bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Trifluralin Metabolites on Goosegrass (Eleusine indica) Root Meristems
Authors: Vaughn Kevin C. , Koskinen William C.
Published: May 2019

The effects of treatment with twelve metabolites of trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine] on the gross morphology and ultrastructure of trifluralin-susceptible (S) and -resistant (R) biotypes of goosegrass [Eleusine indica(L.) Gaertner. # ELEIN] root meristems were examined. Unlike trifluralin, ten of the twelve metabolites including the major metabolites of trifluralin caused no root tip swelling even at water-saturated concentrations. Two of the minor metabolites, 3-methoxy-2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine (TR-36M) andN-(2,6-dinitro-4-(trifluoromethyl)phenyl)-N-propylpropanamide (TR-40), caused root swelling when applied as a saturated solution. The most effective metabolite, TR-36M, caused root swelling at 10μM or greater concentrations. Because trifluralin caused swelling of the root tips even at a 0.01 μM concentration, trifluralin is 1000-fold more effective than the most herbicidally active metabolite. Both herbicidally active metabolites are also much less effective than trifluralin at increasing the mitotic index. Structural studies indicate that the two herbicidally active metabolites arrest mitosis at prometaphase due to the loss of spindle microtubules, similar to trifluralin. Cortical microtubules are also affected by the highest concentrations of these two metabolites. A resistant biotype, in which mitosis is unaffected by trifluralin, was unaffected by any of the trifluralin metabolites.
Factors Influencing Corn (Zea mays) Tolerance to Trifluralin
Authors: Roggenbuck Frank C. , Penner Donald
Published: May 2019

Corn (Zea maysL.) can be injured by carry-over of trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine] in the soil from one crop year to the next. Factors influencing corn tolerance to carry-over concentrations of trifluralin in the soil were studied in controlled-environment chambers and greenhouse experiments. For several hybrids, greater injury occurred at low than at high temperatures. This injury was especially evident for ‘Pioneer 3320’ and ‘Pioneer 3572’ when the soil moisture was at 100% field capacity. Addition of phosphorus fertilizer appeared to have no influence upon trifluralin injury but did interact with alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide]. Alachlor plus trifluralin injured corn in an apparently additive manner. Significant differences were found in genetic tolerance of corn to trifluralin within a group of hybrids. Tolerance of specific hybrids to trifluralin was altered by environmental conditions.
Identification and Utilization of Variation in Herbicide Tolerance in Soybean (Glycine max) Breeding
Authors: Hartwig Edgar E.
Published: May 2019

Herbicides marketed for selected crops were chosen on the basis that major cultivars of the specific crop were tolerant. Our work with soybeans [Glycine max(L.) Merr.] has demonstrated that variability exists with regard to sensitivity or tolerance to several herbicides. As a part of our breeding program to develop improved soybean cultivars, we have evaluated advanced breeding lines and germplasm for reaction to herbicides on the market as well as experimental herbicides. A breeding line was identified and released for production which showed very little injury from two over-the-top applications of a double rate of 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid]. Other strains showed severe injury and depressed seed yield. Variation in reaction to glyphosate [N-(phosphonomethyl)glycine] has been observed. Lines tolerant to 0.56 kg ai/ha in one growing season were severely damaged the following season. When 200 germplasm lines from eastern Asia were treated with glyphosate, 6% showed less than 15% injury while 21% showed over 80% injury. The cultivar ‘Tracy′, selected for tolerance to 2,4-DB and a high level of resistance to the soil-borne disease causing phytophthora rot, was found to be sensitive to metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one]. Tracy has two major genes controlling resistance to phytophthora rot caused byPhytophthora megaspermaDrechs. f. sp.glycineaKuan and Erwin. One of these genes is closely linked with a gene controlling reaction to metribuzin. A crossover type was identified. The cultivar ‘Tracy-M’ retains the high level of resistance to phytophthora rot and is tolerant to metribuzin. A small percentage of germplasm lines evaluated were found to be sensitive to bentazon. Reaction to bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] is simply inherited.
Effect of Haloxyfop and Haloxyfop-Methyl on Elongation and Respiration of Corn (Zea mays) and Soybean (Glycine max) Roots
Authors: Gronwald John W.
Published: May 2019

The effects of haloxyfop {2-[4-[[3-chloro-5(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} and haloxyfop-methyl on elongation and respiration of primary roots of corn [Zea maysL. ‘B37 X Oh43’] and soybean [Glycine max(L.) Merr. ‘Hodgson 78’] were examined. Intact roots of etiolated seedlings were exposed to both forms of the herbicide. At a concentration of 10-6M, neither form of the herbicide had an effect on elongation or respiration of soybean roots. In contrast, elongation of corn roots was completely inhibited within 24 h of exposure to 10-6M haloxyfop. This treatment reduced the respiration rate of corn root apices by 30% but had little effect on ATP content. After 72 h of exposure to haloxyfop [10-6M], both ATP content and respiration rate of corn root apices had declined 35%. Haloxyfop-methyl produced equivalent effects on elongation and respiration of corn roots. Studies with isolated corn root mitochondria indicated that haloxyfop inhibits electron transport at relatively high concentrations (I50= approximately 2 mM for various substrates). Because significant reductions in ATP content and respiration rate of corn root apices were not detected during the period when elongation was inhibited (initial 24 h of exposure), it is concluded that impairment of respiration is a secondary response to the herbicide.
Two Species of Musk Thistle (Carduusspp.) as Hosts ofRhinocyllus conicus
Authors: Rees Norman E.
Published: May 2019

Plant growth, stem numbers per plant, receptacle diameters, number ofRhinocyllus conicusFroelich (Coleoptera:Curculionidae) larval cells per seed head, and mortality of the weevil within cells were monitored in infestations of the thistlesCarduus thoermeriWeinmann andC. macrocephalusDeft. Both species of thistle provided similar seed head area for weevil development, and no differential effects on the biology ofR. conicuswere detected.
Weed Seed Demise in Soil in Weed-Free Corn (Zea mays) Production Across Nebraska
Authors: Burnside Orvin C. , Moomaw Russell S. , Roeth Fred W. , Wicks Gail A. , Wilson Robert G.
Published: May 2019

An experiment was conducted at five locations in Nebraska to determine the extent of demise of weed seed in soil when seed production was eliminated from 1975 through 1979 in corn (Zea maysL.). Weed yields, weed seed production, and corn yields were determined under four weed management levels in 1980. Annual broadleaf weed seed were more prevalent than grass seed in cultivated soil throughout the study. The population of viable weed seed in soil declined 95% during the 5-yr period that weed seed production was eliminated. Weed seed buildup recovered to within 90% of the 1975 level during 1980 at Concord and Clay Center but remained low at Lincoln, North Platte, and Scottsbluff. Thus, seed longevity in soil was sometimes sufficient to withstand modern weed control methods and still reinfest a field after 5 yr of eliminating weed seed production. Corn yields were maintained 1 yr with minimum weed management effort following 5 yr of no weed seed production.
Germination of Seeds of Perennial Pepperweed (Lepidium latifolium)
Authors: Miller Gerald K. , Young James A. , Evans Raymond A.
Published: May 2019

Perennial pepperweed (Lepidium latifoliumL. # LEPLA) is a serious weed of meadows and riparian habitats in the intermountain area of the western United States. Germination of seeds of this species was tested at 55 constant- and alternating-temperature regimes. No significant differences were found in mean germination at a range of temperatures varying from 0 to 40 C for seedlots collected at the same site in different years or at different locations in the same year. Optimum germination not significantly (P = 0.01) lower than the maximum observed occurred most frequently at 5/40 C (5 C for 16 h and 40 C for 8 h), and 10/40 and 15/40 C. Germination was enhanced by alternating regimes with low night temperatures (0, 2, or 5 C) and high day temperatures (35 and 40 C), in comparison with more moderate constant-temperature regimes.
Control of Big Sagebrush (Artemisia tridentata) with Pelleted Tebuthiuron
Authors: McDaniel Kirk C. , Balliette John F.
Published: May 2019

Ground applications of pelleted tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} at 0.6 kg ai/ha (20% formulation) reduced big sagebrush (Artemisia tridentataNutt. # ARTTR) density by an average of 84 and 92% after 28 months, whereas 1.1 kg/ha killed 94 and 97% of the plants when applied in January or May, respectively. Total standing crop of grasses was unaffected 4 months after tebuthiuron applications. Significant increases in grass production occurred during the second and third growing seasons following tebuthiuron treatment. Desirable forage grasses such as galleta [Hilaria jamesii(Torr.) Benth.], blue grama [Bouteloua gracilis(Wild. ex H.B.K.) Lag. ex Griffiths], and crested wheatgrass [Agropyron cristatum(L.) Gaertn.] generally increased in tebuthiuron-treated plots, whereas sand dropseed [Sporobolus cryptandrus(Torr.) Gray # SPECR] and ring muhly [Mulenbergia torreyii(Kunth.) Hitchc. & Chase] production remained unchanged in comparison with untreated areas.
Duration of Tartary Buckwheat (Fagopyrum tataricum) Interference in Several Crops
Authors: De St. Remy E. Ann , O'Sullivan P. Ashley
Published: May 2019

Field studies were conducted over a 7-yr period at Lacombe, Alberta, to study the relationship between the duration of Tartary buckwheat interference [Fagopyrum tatarium(L.) Gaertn. # FAGTA] and yield of barley (Hordeum vulgareL.), oats (Avena sativaL.), wheat (Triticum aestivumL.), flax (Linum usitatissimumL.), and rapeseed (Brassica campestrisL.). The data were pooled over years and analyzed by multiple regression. The equations were as follows: ŷ = 15.46 + 0.39X1+ 0.00x2−0.11x3(barley), ŷ = −15.44 + 0.49x1+ 0.02x2+ 0.08x3(oats), ŷ = −2.04 + 0.39X1+ 0.05x2-0.03x3(wheat), ŷ = −4.38 + 1.14x1−0.04x2+ 0.01x3(flax), and ŷ = −13.85 + 0.40x1– 0.01x2+ 0.04x3(rapeseed); where ŷ was the estimated percent yield loss of the crop, x1was the duration (days) of the Tartary buckwheat in the crop, x2was the number of Tartary buckwheat plants/m2, and x3was the number of crop plants/m2. The time that Tartary buckwheat remains in the crop contributed most to the yield loss observed in all crops. Yield loss between 0.4 and 1.1% per day was attributed to this variable alone. For a given x1, x2, and x3value the order of percent yield loss was flax>oats>wheat> barley>rapeseed.
Yield Response of Weed-Free Soybeans (Glycine max) to Injury from Postemergence Broadleaf Herbicides
Authors: Kapusta George , Jackson Lucinda A. , Mason Delores Schutte
Published: May 2019

Experiments were conducted over 4 yr to investigate the effects of four postemergence herbicides on soybean [Glycine max(L.) Merr. ‘Williams 79’] yield under weed-free conditions. Bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide], acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid}, and naptalam/dinoseb {2-[(1-naphthalenylamino)carbonyl] benzoic acid}/[2-(1-methylpropyl)-4,6-dinitrophenol] alone and in combination with 2,4-DB [4-(2,4-dichlorophenoxy) butyric acid] applied to soybeans at the V3 and V5 soybean growth stages caused early crop injury, but soybeans outgrew most of the injury by 21 days and there was no effect on yield. Bentazon plus 2,4-DB with or without adjuvant did not affect the yield of five soybean cultivars tested.
Effect of Acifluorfen and Bentazon on Absorption and Translocation of Haloxyfop and DPX-Y6202 in Quackgrass (Agropyron repens)
Authors: Wilhm Jerry L. , Meggitt William F. , Penner Donald
Published: May 2019

Translocation of14C-haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} in quackgrass [Agropyron repens(L.) Beauv. # AGRRE] from the treated area (the middle 2.5 cm of the second of three leaves) to the lower leaves was reduced in plants in which 0.56 kg/ha of acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} or bentazon [3-1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide] was added in tank mixture to a 0.07 kg ai/ha application of haloxyfop. Reduced translocation did not occur when haloxyfop rates were increased to 0.28 and 1.1 kg/ha. Bentazon reduced absorption of14C-DPX-Y6202 {2-[4-[(6-chloro-2-quinoxalinyl)oxy] phenoxy] propionic acid} when applied in tank mixtures with 0.28 and 1.1 kg ai/ha DPX-Y6202. There was less14C-DPX-Y6202 in the leaf tips of plants treated with 0.07 kg/ha DPX-Y6202 plus 0.56 kg/ha acifluorfen in tank mixture. Relatively small amounts of both14C-haloxyfop and DPX-Y6202 accumulated in the rhizome and adjacent shoots and acifluorfen did not influence translocation to these plant parts. Considerably more14C-haloxyfop than14C-DPX-Y6202 was absorbed by quackgrass. Treatment of quackgrass with acifluorfen or bentazon 24 h prior to application of14C-haloxyfop or14C-DPX-Y6202 did not influence absorption or translocation.
Inhibition of Legume Seedling Growth by Residues and Extracts of Quackgrass (Agropyron repens)
Authors: Weston Leslie A. , Putnam Alan R.
Published: May 2019

Aqueous extracts of quackgrass [Agropyron repens(L.) Beauv. # AGRRE] shoots and rhizomes inhibited seed germination and root growth of alfalfa (Medicago sativaL. ‘Vernal’), soybean (Glycine max(L.) Merr. ‘Corsoy 79’], navybean (Phaseolus vulgarisL. ‘Seafarer’), and curly cress (Lepidium sativumL.) at concentrations of less than 2.5 mg dried extract/ml. Extracts of quackgrass shoots were generally more inhibitory than extracts of rhizomes. Root and shoot dry weights of snapbeans (Phaseolus vulgarisL. ‘Bush Blue Lake’) grown under sterile conditions were reduced by aqueous extracts of shoots. Root systems were stunted and necrotic and lacked root hairs. The growth ofRhizobiumspecies was not influenced by the presence of 40 or 80 mg/ml concentrations of extracts of shoots or rhizomes. Quackgrass may inhibit indirectly the legume-Rhizobiumsymbiosis by inhibiting root hair formation rather than directly inhibitingRhizobiumgrowth. The presence of soil microorganisms was not necessary for the development of quackgrass toxicity in soil or agar. Soil microorganisms reduced toxicity of quackgrass residues in soil.
Field Trials of Sclerotinia sclerotiorum to Control Canada Thistle (Cirsium arvense)
Authors: Brosten Brenda S. , Sands David C.
Published: May 2019

An isolate of Sclerotinia sclerotiorum (Lib.) de Bary collected from a Canada thistle [Cirsium arvense (L.) Scop. # CIRAR] plant in Montana proved pathogenic on Canada thistle in field trials. In addition to attacking the thistle crown and causing wilting and death of the shoots, S. sclerotiorum also infected the root system. The high percentage of thistle shoot kill (20 to 80%) after treatment, and subsequent reduction in plant thistle density the following year, demonstrated the potential of S. sclerotiorum as a biological control agent for Canada thistle in Montana.
Mode of Reproduction and Inheritance of Leaf Shape inIpomoea hederacea
Authors: Elmore C. Dennis
Published: May 2019

Two distinctive leaf forms have been described in the morningglory speciesIpomoea hederacea(L.) Jacq. These are identified as ivyleaf morningglory [I. hederacea(L.) Jacq. # IPOHE] and entireleaf morningglory [I. hederacea(L.) Jacq. var.integriusculaGray # IPOHG]. Controlled matings were made between pure breeding forms of plants with these two leaf types. The first generation progeny (F1) were all ivyleaf and the second generation (F2) was segregated in a 3:1 ratio (ivyleaf to entireleaf). The data fit a single gene model for determination of leaf shape, with ivyleaf being the dominant allele. Despite the dominance of the ivyleaf trait, the abundance of the entireleaf phenotype in the Mississippi Delta was higher than that of ivyleaf.Ipomoea hederaceais a facultative self-pollinator and other annual morningglory species found in the same area are also self-pollinated.
First Recovery of Oberea erythrocephala on the Leafy Spurge Complex in the United States
Authors: Rees Norman E. , Pemberton Robert W. , Rizza Antonio , Pecora Pasquale
Published: May 2019

The beetle Oberea erythrocephala, whose larvae mine stems and roots of leafy spurge (Euphorbia esula L. # EPHES), was introduced into Oregon, Montana, and Wyoming between 1980 and 1984. Although it was not recovered in Oregon and Wyoming, it became established at two of three release sites in Montana and appears to be accepting leafy spurge plants at a fourth.
Persistence of Phytotoxicity of Metribuzin and Its Ethylthio Analog
Authors: Shaw David R. , Peeper Thomas F. , Westerman Robert L.
Published: May 2019

The persistence of biologically active metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] and its ethylthio analog [4-amino-6-(1,1-dimethylethyl)-3-(ethylthio)-1,2,4-triazin-5(4H)-one] were compared using an intact-plant chlorophyll fluorescence bioassay technique with oats (Avena sativaL.) and wheat (Triticum aestivumL.). Degradation of metribuzin phytotoxicity at concentrations of 0 to 1 ppm (w/w) ai in a Pond Creek silt loam soil was linear over time, with a half-life of 8 days at 35 C. Initial degradation of the biologically active ethylthio analog was much more rapid than for metribuzin, with a decrease in rate at later time intervals. A quadratic function best described this degradation pattern. The initial degradation rate of phytotoxicity for the ethylthio analog indicated a half-life of 4 days at 35 C. Soil pH had no significant influence on the activity or persistence of either herbicide within the range 4.9 to 6.9.
An Economic Analysis of Incorporation Methods for Preplant Herbicides on Clay Loam Soil
Authors: Chenault Ellis W. , Wiese Allen F. , Harman Wyatte L.
Published: May 2019

In order to find the most effective and economical method of incorporation, six preplant herbicides for cotton (Gossypium hirsutumL.) were incorporated with a tandem disk or field cultivator, or sprayed on unbedded soil prior to bedding with a disk bedder. These treatments were compared to incorporating sprayed beds with a rolling cultivator and no incorporation. A mixed population of pigweed (Amaranthus hybridusL. # AMACH andAmaranthus retroflexusL. # AMARE) was present each year. There was no significant difference in pigweed control among incorporation with a disk, field cultivator, or rolling cultivator. Puncturevine (Tribulus terrestris# TRBTE) and barnyardgrass [Echinochloa crus-galli(L.) Beauv. # ECHCG] were controlled best following rolling cultivator incorporation. Cotton lint yields were not affected by incorporation methods or herbicides. Economic analysis and weed control indicate that the field cultivator was the best way of incorporation.
Control of Triazine-Resistant Common Lambsquarters (Chenopodium album) and Two Pigweed Species (Amaranthusspp.) in Corn (Zea mays)
Authors: Fuerst E. Patrick , Barrett Michael , Penner Donald
Published: May 2019

Various chemical treatments were evaluated over two growing seasons for control of triazine-resistant common lambsquarters (Chenopodium albumL. # CHEAL) and for control of a triazine-resistant infestation containing both redroot pigweed (Amaranthus retroflexusL. # AMARE) and Powell amaranth (A. powelliiS. Wats. # AMAPO). Atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl] amino]-2-methylpropanenitrile}, and metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] provided unsatisfactory control of these biotypes. Satisfactory control of common lambsquarters was obtained with preemergence applications of pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] or dicamba (3,6-dichloro-2-methoxybenzoic acid), or postemergence applications of dicamba, bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), or bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide]. Satisfactory control of pigweed was obtained with preemergence applications of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] or postemergence treatments of dicamba, bromoxynil, or 2,4-D [(2,4-dichlorophenoxy) acetic acid].
Competition Between Winter Wheat (Triticum aestivum) Cultivars and Downy Brome (Bromus tectorum)
Authors: Challaiah  , Burnside Orvin C. , Wicks Gail A. , Johnson Virgil A.
Published: May 2019

Field experiments were conducted to select winter wheat (Triticum aestivumL.) cultivar(s) that were competitive to downy brome (Bromus tectorumL. # BROTE). Downy brome significantly reduced winter wheat grain yields of all cultivars by 9 to 21% at Lincoln, while at North Platte yield reduction ranged from 20 to 41% depending upon cultivar. ‘Turkey’ was the most competitive cultivar to downy brome but it had the lowest grain yield. Compared to ‘Centurk 78’, ‘Centura’ at Lincoln and ‘SD 75284’ at North Platte proved to be significantly higher yielding and more competitive to downy brome. Winter wheat tiller number, canopy diameter, and plant height were negatively correlated with downy brome yield, but changes in these growth parameters did not always translate into grain yield advantage in downy brome-infested plots. Based on stepwise regression analysis, wheat height was better correlated with reduction in downy brome yield than were canopy diameter or number of tillers.
Weed Response, Yield, and Economics of Hexazinone and Nitrogen use in Lowbush Blueberry Production
Authors: Yarborough David E. , Hanchar John J. , Skinner Steven P. , Ismail Amr A.
Published: May 2019

Field experiments designed to determine the efficacy and interaction of hexazinone [(3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] and nitrogen on weeds and lowbush blueberry [Vaccinium angustifolium(Ait.)] growth and yield were established at five locations in 1980 and 13 locations in 1981. Hexazinone was applied after pruning, preemergence with nitrogen, using a split-block design, with locations serving as replications. Grasses, goldenrod (Solidagospp.), and meadowsweet [Spiraea latifolia(Ait.) Borkh. # SPVLF] were reduced significantly as the rate of hexazinone was increased. Blueberry injury, plant stand, number of flower buds, and yield all increased with increases in hexazinone rate. Variations in blueberry yields occurred among locations due to differences in plant stand and productivity, as well as climatic and edaphic factors. Within each nitrogen rate, increases in the rate of hexazinone resulted in a quadratic increase in blueberry yield. Within the hexazinone treatments, increasing nitrogen had no effect on yield. Blueberry yield reached a maximum of 3926 kg/ha at a hexazinone rate of 1.83 kg/ha. Partial budgeting was used to evaluate the effect of combinations of hexazinone and nitrogen on net income. Response function analysis determined yield and profit-maximizing combinations of hexazinone and nitrogen. Partial budgeting indicated that hexazinone alone or combined with nitrogen increased net income, but nitrogen without hexazinone decreased net income. Response function analysis indicated that hexazinone at 1.79 kg/ha without nitrogen maximized profits.
Analytical Techniques to Measure Sethoxydim and Breakdown Products
Authors: Shoaf Antony R. , Carlson William C.
Published: May 2019

A method was developed for the quantitative determination of trace levels of the widely used herbicide sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} and its metabolites in an aqueous solution using reversed-phase high-performance liquid chromatography (HPLC). Optimum extraction of sethoxydim was with dichloromethane and was only 15% efficient at pH 3. The limit of detection by HPLC for sethoxydim was 5 ng on column and <5 ppb in soil. At least five different compounds were detected in the commercial formulation, in EPA reference standards, and in commercial sethoxydim standards. Sethoxydim undergoes a rapid decomposition in the presence of water to form more polar products, which accounts for the low extraction efficiency. Decomposition was greatest under alkaline conditions. Acid pH and soil inhibited decomposition and gave greater recoveries of parent compound. At least one breakdown product cochromatographed with a known sulfone derivative. The procedures are directly applicable to soils, environmental waters, and plant and animal tissues.
Absorption and Translocation of MON 0818 Adjuvant in Field Bindweed (Convolvulus arvensis)
Authors: Sherrick Stewart L. , Holt Harvey A. , Hess F. Dan
Published: May 2019

To develop an understanding of how adjuvants might enhance glyphosate [N-(phosphonomethyl)glycine] activity, absorption and translocation of a polyethoxylated tallow amine amphoteric surfactant (MON 0818) were examined in field bindweed (Convolvulus arvensisL. # CONAR). Scanning electron microscopy did not reveal any physical disruption of the epicuticular waxes from spray applications of MON 0818, an oxysorbic (20 POE) (polyoxyethylene sorbitan monolaurate) surfactant, or glyphosate. Radioactive MON 0818 absorption was rapid during the first 6 h. Maximum absorption (84%) occurred by 24 h after application. Less than 3% of the applied radioactivity was recovered from the epicuticular wax of treated leaves. Movement of radioactivity away from the treated area was limited predominantly to movement within the treated leaf. Altering light intensity or humidity in which the plants developed before treatment did not influence MON 0818 absorption.
The Effect of Copper on the Green AlgaPithophora oedogonia
Authors: Pearlmutter Nina L. , Lembi Carole A.
Published: May 2019

Akinetes (spores) of the green, filamentous algaPithophora oedogonia(Montagne) Wittrock were more copper resistant than filamentous cells, tolerating copper concentrations as high as 4μg·ml-1(16μg·ml-1copper sulfate pentahydrate). The localization of copper in viable and nonviable cells was conducted using cell fractionation and cytochemical/ultrastructural methods. In copper-exposed viable akinetes, copper was bound primarily to the outer layers of the cell wall. In nonviable cells, copper was found randomly distributed throughout the cytoplasmic and vacuolar regions. No evidence for compartmentation of copper as vacuolar or intranuclear deposits was demonstrated. Copper uptake into the cell wall was associated with release of equimolar amounts of calcium, magnesium, and zinc. When viable copper-treated akinetes were allowed to recover in copper-free medium, the copper was gradually released from the cell wall, presumably to the culture medium. A portion of the copper also appeared to be redistributed to new cell wall material during the akinete germination process. The differential tolerance ofP. oedogoniaakinetes to copper in comparison to filamentous cells appears to be due to a combination of factors that include cell surface/volume ratios, metabolic activity, and cell wall copper-binding components.
Alteration of Atrazine Uptake and Metabolism by Tridiphane in Giant Foxtail (Setaria faberi) and Corn (Zea mays)
Authors: Boydston Rick A. , Slife Fred W.
Published: May 2019

Partially purified glutathione-s-transferase (GST) isolated from corn (Zea maysL.) seedlings was about 14-fold higher in specific activity than GST isolated from giant foxtail (Setaria faberiHerrm. # SETFA) seedlings. Greater amounts of GST activity were present in leaf tissue than in stem tissue. Four-leaf giant foxtail seedlings contained about threefold more reduced glutathione per gram fresh weight in the leaves than one- to two-leaf giant foxtail seedlings. When atrazine and reduced glutathione were used as substrates, tridiphane [2-(3,5-dichlorophenyl)-2-(2,2,2-trichloroethyl)oxirane] inhibited isolated GST from corn with an I50of about 5μM and from giant foxtail with an I50slightly lower. Tridiphane inhibited the metabolism of atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine] to water-soluble metabolites in giant foxtail leaves but not in corn leaves. Unmetabolized atrazine levels tended to be greater in giant foxtail seedlings treated with tridiphane plus atrazine than in plants treated with atrazine alone. Tridiphane applied 12 h before atrazine increased the uptake of atrazine in both corn and five-leaf giant foxtail seedlings. The amount of atrazine metabolism to water-soluble metabolites increased in corn leaves but remained constant in giant foxtail leaves when atrazine uptake was increased. Tridiphane and atrazine combinations impaired net photosynthetic rates more than atrazine alone in giant foxtail seedlings but did not increase chlorophyll fluorescence. There was no decrease in net photosynthetic rate 12 h following applications of atrazine or tridiphane plus atrazine on corn leaves. Tridiphane did not decrease photosynthesis or increase chlorophyll fluorescence in either species when applied alone.
Evalution of Exotic Rust Fungi in the United States for Classical Biological Control of Weeds
Authors: Bruckart William L. , Dowler William M.
Published: May 2019

Evaluation and introduction of exotic plant pathogens for biological control of weeds in the United States takes place at the Plant Disease Research Laboratory (PDRL) in Frederick, MD. Pathogens of target weed species collected overseas are sent to PDRL and evaluated in a containment greenhouse for aggressiveness and specificity toward the target weed. Currently, rust fungi (Uredinales) are evaluated at PDRL for control of leafy spurge (Euphorbia esual L. #4 EPHES), musk thistle [Carduus nutans L. ssp. leiophyllus (Petrovic) Stoj. & Stef. # CRUNU (= C. thoermeri Weinm.)], and yellow starthistle (Centaurea solstitialis L. # CENSO). Determination of host range is central to the evaluation of potential pathogens, but some difficulty has been experienced in obtaining propagative material of important plant species, especially if the plant is threatened or endangered. A proposal is made to organize a seed bank to meet this need.
Commercialization of Collego™–An Industrialist's View
Authors: Bowers R. C.
Published: May 2019

Collego™ is a selective postemergent mycoherbicide for the control of northern jointvetch [Aeschynomene virginica (L.) B.S.P. # 2 AESVI] in rice (Oryza sativa L.) and soybean [Glycine max (L.) Merr.]. Collego is a two-component product. Component A is a water-soluble spore rehydrating agent while Component B is a water-suspendible dried spore preparation of the fungus Colletotrichum gloesporioides (Penz) Sacc. f. sp. aeschynomene ATCC 20358. Both components are packaged in an 18.9-L plastic mixing container. A mixture containing 0.95 L of Component A and one package of Component B will treat 4 ha. The dried spore component is packaged by number of viable spores rather than by weight. Consequently, the weight of each package will vary from lot to lot, but each package contains a minimum of 75.7 × 1010 viable spores.
Patenting/Licensing of Microbiological Herbicides
Authors: Saliwanchik Roman
Published: May 2019

Legal protection of intellectual property is a requisite to the commercialization of the intellectual property and to the conferring of proper reward to the true owner of the property. Simplistically stated, this situation with regard to intellectual property is no different from the legal protection of a variety of properties, for example, home, land, or automobile. Laws have been established in the various countries of the world that are structured specifically to attain the desired goal of legally protecting property interests. In the intellectual property field, wherein we talk about property such as new inventions, we enter an area of not only protecting the legal rights of the property owner but also insuring the position of the public with respect to the eventual unlimited use of new inventions.
Distribution of Weed Seed Among Soil Structural Units
Authors: Pareja Mario R. , Staniforth David W. , Pareja Gilda P.
Published: May 2019

The depth distribution of weed seed, their location in relation to soil aggregates, and the size distribution of soil aggregates were determined in fields that had been under continual conventional or reduced tillage for more than 12 years. Soil samples were taken at three depths in the spring and fall of 1982, and soil aggregates were classified into seven size classes by dry, rotary sieving. Subsamples were deflocculated and washed through sieves to recover weed seed. In the spring, 85% of all seed in the reduced-tillage and 28% of those in the conventional-tillage soil were in the 0- to 5-cm-depth layer. Conventional tillage incorporated weed seed uniformly into various soil aggregate classes, whereas with reduced tillage more seed accumulated in the unaggregated fraction of the soil. In the fall, weed seed distribution in relation to soil depth and among soil aggregate classes was similar for both tillage regimes.
Factors Influencing Biocontrol of Velvetleaf (Abutilon theophrasti) and Prickly Sida (Sida spinosa) withFusarium lateritium
Authors: Boyette C. Douglas , Walker H. Lynn
Published: May 2019

In greenhouse and controlled-environment tests, velvetleaf (Abutilon theophrastiMedic. ♯ ABUTH) and prickly sida (Sida spinosaL. ♯ SIDSP) control withFusarium lateritiumNees ex Fr. was affected by inoculum concentration and plant growth stage at the time of inoculation, by postinoculative air temperature, and by dew period duration and temperature. A higher level of control of both weeds was obtained with inoculum concentrations of 7.5 × 105and 1.5 × 106macroconidia/ml when the weeds had fewer than seven true leaves. Postinoculative air temperatures above 25 C significantly reduced control of both weeds. Mortality of both species was higher at dew temperatures of 25 C than at temperatures of either 15 or 35 C. At least 12 h of dew at 25 C was required to achieve satisfactory control of prickly sida, while a dew period of 16 h was required to achieve a comparable level of control of velvetleaf.
Progressive Kill of Rhizomatous Johnsongrass (Sorghum Halepense) from Repeated Treatment with Dalapon, MSMA, or Asulam
Authors: Millhollon Rex W.
Published: May 2019

Space-planted johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA] was clipped back to a height of 26 cm after flowering and, when 45 to 61 cm in height, was treated with various rates of the sodium salt of dalapon (2,2-dichloropropionic acid), MSMA (monosodium methanearsonate), or the sodium salt of asulam (methylsulfanilylcarbamate). Treatments were reapplied as needed during the growing season whenever a majority of surviving plants in a plot had initiated new foliar growth. Most plants were not killed by a single application of any herbicide, although rhizome development, as measured by the number of rhizome buds, was inhibited by the initial herbicide treatments. MSMA at 4.5 kg ai/ha was more phytotoxic to johnsongrass than other herbicide treatments or MSMA at 2.3 kg ai/ha; a single application at the higher rate reduced the original number of rhizome buds on plants by 50 to 60%, and two applications killed 86 to 93% of the plants. Asulam at 4.5 and 6.7 kg ae/ha and dalapon at 6.7 and 9.0 kg ae/ha primarily controlled plants by inhibiting growth for an extended period. After two or three applications of asulam or dalapon at 6.7 kg ae/ha, only about 40% of the plants had been killed, but the original number of rhizome buds on surviving plants had been reduced by about 80%.
Modeling Diclofop Activity on ThreeBromusSpecies
Authors: Stahlman Phillip W.
Published: May 2019

The methyl ester of diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} mixed with soil at 1, 2, and 3 ppmw reduced the growth ofBromusspecies in the greenhouse as follows: downy brome (Bromus tectorumL. ♯ BROTE) more than Japanese brome (Bromus japonicusThunb. ex Murr. ♯ BROJA) more than cheat (Bromus secalinusL. ♯ BROSE). The decrease in herbicide effect (decay) over time was described better using a second-order equation than a first-order equation. Plant response-herbicide dose relationships were described best with a cubic polynomial equation.
Interaction of Kochia (Kochia scoparia) andRhizopussp. on Sugarbeet (Beta vulgaris) Germination
Authors: Wiley Ronald B. , Schweizer Edward E. , Ruppel Earl G.
Published: May 2019

Emergence of sugarbeets (Beta vulgarisL. ‘MonoHy D2’) from soil was reduced by germinating kochia [Kochia scoparia(L.) Schrad. ♯ KCHSC] seed at densities greater than 1 seed/cm2when the fungusRhizopussp. was present. Water-soluble exudates from germinated kochia seed did not influenceRhizopusgrowth in vitro or sugarbeet germination. Cell-free culture extracts ofRhizopusreduced sugarbeet germination and radicle elongation. There appeared to be an interaction between kochia andRhizopus, but the responsible compounds were not identified.
Inhibition of Soil Nitrification by Dichlobenil
Authors: Cook William B. , Carr John E.
Published: May 2019

The herbicide dichlobenil (2,6-dichlorobenzonitrile) inhibited soil nitrification significantly at 100 ppm following 1 and 2 weeks incubation but did not inhibit nitrification at the rates recommended for weed control.
Effect of Soil pH, Fertility, and Herbicides on Weed Control and Quality of Bermudagrass (Cynodon dactylon) Turf
Authors: Johnson B. Jack , Burns Robert E.
Published: May 2019

Large crabgrass [Digitaria sanguinalis(L.) Scop. ♯ DIGSA] control was higher when either DCPA (dimethyl tetrachloroterephthalate) or napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] was applied to bermudagrass [Cynodon dactylon(L.) Pers. ‘Common’] growing in soil with a pH of 5 than in soil with a pH of 6.4 in 2 of 3 yr. Soil pH did not influence the response of large crabgrass to oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] or benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine). Herbicides alone did not produce high-quality turf unless fertilizer was applied annually at 300 kg N/ha or more. Bermudagrass quality was higher after three yearly applications of 300 kg N/ha or more of fertilizer when soil pH was 5 than when soil pH was 5.6 or 6.4.
Environment and Chlorsulfuron Phytotoxicity
Authors: Nalewaja John D. , Woznica Zenon
Published: May 2019

Glasshouse and growth chamber experiments were conducted to determine chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} phytotoxicity to kochia [Kochia scoparia(L.) Schrad. ♯ KCHSC] and green foxtail [Setaria viridis(L.) Beauv. ♯ SETVI] as influenced by temperature and humidity for 1 week after treatment, and by soil moisture and nitrogen. Chlorsulfuron was more phytotoxic to both kochia and green foxtail at 95 to 100% than at 45 to 50% relative humidity for 1 week after treatment whether at 10, 20, or 30 C. Chlorsulfuron phytotoxicity was similar with all posttreatment temperatures at each humidity, except that phytotoxicity was lower at 30 C than at 10 or 20 C at 90 to 100% humidity. Surfactant added to chlorsulfuron exhanced control of kochia more than that of green foxtail and overcame temperature and humidity effects on chlorsulfuron phytotoxicity. A simulated rainfall of 2 mm after chlorsulfuron application reduced toxicity of chlorsulfuron to green foxtail more than to kochia. Chlorsulfuron was more phytotoxic to green foxtail growing with a high than a low soil nitrogen level. High soil moisture following chlorsulfuron application enhanced phytotoxicity to kochia and green foxtail compared to high soil moisture before treatment.
Response of Yaupon (Ilex vomitoria) and Understory Vegetation to Herbicides
Authors: Meyer Robert E. , Bovey Rodney W.
Published: May 2019

Yaupon (Ilex vomitoriaAit. ♯ ILEVO) in the Post Oak Savannah of Texas was treated with liquid and dry formulations of herbicides. Sprays of Bay Met 1486 {N-[5-(ethylsulfonyl)-1,3,4-thiadiazol-2-yl]-N, N′-dimethylurea} and picloram (4-amino-3,5,6-trichloropicolinic acid), sprays and pellets of tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea}, and boluses of hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1N,3H)-dione] at 4.5 kg ae or ai/ha were the most effective treatments, reducing the canopy 87 to 99% and killing 68 to 93% of the yaupon after 2 yr. The percentage of dead yaupon after 1 yr was similar to that found 2 or 3 yr after treatment. Most herbicides, except clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), reduced the yaupon canopy sufficiently to allow an increase in understory grass and broadleaf vegetation, particularly 1 yr after treatment.
Method for Bioassaying Chlorsulfuron in Soil and Water
Authors: Morishita Don W. , Thill Donald C. , Flom Duane G. , Campbell Tanaquil C. , Lee Gary A.
Published: May 2019

Bioassay techniques were evaluated for the determination of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} residues in soil and water. A linear response of corn (Zea maysL.) primary root length to chlorsulfuron concentrations (InX+1) of 0.0 to 16.0 μg/L was observed in the water bioassay. Several soil extraction bioassay methods were attempted and found to be highly variable. A Ca(OH)2soil extraction bioassay technique produced a linear response of primary corn root length to chlorsulfuron concentrations ranging from 0.0 to 64.0 μg/kg. The efficiency of the Ca(OH)2extraction bioassay was determined by the use of14C-chlorsulfuron. Recovery efficiency at 1.0 μg/kg was 74% and averaged 62% at all higher chlorsulfuron concentrations.
Phytotoxicity of Products from Rhizospheres of a Sorghum-Sudangrass Hybrid (Sorghum bicolorXSorghum sudanense)
Authors: Forney D. Raymond , Foy Chester L.
Published: May 2019

Products were collected from rhizospheres of a hydroponically grown sorghum-sudangrass hybrid [Sorghum bicolor(L.) Moench. ×Sorghum sudanense(P.) Stapf. ‘DeKalb SX17+’] (SSH) and tested for effects on seedling root growth of selected species. Phytotoxic activity was recovered in CH2Cl2extracts of aqueous solutions of the rhizosphere products. Significant inhibition of annual ryegrass (Lolium multiflorumL.) and alfalfa (Medicago sativaL. was produced by ca. 200 ppmw (H2O weight basis) of the most phytotoxic fraction in filter-paper-disk bioassays. In soils, 70 ppmw (soil weight basis) inhibited alfalfa but not ryegrass. Among several bioassay species, alfalfa was the most sensitive and curly dock (Rumex crispusL. ♯ RUMCR) the least. Treatment of SSH plants with herbicides increased the phytotoxicity but not the amounts of materials collected. Sethoxydim {2-[1-(ethoxyimino)-butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} was detected in rhizosphere products from plants treated with the herbicide. Amounts of products collected from rhizospheres of common rye (Secale cerealeL. ‘Wheeler’), johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA], and cucumber (Cucumis sativusL. ‘PI 169391’) were similar to those from SSH, but their phytotoxicities differed. Johnsongrass products were most phytotoxic, those from common rye and SSH were similar in phytotoxicity, and those from cucumber were least phytotoxic.
Absorption, Translocation, and Metabolism of Metribuzin in Diploid and Tetraploid Soybean (Glycine max) Plants and Cell Cultures
Authors: Abusteit Ezzaldin O. , Corbin Frederick T. , Schmitt Donald P. , Burton Joe W. , Worsham A. Douglas , Thompson Lafayette
Published: May 2019

Field experiments established that tetraploid soybean [Glycine max(L.) Merr.] plants were relatively tolerant while diploid plants were highly susceptible to metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] applied both preemergence and postemergence. Sensitivity of diploids and tolerance of tetraploids was also found in growth chamber experiments. Autoradiographs prepared 4 days after14C-metribuzin application showed a high level of14C-translocation to all parts of diploid plants including meristems. In contrast, only low levels of14C were translocated in tetraploid plants, with no14C-movement into meristems. Tetraploid plants rapidly transformed absorbed metribuzin to nontoxic products. Diploids were incapable of inactivating absorbed metribuzin at a rate sufficient to prevent injury. Differences in absorption, translocation, and metabolism of metribuzin appeared to be the main factors in the diploid and tetraploid differential response in field and growth chamber experiments. Differences in the rate of metribuzin metabolism appeared to be the factor responsible for the differential response in diploid and tetraploid cell suspension cultures. The primary polar metabolites were conjugates of metribuzin and deaminated metribuzin [6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one] with a ratio of 8:1, respectively.
Reduction in Weed Control After Repeat Applications of Thiocarbamate and Other Herbicides
Authors: Gray Reed A. , Joo Grant K.
Published: May 2019

Of 17 thiocarbamate herbicides tested in the greenhouse in repeat soil applications made 4 to 16 weeks apart, 9 showed definite losses in herbicidal activity after the second application. Those showing reduced activity included EPTC (S-ethyl dipropylthiocarbamate), vernolate (S-propyl dipropylthiocarbamate), and butylate (S-ethyl diisobutylthiocarbamate), which have been reported previously to develop accelerated breakdown, plus R-15574 (S-benzyl dipropylthiocarbamate and the sulfoxides of EPTC, vernolate, butylate, SC-7829 (S-propyl diisobutylthiocarbamate), and SC-8149 (S-butyl diisobutylthiocarbamate). Thiocarbamates that showed no significant reduction in activity after the second application were pebulate (S-propyl butylethylthiocarbamate), cycloate (S-ethylN-ethylthiocyclohexanecarbamate), molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate), R-1880 (S-ethyl dibutylthiocarbamate), R-1856 (S-tertiarybutyl dipropylthiocarbamate), R-1853 (S-isobutyl diethylthiocarbamate), R-1906 (S-butyl diisopropylthiocarbamate), and R-12001 [S-isopropyl 1-(5-ethyl-2-methyl)piperidine carbothioate]. Of 16 nonthiocarbamate herbicides tested, a reduction in control of weeds occurred after the second soil application with 2,4-D [(2,4-dichlorophenoxy)acetic acid], dalapon (2,2-dichloropropionic acid), chlorpropham (isopropylm-chlorocarbanilate), propham (isopropyl carbanilate), TCA (trichloroacetic acid), pronamide [3,5-dichloro (N-1,1-dimethyl-2-propynyl)benzamide], napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], bensulide [O,O-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide], alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide], and diethatyl [N-(chloroacetyl)-N-(2,6-diethylphenyl)glycine]. Losses with the latter five herbicides after repeat application have not been reported previously.