere l'autonomia in rapporto al controllo su terzi è, come i tentativi di acquisire il controllo sugli altri, una tendenza fondamentale della vita politica. Le lotte per l'autonomia derivano da conflitti e fratture; quando queste lotte, come spesso si verifica, hanno successo, portano a loro volta a tendenze pluralistiche. Dato che i conflitti e le fratture sono onnipresenti, lo sono anche le tendenze al pluralismo.
L'ANALISI DELLA CLASSE PARLAMENTARE: PROBLEMI E PROSPETTIVE
Authors: Cotta Maurizio
Published: May 2019

Introduzione

Negli ultimi vent'anni gli studi sul personale parlamentare dei paesi dell'area occidentale (e, nel periodo piú recente, anche di altre aree) non sono stati pochi. Si può anzi dire che, nello studio delle istituzioni parlamentari, questo tema è stato tra quelli che piú hanno avuto successo, forse solo superato dagli studi in chiave di decision-making. C'è dunque materia per tentare un bilancio di questo lavoro di ricerca e per delinearne le prospettive. Tracciare un bilancio significa fare una disamina dei modi nei quali questo tema è stato impostato ed evidenziare i risultati che ne sono stati ricavati. Ma, soprattutto, significa valutare l'utilità esplicativa di queste ricerche — al di là del loro apporto puramente descrittivo — entro una piú vasta interpretazione di certe realtà politiche, quali il sottosistema parlamentare o la classe dirigente politica in generale. Mi preme insistere su questo punto perché un esame degli studi che potremmo dire di «sociologia parlamentare» rivela che, in buona parte di essi, la preoccupazione per i risvolti teorici è assai ridotta o comunque limitata alla problematica interna a questo approccio.
Frequency effects on spelling in Hebrew-speaking younger and older adults
Authors: Kavé Gitit , Gorokhod Rita , Yerushalmi Ayelet , Salner Neta
Published: May 2019

Previous research has documented conflicting findings regarding the effect of word frequency on spelling in older adults. The current study examines spelling in Hebrew, in which it is easier to define the type of likely misspellings in each word. Younger and older Hebrew speakers spelled 120 single words that differed in word and letter frequency. Results show that all participants made more phonological substitutions of target letters on low-frequency words and on words with low-frequency letters. Yet, younger adults had a lower percentage of correct responses than did older adults, especially on low-frequency words. Vocabulary knowledge eliminated this age effect. We suggest that aging leads to greater reliance on full lexical retrieval of spelling instead of on sublexical phoneme-to-grapheme processing, due to years of exposure to written language, increase in vocabulary, and consolidation of orthographic representations.
Observations of Comet Kohoutek (1973f) with a Ground-Based Fabry-Perot Spectrometer
Authors: Huppler D. , Reynolds R. J. , Roesler F.L. , Scherb F , Trauger J.
Published: May 2019

Between 1973 December 1 and 1974 February 2, optical emission lines from the gas cloud surrounding comet Kohoutek were observed using a double Fabry-Perot etalon spectrometer at Kitt Peak National Observatory. The spectrometer had a resolving power of 40,000, corresponding to a velocity resolution of about 7.5 km sec-1. With this resolution it was possible to use the cometearth relative velocity to resolve faint cometary Hα λ6563, [01] λ6300 and other emission lines from geocoronal and airglow emissions and to study the cometary line profiles in order to obtain information about the composition, effective temperatures, outflow velocities, and production rates of atoms and ions in the cometary envelope.
Detection of Molecular Microwave Transitions in the 3 mm Wavelength Range in Comet Kohoutek (1973f)
Authors: Buhl D. , Huebner W. F , Snyder L. E.
Published: May 2019

We have recently reported detection of hydrogen cyanide and the first quantitative observations of the velocities of neutral gas jets in the inner part of the coma while the comet was at small heliocentric distances (Huebner, et al., 1974). Now we report the detection of two line transitions from unidentified cometary molecules, provide further evidence of the variability of neutral gas jets, and give a summary of our search program for microwave transitions in molecules of cometary origin.

The observations presented here were made with a 3-mm line receiver mounted on the 11-m NRAO radio dish at Kitt Peak. Observations were carried out before perihelion (15 to 20 December 1973) and after perihelion (3 to 7 January 1974). During these periods the comet was between 0.3 and 0.5 AU heliocentric distance.
A Kinematographic Study of the Tail of Comet Kohoutek (1973f)
Authors: Jockers K. , Roosen R. G. , Cruikshank D. P.
Published: May 2019

By combining observations of Comet Kohoutek (1973 f) made in the Southwest US, Alaska and Hawaii, a cometary tail movie has been made. Parts of the movie were shown at the conference and some frames of the movie are reproduced in Fig. 1, In this paper we give some details of the observations and describe what we see on the movie.

Observers who contributed to the movie are listed in Table 1 with their institutions, instruments, and site locations. In all but one case, fast Schmidt cameras were used; high-speed optics are needed for this work because the interval between successive pictures should not exceed 15 minutes if plasma tail motions are to be properly visualized. The 36 cm f/2 Schmidt camera of the Joint Observatory for Cometary Research (JOCR) is clearly well-suited because of its flat field of about 8 x 10°.
Comet Brightness Parameters: Definition, Determination, and Correlations
Authors: Meisel David D. , Morris Charles S.
Published: May 2019

Visual estimates of comet total magnitude have been made for well over one hundred years. In this paper no attempt has been made to review all previous work on comet magnitudes. Instead we prefer to concentrate on developing a conceptual framework upon which previous work can be evaluated. We have tried to unify the approach as much as possible by filling in gaps that occur between previously published accounts. The present work represents an extension and revision of an earlier attempt at understanding comet magnitudes (Meisel, 1970).
Nongravitational Forces on Comets
Authors: Marsden B. G.
Published: May 2019

The study of the nongravitational effects on comets began slightly more than a century and a half ago. As is well known, Encke (1819) demonstrated that comet 1819 I had a revolution period of not more than a few years and that the same comet had also been observed in 1786, 1795 and 1805. The observations clearly required that the revolution period be about 3.3 years, and Encke went on to remark that, after approximate allowance had been made for the perturbations by the planets, the average revolution period seemed to be 1207.9 days between 1795 and 1805, but only 1207.3 days between 1805 and 1819. As a result of a more refined computation of the planetary perturbations, the following year he (Encke 1820) was able to confirm these figures and find in addition that the average period between 1786 and 1795 was as much as 1208.1 days.