bluuebunny/crossref_metadata_2025 huggingface dataset:
Weed Science: The Emergence of a Vital Technology
Authors: Freed Virgil H.
Published: May 2019

President Hay, distinguished officers of the Society, and learned colleagues. Let me express my deep appreciation for the honor you confer on me.

It was my good fortune to begin a career in weed control at the point of transition between the modern chemical era and what I have chosen to call the cultural-mechanical era of weed control, which just preceded it. It was, therefore, my privilege to have known and worked with some of the handful of scientists who laid the foundation of weed science. Some are yet with us, but most have passed on to a greater glory.
Effects of Starch Xanthate and Sludge Polymer on the Initial Activity with Delayed Incorporation, Residual Activity, and Crop Safety of Several Herbicides
Authors: Foley M. E. , Wax L. M.
Published: May 2019

Field studies were conducted in 1977 and 1978 to compare the efficacy of the starch xanthate and activated-sludge polymer controlled-release herbicide formulations with the emulsifiable-concentrate formulations. As incorporation was delayed from immediately to never incorporated, starch xanthate and sludge polymer thiocarbamate herbicide formulations had activity equal to that of the emulsifiable concentrates at our initial and final rating dates. Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine)-starch xanthate in 1977 had increased activity over that of the emulsifiable concentrate as incorporation was delayed, as indicated by initial and final visual rating. Starch xanthate did not greatly increase the residual activity of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], or several thiocarbamate herbicides. Starch xanthate formulations of EPTC (S-ethyl dipropylthiocarbamate) and vernolate (S-propyl dipropylthiocarbamate) provided significantly less protection to corn than did addition of the protectant R-29148 [3-(dichloroacetyl)-2,2,5-trimethyloxazolidine]. The sludge polymer formulation had no controlled-release properties.
Damage to Common Ragweed (Ambrosia artemisiifolia) Caused by the White Rust Fungus (Albugo tragopogi)
Authors: Hartmann H. , Watson A. K.
Published: May 2019

The plant pathogenic fungusAlbugo tragopogi(Pers.) S. F. Gray (“white rust”), isolated from a local population of common ragweed (Ambrosia artemisiifoliaL.) and inoculated into ragweed seedlings at the two-leaf stage, reduced pollen production by 99%, seed production by 98%, and top weight by 79% of plants that developed systemic disease symptoms while growing in a controlled environment. However, only 14% of the inoculated plants developed systemic symptoms. A convenient method of inoculating leaves of seedling plants with zoospores of a fungus is described.
Site of Action of Oxyfluorfen
Authors: Pritchard M. K. , Warren G. F. , Dilley R. A.
Published: May 2019

The effects of oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] were studied on electron transport and phosphorylation in isolated spinach (Spinacia oleraceaL.) chloroplasts and on the response of green bean (Phaseolus vulgarisL. ‘Spartan Arrow’) to applications of oxyfluorfen alone or in combination with other herbicides. Coupled non-cyclic electron transfer and phosphorylation through photosystems I and II (H2O å methyl viologen) were inhibited about 30% and 55%, respectively, by 10−4M oxyfluorfen. Photosystem II-linked phosphorylation with dimethylbenzoquinone (2,5-dimethyl-p-benzoquinone) as the electron acceptor (H2O å DMQ) was completely inhibited by 10−4M oxyfluorfen. Photosystem II electron transport with dimethylbenzoquinone as the electron acceptor was inhibited 60% by 10−4M oxyfluorfen, whereas photosystem I electron transport with 2,6-dichlorophenol indophenol as electron donor (DCIPH2å MV) was not susceptible to oxyfluorfen inhibition. Photosystem I-linked phosphorylation and the accompanying electron transport supported by durohydroquinone electron donation (DQH2å MV) were inhibited about 50% by 10−4M oxyfluorfen, whereas cyclic phosphorylation was not inhibited at that concentration. Increased conductivity of a solution that contained leaf discs taken from green beans treated with various combinations of foliar-applied herbicides was a measure of membrane damage caused by the herbicides, and revealed that oxyfluorfen has a different site of action than do photosynthesis inhibitor and bipyridilium herbicides. Oxyfluorfen plus dinoseb (2-sec-butyl-4,6-dinitrophenol) injury to green beans was additive, but the two herbicides did not have the same site of action. Oxyfluorfen did not appear to inhibit electron transport in chloroplasts at herbicidal rates, nor was it dependent on electron transport for activation.
Inhibition of Turnip (Brassica rapa) Seed Germination by Velvetleaf (Abutilon theophrasti) Seed
Authors: Elmore C. D.
Published: May 2019

The allelopathic potential of germinating seed of velvetleaf (Abutilon theophrasti Medic.) was established in a laboratory study with germinating seed of turnip (Brassica rapa L. ‘Purple Top’). Two-day-old velvetleaf seedlings inhibited radicle growth of germinating turnip by 17% at 24 h after both were placed in the same petri plate. Alcoholic and aqueous extracts of velvetleaf seed, however, seriously inhibited germination of turnip seed. The extract of velvetleaf seed was fractionated by ion-exchange chromatography into acid, basic, and neutral fractions. Most of the allelopathic activity was located in the acid fraction, which includes the plant phenolics. The basic fraction (amino acids) inhibited radicle growth of turnip by 18% after 48 h. The amino acid profile of velvetleaf seed extracts is presented and discussed, because this fraction has previously been implicated as the allelopathic fraction.
Atrazine Carryover in Soil in a Reduced Tillage Crop Production System
Authors: Burnside O. C. , Wicks G. A.
Published: May 2019

Atrazine [2-chloro-4-(ethylamino)-6-isopropylamino)-s-triazine] carryover under reduced or no-till row crop production systems was measured by planting oats (Avena sativaL.) the following year as a field bioassay during 1970 through 1976 at Lincoln and North Platte, Nebraska. Oat yields indicate that soil persistence of normal-use rates of atrazine into the subsequent year is only a minor residue problem under reduced tillage cropping systems. Atrazine carryover in soil was less of a problem under these reduced tillage systems as compared with prior experiments with conventional tillage systems across Nebraska.
Foliar Uptake and Transport of 2,4-D and Picloram by Drummond's Goldenweed (Isocoma drummondii)
Authors: Mayeux H. S. , Scifres C.J.
Published: May 2019

Detached leaves of Drummond's goldenweed [Isocoma drummondii(T. & G.) Greene] absorbed the potassium salt of 2,4-D [(2,4-dichlorophenoxy)acetic acid] from aqueous solutions more slowly than did sunflower (Helianthus annuusL.), and both species absorbed less of the potassium salt of picloram (4-amino-3,5,6-trichloropicolinic acid) than 2,4-D. However, there was no difference in absorption of the herbicides by Drummond's goldenweed leaves after 6 h of exposure to solutions containing 0.5% (v/v) surfactant. Attached Drummond's goldenweed leaves absorbed about 50% of available 2,4-D (diethylamine) and 25% of available picloram (potassium salt) within 5 days after spraying in the field during July or November. Herbicide accumulation in Drummond's goldenweed taproots after spray applications was generally slow, regardless of season, but translocation to taproots was substantially greater after application in November than after treatment in March or July. Accumulation of picloram in taproots was faster and more extensive than accumulation of 2,4-D. However, based on mortality at 6 months after treatment, both herbicides were translocated in quantities adequate for control. The greater effectiveness of picloram, despite its low foliar uptake, than 2,4-D is attributed to its greater mobility and root uptake in Drummond's goldenweed after broadcast sprays.
Dormancy, Germination, and Emergence Characteristics of Fall Panicum (Panicum dichotomiflorum) Seed
Authors: Brecke B. J. , Duke W. B.
Published: May 2019

Fall panicum (Panicum dichotomiflorumMichx.) seed were found to be dormant at harvest. This dormancy was overcome by an after-ripening period of 17 to 22 weeks, alternating germination temperatures (10 C for 16 h and 30 C for 8 h), stratification, and mechanical or chemical scarification. Soaking seed in gibberellic acid (GA3) or thiourea for 1 day, or washing seed in running tap water for up to 96 h before seed were placed in a germinator, had no effect on dormancy. In the greenhouse, fall panicum emergence was greatest (82%) when seed were placed on the growth media surface. The maximum number of seedlings (39%) emerged in the field when seed were placed 1.3 cm below the soil surface, although some emerged from as deep as 5.1 cm.
Granule Structure and Rate of Release with Starch-Encapsulated Thiocarbamates
Authors: Schreiber M. M. , White M. D.
Published: May 2019

Scanning electron micrographs that depict the surface and internal structure of several starch-encapsulated granular formulations of EPTC (S-ethyl dipropylthiocarbamate) and butylate (S-ethyl diisobutylthiocarbamate) relate well with herbicidal release rates previously reported. Fast-release formulations appear to have a porous surface with little distinctive internal structure. Diffusion would be expected to be more rapid as fewer diffusion barriers are present. Slow-release formulations have a smooth, hard surface with irregular surface pores and a honeycombed internal structure. The slower release characteristics are associated with stronger oxidants used for crosslinking xanthate in the entrapment of herbicides. The scanning electron microscope would be an excellent quality control technique in the preparation of starch-encapsulated herbicides.
Audible Timer for Hand-Carried Plot Sprayers
Authors: Regehr D. L. , Eastburn R. P.
Published: May 2019

We describe a small, light-weight, battery-powered timer that emits an audible signal at 1-s intervals. This audible timer is used to monitor ground speed when applying chemicals to plots, thereby eliminating the need for manual manipulation of a stop watch.
Effectiveness of Glyphosate in Broomrape (Orobanchespp.) Control in Four Crops
Authors: Jacobsohn R. , Kelman Y.
Published: May 2019

We studied the effectiveness of glyphosate [N-(phosphono-methyl)glycine] for the control ofOrobanchespp. in the field when applied to the crop foliage prior to the emergence of the parasite. The bestOrobanchecontrol in October-sown carrots (Daucus carotaL.) parasitized byOrobanche crenataForsk. andO. aegyptiacaPers. and in December-sown broad bean (Vicia fabaL.) and peas (Pisum sativumL.) parasitized byO. crenatawas obtained by spraying twice, 2 weeks apart, in late January and in February, respectively. Carrot root yield remained unaffected by glyphosate at rates up to 200 g/ha. In heavily infested fields, carrots were irreversibly damaged by earlyOrobancheparasitism. The highest yields of pods of broad beans occurred after two or three applications of 150 g/ha glyphosate. Peas were seriously damaged by 150 g/ha. Two or three sprays of 50 g/ha glyphosate resulted in the highest green-kernel yield of pea where the soil was not heavily infested. Glyphosate effectively reducedO. cernuaLoeffl. emergence in non-irrigated tomatoes (Lycopersicum esculentumMill.), but was very phytotoxic to the crop. Glyphosate was highly effective in controllingOrobanchespp.; however, marginal selectivity may be sufficient in some crops and not in glyphosate-susceptible ones.
A Continuous-Belt Herbicide Wiper
Authors: Welker W. V. , Darlington T.
Published: May 2019

A continuous-belt herbicide wiper was developed to apply herbicides to weeds that are taller than cranberry (Vaccinium macrocarponAit.) plants. An endless belt with a sponge attached to the entire length of the belt moves through a reservoir containing a herbicide solution. A variable pressure wheel squeezes the excess liquid out of the sponge and returns it to the reservoir. The herbicide is deposited on the leaves of the weeds as the belt moves in a horizontal plane, perpendicular to the forward movement of the wiper. Control of Walter's sedge (Carex walterianaBailey), woolgrass [Scirpus cyperinus(L.) Kunth] and switchgrass (Panicum virgatumL.) was obtained when glyphosate [N-(phosphonomethyl)glycine], dalapon (2,2-dichloropropionic acid), and paraquat (1, 1′-dimethyl-4,4′-bipyridinium ion) were applied using the continuous-belt wiper. No injury to cranberry plants was observed.
Response of Yellow (Cyperus esculentus) and Purple (Cyperus rotundus) Nutsedge to Metolachlor
Authors: Obrigawitch T. , Abernathy J. R. , Gipson J. R.
Published: May 2019

Two 1-yr field studies were conducted to evaluate preemergence and preplant incorporated treatments of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], EPTC (S-ethyl dipropylthiocarbamate), fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone}, and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] for the control of yellow nutsedge (Cyperus esculentusL.). Preemergence applications of metolachlor at 2.24, 3.36, and 4.48 kg/ha gave the best control with no significant differences observed among rates of metolachlor. Depth of herbicide incorporation did not result in any significant increase in control. Preplant incorporation of metolachlor at all rates, or fluridone at 0.56 and 0.84 kg/ha provided seasonal control of yellow nutsedge. Translocation of14C-metolachlor applied to the root or shoot of yellow nutsedge was primarily acropetal with some limited basipetal movement. Application of14C-metolachlor to the root or shoot of purple nutsedge (Cyperus rotundusL.) resulted in mostly acropetal translocation with little movement of14C from the treatment site.
Effect of pH, Nitrogen, and Tillage on Weed Control and Corn (Zea mays) Yield
Authors: Kells J. J. , Blevins R. L. , Rieck C. E. , Muir W. M.
Published: May 2019

Field studies were conducted to determine the effect of soil surface (upper 5 cm) pH and tillage on weed control and corn (Zea maysL.) yield using simazine [2-chloro-4,6-bis-(ethylamino)-s-triazine] as the herbicide for weed control. Soil pH, weed control, and corn yield were examined under no-tillage and conventional tillage systems with and without added lime and different rates of nitrogen. Increased soil pH significantly increased weed control as compared with added lime vs. no added lime, where the surface soil pH influenced the effectiveness of the applied simazine. Soil pH had a greater effect on weed control under no-tillage than under conventional tillage. Conventional tillage significantly (P<.01) increased weed control, yield, and soil pH over no-tillage. Additions of lime as compared to unlimed treatments resulted in significantly increased weed control (83% vs. 63%), yield (5,930 vs. 5,290 kg/ha) and soil pH (5.91 vs. 5.22). The poorest weed control was observed with no-tillage on unlimed plots. A significant tillage by linear effect of nitrogen interaction for all variables resulted from a greater decrease (P<.01) in weed control and soil pH and a greater increase in yield with increased nitrogen under no-tillage than with conventional tillage.
Response of Honeyvine Milkweed (Ampelamus albidus) to Herbicide Applications
Authors: Moshier L. J.
Published: May 2019

Greenhouse studies revealed that glyphosate [N-(phosphonomethyl)glycine] at 3.4 kg/ha or picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.3 kg/ha more effectively reduced further growth of honeyvine milkweed [Ampelamus albidus(Nutt.) Britt.] when treated at a height of 30 cm than did 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 1.1 kg/ha or dicamba (3,6-dichloro-o-anisic acid) at 0.6 kg/ha. Glyphosate or picloram applications were also more effective than 2,4-D or dicamba applications in reducing amount of regrowth that occurred after treated plants were cut at the soil surface. Glyphosate plus 2,4-D, glyphosate plus dicamba, glyphosate plus picloram or 2,4-D plus picloram combinations also effectively reduced further growth of treated plants and subsequent regrowth after plants were initially harvested. Greenhouse studies revealed that glyphosate plus ethephon [(2-chloroethyl)phosphonic acid] at 1.7 plus 0.6 kg/ha or glyphosate plus ammonium sulfate at 1.1 plus 6.7 kg/ha were no more effective than glyphosate alone at 1.7 kg/ha. Dowco 290 (3,6-dichloropicolinic acid) at up to 2.2 kg/ha did not effectively inhibit growth of honeyvine milkweed.
Growth Analysis of Soybeans (Glycine max) in Competition with Velvetleaf (Abutilon theophrasti)
Authors: Hagood E. S. , Bauman T. T. , Williams J. L. , Schreiber M. M.
Published: May 2019

Field experiments were conducted to study the effects of varying velvetleaf (Abutilon theophrastiMedic.) densities and planting dates on the growth and yield of soybeans [Glycine max(L.) Merr. ‘Amsoy 71’]. Velvetleaf densities ranging from 2.5 to 40 plants/m2caused reductions in the dry weight of soybean leaves, stems, roots, and pods and seeds, and in the leaf area index, pod number, and seed yield when velvetleaf and soybean plants emerged at the same time. The magnitude of reduction in soybean growth and the time at which the reduction was first observed was dependent on weed density. Soybean growth reductions caused by high velvetleaf densities were less when conditions of high soil moisture content minimized the effects of competition for water. Velvetleaf emerging 21 and 23 days after soybean emergence did not reduce crop growth or yield.
Triallate Phytotoxicity and Nitrogen Fertilization
Authors: McKercher R. B. , McGregor W. R.
Published: May 2019

Application of NH4+-bearing fertilizer in field and pot experiments increased triallate [S-(2,3,3-trichloroallyl)diisopropylthiocarbamate] activity on oats (Avena sativa‘Harmon’). The effect was consistent in the growth chamber, but field results were more variable, depending on soil moisture and temperature conditions. Because the pot experiments showed that the major effect was in shoot-zone-treated soils, the increased triallate activity was attributed to a reduction in triallate adsorption to the soil colloids. However, a smaller effect was measured in root-zone-treated soil, thus a physiological effect is also possible.
Isolation of a Phytotoxin from Quackgrass (Agropyron repens) Rhizomes
Authors: Gabor W. E. , Veatch C.
Published: May 2019

A phytotoxin that inhibited seedling root growth was isolated and purified from rhizomes of quackgrass [Agropyron repens(L.) Beauv.]. Aqueous solutions of the phytotoxin (0.1%, w/v) significantly inhibited the seedling root growth of corn (Zea maysL. ‘New Jersey 8’), oat (Avena sativaL. ‘Clintland 60’), cucumber (Cucumis sativusL. ‘Straight Eight’), and alfalfa (Medicago sativaL. ‘Vernal’). Growth inhibition was not due to extremes of pH or osmotic potential of the inhibitor solutions. The phytotoxin was isolated and purified from a methanol:water extract of dried and ground rhizomes by adsorption and elution from charcoal. A golden-brown, crystalline substance was obtained that was soluble in water, partly soluble in semipolar solvents, and insoluble in nonpolar solvents. Thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) suggested that a single compound was present. Elemental analysis showed that it contained 42.17% carbon, 5.06% hydrogen, 38.28% oxygen, 4.02% nitrogen, 2.03% sulfur, 0.03% chlorine, and 0.03% phosphorus. The compound was tentatively identified as a glycoside with a molecular weight of 460. Its ultraviolet (UV) absorption spectrum showed an intense maximum at 307 nm.
The Effects of Fall Application of Glyphosate on Corn (Zea mays), Soybeans (Glycine max), and Johnsongrass (Sorghum halepense)
Authors: Jeffery L. S. , English J. R. , Connell John
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine] was applied at various stages of maturity to corn (Zea mays L. ‘Pioneer brand 3147’ and ‘Dekalb XL 394’), soybeans [Glycine max (L.) Merr. ‘Forrest’ and ‘Essex’], and johnsongrass [Sorghum halepense (L.) Pers.]. Glyphosate applied over-the-top of corn before the grain moisture level decreased to 30% (black layer will have been formed) caused various seed and subsequent progeny abnormalities. Depending on grain moisture level at the time of glyphosate application, seed weight was sometimes reduced and progeny seedling emergence, vigor, and weight were reduced. Also, abnormal seedlings, albino or straited, occurred. Glyphosate applied 2½ weeks or more before soybean maturity reduced seed weight, caused seed discoloration, and drastically reduced progeny seedling emergence, vigor, and weight. Glyphosate applied in September or early October controlled semimature johnsongrass. Later applications were less effective because of advanced senescence.
Response of Cucumber (Cucumis sativus) to Annual Weeds and Herbicides
Authors: Menges R. M. , Tamez Simon
Published: May 2019

Weed and cucumber (Cucumis sativusL. ‘Poinsett’) growth was studied where herbicides were soil-applied or applied to emerged weeds in the established crop. Cucumber yields were decreased at least 36% in 2 of 5 yr when weeds interfered for 4 weeks after emergence. Sequential applications of bensulide [O,O-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide] applied preplant and incorporated (PPI) + trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) applied postemergence and incorporated (POI) were outstanding and controlled Japanese millet (Echinochloa crus-galliLink. var.frumentacea), Texas panicum (Panicum texanumBuckl.), Palmer amaranth (Amaranthus palmeriS. Wats.), and common purslane (Portulaca oleraceaL.) without affecting the growth or yield of cucumber. Compared with bensulide, the selectivity of soil-incorporated butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] with cucumber was limited. Laboratory bioassays showed that under warm field soil conditions, PPI applications of 1.7 kg/ha of butralin persisted more than 2 months, but were dissipated after 4 months. Ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)benzenamine] reduced cucumber yields only when it was soil-incorporated to the crop-seed depth at planting. Applications to soil of bensulide + DCPA (dimethyl tetrachloroterephthalate) stunted cucumber plants, reduced leaf area, increased leaf thickness, and caused higher near-infrared (0.75 to 1.34 μm) leaf reflectance.
Mefluidide-Bentazon Interactions on Soybeans (Glycine max) and Red Rice (Oryza sativa)
Authors: Rao S. R. , Harger T. R.
Published: May 2019

Responses of soybeans [Glycine max(L.) Merr. ‘Bragg’] and red rice (Oryza sativaL.) to postemergence applications of mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] alone and in combinations were evaluated in greenhouse studies. Soybeans were tolerant to bentazon up to the highest tested rate of 2.0 kg/ha, but their height was reduced by mefluidide at 1.0 kg/ha. Soybeans were not injured by any tested combination of the two herbicides. Bentazon applied alone at rates of 5.0 kg/ha and above had a significant effect on red rice injury. Mefluidide applied at rates above 0.25 kg/ha severely reduced height and fresh weight of red rice. When these two herbicides were combined, a synergistic reaction occurred, and the combination was much more effective in controlling red rice than was either herbicide applied alone. The addition of a surfactant significantly increased the activity of the combination on red rice up to 0.25 kg/ha of mefluidide and at all rates of bentazon.
Effect of Seeding Dates and Densities of Green Foxtail (Setaria viridis) on the Growth and Productivity of Spring Wheat (Triticum aestivum)
Authors: Blackshaw R. E. , Stobbe E. H. , Sturko A. R. W.
Published: May 2019

Competition of green foxtail [Setaria viridis(L.) Beauv.] was studied in a semi-dwarf wheat (Triticum aestivumL. ‘Norquay’) and in two normal-height wheats (‘Napayo’ and ‘Sinton’) from 1975 through 1978. Green foxtail suppressed wheat growth as well as grain yield. Tiller number, leaf area, and dry weight of wheat were reduced. Green foxtail was more competitive in the semi-dwarf variety than in either normal height variety. The intensity of green foxtail competition could not be determined by density alone. In 1975, as few as 100 green foxtail plants/m2significantly reduced yield of Napayo and Norquay wheat by 21 and 44%, respectively. In 1977, however, 1600 green foxtail plants/m2did not reduce the yield of Sinton wheat significantly. The intensity of green foxtail competition was highly variable from one date of seeding to the next, but there was no correlation between the level of green foxtail competition and the date of seeding. Soil temperature and moisture at the time of seeding and early growth are thought to affect green foxtail competition in wheat critically.
Absorption and Translocation of Fluridone and Glyphosate in Submersed Vascular Plants
Authors: Marquis L. Y. , Comes R. D. , Yang C. P.
Published: May 2019

The uptake and translocation of fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone} were examined in sago pondweed (Potamogeton pectinatusL.) and Richardson pondweed [Potamogeton richardsonii(Ar. Benn.) Rydb.]. Root and shoot tissues of both species were isolated from each other with wax barriers and treated individually with 1.0 ppm14C-fluridone. Both tissues bioconcentrated fluridone, but the amount absorbed represented 1% or less of the total herbicide available. Limited root-to-shoot translocation occurred, but shoot-to-root transport was negligible. In contrast to fluridone, highly mobile glyphosate [N-(phosphonomethyl) glycine] translocated from the shoots to the roots in sago pondweed. No metabolism of fluridone was detected in sago pondweed.
Influence of Cotton (Gossypium hirsutum) Densities on Competitiveness of Pigweed (Amaranthusspp.) and Sicklepod (Cassia obtusifolia)
Authors: Street J. E. , Buchanan G. A. , Crowley R. H. , McGuire J. A.
Published: May 2019

Experiments were conducted from 1973 through 1975 on Lucedale sandy loam to determine the influence of in-row cotton (Gossypium hirsutumL. ‘Stoneville 213’) densities on the competitiveness of low-level infestations of sicklepod (Cassia obtusifoliaL.) and pigweed (Amaranthusspp.). Weeds were established at densities of 0, 4, 12, and 32 weeds per 15 m of row and allowed to compete the entire season with cotton grown at densities of 5, 10, or 20 plants/m of row corresponding to 47000, 94000 and 187000 cotton plants/ha. Conventional cultural practices were employed in these experiments. Cotton yields were inversely related to weed density; however, the density of cotton did not influence the competitive effect of sicklepod or pigweed. Pigweed or sicklepod dry weed weight was reduced when competing with 187000 cotton plants/ha.
Nitro Compounds in Foreign Species ofAstragalus
Authors: Williams M. C.
Published: May 2019

Leaflets of 1690 species of Old World and South AmericanAstragaluscollected from herbaria at Kew, England; Edinburgh, Scotland; Munich, Germany; and Vienna, Austria were analyzed qualitatively for toxic aliphatic nitro compounds. The catabolites of nitro compounds found in species ofAstragalus(nitro-bearing), 3-nitro-1-propanol and 3-nitropropionic acid, are especially toxic to cattle and sheep. A total of 190 of 1624 (12%) Old World species, 30 of66(45%) South American species, and a single species of oneAstragalussubgenus were positive for nitro compounds. Most Old World species that contained aliphatic nitro compounds were collected in the Middle East and the Union of Soviet Socialist Republics. Nitro compounds were detected in specimens of eight species collected between 1822 and 1836. The nitro-bearing species were chemotaxonomically related and grouped within taxonomic sections. The presence of two or three nitro-bearing species within a section indicated that other species within the same section might also be nitro-bearing.
Enhancement of Herbicidal Weed Control in Sweet Potatoes (Ipomoea batatas) with Cultivation
Authors: Glaze N. C. , Harmon S. A. , Phatak S. C.
Published: May 2019

Six herbicides were evaluated at two rates on sweet potatoes [Ipomoea batatas(L.) Lam. ‘Georgia Red’, ‘Georgia Jet’] with and without cultivation from 1972 through 1976. Cultivation with a ground-driven rotary hoe about 2 weeks later improved the control of late-season broadleaf weeds such as Florida beggarweed [Desmodium tortuosum(Sw.) DC] and showy crotalaria (Crotalaria spectabilisRoth.). Cultivation improved weed control where vernolate (S-propyl dipropylthiocarbamate), DCPA (dimethyl tetrachloroterephthalate), and napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] were applied. The improved weed control in cultivated treatments resulted in increased sweet potato yields in 1972 and 1973, which also were the years with the highest weed populations.
Effects of Simulated MSMA Drift on Rice (Oryza sativa) Growth and Yield
Authors: Richard E. P. , Hurst H. R. , Wauchope R. D.
Published: May 2019

Levels of MSMA (monosodium methanearsonate) that simulated drift (0.2, 0.39, and 0.78 kg/ha) were applied over-the-top to rice (Oryza sativaL. ‘Vista’, ‘Starbonnet’, or ‘Labelle’) after flooding at four developmental stages between early tillering and late jointing. The MSMA rates used were equivalent to, or lower than, the 0.78-kg/ha rate that would be applied as an over-the-top application to cotton (Gossypium hirsutumL.) for early season weed control. Over-the-top applications of MSMA did not affect heading and maturity dates of filled grains regardless of the rate or application timing. Reductions occurred, however, in plant height, number of panicles, and yield. In addition, the percentage of erect panicles showing typical “straighthead” symptoms increased. Rice sensitivity to MSMA depended on MSMA rate and stage of growth with injury being most severe as rice approached the reproductive stages of development. Because aerial applications of MSMA to cotton are normally made before rice reaches the reproductive stage, injury resulting from MSMA drift should be minimal.
Soil Herbicidal Activity from HOE 29152 and Diclofop Applied Postemergence
Authors: Dekker J. H. , Meggitt W. F. , Boldt P. F.
Published: May 2019

The soil activity of foliar-applied HOE 29152 {2-[4-trifluoromethyl-phenoxy)phenoxy] propanoic acid} and diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} on barnyardgrass [Echinochloa crus-galli(L.) Beauv.] and yellow foxtail [Setaria lutescens(Weigel) Hubb.] was evaluated in the greenhouse. HOE 29152 was applied at 0.1, 1.2, 2.4, and 3.5 kg/ha; and diclofop was applied at 0.5, 2.7, 4.9, and 7.2 kg/ha. Both compounds applied to roots or shoots before emergence reduced growth. Neither compound had much, if any, effect on the germination of barnyardgrass or yellow foxtail; however, the survival of both weed species that germinated in solutions of these two compounds was reduced. The number of seedlings surviving for both weed species was reduced by both compounds. Seedling survival from germination imbibition by diclofop and HOE 29152 was influenced by the presence of light at the time of seed germination.
Adsorption, Desorption, and Mobility of Metolachlor in Soils
Authors: Obrigawitch T. , Hons F. M. , Abernathy J. R. , Gipson J. R.
Published: May 2019

Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] has considerable potential for yellow nutsedge (Cyperus esculentusL.) control in crops commonly produced in the Texas High Plains. Little information is available, however, concerning adsorption characteristics of metolachlor in soils of this region. Adsorption and movement of metolachlor were determined in three commonly occurring soils of the Texas High Plains. Organic carbon contents of the soils by weight varied from 0.3 to 0.5%, and the clay fraction ranged from 16 to 33%. Freundlich adsorption isotherms exhibited two linear regions for each soil, suggesting the possibility of multilayer adsorption. K′ocvalues and coefficients of determination for organic carbon and clay content vs. Freundlich K values indicated that organic matter was the predominant adsorbent for metolachlor in the soils studied. Desorption, soil column leaching, and thin-layer plate studies demonstrated metolachlor to be sufficiently mobile in scils low in organic matter to cause possible crop injury or loss of efficacy.
Granular Formulation ofAlternaria macrosporafor Control of Spurred Anoda (Anoda cristata)
Authors: Walker H. L.
Published: May 2019

A method is described for the large-scale production of a granular formulation ofAlternaria macrosporaZimm. The granular preparation consisted of spores, mycelia, and vermiculite. This formulation ofA. macrospora, applied preemergence or postemergence, controlled spurred anoda (Anoda cristataSchlecht.) plants in greenhouse and field tests. The pathogen did not significantly affect emergence or dry weight production of cotton (Gossypium hirsutumL. ‘Stoneville 213’) seedlings. The fungicides PCNB (pentachloronitrobenzene) and ETMT [5-ethoxy-3-(trichloromethyl)-1,2,4-thiadiazole] did not significantly affect spurred anoda control withA. macrospora.The method for production and formulation ofA. macrosporawas modified to produce spores and granular formulations of other Fungi Imperfecti:Drechslerasp. andFusariumspp. (Moniliales),Colletotrichumspp. (Melanconiales), andPhyllostictasp. (Sphaeropsidales).
Control and Competitiveness of Johnsongrass (Sorghum halepense) in Cotton (Gossypium hirsutum)
Authors: Keeley P. E. , Thullen R. J.
Published: May 2019

Four field experiments conducted over 3 yr indicated that cultivation alone failed to prevent johnsongrass [Sorghum halepense(L.) Pers.] from reaching densities that severely reduced yields of cotton (Gossypium hirsutumL. ‘Acala SJ-2’). Density of johnsongrass in plots cultivated four times and hoed weekly for 8 weeks after emergence was reduced to 1 shoot/m2at harvest compared to 74 shoots/m2for plots that were only cultivated. In addition to a 60% average yield loss of seed cotton, yield losses ranging from 40 to 76%, ginning losses were also greater from cultivated than from hand-weeded plots. Compared to cultivated plots, supplementing cultivation with two postemergence applications of 3.0 kg/ha of DSMA (disodium methanearsonate) increased the average yield of cotton by 20% and reduced perennial johnsongrass densities by 64% at harvest. Although yields were improved by applying DSMA, they averaged 40% less than those of hand-weeded plots. The temporary weed control obtained with DSMA was profitable in terms of the additional lint and seed obtained, but insufficient cotton was produced to pay expenses for producing the crop by any of the methods of weed control. High labor costs for hoeing prevented this treatment from being profitable.
Corn Cockle (Agrostemma githago) Competition in Winter Wheat (Triticum aestivum)
Authors: Rydrych D. J.
Published: May 2019

The experiment was conducted during 3 yr to measure the effect of corn cockle (Agrostemma githagoL.) competition on winter wheat (Triticum aestivumL. ‘McDermid’) grain yield. In all years corn cockle was removed monthly in separate treatments from emergence (October) to harvest (July). Hand-weeded and weedy controls were compared to herbicidal control using treatments of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile). Reductions in yield of wheat as affected by competition from corn cockle were not significant if weeds were removed before February of each year in winter wheat that had been seeded the previous October. Bromoxynil controlled more weed plants when applied on corn cockle that had less than four leaves (fall treatment). Corn cockle densities of 170 to 340 plants/m2at the Pendleton, Oregon site lowered wheat yields an average of 18% when competition was eliminated by March. Competition that continued until wheat harvest (July) reduced yields 60%.
Fringed Sagebrush (Artemisia frigida) Control in Western Nebraska
Authors: Wilson Robert G. , Stubbendieck James
Published: May 2019

Two experiments were conducted to determine the most effective herbicide treatments for fringed sagebrush (Artemisia frigida Willd.) control in rangelands. In the first study the potassium salt of picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.1, 0.6, and 0.8 kg/ha; picloram + the propylene glycol butyl ether ester of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 0.1 + 1.1 kg/ha; the monoethanolamine salt of 3,6-dichloropicolinic acid at 1.1 kg/ha; 3,6-dichloropicolinic acid + 2,4-D at 0.6 + 1.1 kg/ha; and the dimethylamine salt of dicamba (3,6-dichloro-o-anisic acid) + 2,4-D at 0.6 + 1.1 kg/ha applied in late summer at flowering, showed the greatest potential for fringed sagebrush control. In the second experiment, the potassium salt of picloram at 0.3 kg/ha applied either in the spring or late summer gave 94 to 100% fringed sagebrush control, respectively, 1 yr after application. Control of fringed sagebrush had declined to 50% 3 yr after application. Production of perennial grasses from plots receiving picloram at 0.3 kg/ha in 1976 was increased by 410 kg/ha in 1977, 450 kg/ha in 1978, and 430 kg/ha in 1979 over that of the untreated plots.
Germination of Broom Snakeweed (Gutierrezia sarothrae) and Threadleaf Snakeweed (G. microcephalum) Seed
Authors: Mayeux H. S. , Leotta Laura
Published: May 2019

Most seed of broom snakeweed [Gutierrezia sarothrae(Pursh) Britt. & Rusby] and threadleaf snakeweed [G. microcephala(DC.) Gray] were dormant when collected soon after maturity, requiring 4 to 6 months of storage at room conditions to break dormancy. An alternating temperature regime of 10 C (16 h) and 20 C (8 h) favored snakeweed germination during the afterripening period, but germination was greatest under alternating temperatures of 20 C (16 h) and 30 C (8 h) after 24 months of storage. After 6 months of storage, maximum germination (70% or more) of threadleaf snakeweed seed occurred at continuous temperatures of 15 to 25 C; whereas, broom snakeweed seed germinated best at 15 and 30 C. Germination of both species in darkness was half or less of germination with daily 8-h periods of light. Germination of seed lots containing a high proportion of dormant achenes was enhanced by preimbibition storage at 50 C; after dormancy was naturally broken, exposure to 50 C prior to germination decreased early seedling vigor and growth but not germination.
Forage and Livestock Production Following Oak (Quercusspp.) Control with Tebuthiuron
Authors: Scifres Charles J. , Stuth Jerry W. , Kirby Donald R. , Angell Raymond F.
Published: May 2019

Aerial applications of 20% tebuthiuron JA/-[5-(1,1- dimethylethyl) - 1, 3, 4 - thiadiazol-2 -yl] -N, N' dimethylurea pellets at 2.2 or 4.4 kg/ha in the spring to heavy brush cover in Texas Post Oak Savannah did not increase the amount of grass, compared to that of untreated pastures, until the growing season after application. By the second growing season after tebuthiuron application, however, native grass stands were composed of a higher proportion of perennial species of good-to-excellent grazing value than were stands on adjacent, untreated rangeland. Tebuthiuron at 4.4 kg/ha did not improve botanical composition of grass stands, but increased the amount of grass during the second and third growing season after application compared to those where 2.2 kg/ha were applied. Daily steer gains were increased in one experiment in the fall after application of 2.2 kg/ha of tebuthiuron in the spring, but were unchanged after two growing seasons in another. Days of available grazing were increased, however, by the second or third growing season after treatment with 2.2 kg/ha of the herbicide in both experiments.
Absorption, Translocation, and Exudation of Glyphosate, Fosamine, and Amitrole in Field Horsetail (Equisetum arvense)
Authors: Coupland David , Peabody Dwight V.
Published: May 2019

The absorption, translocation, and exudation of14C-glyphosate [N-(phosphonomethyl) glycine],14C-fosamine [ethyl hydrogen (aminocarbonyl)phosphonate] and14C-amitrole (3-amino-s-triazole) in field horsetail (Equisetum arvenseL.) were examined in glasshouse experiments. Amitrole was absorbed much more readily than either fosamine or glyphosate, and although the initial translocation of amitrole was faster, eventually more14C was recovered from the underground parts of plants treated with14C-glyphosate and fosamine. Radioactivity from all three compounds was translocated to areas of meristematic activity such as shoot and rhizome apices and rhizome nodes. The amounts of radioactivity recovered from the roots and rhizomes were small in relation to the amounts applied. Root exudation and guttation could account for some loss of herbicide from the plant. Radioactivity from14C-amitrole, in particular, was present in relatively large amounts in guttation fluid.
Studies on Indigo Witchweed, the American Strain of Striga gesnerioides (Scrophulariaceae)
Authors: Musselman Lytton J. , Parker Chris
Published: May 2019

In greenhouse studies, the American strain of Striga gesnerioides (Willd.) Vatke, indigo witchweed, was potted with a wide range of potential hosts, including some known to be parasitized by this species elsewhere, and with agricultural and ornamental crops of importance in the southern United States. The host range of the indigo witchweed was very limited and no major crop species were seriously affected. Based on these host studies, it appears that indigo witchweed poses little danger to American agriculture. Other strains of the parasite were likewise shown to be host specific.
Diclofop and MCPA Influence on Coleoptile Growth
Authors: Olson Wayne A. , Nalewaja John D. , Schroeder Glen L. , Duysen Murray E.
Published: May 2019

Experiments were conducted using theAvenacoleoptile straight-growth test to determine the influence of diclofop {2-[4-(2,4-diclorophenoxy)phenoxy] propanoic acid}, as the acid or methyl ester, and MCPA {[(4-chloro-o-tolyl)oxy] acetic acid} on coleoptile growth of several species. Diclofop ester was a three-fold stronger inhibitor of oat (Avena sativaL. ‘Terra’) coleoptile growth than the free acid. The concentration of diclofop ester needed to inhibit 50% of the oat coleoptile growth was not influenced by IAA (indole-3-acetic acid) concentration. Oat coleoptile growth in the presence of 5 μM IAA plus 5 μM diclofop ester increased for 2 h after treatment and then decreased, so that the coleoptile length was less at the end of the 24-h assay period than at the beginning of the diclofop-ester treatment. Diclofop ester inhibited the coleoptile growth of wild oat (Avena fatuaL.) > oat > wheat (Triticum aestivumL. ‘Era’) > corn (Zea maysL. inbred ‘A-239’) > corn inbred ‘CI-66’. MCPA added to the treatment solution did not overcome oat coleoptile growth inhibition from diclofop ester or acid.
Influence of Shading by Soybeans (Glycine max) on Weed Suppression
Authors: Murphy T. R. , Gossett B. J.
Published: May 2019

Field studies were conducted at Florence and Clemson, South Carolina to measure the influence of soybean [Glycine max(L.) Merr.] planting dates on the length of early-season weed control needed to prevent yield reductions, the rate of shade development, and suppression of annual weeds by soybeans. The rate of shade development was similar for both planting dates during the 9- to 11-week period after planting for Florence and Clemson, respectively. The period of weed-free maintenance required to prevent soybean yield reductions was not affected by planting dates. With cultivation between rows, early- and late-planted soybeans required 3 weeks of weed-free maintenance to achieve maximum yields. Lower weed weights resulted from late than early soybean plantings. At Clemson, 3 weeks of weed-free maintenance for early and late plantings reduced weed weights 97 and 91%, respectively. Weed weights at Florence were reduced 85% with 3 weeks of weed-free maintenance for the late plantings, whereas 5 weeks were required to reduce weed weights 88% for early plantings.
Weed Control in Established Dryland Alfalfa (Medicago sativa)
Authors: Wilson Robert G.
Published: May 2019

Fall-applied herbicides were evaluated in field studies conducted in 1978 through 1980 in western Nebraska for selective weed control in nonirrigated, established alfalfa (Medicago sativaL. ‘Ranger’). All herbicides effectively controlled downy brome (Bromus tectorumL.). Broadleaf weeds were differentially controlled by the herbicides tested. All herbicide treatments increased forage production and protein content over that produced in the untreated check. Increasing the rate of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] above amounts needed for effective weed control caused an increase in the protein content of alfalfa forage above that resulting from normal use rates.
LA TEORIA DI STEIN ROKKAN
Authors: L.M.
Published: May 2019

Introduzione

Stein Rokkan è stato uno dei piú importanti scienziati sociali del secondo dopoguerra. L'originalità della sua elaborazione teorica, l'influenza del suo pensiero nella disciplina e l'indefessa attività di organizzatore culturale sono gli aspetti principali che lo pongono in questa posizione di preminenza. Eppure in Italia l'opera dello studioso norvegese è conosciuta solo da una ristretta cerchia di addetti ai lavori. A parte le poche pagine di un suo saggio (I voti contano, le risorse decidono), pubblicato da questa Rivista nel 1975, tutto il resto della sua vasta opera non è stato ancora tradotto. Questo è il motivo che, a un anno dalla sua prematura scomparsa, ci ha spinto a dedicargli parte di un numero della Rivista. è la prima volta che a un solo autore diamo tanto spazio. Tuttavia, quanto sopra detto giustifica l'eccezione.
TERRITORI, NAZIONI, PARTITI: VERSO UN MODELLO GEOPOLITICO DELLO SVILUPPO EUROPEO
Authors: Rokkan Stein
Published: May 2019

Introduzione

Karl Deutsch ha insegnato alla mia generazione di scienziati sociali a sviluppare dei modelli o a provarne la validità attraverso l'uso di dati storici. Le mie prime ricerche sull'estensione dei diritti politici e sulla mobilitazione delle periferie sono state fortemente influenzate dalle idee di Deutsch. I miei successivi lavori sulle dimensioni del processo di edificazione dello Stato (State-Building) e di formazione della nazione (Nation-Building) sono state direttamente ispirate dallo studio pionieristico di DeutschNationalism and Social Communication. È stato Deutsch ad insegnarmi a prendere in esame le caratteristiche decisive delle strutture responsabili della formazione del «centro» e a studiare le funzioni dei mezzi di comunicazione a stampa e delle istituzioni educative nello sviluppo di identità su basi territoriali. In questo tributo allaleadershipintellettuale di Karl Deutsch, mi propongo di tentare una prima sintesi di queste due linee di ricerca: vale a dire, intendo tracciare i lineamenti di un possibile modello globale mettendo insieme alcuni elementi tratti dai miei primi studi sui processi di mobilitazione con altri che fanno parte delle mie ricerche attuali sullo schema di base della storia geopolitica-geoeconomica dell'Europa Occidentale.