bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulation and Metabolism of Bromacil in Pineapple Sweet Orange (Citrus sinensis) and Cleopatra Mandarin (Citrus reticulata)
Authors: Jordan L. S. , Clerx W. A.
Published: May 2019

Young orange [Citrus sinensis (L.) Osbeck ‘Pineapple sweet orange’] trees are more sensitive to bromacil (5-bromo-3-sec-butyl-6-methyluracil) than young mandarin (Citrus reticulata Blanco ‘Cleopatra mandarin’) trees. Pineapple sweet orange roots absorbed twice as much 14C from bromacil, and accumulated three times as much in the leaves, as did Cleopatra mandarin. The amount of conjugated metabolites formed was the same in the roots of the two cultivars, but twice as much formed in the leaves of Cleopatra mandarin as in the leaves of Pineapple sweet orange. The principle metabolite was 5-bromo-3-sec-butyl-6-hydroxymethyluracil; a minor metabolite was tentatively identified as 5-bromo-3-(3-hydroxyl-1-methylpropyl)-6-methyluracil. No 5-bromouracil was detected. Citrus cultivars differ in their ability to accumulate and metabolize bromacil into conjugated nonphytotoxic compounds.
Response of Hemp Broomrape (Orobanche ramosa) Infestation to some Nitrogenous Compounds
Authors: Abu-Irmaileh B. E.
Published: May 2019

Greenhouse pot experiments were conducted to study the effect of various levels of nitrogen, applied as ammonium nitrate (NH4NO3) and ammonium sulfate [(NH4)2SO4], on hemp broomrape (Orobanche ramosaL.) infestation on tobacco (Nicotiana tabacumL. ‘Jordan 1’) and tomato (Lycopersicon esculentumMill. ‘Caludia Raf’). Infestation of tobacco and tomato by hemp broomrape was drastically reduced as higher levels of both fertilizers were applied. However, the dry weights of roots and shoots of both crop plants, as well as tomato yield, were reduced when NH4NO3was applied at 50 g/pot, and when (NH4)2SO4was applied at higher than 60 g/pot. In a separate pot experiment in the field, hemp broomrape infestation on tomato was drastically reduced, and tomato shoot dry weight, as well as tomato yield, were increased when (NH4)2SO4was applied at higher than 40 g/pot as 20-g increments repeated at 10-day intervals compared to those of the control.
Goosegrass (Eleusine indica) Control during Bermudagrass (Cynodon dactylon) Establishment
Authors: Bingham S. W. , Shaver R. L.
Published: May 2019

Oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-δ2-1,3,4-oxadiazolin-5-one] applied early enough for large crabgrass [Digitaria sanguinalis(L.) Scop.] control provided full season goosegrass [Eleusine indica(L.) Gaertn.] control during bermudagrass [Cynodon dactylon(L.) Pers. ‘Midiron’ and ‘Tufcoat’] establishment from sod strips. Prosulfalin {N-[[4-(dipropylamino)-3,5-dinitrophenyl]sulfonyl]-S,S-dimethylsulfilimine}, DCPA (dimethyl tetrachloroterephthalate), pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] and bensulide [0,0-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide] gave full season goosegrass control in well-established Midiron bermudagrass, but not during the initial establishment period where open bare soil was present. Napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] provided long term residual control of goosegrass with some interference with rooting of bermudagrass from stolon nodes. Winter survival of Midiron bermudagrass was superior to Tufcoat bermudagrass. Controlling annual grasses permitted superior bermudagrass growth, and winter survival was improved tremendously. Postemergence goosegrass control was obtained with MSMA (monosodium methanearsonate) and methazole [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] when repeated several times during the season. A mixture of MSMA and methazole was superior to either used alone. The rate of bermudagrass establishment was increased through the control of goosegrass with herbicides.
Ten-Year Control of Western False Hellebore (Veratrum californicum)
Authors: Williams M. C. , Cronin E. H.
Published: May 2019

Plots of western false hellebore (Veratrum californicumDurand), treated in 1968 and 1969 with 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 2.2 kg/ha, were reexamined in July 1979 to determine vegetative changes, especially any increases in the production of desirable species and long-term control of western false hellebore. Grass, sedge, and rush production had doubled, and broadleaved plant production, excluding western false hellebore, which was eliminated, decreased on treated plots. Western false hellebore had not reinvaded the treated plots; control remained at 100% for 10 yr. Removal of the western false hellebore on treated plots allowed an increase in grass, sedge, and rush production of 1,500 kg/ha over check plots.
Optical Parameters of Leaves of Seven Weed Species
Authors: Gausman H. W. , Menges R. M. , Richardson A. J. , Walter H. , Rodriguez R. R. , Tamez S.
Published: May 2019

Absorption coefficient (k), infinite reflectance (Ri), and scattering coefficient (s) were tabulated for five wavelengths and analyzed for statistical differences for seven weed species. The wavelengths were: 0.55 μm, 0.65 μm, 0.85 μm, 1.65 μm, and 2.20 μm. The Riof common lambsquarters (Chenopodium albumL.), johnsongrass [Sorghum halepense(L.) Pers.], and annual sowthistle (Sonchus oleraceusL.) leaves at the 0.85-μm wavelength were significantly (p = 0.05) higher than for sunflower (Helianthus annuusL.), ragweed parthenium (Parthenium hysterophorusL.), or London rocket (Sisymbrium irioL.). Annual sowthistle had the largest k value, and Palmer amaranth (Amaranthus palmeriS. Wats.) had the smallest k value at the 0.65-μm chlorophyll absorption wavelength. In general, johnsongrass, ragweed parthenium, or London rocket had the largest s values among the five wavelengths, whereas annual sowthistle and Palmer amaranth were usually lowest.
Characterization of Black Nightshade (Solanum nigrum) and Related Species in the United States
Authors: Ogg A. G. , Rogers B. S. , Schilling E. E.
Published: May 2019

Information from taxonomic treatments and comparisons of accessions from numerous locations grown in the field and greenhouse were combined and summarized to produce a key and descriptions of common agricultural nightshades in North America (Solanum americanumMill.,S. nigrumL.,S. ptycanthumDun., andS. sarrachoidesSendt.). Quantitative and qualitative descriptions of key characters and photographs of important morphological structures are provided to facilitate field identification. Problems with nomenclature among these species are discussed, and a system of common names that would standardize usage is proposed.
Growth and Development of Quackgrass (Agropyron repens) Biotypes
Authors: Westra P. H. , Wyse D. L.
Published: May 2019

Greenhouse and field experiments (at Rosemount and Roseau, Minnesota) were conducted to characterize the growth and development of 10 quackgrass [Agropyron repens (L.) Beauv.] biotypes selected near Roseau, Minnesota. The biotypes were highly variable for all traits studied. Eight of the biotypes had flag leaves approximately 1 cm wide, but two biotypes had flag leaves approximately 1.5 cm wide. Four biotypes were glaucous and blue-green in color, and the other biotypes varied from light to dark green and had varying leaf pubescence. In the field, plant height varied from 59 to 79 cm, and rhizome length varied from 105 to 135 cm. Spike production varied from 4 to 62 spikes per plant, and mid-season rhizome bud production varied from 246 to 1,211 buds, suggesting that the biotypes varied in their reproductive potential. Shoot dry weight varied from 48 to 362 g per plant, and daughter shoot production varied from 7 to 235 shoots per plant. The quackgrass near Roseau, Minnesota, appears to be made up of several distinct biotypes.
Photosynthetic Electron Transport Inhibition by Buthidazole
Authors: York A. C. , Arntzen C. J. , Slife F. W.
Published: May 2019

The effects of buthidazole {3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone} on the photochemical reactions of isolated pea (Pisum sativumL.) chloroplast thylakoids were analyzed. Buthidazole was found to inhibit electron transport at two distinct sites in the photosynthetic electron transport chain. The major site of inhibition was on the reducing side of photosystem II at the site of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] inhibition. Buthidazole also had a secondary site of electron transport inhibition on the oxidizing side of photosystem II. No evidence was found for buthidazole to act as an uncoupler or as an energy transfer inhibitor.
Response of Onion (Allium cepa) to Annual Weeds and Postemergence Herbicides
Authors: Menges R. M. , Tamez S.
Published: May 2019

Several herbicides were sprayed on emerged London rocket (Sisymbrium irioL.), common sunflower (Helianthus annuusL.), ragweed parthenium (Parthenium hysterophorusL.), annual sowthistle (Sonchus oleraceusL.), and onion (Allium cepaL. ‘yellow granex PRR’), to determine selectivity. Onion yields were reduced with common sunflower and London rocket interference within 7 weeks after emergence. Oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-δ2-1,3,4-oxadiazolin-5-one] at 2.2 kg/ha controlled all but common sunflower under most field conditions and reduced the yield of onion in one experiment out of six. Methazole [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] and bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) reduced the yields of onion in two of four experiments and three of six experiments, respectively. Both herbicides controlled most weed species, but only bromoxynil controlled annual sunflower adequately. Onion was injured when low temperature, low light intensity, and high relative humidity occurred within 3 days of the application of herbicides. Bioassays showed that oxadiazon persisted 5 months in soil in three of five experiments. Seeded London rocket populations reduced the growth of onion 20% within the first 4 weeks and 65% within 12 weeks after planting.
Effects of Diluent Volumes and Surfactant on the Phytotoxicity of Glyphosate to Bermudagrass (Cynodon dactylon)
Authors: Jordan T. N.
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine] toxicity to bermudagrass [Cynodon dactylon(L.) Pers.] increased as 0.84 kg/ha of the herbicide was applied in decreasing volumes of diluent from 374 to 47 L/ha. Visible injury to bermudagrass varied from 18 to 91% depending upon the spray solution formulation and diluent volume. The addition of surfactant to glyphosate (MON 0139) formulated without surfactant increased bermudagrass injury at each diluent volume tested. Glyphosate commercially formulated with surfactant (MON 2139) was the most toxic of the three formulations to bermudagrass. Regrowth of bermudagrass clipped at the soil surface 48 h after treatment ranged from 10% of the untreated control with MON 2139 at 47 L/ha to 100% of the control with MON 0139 at 374 L/ha. The MON 2139 formulation showed as much as a six-fold increase in foliage regrowth when the diluent volume was increased from 47 to 374 L/ha.
Germination and Emergence of Burcucumber (Sicyos angulatus)
Authors: Mann R. K. , Rieck C. E. , Witt W. W.
Published: May 2019

Mechanical scarification of burcucumber (Sicyos angulatusL.) seeds resulted in increased water absorption and germination. Burcucumber germination occurred at temperatures ranging from 15 to 35 C with optimum germination occurring from 20 to 30 C. Scarified burcucumber seeds were more sensitive to simulated moisture stress than were either soybean [Glycine max(L.) Merr. ‘Williams’] or corn [Zea maysL. ‘Pioneer Brand 3369A’]. Regardless of osmotic potential, intact burcucumber seeds did not germinate; scarified seeds germinated at osmotic potentials to −6 bars. Cold stratification at 4 C for 18 weeks modified seedcoat permeability so that 11% of non-scarified burcucumber seeds germinated. Increasing depth of planting decreased emergence with limited emergence occurring at depths of 15 and 16 cm in field and growth chamber studies, respectively.
Regulation of Witchweed (Striga asiatica) Conditioning and Germination by dl-Strigol
Authors: Hsiao A. I. , Worsham A. D. , Moreland D. E.
Published: May 2019

The conditioning and germination processes of witchweed [Striga asiatica (L.) Kuntze] seeds were regulated by synthetic dl-strigol (ST) or natural stimulants (STM) present in a corn (Zea mays L.) root-exudate solution. Seeds conditioned in water for 7 and 14 days required 10−10 and 10−12M ST, respectively, to induce maximum germination (ca. 80%). Surprisingly, conditioning seeds in ST or STM had an adverse effect on the responsiveness of the seeds to the same compounds after conditioning. Compared to seeds conditioned in water, these ST- or STM-conditioned seeds required not only higher concentrations of ST or STM to induce maximum germination, but also longer immersion time to become conditioned. ST or STM inhibits conditioning and thus the regulation of germination by ST or STM depends mainly on the stage of conditioning of seeds when they are exposed to ST or STM. ST or STM stimulates germination only after a pre-germination threshold is reached during conditioning. Exposure of seeds to ST or STM before this critical level is reached apparently inhibits conditioning.
Effects of Date and Depth of Burial on Wild Garlic (Allium vineale) Plants
Authors: Peters E. J. , Lowance S. A.
Published: May 2019

Wild garlic (Allium vinealeL.) plants were buried 10, 15, and 20 cm deep in soil at 2-week intervals from September 1 until November during a 4-yr period. Plants were also buried in early spring. When buried 15 to 20 cm deep after mid-October, less than 5% of the plants produced above-ground shoots during the following 2 yr. When buried 15 to 20 cm deep on April 1, no above-ground shoots were produced during the following 2 yr, but burial on April 15 was less effective. These data suggest that deep plowing at the proper date may control wild garlic if subsequent tillage is shallow enough to avoid bringing wild garlic bulbs to the surface.
Effect of Four Foliage-Applied Herbicides on Field Horsetail (Equisetum arvense)
Authors: Coupland D. , Peabody D. V.
Published: May 2019

Amitrole (3-amino-s-triazole), asulam (methyl sulfanilylcarbamate), glyphosate [N-(phosphonomethyl)glycine], and fosamine [ethyl hydrogen (aminocarbonyl)phosphonate] were effective in reducing the amount of shoot regrowth from field horsetail (Equisetum arvenseL.) 3 months after treatment. The order of effectiveness was amitrole > glyphosate > asulam > fosamine. The advantage of adding surfactant to the spray formulation or applying herbicides to wet foliage was rate dependent for all herbicides except fosamine. Spray retention was increased by application to wet foliage and by the inclusion of surfactant in the formulation. Spray retention increased as spray volume and plant size increased and as plant growth became prostrate. A scanning electron microscope study of the shoot surfaces showed an abundance of silica-containing structures and the presence of epicuticular wax. Certain surfaces of the scale leaves did not have these characteristics, indicating that redistribution of spray to these areas may result in greater penetration with subsequent increases in herbicide performance.
Effect of Consecutive Annual Applications of Fluometuron on Cotton (Gossypium hirsutum)
Authors: Hayes R. M. , Hoskinson P. E. , Overton J. R. , Jeffery L. S.
Published: May 2019

Cotton [Gossypium hirsutum(L.) ‘Hancock’] lint yield or quality was not adversely affected under weed free conditions by three consecutive annual preemergence applications of up to 1.68 kg/ha fluometuron [1,1-dimethyl-3-(a,a,a-trifluoro-m-tolyl)urea] alone or in combination with 0.84 kg/ha trifluralin (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) preplant incorporated on silt loam soils of the Memphis catena containing less than 1% organic matter. Similar applications of fluometuron at 3.36 kg/ha delayed maturity of cotton plants and ultimately reduced lint yields. Trifluralin treatments tended to overcome the detrimental effects of high rates of fluometuron. There was no effect on fiber development and maturation because fiber length and fineness (micronaire) were virtually identical for all treatments. The effect on maturity as determined by percent first harvest was a reflection of slower plant growth and fruiting and not of the development of the fiber itself. These results indicate no detrimental effects on cotton yield, maturity, and quality from annual applications of these herbicides at rates recommended and normally used in Tennessee.
Broadleaf Weed Interference in Sugarbeets (Beta vulgaris)
Authors: Schweizer E. E.
Published: May 2019

Interference within a mixture of equal densities of common lambsquarters (Chenopodium albumL.), kochia [Kochia scoparia(L.) Schrad.], and redroot pigweed (Amaranthus retroflexusL.) in sugarbeets (Beta vulgarisL. ‘Mono Hy D2’) was determined in a 3-yr field study. Yield of sugarbeet roots and sucrose per hectare decreased as intensity of competition from equal populations of these three weeds increased. At densities of 6, 12, 18, and 24 broadleaf weeds per 30 m of row, root yields were reduced 13, 24, 33, and 39%, respectively. Sucrose yields were reduced similarly. Fewer than three weeds per 30 m of row did not significantly reduce root yield. Reduction in root yield (Y) of sugarbeets caused by specific densities (X) of the three broadleaf weeds was predicted by using the linear equation Y = 1.64 + 1.88 X. The actual reductions in yield were always less than the predicted reductions when this equation was tested against 36 weed control systems because the competitive ability of broadleaf weeds that were treated with herbicides, but not killed, was suppressed during the growing season. By harvest, broadleaf weeds present in weed-control-system plots weighed an average of 75 to 85% less than broadleaf weeds present in nontreated plots.
Fluometuron Adsorption-Desorption Equilibria in Soil
Authors: Savage K. E. , Wauchope R. D.
Published: May 2019

The adsorption-desorption equilibria of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] were studied; a slurry technique with soil at 0-bar moisture tension was used. The equilibria established with Bosket very fine sandy loam (VFSL) were evaluated by three equations. The equation best describing the adsorption isotherm was x/m = K1Ce+ K2Ce2. Successive equilibrations resulted in a shift in the equilibria toward the adsorbed state, most likeiy due to a physical change in the adsorption capacity of the soil with repeated agitation. Desorption studies with seven additional soils indicated the importance of soil organic matter content in the adsorption-desorption equilibria of fluometuron. The relationship between soil organic matter contents and the adsorption-desorption equilibrium constants was characterized by a highly significant linear correlation (r = 0.93) and the resulting regression equation: K1= 0.46 + 0.45(O.M.%). Clay content of these soils was not significantly correlated with fluometuron equilibrium constants.
Arthropods Exported from California to the U.S.S.R. for Ragweed Control
Authors: Goeden R. D. , Kovalev O. V. , Ricker D. W.
Published: May 2019

The following species of arthropods were exported from California to the U.S.S.R. for the biological control of ragweed (Ambrosiaspp.):Tarachidia candefactaHübner (Lepidoptera: Noctuidae);Coleophorasp. nearannulatellaBraun (Lepidoptera: Coleophoridae); andEriophyes boyceiKeifer (Acarina: Eriophyidae).Tarachidia candefactarepresents the first insect species intentionally introduced from North America into Europe and established for biological weed control.
Selectivity Factors in the Response of Plants to 2,4-DB
Authors: Hawf Larry R. , Behrens Richard
Published: May 2019

Foliar spray retention, absorption and translocation, and the dissipation of 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] and 2,4-D [(2,4-dichlorophenoxy)acetic acid] were examined to determine their importance as selectivity factors in the response of two 2,4-DB-tolerant legumes, alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.), and two susceptible broadleaf weeds, redroot pigweed (Amaranthus retroflexus L.) and common cocklebur (Xanthium pensylvanicum Wallr.). The legumes were as effective as the broadleaf weeds in metabolizing (beta-oxidizing) 2,4-DB to 2,4-D. The relatively greater tolerance of the legumes than of the broadleaf weeds to 2,4-DB arose from a combination of poorer spray retention, less effective absorption and translocation, and a more rapid degradation of the 2,4-D arising from the beta-oxidation of 2,4-DB.
Adsorption and Desorption of Trifluralin, Triallate, and Diallate by Various Adsorbents
Authors: Grover R.
Published: May 2019

The relative adsorption of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), triallate [S-(2,3,3-trichloroallyl)-diisopropylthiocarbamate], and diallate [S-(2,3-dichloroallyl)diisopropylthiocarbamate] was studied on several adsorptive surfaces. The herbicides were strongly adsorbed, with the following general trend: activated charcoal > peat moss > wheat straw (Triticum aestivumL.) ∼ cellulose triacetate > cation exchange resin > anion exchange resin > silica gel ∼ cellulose powder > kaolinite ∼ montmorillonite. Trifluralin and triallate were readily desorbed from montmorillonite by water, with miniminal desorption for peat moss, cellulose triacetate, and wheat straw.
Control of Purple Nutsedge by 2,4-D, Paraquat, and Dinoseb
Authors: Standifer L.C.
Published: May 2019

Purple nutsedge (Cyperus rotundusL.) plants from tubers uniformly planted in fumigated soil were treated with 2,4-D [(2,4-dichlorophenoxy)acetic acid], paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), or dinoseb (2-sec-butyl-4-6-dinitrophenol). Repeated applications were made as required on the 1972 and 1973 plantings for one growing season. Emerged plants and their parent tubers were killed by four (1972) or five (1973) applications of paraquat. Three applications of 2,4-D were required for control in 1972. In 1973, a single treatment of 2,4-D afforded almost complete control. Three applications of dinoseb were required in 1972, but five were required in 1973.
Resistance of Canada Thistle (Cirsium arvense) Ecotypes to a Rust Pathogen (Puccinia obtegens)
Authors: Turner Sherry K. , Fay Peter K. , Sharp Eugene L. , Sands David C.
Published: May 2019

Puccinia obtegens(Link) Tul., an autoecious rust pathogen, is a potential biological control agent of Canada thistle [Cirsium arvense(L.) Scop.]. Ten ecotypes of Canada thistle were inoculated with uredospores ofP. obtegensand sporulation was observed on all ecotypes. Infection types varied among and within ecotypes, indicating that host-resistance is one factor limiting rust infection. No correlation was found between Canada thistle susceptibility to the rust and host plant ecotype classification, stomatal density, amount of leaf pubescence, or spore germinability on leaf surfaces.
Germination and Development of Honeyvine Milkweed (Ampelamus albidus) Seed
Authors: Soteres John K. , Murray Don S.
Published: May 2019

The ability of honeyvine milkweed [Ampelamus albidus(Nutt.) Britt.] to establish and develop from seed was studied in laboratory and field experiments. Optimum germination temperature was 30 C. Seed incubated at cooler temperatures and then transferred to 30 C germinated equally as well as seed incubated continually at 30 C. Germination was unaffected at moisture stress levels between 0 and −4.6 bars, but was decreased at levels between −4.6 and −12.8 bars. The optimum pH range for germination was between 5 and 7. The greatest emergence of seedlings occurred at a depth of 0.5 cm with no emergence occurring at depths greater than 5 cm. Greater emergence was obtained with a loam than sandy loam at all planting depths except 0.5 cm. Field plots seeded on May 1 gave maximum seed production. Seed production decreased with each 2-week delay in planting. Planting dates of July 10 or later produced no seed. Seed germination was affected little by delayed planting. The following spring, regrowth from plants seeded on June 12 or later was less vigorous than regrowth from plants seeded earlier.
Fusarium lateritium: A Pathogen of Spurred Anoda (Anoda cristata), Prickly Sida (Sida spinosa), and Velvetleaf (Abutilon theophrasti)
Authors: Walker H. Lynn
Published: May 2019

An isolate ofFusarium lateritium(Nees) emend. Snyder and Hansen was associated with naturally occurring disease of spurred anoda [Anoda cristata(L.) Schlecht.] and prickly sida (Sida spinosaL.) plants. In greenhouse inoculation studies, theFusariumisolate was pathogenic to healthy spurred anoda and prickly sida plants. The disease symptoms were characterized by leaf, stem, and root lesions. The stem lesions enlarged with time and formed cankers that often girdled the stems and killed inoculated plants. In host-range studies, velvetleaf (Abutilon theophrastiMedic.), Venice mallow (Hibiscus trionumL.), okra [Abelmoschus esculentus(L.) Moench], and hollyhock [Althaea rosea(L.) Cav.] were also susceptible to the pathogen. This is the first report of these six species as hosts for this pathogen. Corn (Zea maysL.), cotton (Gossypium hirsutumL. andG. barbadenseL.), soybean [Glycine max(L.) Merr.], and 18 other representative crop and weed species in eight families were resistant to the pathogen.F. lateritiummay be a useful biological herbicide for susceptible malvaceous weeds.
Response of Vegetable Crops to Sublethal Application of 2,4-D
Authors: Hemphill Delbert D. , Montgomery Marvin L.
Published: May 2019

Sublethal amounts of 2,4-D [(2,4-dichlorophenoxy) acetic acid] were applied to several vegetable crops in order to determine effect on yield and quality in a simulated drift experiment. Tomato (Lycopersicon esculentumMill.) and root crops were most sensitive to 2,4-D; as little as 2.1 g/ha of acid distorted tomato fruit shape and elongated radish (Raphanus sativusL.) roots. All root crops were rendered unmarketable by 10.4 g/ha and gross yields were reduced by exposure to 104 g/ha. Yield of peppers (Capsicum frutescensL. var.grossum) was increased by exposure to 2.1 g/ha and severely depressed by 104 g/ha. Cucumber (Cucumis sativusL.) fruit shape was distorted at 11 g/ha and yield was reduced slightly. Lettuce (Lactuca sativaL.), onion (Allium cepaL.), and cabbage (Brassica oleraceaL. var.capitata) were least sensitive to 2,4-D. Exposure to 20.8 g/ha did not reduce yields of lettuce or cabbage. Onion yields were reduced by application of 104 g/ha. Bush bean (Phaseolus vulgarisL.) yield was decreased by exposure to 22 g/ha, but potato (Solarium tuberosumL.) yield increased at 16 g/ha. Herbicide residues in the crop foliage were proportional to the degree of exposure. Residue analysis combined with foliar symptoms may be useful in predicting crop damage following 2,4-D drift.
Control of Common Milkweed (Asclepias syriaca)
Authors: Cramer Gary L. , Burnside Orvin C.
Published: May 2019

Control of common milkweed (Asclepias syriacaL.) with postemergence herbicides was investigated in greenhouse and field experiments. In greenhouse experiments, amitrole (3-amino-s-triazole), dicamba (3,6-dichloro-o-anisic acid), glyphosate [N-(phosphonomethyl)glycine], and combinations of amitrole + dicamba, dicamba + 2,4-D [(2,4-dichlorophenoxy) acetic acid], glyphosate + 2,4-D, and glyphosate + dicamba reduced regrowth of 6-week-old common milkweed as compared with the untreated check. Postemergence herbicides commonly used in corn (Zea maysL.), sorghum [Sorghum bicolor(L.) Moench], and soybeans [Glycine max(L.) Merr.] had little effect on emerged common milkweed. Removal of common milkweed top-growth as early as 1 day after treatment did not effect subsequent growth reduction from glyphosate at 0.3 kg/ha or higher. In the field, satisfactory control (70% or better) of common milkweed was obtained with glyphosate at 2.2 kg/ha applied at the early or late bud growth stage. Plots plowed 1 day after application of glyphosate at 2.2 kg/ha still retained satisfactory control of common milkweed 1 yr after treatment. Herbicides applied with a herbicide glove or a roller applicator resulted in common milkweed control similar to that obtained from broadcast spray applications.
Physiological Bases of Sugarbeet (Beta vulgaris) Tolerance to Foliar Application of Ethofumesate
Authors: Duncan David N. , Meggitt William F. , Penner Donald
Published: May 2019

Absorption, translocation, and metabolism of foliar-applied ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulphonate] were studied to explain field observations showing differences in susceptibility among sugarbeet (Beta vulgarisL.), common ragweed (Ambrosia artemisiifoliaL.), redroot pigweed (Amaranthus retroflexusL.), and common lambsquarters (Chenopodium albumL.). In laboratory studies, two- to four-leaf seedlings of the highly susceptible species, redroot pigweed and common lambsquarter, absorbed greater amounts of14C-ethofumesate from foliar application than the moderately susceptible common ragweed and tolerant sugarbeet. Sugarbeet translocated very little14C from treated foliage to untreated plant tissue. All weed species translocated14C-ethofumesate to untreated leaf tissue when14C-ethofumesate was applied to seedlings at the two-leaf stage. Ethofumesate was translocated basipetally to the stem and root of two-leaf redroot pigweed and common lambsquarter seedlings. A high percentage of the14C was found in the water-soluble fraction in sugarbeet seedlings, indicating inactivation. The amount of metabolites recovered in the non-polar fraction depended on the stage of plant growth. Total photosynthesis and respiration in redroot pigweed was inhibited 4 h after foliar application and did not recover after 96 h. Uptake and evolution of CO2were also inhibited in sugarbeet leaves, but they recovered rapidly, depending on age of plant at treatment. The stage of plant development was the key factor determining species response to foliar treatments of ethofumesate in terms of absorption, metabolism, and total photosynthesis and respiration.
Control of Herbaceous Weeds in Allegheny Hardwood Forests with Herbicides
Authors: Horsley Stephen B.
Published: May 2019

Bromacil (5-bromo-3-sec-butyl-6-methyluracil), glyphosate (N-phosphonomethylglycine), picloram (4-amino-3,5,6-trichloropicolinic acid), simazine [2-chloro-4,6-bis (ethylamino)-s-triazine], and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] were evaluated at four application rates and five application dates, May 1, June 1, July 1, August 1, and September 1, for their ability to control seven herbaceous, forest ground covers, hayscented fern (Dennstaedtia punctilobula (Michx.) Moore), New York fern (Thelypteris noveboracensis L.), short husk grass (Brachyelytrum erectum Schreb.), bracken fern [Pteridium aquilinum (L.) Kuhn var. latiusculum (Desv.) Underw.], wild oat grass (Danthonia compressa Aust.), rough goldenrod (Solidago rugosa Mill.), and flattop aster (Aster umbellatus Mill.) without residual effects on black cherry (Prunus serotina Ehrh.) seed stored in the forest floor, or on survival and growth of natural or planted black cherry seedlings. Control of most of the target species depended on the date and rate of application. Simazine had no herbicidal effect on these extremely acid (pH 3.9 to 4.4) Allegheny Plateau sites. None of the herbicides interfered with germination of black cherry seed stored in the forest floor or with establishment of seedlings. Bromacil applied at 22.4 kg/ha, picloram, at 9.0 kg/ha, and hexazinone at 13.4 kg/ha reduced survival, or growth, or both, of black cherry seedlings planted in a forest opening. Glyphosate was the most economical herbicide that met the control criteria. Application of 1.1 kg/ha between August 1 and September 1 produced acceptable control of all target species for at least 3 yr.
Control of Red Rice (Oryza sativa) in Water-Seeded Rice (O.sativa)
Authors: Smith Roy J.
Published: May 2019

Field research was conducted in 1973, 1974, 1977, and 1978 to compare water-culture practices and rates of molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) for control of “strawhull” red rice (Oryza sativaL.) in water-seeded rice (O.sativaL.). Water-culture treatments (continuously drained, alternately drained and flooded, or continuously flooded during the first 28 days after seeding) alone, or preplant, soil-incorporated treatments of molinate (3.4, 4.5, and 6.7 kg/ha) alone did not control red rice. Treatments of preplant-incorporated molinate at 4.5 and 6.7 kg/ha in a continuously flooded culture or 6.7 kg/ha in an alternately drained-flooded culture controlled 87 to 93% of the red rice and permitted production of satisfactory yields of high quality rice grain.
Common Dandelion (Taraxacum officinale) Control with 2,4-D and Mechanical Treatments
Authors: Mann Henrietta
Published: May 2019

The application of 2,4-D [(2,4-dichlorophenoxy) acetic acid], at 1.1 kg/ha to common dandelion (Taraxacum officinale Weber) resulted in 40% or less survival in lawn and hayfield habitats, in both spring and fall treatments. A significantly lower incidence of regeneration (12 to 20%) was attained independent of the season by shoot removal (spudding) combined with 2,4-D in the lawn, but not in the hayfield habitat. No measure of control was obtained by spudding alone, confirming the high capacity of common dandelion for root regeneration. Removal of leaves 2 weeks after application of 2,4-D diminished the effectiveness of control in both lawn and hayfield habitats, with 49 to 50% and 60 to 70% regeneration, respectively. Apparently, there is incomplete translocation of the herbicide within this interval. Significant mortality from spudding alone was observed only in plants less than 4 months old (64% survival). One-year-old plants responded to all treatments in the same manner as common dandelion populations as a whole. Optimum control of common dandelion in lawns was obtained by 2,4-D application in combination with spudding, during the spring.
Control of Johnsongrass (Sorghum halepense) and Volunteer Corn (Zea mays) in Soybeans (Glycine max)
Authors: Dale Jim E.
Published: May 2019

Rhizome johnsongrass [Sorghum halepense(L.) Pers.] in late-planted soybeans [Glycine max(L.) Merr. ‘Forrest’] was effectively controlled with glyphosate [N-(phosphonomethyl)glycine] applied twice by a rope-wick applicator at 0.1 kg/ha each time. At crop maturity, wick-applied glyphosate controlled an average of 92% of the johnsongrass over a 2-yr period as compared to 51% where 2.2 kg/ha of glyphosate was applied conventionally to rhizome johnsongrass prior to planting. There was no difference in soybean yields and no visible injury to soybeans. Rhizome johnsongrass and volunteer corn (Zea maysL.) were effectively controlled in soybeans planted at the proper time with glyphosate applied by either the rope-wick applicator or recirculating sprayer. Soybean yields were reduced more when volunteer corn was treated with glyphosate that was applied with a recirculating sprayer than with a rope-wick applicator. This reduction in yield was attributed to splattering of the herbicide.
Effect of Light on the Phytotoxicity of Fluridone in American Pondweed (Potamogeton nodosus) and Sago Pondweed (P. pectinatus)
Authors: Anderson Lars W. J.
Published: May 2019

The effect of 1.0 ppmw fluridone {1-methyl-3-phenyl-5-[3-trifluoromethyl)phenyl]-4(1H)-pyridinone} on growth of American pondweed (Potamogeton nodosusPoir.) and sago pondweed (Potamogeton pectinatusL.) was examined in plants kept in darkness or under various numbers of 12-h photoperiods. When plants were exposed to 1.0 ppmw fluridone for 1 to 10 12-h days, no stunting of American pondweed occurred until 21 days after treatment. Thirtythree days after treatment, plants that had received 4 to 10 days' exposure were most stunted. Sago pondweed was slightly more susceptible than American pondweed (87% and 50% reduction in length, respectively) 37 days after a 10-day exposure. Chlorophyllsaandbwere significantly lower in both species 14 days after all fluridone treatments. American pondweed plants exposed to fluridone continuously (1.0 ppmw) for 15 days, but given 0, 3, 6, 9, 12, or 15 12-h days were stunted only after having received at least six photoperiods. Stunting in sago pondweed was only slightly light-dependent. Neither species absorbed significantly more14C-labeled fluridone after 2, 4, or 14 photoperiods compared to plants kept in darkness for the same time.
Effect of Light and Temperature on Growth of Purple Nutsedge
Authors: Wills G. D.
Published: May 2019

Purple nutsedge (Cyperus rotundusL.) from single tubers was grown for 3 months at 24, 32, and 40 C and 9, 13, and 19 klux illumination. Growth in number and dry weight of shoots, bulbs, and tubers were determined at monthly intervals. Maximum growth for all portions of the plant occurred after 3 months at 32 C and 19 klux illumination. Minimum growth occurred at 40 C and 9 klux illumination. Growth at 24 C was not significantly affected by increased illumination above 9 klux.
Influence of Yellow Nutsedge Competition on Furrow-Irrigated Cotton
Authors: Keeley P. E. , Thullen R. J.
Published: May 2019

In five field experiments conducted during 1972 and 1973, yellow nutsedge (Cyperus esculentusL.) was either undisturbed or removed from planting beds by hoeing 0, 2, 4, 6, and 8 weeks after cotton (Gossypium hirsutumL. ‘Acala SJ-1’) emergence. Yellow nutsedge undisturbed in beds increased from 23 plants/m of row at cotton emergence to 100 plants/m at harvest. Nutsedge competing with cotton for more than 4 weeks reduced yield of seed cotton. Nutsedge that competed all season reduced yields 34%, as compared with 20% when it competed for 6 and 8 weeks. Nutsedge that competed with cotton for more than 4 weeks reduced height and number of cotton plants and delayed maturity. Although nutsedge competition reduced yields and delayed maturity, it generally did not alter fiber properties. When nutsedge was removed at cotton emergence and was followed by 14 weekly hoeings, the final tuber population was reduced to 24% of the beginning population. When nutsedge removal was delayed for 6 weeks and was followed by nine weekly hoeings, a fourfold increase in tubers resulted. A further tenfold increase resulted when nutsedge was not removed.
Rapid Inactivation of Glyphosate in the Soil
Authors: Sprankle Paul , Meggitt W. F. , Penner Donald
Published: May 2019

In greenhouse studies, soil applications of 14C-methyl-labeled glyphosate [N-(phosphonomethyl)glycine] were not readily absorbed by corn (Zea mays L. ‘Michigan 400’) and soybean [Glycine max (L.) Merr. ‘Hark’]. However, glyphosate available to plants in sand culture was absorbed. Wheat (Triticum aestivum L. ‘Avon’) a sensitive bioassay plant, was used to detect the herbicide. Clay loam and muck soil rapidly inactivated 56 kg/ha of glyphosate. Autoclaving of the soil did not prevent the inactivation of glyphosate. In a sandy clay loam soil, application of 56 kg/ha of glyphosate decreased plant growth with increasing pH. Additions of 98 or 196 kg/ha of phosphate to the soil surface decreased glyphosate inactivation in the soil. It is postulated that initial inactivation of glyphosate in soil is by reversible adsorption to clay and organic matter through the phosphonic acid moiety.
Factors Influencing Barnyardgrass (Echinochloa crus-galli) Control with Diclofop
Authors: West L. D. , Dawson J. H. , Appleby A. P.
Published: May 2019

Studies were conducted to determine the effect of soil moisture, seedling age, and exposure of plant parts on control of barnyardgrass [Echinochloa crus-galli(L.) Beauv.] with diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid}, formulated as the methyl ester. In a Warden silt loam, moisture content of 10% or more was needed for satisfactory diclofop control of slow-growing barnyardgrass under cool, early-season conditions. Soil moisture was less critical when temperatures were higher and barnyardgrass was growing rapidly. Roots and emerging shoots both absorbed diclofop from the soil, but both plant parts were inhibited more when diclofop was applied to the roots than to the shoots. Barnyardgrass was injured from diclofop applied postemergence to either roots or shoots separately, but phytotoxicity was greatest when the whole plant was exposed. When the soil was treated, control increased with increasing amounts of post-treatment overhead irrigation. Two-leaf and four-leaf barnyardgrass plants were equally susceptible to diclofop applied postemergence, but resistance increased with age in plants with more than four leaves.
The Basis of the Antagonistic Effect of 2,4-D on Diclofop-Methyl Toxicity to Wild Oat (Avena fatua)
Authors: Todd B. G. , Stobbe E. H.
Published: May 2019

The interaction between diclofop-methyl {2-[4-(2,4-dichlorophenoxy)phenoxy] methyl propanoate} and 2,4-D [(2,4-dichlorophenoxy)acetic acid] was evaluated. Foliar applications of the two herbicides in a tank mixture were antagonistic with respect to wild oat (Avena fatuaL.) control. Application of mixtures of the two herbicides to wild oat roots resulted in an additive herbicidal effect. The acid form of 2,4-D was determined to be the component of the 2,4-D formulation that reduced the toxicity of foliar-applied diclofop-methyl to wild oat. Analysis of diclofop-methyl solutions with and without added 2,4-D revealed no degradation products of dichlofop-methyl, nor any evidence of complexing between diclofop-methyl and 2,4-D. Addition of 2,4-D to the diclofop-methyl spray solution did not affect diclofop-methyl spray retention by, or penetration into, wild oat leaves. Movement of radioactivity to roots and to shoot apices following application of14C-diclofop-methyl to wild oat leaves was reduced by addition of 2,4-D to the treatment solution. Deesterification of diclofop-methyl was inhibited by 2,4-D. The accumulation of diclofop-methyl in these wild oat leaves resulted in membrane damage and leaf necrosis. Symplastic movement of the des-methyl acid, diclofop, to sensitive meristematic areas was reduced. As insufficient toxicant reached meristematic areas to permanently interrupt meristematic activity, the wild oat plants were able to outgrow the contact damage to their leaves.
Postemergence Winter Weed Control in Bermudagrass (Cynodon dactylon) Turf
Authors: Johnson B. J.
Published: May 2019

Several herbicides were applied in January, February, and March with a comparison of the intervals of treatment of 2 and 4 weeks after the initial treatment each month for postemergence control of winter annual weeds in bermudagrass [Cynodon dactylon(L.) Pers.] turf. Glyphosphate [N-(phosphonomethyl)glycine] treatments applied at 2-week intervals with the initial treatment made in January or February controlled a higher percentage of annual bluegrass (Poa annuaL.) than when applied in March. Hop clover (Trifolium agrariumL.) control was also higher when glyphosate was initially applied in January or February than when applied in March regardless of time interval between first and second treatment. Combination treatments of (a) 2,4-D [(2,4-dichlorophenoxy)acetic acid] + dicamba (3,6-dichloro-o-anisic acid) and (b) 2,4-D + mecoprop {2-[(4-chloro-o-tolyl)oxy] propionic acid} + dicamba applied at 2-week intervals with the initial treatment made in January or February controlled more corn speedwell (Veronica arvensisL.) and hop clover than when applied in March. Highest henbit (Lamium amplexicauleL.) control was obtained from the combination 2,4-D treatments made at 4-week intervals when initial treatment was made in February and March. Weed control was not influenced by dates and interval of repeated treatments with either paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] treatments. Germination and regrowth of weeds were greater in plots treated with glyphosate and paraquat initially in January or February than other herbicide-treated plots. Weeds were not reestablished in any of the atrazine-treated plots. Paraquat and combinations of 2,4-D + dicamba or 2,4-D + mecoprop + dicamba injured bermudagrass when applied initially in January and February even though they were applied to turf that appeared dormant. All herbicides injured bermudagrass more when applied to semi-dormant turf in March than to dormant turf in January or February. Atrazine affected bermudagrass less than any of the other herbicides tested when initial treatment was applied in March to semi-dormant turf.
Wild Oat (Avena fatua) Control with Fall- and Spring-Applied Triallate
Authors: Miller S. D. , Nalewaja J. D.
Published: May 2019

Two formulations of triallate [S-(2, 3, 3-trichloroallyl)diisopropylthiocarbamate] were evaluated for their effectiveness in controlling wild oat (Avena fatuaL.) in spring wheat (Triticum aestivumL.) in 12 field experiments conducted between 1967 and 1978. Control of wild oat was greater with fall applications of triallate granules than liquid or with spring applications of either liquid or granules. Further-more, 1.1 kg/ha of triallate granules applied in the fall controlled wild oat as well as did 1.7 kg/ha of liquid triallate applied in the fall. Wild oat control with triallate was usually better when soil incorporated than when surface applied regardless of formulation or time of application. Triallate granules controlled wild oat similarly on either plowed ground or wheat stubble; whereas, liquid triallate controlled wild oat better on plowed ground than wheat stubble. A delay of 8 h in triallate incorporation did not reduce wild oat control with either formulation; however, a delay of 24 h reduced wild oat control with the liquid formulation.
Movements of Herbicides through Isolated American Pondweed (Potamogeton nodosus) Epidermal Tissues
Authors: Pringle John C. , Anderson Lars W. J.
Published: May 2019

Enzymatically isolated American pondweed (Potamogeton nodosusPoir.) epidermal tissues were exposed to14C-labeled dichlobenil (2,6-dichlorobenzonitrile), diquat (6,7-dihydrodipyrido[1,2-α: 2′, 1′-c] pyrazinediium ion), silvex [2-(2,4,5-trichlorophenoxy) propionic acid] or 2,4-D [(2,4-dichlorophenoxy)acetic acid] at concentrations of 5 × 10−4, 5 × 10−5, and 5 × 10−610M, and the amount of herbicide crossing the tissue layer was measured. Rates of herbicide movement were compared to those found when copper sulfate pentahydrate was added as a potential synergist at concentrations of 5 × 10−5M (12.5 ppm), 5 × 10−6M (1.25 ppm), and 5 × 10−7M (0.125 ppm). Copper sulfate at 5 × 10−6M increased the rate of movement of all herbicides. However, diquat and dichlobenil exhibited the most enhanced movement in the presence of copper sulfate. Without copper sulfate, 0.1 nmoles of 5 × 10−6M14C diquat penetrated the tissue within 24 h, compared to 1.3 nmoles following the addition of 5 × 10−7M of copper sulfate.
Weed Science Research at the International Institute of Tropical Agriculture and Research Needs in Africa
Authors: Akobundu I. Okezie
Published: May 2019

The International Institute of Tropical Agriculture (IITA) is one of the agricultural institutes financed through the Consultative Group on International Agricultural Research (CGIAR) sponsored by FAO, UNDP (United Nations Development Program), and the World Bank. One of IITA's mandates is to conduct research on farming systems in the humid and subhumid tropical zones to identify viable alternatives to shifting cultivation capable of maintaining productivity of food crops under continuous cultivation (14). The research efforts of the institute are organized into four programs. The three commodity-oriented research programs—the Cereals Improvement, the Grain Legume Improvement, and the Root and Tuber Improvement programs – provide improved planting materials that the scientists in the fourth program – the Farming Systems Program – use to develop land use systems capable of sustaining soil productivity as land and economic pressures accelerate the transition from shifting to continuous cultivation (13).