bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperature and Photoperiod on Triclopyr, Picloram, and 2,4,5-T Translocation
Authors: Radosevich S. R. , Bayer D. E.
Published: May 2019

The effects of photoperiod and temperature on the translocation of triclopyr {[1(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, picloram (4-amino-3,5,6-trichloropicolinic acid) and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] were studied on tanoak [Lithocarpus densiflorus(Hook. & Arn.) Rehd.], snowbush ceanothus (Ceanothus velutinusDougl.), bigleaf maple (Acer macrophyllumPursh), bean (Phaseolus vulgarisL. var. ‘Red Kidney’) and barley (Hordeum vulgareL. var. CM-67). Isolation of14C and analysis for the radioactive herbicides revealed little metabolism of the herbicides. Regardless of herbicide or plant species herbicide movement was greatest under warm temperature and long day conditions. Among the herbicides tested,14C associated with triclopyr was the most mobile in each species. Each herbicide moved readily in the symplast but root applications of each herbicide revealed limited apoplastic mobility.
Response of Sugarbeets (Beta vulgaris) and Four Weed Species to Dinitramine
Authors: Schweizer E. E.
Published: May 2019

Dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) applied at 0.37 kg/ha controlled black nightshade (Solanum nigrumL.) better than did trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0.56 kg/ha. Dinitramine applied at 0.37 kg/ha was equal to 0.56 kg/ha of trifluralin for control of green foxtail [Setaria viridis(L.) Beauv.], yellow foxtail [Setaria glauca(L.) Beauv.], and redroot pigweed (Amaranthus retroflexusL.). Dinitramine produced more root aberrations in sugarbeets (Beta vulgarisL. ‘Mono Hy D2′) than did trifluralin when sprayed on nonexposed or exposed hypotcotyledonary tissues of seedlings. When soil surrounded most of the hypocotyls at the time of application, 0.56 kg/ha of dinitramine affected 57 to 87% of the roots, whereas the same rate of trifluralin affected 1 to 8% of the roots. When the hypocotyls were exposed at the time of application, 100% of the roots were affected by dinitramine compared to 25% of all roots treated with trifluralin. Dinitramine applied at 0.37, 0.42, and 0.56 kg/ha lowered the quality and yield of sugarbeet roots, with the highest rate significantly reducing percentage purity, percentage sucrose, and recoverable sucrose. Trifluralin did not affect these parameters.
Yellow Nutsedge (Cyperus esculentus) Competition and Control in Corn (Zea mays)
Authors: Stoller E. W. , Wax L. M. , Slife F. W.
Published: May 2019

Competition of yellow nutsedge (Cyperus esculentusL.) with corn (Zea maysL.) was evaluated in the field at various yellow nutsedge densities over a 3-yr period. A relationship between yellow nutsedge density (shoots/m2) and percentage yield reduction revealed an 8% yield reduction for every 100 shoots/m2. Two 3-yr studies were conducted to determine the most effective combination of preplant-incorporated, postemergence, or postemergence-directed treatments for yellow nutsedge control in corn. The preplant incorporated treatments were alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], EPTC (S-ethyl dipropylthiocarbamate), or nothing; postemergence treatments were bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one 2,2-dioxide], two cultivations, or nothing; and the postemergence-directed treatments were ametryn [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] or nothing. One preplant-incorporated treatment of EPTC or alachlor prevented yield reductions from yellow nutsedge competition. When no control was practiced, yields were reduced 17% in a moderate yellow nutsedge infestation (initially infested with 300 tubers/m2) and 41% in a heavy infestation (initially infested with 1200 tubers/m2). Yields were reduced 7 to 8% in the moderate infestation when no preplant-incorporated treatments were used regardless of whether postemergence or postemergence-directed treatments were also used. After 1 yr, all control measures resulted in less tuber density than no control measures, but all control treatments had essentially similar tuber densities. After the second year, several herbicide treatments were as effective as hand weeding in reducing tuber density. At least 2 yr of effective control treatments were required to reduce tubers to 20% of the original density, and 3 yr of treatment to reduce the density to 15% of the original density. No combination of treatments, including hand weeding, eliminated tubers after 3 yr.
Effects of Water Quality and Spray Volume on Glyphosate Phytotoxicity
Authors: Stahlman P. W. , Phillips W. M.
Published: May 2019

Several inorganic salts added to the spray solution reduced the herbicidal activity of glyphosate [N-(phosphonomethyl)glycine]. Of the salts tested, iron and aluminum reduced herbicidal activity most. Reductions by calcium and zinc were moderately severe; by magnesium, moderate; by potassium and sodium, none. The reduction in phytotoxicity seems to be caused by cations, but factors other than valence also may be involved.

Reduction in phytotoxicity was related to salt concentration and spray volume. Glyphosate at 0.84 kg/ha in 93 to 374 L/ha distilled water killed test plants. Tap water was an equally effective carrier at 93 and 187 L/ha volumes, but was significantly less effective at the 374 L/ha volume. Activity decreased as the molar concentration of CaCl2 increased to 0.01. Herbicidal activity was eliminated at 0.01 M and 374 L/ha; however, concentrations of CaCl2 exceeding 0.04 M reversed the trend and reacted similarly to a 0.005 M solution, which approximates the minimum hardness of most ground waters in Kansas.
Weed Control in Soybeans (Glycine max) with Mefluidide Applied Postemergence
Authors: McWhorter C. G. , Barrentine W. L.
Published: May 2019

Mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]-amino] phenyl] acetamide} was applied postemergence in soybean [Glycine max (L.) Merr.] fields and its effectiveness in controlling johnsongrass [Sorghum halepense (L.) Pers.], hemp sesbania [Sesbania exaltata (Raf.) Cory], and common cocklebur (Xanthium pensylvanicum Wallr.) was evaluated. In plots treated preplanting with trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), mefluidide gave 95% johnsongrass control when it was applied postemergence (over-the-top without surfactant) once at 0.90 kg/ha or twice at 0.44 kg/ha. Directed sprays of mefluidide at 0.22 to 0.67 kg/ha without surfactant were more effective on johnsongrass than similar treatments applied over-the-top. When 0.5% (v/v) nonoxynol [α-(p-nonyl-phenyl)-ω-hydroxypoly (oxyethylene)] surfactant was added, mefluidide at 0.44 or 0.67 kg/ha applied as directed or over-the-top sprays provided 76 to 90% johnsongrass control. Mefluidide at 1.12 kg/ha plus nonoxynol surfactant, applied as a directed spray, was required to provide 81% control of hemp sesbania. Directed sprays containing mixtures of mefluidide at 0.28 kg/ha plus dinoseb (2-sec-butyl-4,6-dinitrophenol) at 2.2 kg/ha, or mefluidide at 0.28 kg/ha plus a 2:1 mixture of naptalam (N-1-naphthylphthalamic acid)/dinoseb at 4.7 L/ha, effectively controlled 40- to 60-cm-tall hemp sesbania. A single, directed spray of mefluidide at 0.56 kg/ha plus nonoxynol provided 92% common cocklebur control, and mixtures of mefluidide at 0.28 kg/ha plus dinoseb at 2.2 kg/ha or naptalam/dinoseb (a 2:1 mixture) at 4.7 L/ha increased control above that provided by either of the herbicides alone.
Prevention of EPTC—Induced Epicuticular Wax Aggregation on Corn (Zea mays) with R-25788
Authors: Leavitt J. R. C. , Penner Donald
Published: May 2019

Scanning electron microscopy (SEM) showed that EPTC (S-ethyl dipropylthiocarbamate) caused an aggregation of the epicuticular wax layer of corn (Zea maysL.). R-25788 (2,2-dichloro-N,N-diallylacetamide) prevented this aggregation when applied in combination with EPTC. Neither EPTC, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], nor R-25788 changed the weight of chloroform extractable epicuticular wax on corn leaves. EPTC apparently does not block lipid synthesis in corn as it does in other plant species. Thus R-25788 does not protect corn from EPTC or metolachlor by overcoming such a block. EPTC did affect wax arrangement on the leaf surface and caused an increase in the cuticular transpiration of corn and predisposed corn to injury from subsequent postemergence applications of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion). R-25788 protected corn against these deleterious effect.
Hemp Sesbania (Sesbania exaltata) Competition in Soybeans (Glycine max)
Authors: McWhorter C. G. , Anderson J. M.
Published: May 2019

The competitive effects of hemp sesbania [Sesbania exaltata(Raf.) Cory] on soybeans [Glycine max(L.) Merr. ‘Forrest’] were studied on Sharkey clay for 2 yr. In full-season competition, hemp sesbania populations of 1,600, 3,200, 3,900, and 5,500 plants/ha did not reduce adjusted soybean yields, but populations of 8,100 to 129,200 plants/ha reduced yields 10 to 80%. Competition by hemp sesbania at 68,000 plants/ha for 1 to 4 weeks after soybean emergence reduced soybean yields 8% or less, whereas competition by the same population for 6, 8, and 10 weeks after soybean emergence reduced adjusted yields 18, 27, and 43%, respectively. Hemp sesbania populations of 3,200 plants/ha or more reduced the grade of harvested soybeans and populations of 5,500 plants/ha increased the level of foreign material found in seed samples taken at harvest. Hemp sesbania populations above 10,700 plants/ha increased the levels of damaged kernels and moisture in harvested soybean seed. Early-season control was required for highest soybean yields and total returns. The most critical period for control was 4 to 10 weeks after emergence of soybeans.
Effect of Incorporation Methods and Time of Application on the Performance of Trifluralin Plus Metribuzin
Authors: Barrentine W. L. , Wooten O. B. , Williford J. R.
Published: May 2019

Disk harrowing, spring tooth harrowing, and bed conditioning, alone or followed by bedding the rows, were evaluated in field studies to determine their efficacy to soil incorporate trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) plus metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5 (4H)-one] in soybeans [Glycine max(L.) Merr.]. Effects of the time interval between herbicide application and soybean planting were also evaluated. Effective weed control and adequate crop selectivity were obtained from all incorporation methods except those followed by bedding. Bedding occasionally reduced weed control and soybean stands as compared to incorporation without bedding. Excessive crop injury resulted from the application of a band of the herbicide mixture as a subsurface layer. The herbicide mixture was applied up to 6 weeks before soybean planting without adversely affecting crop or weed selectivity when incorporated with the spring tooth harrow without bedding.
Reduction of Glyphosate-Induced Tillering in Sorghum (Sorghum bicolor) by Several Chemicals
Authors: Baur J. R.
Published: May 2019

Sublethal doses of glyphosate [N-(phosphonomethyl)glycine] applied in a 50-μl drop in the partially furled third true leaf of 30-day-old sorghum [Sorghum bicolor(L.) Moench ‘Tophand’] seedlings induced basal stem swelling and bud release. Combining glyphosate with cycloheximide {3-[2-(3,5-dimethyl-2-oxycyclohexyl)-2-hydroxyethyl]glutarimide}, a cytokinin [N6(2-isopentenyl)adenine], or L-phenylalanine significantly reduced the incidence of basal stem swelling. No such reductions was observed when indole-3-acetic acid or L-tyrosine was combined with glyphosate. The fresh weights of the seedlings given the combination treatments reflected the effects of glyphosate, except one combination that included tyrosine significantly reduced fresh weight and three combinations that included phenylalanine significantly increased fresh weight.
Germination and Emergence of Balloonvine (Cardiospermum halicacabum)
Authors: Johnston S. K. , Murray D. S. , Williams J. C.
Published: May 2019

Concentrated sulfuric acid (H2SO4) scarification of balloonvine (Cardiospermum halicacabumL.) for 3 h reduced balloonvine seed coat thickness by 25%, and resulted in increased water absorption and maximum germination. Germination of balloonvine occurred at temperatures of 15 to 40 C with optimum germination occurring at 35 C. Intact balloonvine seed was more sensitive to simulated moisture stress than soybean [Glycine max(L.) Merr. ‘Bragg’]. No balloonvine germination occurred at osmotic potentials of −2 bars and less with intact seeds. Balloonvine seed with seed coats removed germinated at osmotic potentials of −8 bars. Maximum emergence of balloonvine occurred at the 1- and 3-cm depths with limited emergence at a depth of 12 cm.
Temperature Responses and Potential Distribution of Itchgrass (Rottboellia exaltata) in the United States
Authors: Patterson David T. , Meyer Charles R. , Flint Elizabeth P. , Quimby P. C.
Published: May 2019

To estimate the potential growth and distribution of itchgrass (Rottboellia exaltata L. f.) in the United States, we grew the plant in 36 combinations of day and night temperatures in controlled-environment greenhouses. Day temperatures ranged from 17 to 32 C and night temperatures from 11 to 26 C. Total dry weights, leaf areas, heights, and numbers of tillers were determined at 3, 31, and 58 days after emergence. Mathematical growth analysis techniques were used to calculate net assimilation rates (NAR) and leaf area durations (LAD). Maximum dry matter production (the product of NAR and LAD) and maximum leaf area production occurred at 32/26 C. Dry matter production and leaf area production were greatly reduced by day temperatures below 29 C and night temperatures below 23 C. The retardation of dry matter production by low night temperature was due mainly to reductions in LAD rather than to reductions in NAR. Low day temperatures reduced dry matter production through combined effects on LAD and NAR. At the warmer day temperatures, tiller production increased with decreasing night temperature. Flowering occurred at all day temperatures and at all night temperatures of 14 C or greater. Based on its growth responses to temperature, itchgrass would reach 75 to 100% of its maximum potential growth in the Gulf Coast states, the lower Midwest, the South Atlantic states, and the Southwest. Therefore, it represents a serious potential weed problem in these regions.
Influence of Moisture on Soil-Incorporated Diclofop
Authors: Mulder Christiaan E. G. , Nalewaja John D.
Published: May 2019

The influence of soil moisture on wild oat control from soil-incorporated methyl ester of diclofop {2-[4-(2,4-dichlorophenoxy)-phenoxy] propanoic} was determined in the greenhouse. Wild oat control with soil-incorporated diclofop at 1.5 or 3 ppmw increased linearly when soil moisture in a Tiffany sandy loam increased from 18.5 to 23.5% (75% to 125% of field capacity). The efficacy of soil-incorporated diclofop was not reduced when soil moisture was allowed to decrease from 21 (field capacity) to 18.5, 16, 13.5, or 11% (wilting point) before rewatering to 21%. The soil moisture level at the time of herbicide application determined the degree of wild oat control with soil-incorporated diclofop. Wild oat control with diclofop increased when a Tiffany sandy loam with 16% moisture (50% of field capacity) at the time of herbicide application, was watered to field capacity after 8 or 12 days delay, and control did not change with watering to field capacity at the time of herbicide application or when delayed 4 or 16 days. The movement of14C-diclofop in soil columns was greater within coarse than fine textured soils and increased with water volumes applied, regardless of soil type. Further, the leachability of14C-diclofop was two and a half times greater than that of14C-trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine).
Wild Oat (Avena fatua) Control by Flufenprop-methyl
Authors: Miller S. D. , Nalewaja J. D. , Olson W. A.
Published: May 2019

Postemergence applications of flufenprop-methyl [methyl-N-benzoyl-N(3-chloro-4-fluorophenyl)-2-amino-propionate] for wild oat (Avena fatuaL.) control in spring wheat (Triticum aestivumL.), durum wheat (Triticum durumL.), and barley (Hordeum vulgareL.) were evaluated in the field, greenhouse, and controlled environmental chambers. Wild oat control with flufenprop-methyl was greater at the five-leaf stage than three and one-half or two-leaf stage of growth. Wild oat control was not reduced when flufenprop-methyl was tank-mixed with bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one, 2,2-dioxide]. Tolerance of spring and durum wheat cultivars to flufenprop-methyl was acceptable; however, tolerance of barley cultivars was considerably more variable. Air temperature after treatment, soil fertility, and moisture did not influence wild oat control with flufenprop-methyl; however, a simulated rainfall of 1 mm within 1/2 h or 4 mm within 4 h after application reduced wild oat control.
A Numerical Taxonomic Study of Portulaca oleracea
Authors: Gorske S. F. , Rhodes A. M. , Hopen H. J.
Published: May 2019

A phenetic classification of 44 ecotypes of common purslane (Portulaca oleracea L.) produced 4 major groups: cool temperate; warm temperate to wet dry subtropic; humid subtropic to tropic; and cultivated. These groups were based on 36 plant characteristics; the ecotypes were collected from 18 countries and are representative of climates inhabited by common purslane. The cultivated group is comprised of robust forms which are raised for culinary purposes. For weed forms, plants of the cool temperate group were small, prostrate plants with size and growth habit increasing to maximum in the humid subtropic to tropic group.
Enhancement of CO2and Ethylene Production and Cellulase Activity by Glyphosate inPhaseolus vulgaris
Authors: Abu-Irmaileh B. E. , Jordan L. S. , Kumamoto J.
Published: May 2019

The effect of glyphosate [N-(phosphonomethyl)glycine] on carbon dioxide. (CO2) levels, ethylene production, and cellulase activity was investigated. Production of ethylene increased within 12 h and CO2increased within 24 h when 12-day-old bean plants (Phaseolus vulgarisL. ‘Red Kidney’) were treated with 20 mM isopropylamine salt of glyphosate. The CO2cycled for 3 days and then increased around treated plants. Specific activity of cellulase was increased in debladed bean seedlings that had been pretreated with 20 mM isopropylamine salt of glyphosate. Cellulase enhancement was detected 2 days after the pretreated plants were debladed. Glyphosate-enhanced ethylene production may have increased the cellulase activity.
Studies on the Reproductive Biology of Leafy Spurge (Euphoriba esula)
Authors: Morrow L. A.
Published: May 2019

Studies on the development of leafy spurge (Euphorbia esula L.) were conducted in the field and growth room. Sixteen months after planting in field plots, leafy spurge plants arising from underground bud-producing root segments, transplanted seedlings, or seeds averaged 96, 83, and 136 shoots per plant, respectively, when grown free of interference from other vegetation. A number of plants arising from each source flowered the first year, and all plants flowered and produced seed the second year after planting. When grown in a perennial grass sod consisting of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] and smooth brome (Bromus inermis Leyss.), no plant flowered or produced additional shoots. Soil moisture was less where a dense sod was present. In the growth room, total dry matter of tops and roots was greatest at a soil temperature of 18.3 C or higher, and plant height was greatest at 33.3 C. An early emerging crop might suppress leafy spurge by utilizing the available soil moisture early in the growing season.
Effects of Frost and Maturity on Glyphosate Phytotoxicity, Uptake, and Translocation
Authors: Davis H. E. , Fawcett R. S. , Harvey R. G.
Published: May 2019

The effect of temperatures below 0 C and plant maturity on the phytotoxicity of glyphosate [N-(phosphonomethyl)glycine] on rapidly growing alfalfa (Medicago sativaL. ‘Vernal’) and quackgrass [Agropyron repens(L.) Beauv.] plants was studied in a controlled environment. Pretreatment at −4 C partially protected alfalfa from injury by 0.8 kg/ha of glyphosate at six alfalfa maturities. This same treatment had no significant effect on glyphosate phytotoxicity to quackgrass. Pretreatment at −4 C increased translocation of glyphosate in quackgrass but reduced its translocation in alfalfa. A greater reduction in translocation occurred in the smaller alfalfa plants.
Combinations of Diquat and Several Cations for Control of Hydrilla (Hydrilla verticillata)
Authors: Frank P. A. , Dechoretz N. , Raines R. W.
Published: May 2019

Numerous cations were evaluated as possible substitutes for copper in mixtures with diquat (6,7-dihydrodipyrido[1,2-α:2′,1′-c] pyrazinediium ion) for control of hydrilla [Hydrilla verticillata(L.f.) Royle]. Several cations, including ferrous and ferric iron, when substituted for equal weights of copper in the mixtures, were as effective as copper in enhancing the phytotoxicity of diquat to hydrilla. In most instances, death of the test plants occurred more rapidly when the substitutes were used. Ferric chloride, because of its apparent innocuous behavior in the aquatic environment, is a desirable substitute for the more toxic copper. Bluegill sunfish (Lepomis macrochirusRAf.) were unaffected by week-long exposure to ferric chloride at concentrations as high as 100 ppmw. Since ferric chloride alone exhibited no toxicity to hydrilla in the range of concentrations tested, the greater phytotoxicity of the mixtures probably was due to the increased toxicity of diquat. In evaluations using other species of aquatic weeds, neither the addition of copper nor the addition of other cations increased the phytotoxicity of diquat. In most tests, the mixtures of diquat with other cations reduced the level of activity of diquat on weeds other than hydrilla.
EPTC Effects on Corn (Zea Mays) Growth and Endogenous Gibberellins.
Authors: Donald W. W. , Fawcett R. S. , Harvey R. G.
Published: May 2019

Hydroponic treatment with EPTC (S-ethyl dipropylthiocarbamate) inhibited leaf growth and stimulated stem growth of hybrid corn (Zea maysL. ‘Wisconsin 473′). Root treatment with GA3(gibberellic acid) prevented leaf stunting from EPTC. Most abnormalities in foliar display and height from treatment with 50 μM EPTC were prevented by increasing GA3levels from 0.5 μM to 10 μM over a week. The effect of EPTC on endogenous gibberellin activity was measured by bioassay of shoot extracts. EPTC (6.7 kg/ha) reduced the levels of total endogenous gibberellin-like substances in eight-day-old seedlings grown in treated soil. Under the environmental condtions of the experiment, this corresponded to the first discernable signs of injury. In addition EPTC induced an abnormal distribution of endogenous gibberellins in the shoots of older corn plants. Leaves of two-week-old EPTC-treated plants contained less gibberellin activity than the leaves of controls. Stems of herbicide-treated plants contained the same levels of gibberellin-like substances as the controls.
Forage Quality and Animal Performance as Influenced by Quackgrass (Agropyron repens) Control in Alfalfa (Medicago sativa) with Pronamide
Authors: Dutt T. E. , Harvey R. G. , Fawcett R. S. , Jorgensen N. A. , Larsen H. J. , Schlough D. A.
Published: May 2019

Fall applications of pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide] control or suppress quackgrass [Agropyron repens(L.) Beauv.] in established alfalfa (Medicago sativaL.). Studies were initiated to evaluate benefits of pronamide usage in areas where quackgrass is a problem. Alfalfa swards severely infested with quackgrass were treated with pronamide. Forage quality of first cutting alfalfa was significantly improved with pronamide usage, but second and third cutting forage quality was not greatly affected. First cutting hay from pronamide-treated and untreated areas was fed to goats and dairy cows in feeding trials. Animal intake of total forage dry matter, digestible dry matter, and digestible crude protein was increased with pronamide usage. A reduction in need for supplemental protein, an increase in efficiency in dry matter conversion into milk, and a 20% increase in milk production resulted from controlling quackgrass in alfalfa with pronamide.
Germination, Control, and Competition of Cutleaf Groundcherry (Physalis angulata) in Soybeans (Glycine max)
Authors: Bell V. D. , Oliver L. R.
Published: May 2019

Viable cutleaf groundcherry (Physalis angulataL. var.angulata) seed were produced 4 weeks after flowering began. Constant temperatures of 10 and 40 C totally inhibited germination. Varying photoperiods had no effect on the germination. Seedling emergence decreased (89% to 0%) as planting depth increased (0 to 10 cm). Greater than 97% preemergence control of cutleaf groundcherry was obtained with metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one], linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea], alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-δ2-1,3,4-oxadiazolin-5-one], oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], and bifenox [methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate]. Postemergence applications of dinoseb (2-sec-butyl-4,6-dinitrophenol), chloroxuron {3-[p-(p-chlorophenoxy)phenyl]-1,1-dimethylurea}, naptalam (N-1-naphthylphthalamic acid) plus dinoseb, oxyfluorfen, and acifluorfen {sodium 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate} linuron plus 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid], metribuzin plus 2,4-DB, and bifenox resulted in 96 to 100% control of cutleaf groundcherry. When confined to the soybean [Glycine max(L.) Merr.] drill, no significant reductions in soybean leaf area index (LAI), plant height, dry weight accumulation, crop growth rate (CGR), or seed yield were obtained from cutleaf groundcherry competition at densities as high as 60 plants/m of row. Presently, cutleaf groundcherry does not appear to be a major weed problem in soybean production.
Influence of Thatch on Preemergence Herbicide Activity in Kentucky Bluegrass (Poa pratensis)Turf
Authors: Hurto K. A. , Turgeon A. J.
Published: May 2019

The effects of five preemergence herbicides on turfgrass quality and control of crabgrass (Digitariaspp.) were measured to determine the influence of thatch on preemergence herbicide activity in Kentucky bluegrass (Poa pratensisL.) turf. Field applications of benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine), oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin -5-one], and prosulfalin {N-[[4-(dipropylamino)-3,5-dinitrophenyl] sulfonyl]-S,S-dimethylsulfilimine} to thatchy Kentucky bluegrass turf in spring caused injury that was apparent during periods of summer stress, while DCPA (dimethyl tetrachloroterephthalate) and bensulide [O,O-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide] caused little or no injury. The same treatments on thatch-free sites revealed that only prosulfalin was injurious. Adsorption of benefin, bensulide, and DCPA from solution was greater by thatch than by soil; however, the mobility of these herbicides in undisturbed thatch profiles was greater than measured in undisturbed surface soil from thatch-free sites. Thus, turfgrass injury from preemergence herbicides on thatchy sites is due to at least two factors: the greater mobility of preemergence herbicides in thatch than in soil; and the inherent susceptibility of Kentucky bluegrass to injury from preemergence herbicides that come into direct contact with roots and other absorbing organs.
Effect of Soil Organic Matter on the Phytotoxicity of Thirteens-Triazine Herbicides
Authors: Rahman A. , Matthews L. J.
Published: May 2019

The influence of soil organic matter on the initial and residual phytotoxicity of thirteens-triazine herbicides was investigated in greenhouse experiments using three Horotiu sandy loam soils with organic matter levels of 9.8, 15.5, and 20.6%. The amount of herbicide required to reduce the growth of oats (Avena sativaL. ‘Mapua’) by 50% (GR50) when compared with the control was determined for each herbicide and each organic matter level. Results showed that the GR50values for all herbicides were highly and positively correlated with the soil organic matter. In general, the phytotoxicity of compounds of high water solubility was less influenced by soil organic matter than those having low water solubility. The chloro-triazines persisted longer in soil than did the methoxy- or methylthio-triazines. Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] were the most persistent of the chloro-triazines.
Effect of Fire and 2,4-D on the Early Stages of Beaked Hazel (Corylus cornuta) Understories
Authors: Tappeiner J. C.
Published: May 2019

Burning and 2,4-D [(2,4-dichlorophenoxy)acetic acid] were used on the early stages of beaked hazel (Corylus cornuta Marsh.) understory to prevent development of a dense, continuous understory. At this early stage beaked hazel understories consisted of seedlings, small clones, and large clones. The application of 1.12 kg/ha of 2,4-D in July and August killed 84 to 100% of the seedlings and small clones, 86 to 98% percent of the large clones; while the application of 0.56 kg/ha of 2,4-D in June, July, or August caused 77 to 98% mortality of seedlings and small clones, but only 57 to 83% of large clones. Effects of burning were much more variable and generally mortality was less than with 2,4-D. One or two burns killed 23 to 100% of seedlings and small clones, and an average of only 13% (range 0 to 93%) of large clones.
The Influence of Three Herbicides on the Sensitivity of Greenhouse-grown Flue-cured Tobacco (Nicotiana tabacum)Plants to Ozone
Authors: Sung Shi-Jean Susana , Moore Laurence D.
Published: May 2019

TwoNicotiana tabacumL. cultivars, ‘North Carolina 88’ and ‘Coker 319′, were grown in a charcoal-filtered greenhouse and treated with three different herbicides according to the herbicide labels. Labeled rates (X) for diphenamid (N,N-dimethyl-2,2-diphenylacetamide), isopropalin (2,6-dinitro-N,N-dipropylcumidine), and pebulate (S-propyl butylethylthiocarbamate) were 9.2 kg/ha, 2.3 kg/ha, and 6.2 kg/ha, respectively. Three weeks after treatment with 1/2X, X, or 2X rates of herbicide, half of the plants were fumigated with 15 μl/liter ozone for 2.5 h for four consecutive days. North Carolina 88 and Coker 319 grew equally well and were equally sensitive to ozone injury. Ozone reduced plant height and levels of reducing sugars and total nonstructural carbohydrates of both cultivars. Isopropalin, at X and 2X, reduced the ozone sensitivity and growth of both cultivars, while the X rate of pebulate reduced the ozone sensitivity of North Carolina 88. The chemical composition of the plants was not correlated with the sensitivity of the tobacco plants to ozone-induced injury. The major factors governing fleck intensity, growth, and chemical compositions were ozone and herbicide treatments.
Effect of Selected Herbicides on Production of Southern Pines (Pinusspp.) in Nursery Seedbeds
Authors: Gjerstad D. H. , South D. B. , Crowley R. H.
Published: May 2019

Regional pine seedling tolerance experiments were conducted on five pine (Pinusspp.) species at ten forest nurseries in 1974. Similar studies in 1975 included four pine species at nine locations. From these studies, herbicides appearing safe for preemergence use are bifenox [methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate] at 1.7, 3.4, and 6.7 kg/ha; butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] at 2.2, 3.4, 4.5, and 6.7 kg/ha, napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] at 1.7 kg/ha; napropamide at 1.1 kg/ha plus bifenox at 3.4 kg/ha; dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) at 0.37 and 0.74 kg/ha; diphenamid (N,N-dimethyl-2,2-diphenylacetamide) at 4.5 kg/ha, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 1.1 kg/ha; and profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] at 1.1 and 2.2 kg/ha. Southern pine seedling tolerance to oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) was unacceptable at 1.1 and 2.2 kg/ha. Napropamide severely stunted seedlings at 6.7 kg/ha but affected seedlings only slightly at 3.4 kg/ha.
Influence of Soybean (Glycine max)Planting Date on Velvetleaf (Abutilon theophrasti)Competition
Authors: Oliver L. R.
Published: May 2019

A 2-yr study was conducted to determine the influence of early and late soybean [Glycine max(L.) Merr.] planting dates on the competitiveness of velvetleaf (Abutilon theophrastiMedic). Velvetleaf was planted at densities of one plant per 61 and 30 cm of row, and competition ranged from 4 weeks to full season. Soybean planting dates were mid-May and late-June. Velvetleaf emerging with soybeans in mid-May were twice as competitive as those emerging with soybeans planted in late-June. A density of one velvetleaf per 30 cm of row competing full season reduced soybean yields 27% for the early and only 14% for the late planting date. The competitive difference was due to the short-day photoperiodic response of velvetleaf. Although the early growth stages of soybeans are more competitive than those of velvetleaf, 10 weeks after emergence velvetleaf competition reduced soybean growth and development. Velvetleaf does not appear to be a potential major problem in Arkansas for soybeans planted in June due to its photoperiodic response and late season competitiveness. However, the weed could present problems for soybeans planted early, especially when an early maturing variety is used.
Differential Susceptibility of two Pigweed (Amaranthusspp.) Species to Napropamide
Authors: Jachetta J. J. , Radosevich S. R. , Elmore C. L.
Published: May 2019

Differential napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] tolerance by redroot pigweed (Amaranthus retroflexusL.) and prostrate pigweed (Amaranthus blitoidesS. Wats.) was noted in field study. Redroot pigweed was readily controlled whereas prostrate pigweed was not. Germination studies in which both pigweed species were directly exposed to napropamide (0 to 25 ppm) indicated that prostrate pigweed was the most susceptible of the two species. Root growth rates of untreated prostrate pigweed were 30% greater than redroot pigweed. When seeds of both species were germinated in a 4-cm layer of napropamide in greenhouse study each species was controlled equally well. Exposure of germinating seedlings of the two pigweed species to napropamide 1 day before emergence resulted in differential control. Seedlings of redroot pigweed never developed beyond the cotyledon stage; whereas, prostrate pigweed seedlings were initially suppressed by the herbicide, but surviving plants continued to grow. An early preemergence application or mechanical incorporation of napropamide should enhance control of prostrate pigweed.
Physiological Responses of Soybean (Glycine max)Plants to Metribuzin
Authors: Fedtke C.
Published: May 2019

Soybean [Glycine max(L.) Merr. ‘Hark’] plants responded similarly to a sublethal application of metribuzin [2-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] or to low light intensities. Both treatments increased soluble amino acid, ATP, nitrate reductase, and nitrate levels (up to 67, 140, 190, and 10,000%, respectively) and decreased soluble reducing sugars (33%), malate levels (86%), and the chlorophyll a/b ratio (24%). The similar response of light-limited and of chemically photosynthesis-inhibited plants is thought to be induced by a carbohydrate stress or another parameter related to a decreased rate of photosynthetic electron flow. However, during the induction process in shaded plants, light quality might play an important role in some cases. The results obtained with metribuzin and soybean plants are compared to and discussed together with (a) the results obtained by other authors working withs-triazine herbicides and (b) results obtained with methabenzthiazuron [N-(benzothiazol-2-yl)-N,N′-dimethylurea] in earlier experiments.
Growth and Water use by Common Cocklebur (Xanthium pensylvanicum)and Soybeans (Glycine max)Under Field Conditions
Authors: Geddes R. D. , Scott H. D. , Oliver L. R.
Published: May 2019

The competitive effects of common cocklebur (Xanthium pensylvanicumWallr.) on soybean [Glycine max(L.) Merr. ‘Lee 74′] were studied on Peridge silt loam during 1975 and 1976. Interspecific competition reduced the dry matter (DM) and leaf area of the individual plants in comparison to the plants grown under intraspecific conditions. Twelve weeks after emergence the percentage reductions in DM and leaf area due to interspecific competition were similar, were greater in common cocklebur than soybeans, and were greater in the dry year (1976) than in the wet year (1975). The root systems of both species varied with plant age, soil depth, and seasonal moisture. In general, the density of roots of both species was greatest in the soil profile at a depth interval of 0 to 13 cm and in the dry year more roots were found deeper in the soil. Extraction of soil water began in mid-July at the 91-cm depth and in late July at the 137-cm depth. Roots of common cocklebur and of the interspecific treatment explored a greater volume of soil for water than did those of soybeans. The total amount of water used by a pure stand of soybeans and a mixed stand of soybeans and common cocklebur was greater than that used by a pure stand of common cocklebur. Approximately 25% less water was lost as evapotranspiration (ET) in the dry year than in the wet year. Values for water use efficiency (WUE) increased during the season. Little difference in WUE between species was found in the wet year and up to 10 weeks after emergence in the dry year.
Response of Wild Oat (Avena fatua), Flax (Linum usitatissimum), and Rapeseed (Brassica campestrisandB. napus)to Diclofop-methyl
Authors: Chow P. N. P. , Dorrell D. G.
Published: May 2019

Diclofop-methyl {methyl ester of 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} applied as postemergence treatment at rates of 0.84 to 1.68 kg/ha controlled 65 to 87% of the wild oat (Avena fatuaL.) without injuring flax (Linum usitatissimumL.) or rapeseed (Brassica campestrisL. andB. napusL.) Yields of both crops were significantly increased because wild oat competition was minimized. Wild oat control was further improved when adjuvants were added with the herbicide at a concentration of 0.5% (v/v) to the spray mixture. Oil content, iodine number, and linolenic acid concentration of flax, and oil content of rapeseed were increased with the application of the herbicide, while the protein content of meal from both crops was unaffected. When flax was grown in the greenhouse under weed-free conditions, the 0.84 and 1.12 kg/ha rates of the herbicide did not affect seed and oil composition, whereas the 1.68 kg/ha rate decreased protein content, and slightly increased oil content, but had no significant effect on iodine number when compared with the untreated check. The change in seed and oil quality of flax appears to be related to a reduction in weed competition by the herbicide.
Effect of Photosystem II Inhibitors on Thylakoid Membranes of Two Common Groundsel (Senecio vulgaris)Biotypes
Authors: Radosevich S. R. , Steinback K. E. , Arntzen C. J.
Published: May 2019

Thylakoid membranes isolated from chloroplasts of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]-susceptible (S) and -resistant (R) biotypes of common groundsel (Senecio vulgarisL.) were assayed to determine the effect of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], bromacil (5-bromo-3-sec-butyl-6-methyluracil) and severals-triazine herbicides on photosystem II (PSII) activity. Each herbicide inhibited photosynthetic electron transport on the reducing side of PSII in thylakoid membranes from the susceptible biotype. Thylakoids isolated from the resistant biotype were 60 to 3200 times more tolerant to the inhibitors than thylakoids from the susceptible biotype. Electrophoretic analysis revealed no differences in molecular weight of membrane polypeptides of either common groundsel biotype. Three-hour dark incubation did not enhance inhibitor activity in the resistant-type thylakoid membranes. Specific structural or configurational changes associated with the reactive site may account for the differences in Hill reaction inhibition between biotypes. A relationship between herbicide structure and Hill reaction activity is discussed.
Response of Selected Rice (Oryza sativa)Lines to Molinate
Authors: Richard E. P. , Baker J. B.
Published: May 2019

Seventy-three rice (Oryza sativaL.) cultivars and uniform advanced-generation dwarf lines were evaluated for their response to molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) at concentrations of 0, 1, 2, and 4 ppmw in a 7-day laboratory screening test. These rice entries varied significantly in their response to each molinate concentration when shoot height of each entry was compared to that at the 0 ppmw level. Entries were ranked according to their molinate response at the 2 ppmw concentration and categorized as being either tolerant, intermediate or susceptible. Entries categorized as susceptible at 2 ppmw were further subdivided into highly susceptible and moderately susceptible categories based on their response to the 1 ppmw concentration. Those categorized as tolerant at the 2 ppmw concentration were likewise divided into highly tolerant and moderately tolerant categories on the basis of their response to the 4 ppmw concentration. The results of this bioassay indicates the possible existence of a genetically inherited response to molinate which might be manipulated by plant breeders to develop cultivars which have a high tolerance to molinate.
Effects of Illuminance and Time on Accumulation of Glyphosate in Johnsongrass (Sorghum halepense)
Authors: Kells J. J. , Rieck C. E.
Published: May 2019

Translocation of14C-glyphosate [N-(phosphonomethyl) glycine] in johnsongrass [Sorghum halepense(L.) Pers.] was examined in relation to time and illuminance. Plants were treated with14C-glyphosate and harvested 3 days and 6 days after treatment. Translocation increased significantly between the 3 day and 6 day harvest. The greatest accumulation of14C occurred in areas of meristematic growth. The concentration of14C recovered in rhizomes nearly doubled between the 3 day and 6 day harvest. Plants harvested after 3 days of treatment in the dark translocated 1.3% of the applied14C, while plants exposed to full light translocated 4.7%. Plants harvested after 6 days of treatment in the dark translocated 2.1% of the applied14C, while plants exposed to full light translocated 5.8%. Translocation data indicated that movement of glyphosate in johnsongrass was via the phloem. Accumulation of14C in roots and rhizomes was significantly greater in plants exposed to full light compared with plants exposed to either darkness or shade.
Residues of Simazine and Hydroxysimazine in an Orchard Soil
Authors: Khan S. U. , Marriage P. B.
Published: May 2019

Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] was applied annually at 4.5 kg/ha to uncultivated sandy loam of peach (Prunus persicaBatsch) for 7 yr (orchard A) and 9 yr (orchard B). Simazine and the metabolite, hydroxysimazine [2-hydroxy-4,6-bis (ethylamino)-s-triazine] as determined by gas chromatography (GC) persisted for 40 and 28 months in soil of orchard A and B, respectively. However, no progressive accumulation of either compound in large quantities occurred from repeated annual applications of simazine to the orchard soils. No metabolites other than hydroxysimazine were detected. Hydroxysimazine was degraded more slowly than simazine and the residue levels of hydroxysimazine were at least 40 times those of simazine 40 months and 28 months after the final application in orchard A and B, respectively. Both simazine and hydroxysimazine residues were detected in the upper 30 cm of the soil profile.
Cost of Biological Control of Weeds by Insects in Canada
Authors: Harris P.
Published: May 2019

The purpose of the paper is to permit the calculation of prospective costs before starting the biological control of a weed. The cost of the Canadian program from its start in 1950 to the end of 1976 was tabulated in scientist-years by target weed, agent, and the type of study done. This information and international data on the number of agents required to control a weed were used to calculate expected costs. A complete biological control program is likely to cost 18.8–23.7 scientist-years or currently $1.2 to 1.5 million and thus is only economic for use against major weeds. However, it is often possible to capitalize on studies done elsewhere, and under these circumstances biological control may be economic for solving more minor weed problems.
Establishment of Pine (Pinusspp.) Transplants in Perennial Grass Stands with Atrazine
Authors: Eckert Richard E.
Published: May 2019

Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] applied as a preplant treatment at rates of 2.24 to 8.96 kg/ha was evaluated for the control of perennial grasses and the establishment of jeffrey (Pinus jeffreyiGrev. & Balf.) and ponderosa (Pinus ponderosaLaws.) pine transplants. The most consistent and effective rates of atrazine (6.72 and 8.96 kg/ha) reduced grass herbage biomass an average of 72% over a 3-yr period and increased average final survival of transplants from 1% on the control to 66% with treatment. These rates also gave continued grass control for at least 3 to 4 yr after treatment. Stem diameter and top growth tended to be greater on the most effective treatments. High survival and increased growth of transplants on these treatments were attributed to low soil moisture tensions and increased NO3-N accumulation throughout the summer to depths of 30 cm during the year of planting and subsequent years.
Differential Metabolism of Metribuzin by Two Soybean (Glycine max) Cultivars
Authors: Mangeot B. L. , Slife F. E. , Rieck C. E.
Published: May 2019

Metribuzin-3-14C [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] was absorbed, translocated, and metabolized by both metribuzin-tolerant ‘Essex’ and metribuzin-sensitive ‘Coker 102’ soybean cultivars [Glycine max(L.) Merr.]. After 48 h Coker 102 accumulated 40% greater metribuzin equivalents in the shoots than Essex, but Essex shoots contained only 29% as much unaltered metribuzin as Coker 102, 1.08 and 3.68 μg per g dry weight, respectively. Essex is resistant to metribuzin primarily owing to a capacity to rapidly detoxify metribuzin to DA [6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one], to at least seven unidentified metabolites which remained in the aqueous fraction, and to an insoluble fraction. The unidentified metabolites in the aqueous fraction constituted the major detoxified breakdown products in both cultivars.
Soybean (Glycine max) Cultivar Response to Metribuzin in Solution Culture
Authors: Hardcastle W. S.
Published: May 2019

Twenty-eight commercial soybean [Glycine max(L.) Merr.] cultivars of maturity classes V through VIII were evaluated for differences in response to metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] 0.125 ppm w/w in hydroponic culture. Top dry weight (TDW) of treated ‘FFR 666’ soybeans equaled that of the cultivar check and five other cultivars were not significantly different (P = 5%). ‘Semmes' was most sensitive to the herbicide with TDW 40% of cultivar check. ‘Tracy’ and ‘Coker 156’ were not significantly different (P = 5%) from Semmes. The other cultivars tested were intermediate in response to metribuzin.