bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Selected Pesticides on Survival ofColletotrichum gloeosporioidesf. sp.malvae, a Bioherbicide for Round-leaved Mallow (Malva pusilla)
Authors: Grant Nelson T. , Prusinkiewicz Elizabeth , Makowski Roberte M. D. , Holmstrom-Ruddick Britt , Mortensen Knud
Published: March 2018

Commercial formulations of 33 herbicides, 12 fungicides, and 16 adjuvants were evaluated for their toxic effects on germination ofColletotrichum gloeosporioidesf. sp.malvae(C.g.m.) spores. At the recommended rates, none of the herbicides for grass weed control (diclofop, difenzoquat, fenoxaprop-ethyl, flamprop-methyl, and sethoxydim) or formulated herbicides registered for both broadleaf and grass weed control [diclofop plus bromoxynil (23:8), propanil, and propanil plus MCPA (7:2)] were compatible with C.g.m. spores. C.g.m. spore germination and appressorial formation recorded 24 h after exposure were totally inhibited by these herbicides. At recommended rates, herbicides for broadleaf weed control (2,4-D ester, 2,4-D amine, benazolin, bentazon, clopyralid, cyanazine, cyanazine plus MCPA (1:2), dicamba, dicamba plus MCPA (1:4), dicamba plus mecoprop plus MCPA (1:1:4.4), dicamba plus 2,4-D plus mecoprop (4.2:11:3), MCPA amine, MCPA-K, MCPA-Na, and metribuzin), caused no more than a 20% reduction in C.g.m. spore germination, and appressorial formation was not significantly reduced except by benazolin and metribuzin. Cyanazine and dicamba at recommended rates increased appressorial formation without reducing germination compared to the control. At lower concentrations, the other herbicides recommended for broadleaf weed control (2,4-DB, bromoxynil, bromoxynil plus MCPA (1:1), dichlorprop plus 2,4-D (1:1), imazethapyr, linuron, and picloram) were less toxic to C.g.m. spores. The fungicide triadimefon at recommended rate had no effect on C.g.m. spores. Dicloran reduced germination more than 50% at recommended rate and growth was distorted. At recommended rates, spore germination was inhibited by more than 90% with benomyl, carbathiin, chlorothalonil, iprodione, mancozeb, and thiophanate-methyl although germination increased as concentration declined. Spore germination was totally inhibited at all concentrations with ferbam, thiram, and captan. Exposure to the adjuvants—Agral 90, Alkasurf-0P-10, Atplus-555, Citowett Plus, Enhance, Renex 36, Triton XR, and X-77–inhibited C.g.m. spore germination and reduced spore production compared to the control. Spore germination was significantly higher in suspensions containing ammonium sulfate, Assist, Bio-veg, CD-407, and Tween 20, as well as with starch, sucrose, and water (control) than with the other adjuvants. Spore production was higher in suspensions containing starch and Bio-veg than in those with water and the other adjuvants.
Performance of Imazethapyr on Pulse Crops
Authors: Malik Najib , Townley-Smith Lawrence
Published: March 2018

The potential of imazethapyr as a selective herbicide in four pulse crops was investigated at Melfort, Saskatchewan in 1988 and 1989. Lentil, field pea, faba bean and annual vetch were tolerant to imazethapyr applied preemergence to a silty clay loam soil at 0.05, 0.10, 0.15, and 0.20 kg ai ha-1. Postemergence treatments above 0.05 kg ha-1, however, stunted lentil and vetch in both years. Environmental factors, the dominant weed in the experimental site, as well as timing of application strongly influenced the performance of imazethapyr. Seed yield increases observed with imazethapyr treatments, compared to metribuzin or untreated check, were greater in 1989 when wild oat was the dominant weed and moisture was not a limiting factor in the early stages of crop development, than in 1988 when field pennycress was the dominant weed. Mean seed yield for all imazethapyr treatments, compared to the check, increased 0 and 930%, 24 and 89%, 21 and 600%, and 47 and 44% in 1988 and 1989, for lentil, field pea, faba bean and vetch, respectively. Significant increases in lentil seed density, seed size, and germination were also obtained though protein content decreased 2%.
Carryover Injury of Clomazone Applied in Soybeans (Glycine max) and Fallow
Authors: Ahrens William H. , Fuerst E. Patrick
Published: March 2018

Field experiments were conducted to determine wheat injury following clomazone application in soybeans and fallow in North Dakota. Clomazone at recommended rates generally caused 10% or less visible chlorosis in spring wheat planted 11 to 12 mo after application or winter wheat planted 11 mo after application, although greater chlorosis was observed in two of seven location/year environments. Tillage preceding wheat planting increased chlorosis from clomazone residues in some environments. Clomazone residues reduced wheat grain yield only in three of seven location/year environments and usually at application rates of 1.4 kg ai ha-1or greater. Severe drought prevailed during the study and probably increased clomazone persistence and wheat chlorosis. Drought also may have limited expression of grain yield reductions attributable to clomazone residues.
Alachlor Movement Through Intact Soil Columns Taken From Two Tillage Systems
Authors: Clay Sharon A. , Koskinen William C. , Carlson Paul
Published: March 2018

Intact soil columns were evaluated as a screening technique to determine the effect of tillage on herbicide movement through soil. Alachlor was applied at 3.3 kg ai ha-1to intact surface 0- to 10-cm and subsurface 10- to 20-cm soil columns (15-cm diam) taken from long-term no-till and conventional tillage plots and leached with 11.6 pore volumes (7 L; 39 cm) of water at a rate that did not create ponding. Leachate was collected in 0.07 pore volume fractions. Twice as much alachlor leached from surface no-till than from surface conventional tillage columns. The differences in leaching patterns from the surface soil can be attributed to the effect of tillage on soil physical and chemical properties. Using intact soil columns in the laboratory can be a useful rapid screening technique to evaluate tillage impacts on herbicide movement.
Bluejoint Reedgrass (Calamagrostis canadensis) Control with Glyphosate and Additives
Authors: Conn Jeffery S. , Deck Richard E.
Published: March 2018

Optimal rates and time of application of glyphosate for control of the native perennial bluejoint reedgrass [Calamagrostis canadensis(Michx.) Nutt.] were determined from 1986 to 1989 near Delta Junction, AK. Applications were made 2 wk apart from late May or early June to September. Glyphosate did not provide control before June 15 or after September 1. Bluejoint reedgrass was controlled best when glyphosate was applied from late July to mid-August. Ammonium sulfate (2.2 kg ha-1) or nonionic surfactant (0.5% v/v) increased control except on the earliest and latest application dates. Control was consistently better with 1.1 than 0.6 kg ha-1(ai) of the isopropylamine salt of glyphosate.
Pathogenicity of Colletotrichum coccodes Isolates to Potato (Solanum tuberosum) and Two Nightshade (Solanum spp.) Species
Authors: Eberlein Charlotte V. , Barkdoll Anne W. , Davis James R.
Published: March 2018

Pathogenicity of four Colletotrichum coccodes isolates to potato, eastern black nightshade, and hairy nightshade was evaluated in greenhouse studies. Three Idaho isolates, AC-14, AC-28, and AC-44, and an isolate obtained from Mycogen Corporation, AC-Myc, produced lesions on potato foliage. Plants inoculated with AC-14, AC-28, and AC-44 also showed wilt symptoms similar to those produced by Verticillium dahliae as potatoes were beginning to senesce. Infection by AC-44 reduced tuber fresh weight and specific gravity. All isolates colonized eastern black and hairy nightshade, although some isolates caused little or no symptom development. Thus, both species may serve as sources of primary inoculum for C. coccodes isolates that are pathogenic to potatoes. Only AC-Myc substantially injured the leaves of both nightshade species. AC-Myc was more pathogenic to eastern black than to hairy nightshade, and to plants inoculated at the 3- to 4-leaf versus the 7- to 8-leaf stage.
Germination and Root Growth of Two Noxious Weeds as Affected by Water and Salt Stresses
Authors: Kiemnec Gary , Larson Larry
Published: March 2018

Hoary cress germination decreased with lower osmotic potential. Knapweed germination was greatest at 0.0 and −0.5 MPa of osmotic potential. Salinity increases up to an electrical conductivity (EC) of 12 dS m-1had no effect on germination of either species. Hoary cress and knapweed root growth were reduced by decreases in osmotic potential. Hoary cress root growth was not affected by increasing salinity up to an EC of 12 dS m-1. Knapweed root growth was reduced by the initial increase in salinity (4 dS m-1), but not by higher salt concentrations.
Response of Sugarbeet (Beta vulgaris) to Herbicide Residues in Soil
Authors: Renner Karen A. , Powell Gary E.
Published: March 2018

Herbicides can persist in the soil and injure sensitive crops planted in the years following herbicide application. The response of sugarbeet to clomazone, imazaquin, imazethapyr, and chlorimuron residues in soil was examined. Clomazone at 1.1 or 2.2 kg ai ha-1did not reduce yield of sugarbeet planted 1 or 2 yr after application. Imazaquin at 0.07 to 0.28 kg ai ha-1, and imazethapyr at 0.09 to 0.14 kg ai ha-1, can reduce yield of sugarbeet planted 1 yr after application. Imazaquin at 0.07 to 0.14 kg ha-1caused 28 to 47% sugarbeet injury and imazethapyr at 0.09 kg ha-1caused 54% injury 2 yr after application in soybean. A 25% yield loss occurred from the imazethapyr treatment. Sugarbeet injury 2 yr after application was greatest when sugarbeet also was planted the year following soybean. Chlorimuron at 0.02 to 0.08 kg ai ha-1plus linuron at 0.4 to 0.9 kg ai ha-1reduced yield of sugarbeet planted 1 yr after application when compared with linuron alone, regardless of soil pH. Visible sugarbeet injury of 38 to 66% was still evident from chlorimuron plus linuron treatments 2 yr after application. Sugarbeet should not be planted less than 25 mo following imazaquin, imazethapyr, or chlorimuron application.
Aspects of the Design and Interpretation of Competition (Interference) Experiments
Authors: Cousens Roger
Published: March 2018

The design and analysis of competition experiments should be based on an unambiguous objective. Recent criticisms of particular designs have been made without reference to objectives and may be misleading. Three common designs are discussed: additive, replacement series, and response surface. Additive designs are well suited to agronomic objectives; replacement series are useful for comparing pairs of species; response surface designs can be used for most objectives but may be unnecessarily complex. The published criticisms of additive and replacement series designs are argued to be acceptable limitations within the bounds of the objectives for which they are used. Concerns about these designs confounding density and proportion are irrelevant to the objectives for which they are most suited. The continued use of multiple comparison tests is argued to be illogical. Regression approaches to analysis are more relevant, many non-linear equations are now easy to fit to data and these can be used without the need for linearization. However, there are various pitfalls not adequately reported to date. In particular, error structures need to be checked carefully and over-elaborate equations should be avoided.
Uptake, Translocation, and Metabolism of Chlorimuron in Soybean (Glycine max) and Morningglory (Ipomoeaspp.)
Authors: Moseley Carroll , Hatzios Kriton K. , Hagood Edward S.
Published: March 2018

The uptake, translocation, and metabolism of the ethyl ester of chlorimuron in three soybean cultivars and two morningglory species was investigated. Soybean used included the normal cultivars ‘Vance’ and ‘Essex,’ and the sulfonylurea-resistant cultivar ‘W-20.’ Entireleaf morningglory and pitted morningglory, both moderately tolerant to chlorimuron, were used. Twenty-day-old seedlings of all plant species were exposed to root-applied14C-labeled chlorimuron for 6, 24, and 72 h. After 24 and 72 h, chlorimuron uptake was lowest in W-20 soybean and the two morningglory species. Translocation of root-absorbed chlorimuron to shoots and leaves of all species was limited and it did not differ among species. The moderate tolerance of pitted and entireleaf morningglories to chlorimuron may be due to reduced herbicide uptake. The response of Essex and Vance soybean to chlorimuron was related to herbicide metabolism. At 6 h after treatment with radiolabeled chlorimuron, Essex soybean metabolized the herbicide more rapidly than either W-20 or Vance soybean. At 24 h and 72 h, Essex and Vance soybean metabolized chlorimuron to the same extent. W-20 was not very efficient in metabolizing chlorimuron at any time after treatment and its resistance to chlorimuron is due to an altered target site.
Washoff of Dicamba and 3,6-Dichlorosalicylic Acid from Turfgrass Foliage
Authors: Carroll Mark J. , Hill Robert L. , Pfeil Emy , Herner Albert E.
Published: March 2018

The functional relationships between rainfall intensities and amounts, and the washoff of dicamba and 3,6-DCSA from turfgrass foliage were determined. Dicamba was applied to Kentucky bluegrass field plots and the turfgrass was subjected to 2 to 58 mm of simulated rainfall 18 to 48 h later. Rainfall was applied at an average intensity of 20.6 or 39.9 mm h−1. The 39.9 mm h−1intensity reduced dicamba washoff by 10% for a given amount of rainfall. Washoff of 3,6-DCSA was independent of rainfall intensity. When averaged over intensities, washoff of dicamba was best described by the equation y = 1 − 0.341x0.187, and 3,6-DCSA washoff by the equation y = exp(-0.210x), where x represents millimeters of rainfall and y, the proportion of compound remaining on the foliage after rainfall.
Weed Control and Yield are Equal in Conventional, Reduced-, and No-Tillage Soybean (Glycine max) After 11 Years
Authors: Kapusta George , Krausz Ronald F.
Published: March 2018

Field experiments were conducted from 1979 to 1989 to determine the influence of conventional, reduced, and no-tillage systems and different herbicide combinations on weed species and population, weed control, and soybean injury, population, and yield. In no-till (NT) non-treated plots, there was an abrupt shift from horseweed as the dominant early spring emerging weed to gray goldenrod in 1985. Following its initial observation, gray goldenrod became the dominant species within 2 yr, with giant foxtail as the only other species observed in these plots. Giant foxtail was the dominant weed species from 1980 to 1989 in conventional till (CT) and reduced-till (RT) plots. There also was a shift in the frequency of occurrence and in density of several broadleaf weed species during the 11-yr study. Most herbicides provided excellent control of all weeds in all tillage systems, especially those that included POST herbicides. There was little difference between glyphosate and paraquat in controlling weeds present at the time of planting in NT. PRE herbicides caused 2 to 9% soybean injury with slightly greater injury occurring in CT and RT than in NT. The POST broadleaf herbicides did not significantly increase soybean injury. There were no differences in soybean population or yield among the herbicide treatments regardless of tillage. There also was no difference in soybean population or yield in NT compared with CT when averaged over all herbicide treatments.
Residual Herbicides for Weed Control in Established Alfalfa (Medicago sativa) Grown for Seed
Authors: Malik Najib , Bowes Garry G. , Waddington John
Published: March 2018

The long-term effect of repeated late-fall versus early-spring imazethapyr, hexazinone, terbacil, metribuzin, dichlobenil, or chlorsulfuron treatments, when applied on dormant stands of alfalfa was investigated at three sites for weed management of alfalfa grown for seed. Dichlobenil applied at 1.2 to 2.4 kg ha−1and chlorsulfuron applied at 11 to 22 g ha−1in fall or spring were the only herbicides to injure alfalfa at one location. Hexazinone provided the most consistent weed control of the herbicides evaluated. Average control of Canada thistle, catchweed bedstraw, dandelion, perennial sowthistle, quackgrass, Russian pigweed, and scentless chamomile was 80%. When averaged over three sites, weed control by hexazinone resulted in a 33% increase in seed yield.
Orobanche—The Broomrapes
Authors: Mitich Larry W.
Published: March 2018

Orobanchaceae, the broomrape family, comprises approximately 150 species in 17 genera. Four genera represented by four species occur in the southeastern U.S. A majority of the genera and about 90% of the species in Orobanchaceae are Old World natives. The family is primarily one of the northern warm and temperate zones. Only about 10% of the species occur in the tropics; only one species reaches the arctic.
Temperature Responses and Potential Range of the Grass Weed, Serrated Tussock (Nassella trichotoma), in the United States
Authors: Patterson David T.
Published: March 2018

In controlled-environment chambers, serrated tussock achieved maximum growth in temperature regimes of 18/11, 18/23, 24/23, or 24/17 C day/night. Growth was significantly reduced at 30/11 C, and no plants survived at 36/29 C. Serrated tussock seedlings grew slowly at first but eventually produced vigorous tussocks with as many as 2800 tillers after 140 d in the 24/17 C regime. Comparisons of climatic conditions in New South Wales, Victoria, New Zealand, South Africa, and the United States revealed that similar temperature conditions occur during the warmest eight mo of the year in areas as diverse as Oregon, Washington, the Sierran Nevada foothills of California, upper elevation rangelands in Arizona, and the southern Appalachian highlands. None of these areas has a precipitation pattern similar to those of the sites of serrated tussock weed infestation in the Southern Hemisphere. However, poorly managed pastures and unimproved rangelands in these diverse areas may be vulnerable to invasion by serrated tussock, should the weed become established in the United States.
Silverleaf Nightshade (Solanum elaeagnifolium) Control in Cotton (Gossypium hirsutum) with Glyphosate
Authors: Westerman R. Brent , Murray Don S.
Published: March 2018

Glyphosate, alone and in combination with other herbicides or additives, was evaluated as a spot or shielded treatment for the control of silverleaf nightshade in cotton in three experiments over four years. Glyphosate used at 10.8 g ae/L in 1985 on dryland cotton controlled 81 to 98% of the silverleaf nightshade, but cotton lint yields were reduced by all treatments compared to the weed-free check. Glyphosate used at 7.2 g ae/L in 1986 on irrigated cotton controlled 6 to 83% of the silverleaf nightshade, and lint yields were reduced only when multiple spot applications were made. Spot applications of glyphosate were effective for silverleaf nightshade control when applied 7 wk after crop emergence in 1988. Weed control and cotton injury were lower with shielded applications than spot applications. In 1989, retreatments during a season or the next year resulted in 95% or greater silverleaf nightshade control. Cotton yield increases from herbicide treatment were not observed in 1988; however, yield increases were observed in 1989 when spot treatments were applied to the more successful 1988 plots.
Influence of Cultivation Timing On Weed Control in Soybean (Glycine Max) with Ac 263,222
Authors: Newsom Larry J. , Shaw David R.
Published: March 2018

Cultivation timings and postemergence applications of AC 263,222 were evaluated for sicklepod and pitted morningglory control in soybean. Cultivation alone controlled each less than 35% season-long. A cultivation made 7 d after POST applications of AC 263,222 more consistently improved sicklepod and pitted morningglory control than a cultivation made 3 d before, immediately after, or 3 d after the POST application. Imazaquin PRE followed by 18 g ai/ha AC 263,222 controlled sicklepod 88% or more and pitted morningglory 83% or more two of three years. A cultivation made immediately after AC 263,222 POST resulted in reduced soybean yields in several instances compared to the same treatment without cultivation. A cultivation made 7 d after application of AC 263,222 increased soybean yields the most in several instances compared to all other timings.
Suction Trap Records of Myzus lythri (Homoptera: Aphididae) Associated with Purple Loosestrife (Lythrum salicaria) Infestations in Idaho
Authors: Halbert Susan E. , Voegtlin David J.
Published: March 2018

Mean Idaho suction trap collections of Myzus lythri, an aphid which infests purple loosestrife, reflected weed distribution and were used successfully to predict undocumented weed populations. To our knowledge, this is the first time insect survey records have been used to document the range of an introduced weed.
Economic Returns from Broadleaf Weed Control in Hard Red Winter Wheat (Triticum aestivum)
Authors: Scott Robert C. , Peeper Thomas F.
Published: March 2018

Seventeen on-farm and two experiment station experiments were conducted to evaluate farmers' decisions to apply broadleaf weed control herbicides to tillered hard red winter wheat in February or March with or without urea-ammonium nitrate (28-0-0) fertilizer carrier. The herbicides and rates varied by farm, but all farmers applied a residual sulfonylurea herbicide and four added a phenoxy herbicide. Most farmer-selected herbicide treatments controlled target weeds including bushy wallflower, flixweed, henbit, plains coreopsis, smallflowered bittercress, and wild buckwheat. Controlling these weeds increased wheat yield on only two farms. Farmer-selected, commercially applied treatments increased net returns at two of seventeen farms, decreased net returns at seven farms, and did not affect returns at eight farms. Net returns were increased over the farmer-selected treatments at two farms when half the farmer-selected rate of herbicide was used. Half-rate herbicide treatments controlled weeds up to 25% less than farmer-selected treatments. Weed control with the half-rate treatments ranged from 60 to 98%. None of the farmers expected that herbicide use would increase yield. Their primary objective was to have weed-free fields at harvest. Nitrogen rates appeared to be selected without a rational basis for decision making.
Efficacy of Corn (Zea mays) Herbicides Applied at Reduced Rates Impregnated in Dry Fertilizer
Authors: Rabaey Thomas L. , Harvey R. Gordon
Published: March 2018

Field studies were conducted in 1992 and 1993 to evaluate the efficacy of EPTC plus R-29148 (EPTC+) plus cyanazine and alachlor plus cyanazine. Materials were applied PPI and PRE to corn at 25, 50, 75, and 100% of labeled rates in an aqueous solution (sprays) and as herbicide-impregnated fertilizer. EPTC+plus cyanazine at all rates applied as sprays or as herbicide-impregnated fertilizer controlled 89% or more of giant foxtail. Velvetleaf and common lambsquarters control was less when alachlor plus cyanazine was applied as herbicide-impregnated fertilizer than when applied as sprays. When sprayed, alachlor plus cyanazine applied PPI controlled 95% giant foxtail only at the 100% rate without cultivation, but at all rates with cultivation. Alachlor plus cyanazine applied as impregnated fertilizer at 50, 75, and 100% labeled rates controlled 88% or more of giant foxtail when these treatments received a interrow cultivation. PRE treatments of alachlor plus cyanazine applied as herbicide-impregnated fertilizer were less effective in 1992 than in 1993 because of lack of timely precipitation following application.
Potential Regulatory Problems Associated with Atrazine, Cyanazine, and Alachlor in Surface Water Source Drinking Water
Authors: Nelson Henry , Jones R. David
Published: March 2018

Post-application seasonal (May-July) average concentrations of atrazine, cyanazine, and, to a lesser extent, alachlor sometimes exceed their Maximum Contaminant Levels (MCLs) (3 ug/L for atrazine and 2 ug/L for alachlor) or Maximum Contaminant Level Goal (MCLG) (1 ug/L for cyanazine) in surface waters of the Mississippi and Great Lakes Basins. These three chemicals are among the primary pre-emergent herbicides applied to corn. MCLs and MCLGs are compared to annual average concentrations for regulatory purposes. However, annual average concentrations are much less frequently reported than post-application seasonal averages. In most cases, both seasonal and annual average concentrations are substantially less than the MCLs or MCLG. However, actual and estimated annual mean concentrations occasionally exceed the MCLs or MCLG. Actual or estimated exceedences occur more frequently for atrazine and cyanazine than for alachlor, and may occur more frequently in lakes or reservoirs with long retention times than in streams and rivers. Additional year round data, and data for lakes and reservoirs, are needed to determine the extent to which such exceedences occur throughout the corn belt. The American Water Works Association (AWWA) believes that substantial numbers of Community Water Systems (CWSs) within the corn belt are currently, or will be, in violation of the revised Safe Drinking Water Act (SDWA) with respect to atrazine and cyanazine. They are concerned that such violations could result in numerous CWSs having to implement expensive tertiary treatment systems such as granular activated carbon to decrease herbicide concentrations. The United States Environmental Protection Agency, (US EPA) is continuing to review data on the pesticide concentrations in reservoirs and lakes that registrants have been submitting over the last 18 mo under the 6(a)(2) adverse impact provision of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). The US EPA is also currently using computer modeling and other methods to evaluate potential alternative and/or supplemental herbicides to reduce atrazine use. In June 1992, the US EPA approved revised labeling that is designed to reduce indirect atrazine loadings to surface waters. Additional mitigation methods have been proposed and are being considered.
Control of Growth Regulator Preconditioned Field Bindweed (Convolvulus arvensis) with Herbicides
Authors: Lym Rodney G. , Humburg Neil E.
Published: March 2018

The effect of various growth regulators on seedling field bindweed (Convolvulus arvensisL. # CONAR) growth and control with herbicides was evaluated. Fourteen growth regulators were applied at 0.38 to 380 g/ha 7 days before herbicide application in greenhouse, growth chamber and field studies. Field bindweed seedlings pretreated with growth regulators were more effectively controlled by herbicides compared to those not pretreated in greenhouse evaluations. Abscisic acid [[R-(Z,E)]-(+)-5-(1-hydroxy-2,6-6-trimethyl-4-oxo-2-cyclohexane-1-yl)-3-methyl-2,4-pentadicenoic acid] (ABA), ancymidol [a-cyclopropyl-a-(p-methoxyphenyl)-5-pyrimidine methanol], cycloheximide {3-[2-(3,5-dimethyl-2-oxocylohexyl)-2-hydroxyethyl]glutarimide}, ethylenediamine tetraacetic acid [N,N′-1,2-ethanediyl-bis-(N-(carboxymethyl) glycine] (EDTA), and 1-naphthaleneacetic acid (NAA) increased field bindweed stem length. Ancymidol and gibberellic acid [ent-3α,10,13-trihydroxy-20-norgibberell-1,16-diene-7,19-dioc acid 19,10-lactone] (GA) increased root weight, and GA increased root length. Cycloheximide, ethephon [(2-chloroethyl)phosphonic acid] and MH (1,2-dihydro-3,6-pyridazinedione) decreased field bindweed root weight. Ancymidol, GA and IAA (indole-3-acetic acid) increased the number of shoots per plant of seedling field bindweed. Dicamba (3,6-dichloro-2-methoxybenzoic acid) efficacy was enhanced following field bindweed preconditioning with ethephon and IAA. Ancymidol and cycloheximide applied as pretreatments increased glyphosate [N-(phosphonomethyl)glycine] activity on seedling field bindweed. Ancymidol and IAA pretreatment improved field bindweed control with triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}. Herbicide-growth regulator combination treatments that increased field bindweed control in greenhouse and growth chamber studies did not increase top growth control in the field.
Chlorimuron-Ethyl (Classic)®: A New Broadleaf Postemergence Herbicide in Soybean
Authors: Claus Jon S.
Published: March 2018

Chlorimuron-ethyl is a highly effective postemergence herbicide for control of economically important broadleaf weeds in soybean. It has been developed by E. I. du Pont de Nemours & Co., Wilmington, DE, under the code DPX-F6025 and is marketed in the United States under the trade name of Classic. Chlorimuron-ethyl is a member of a new class of herbicides called sulfonylureas. It is active at extremely low use rates, and soybeans have good tolerance.
Herbicides from Natural Compounds
Authors: Duke Stephen O. , Lydon John
Published: March 2018

Phytotoxic compounds from plants and microorganisms represent a wide range of chemistries and mechanisms of action that have potential in the design and development of new herbicides. Although several natural products of higher plants have been patented as herbicides, none have been developed commercially. Many microbial products have been patented as herbicides and several have been or are being developed, including bialophos {L-2-amino-4-[(hydroxy)(methyl)phosphinoyl] -butyryl-L-alanyl-L-alanine} and glufosinate [L-2-amino-4-(hydroxyl)(methyl)(phosphinoyl)-butyric acid]. The new tools of molecular biology and biotechnology are making natural products more attractive alternatives in herbicide discovery programs.
Effect of Adjuvant and Spray Volume on Quackgrass (Agropyron repens) Control with Selective Postemergence Herbicides
Authors: Kells James J. , Wanamarta Gunawan
Published: March 2018

Soybean-based [Glycine max(L.) Merr.] and petroleum-based crop oil concentrates were equally effective as spray adjuvants for control of quackgrass [Agropyron repens(L.) Beauv. #3AGRRE] with the butyl ester of fluazifop {[±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} and sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}. With favorable growing conditions at application in 1983 and 1985, an adjuvant concentration of 1% (v/v) with these herbicides was adequate for quackgrass control. Unfavorable growing conditions at application in 1984 resulted in unacceptable quackgrass control, and spray volume did not affect control. However, increasing the adjuvant concentration to 4% (v/v) with either herbicide applied in a spray volume of 70 L/ha nearly doubled quackgrass control. In 1983 and 1985, equal or greater quackgrass control with each herbicide was achieved with spray volumes as low as 35 L/ha compared to 280 L/ha.
Effect of Soil-Applied Chlorsulfuron on Canada Thistle (Cirsium arvense) Root and Root Bud Growth
Authors: Donald William W.
Published: March 2018

Chlorsulfuron [2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-amino] carbonyl] benzenesulfonamide], applied at 9 to 560 g ai/ha to the soil surface, stopped shoot elongation of well established Canada thistle [Cirsium arvense(L.) Scop. #4CIRAR] plants in the greenhouse. Root fresh weight decreased progressively as chlorsulfuron rate was increased when measured 1 month after treatment. In contrast, the number of visible root buds plus secondary shoots increased 1.9- to 2.3-fold between 9 and 67 g/ha chlorsulfuron 1 month after soil surface treatment. Despite more numerous root buds, the number of secondary shoots arising from adventitious root buds progressively decreased as chlorsulfuron rate was raised. Increases in the number of visible root buds were observed first between 3 and 4 weeks following soil application with 67 g/ha of chlorsulfuron, 2 weeks after shoot growth stopped.
Combination Effects of Low Rates of Fluridone and Bentazon
Authors: Sterrett J. P.
Published: March 2018

The response of yellow nutsedge (Cyperus esculentusL. #3CYPES) and Canada thistle [Cirsium arvense(L.) Scop. # CIRAR] to combinations of low rates of fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone} and bentazon [3-(1-methylethyl)-(1H)-2,l,3-benzothiadiazin-4(3H)-one 2,2-dioxide] was determined in a controlled environment chamber and on Canada thistle in the field. In the growth chamber, injury to yellow nutsedge was increased with 24 g ai/ha fluridone combined with 323 g ai/ha bentazon. Either 2.7 or 5.4 g/ha fluridone combined with 27 g/ha bentazon caused uniform injury to Canada thistle. In the field, the combinations of 5.6 g/ha fluridone with either 28 or 2800 g/ha bentazon was phytotoxic to Canada thistle.
Training Weed Scientists for Research
Authors: Walker Robert H. , Buchanan Gale A.
Published: March 2018

The objective of this paper is to discuss ways to improve training of weed scientists for research, including student backgrounds, appreciation for total production systems, economics, computer science and technology, reassessment of technical subject matter areas, and practical experience.
Soybean (Glycine max) Cultivar Response to Fluchloralin, Metribuzin, and Vernolate
Authors: Martin M. Daniel , Worthington James P. , Gray Elmer
Published: March 2018

In 1983 and 1984, 20 commercial soybean [Glycine max(L.) Merr.] cultivars were field tested for their response to fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)benzenamine], metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-l,2,4-triazin-5(4H)-one], and vernoiate [S-propyl dipropylcarbamothioate]. Recommended rates for the herbicides were 1.1, 0.4, and 2.8 kg ai/ha, respectively. Each herbicide was applied at recommended (lx), 2x, and 4x rates in both years with an 8x rate added in 1984. Plant height, vigor, and injury were used to determine herbicide effects. Differences existed among cultivars, herbicides, and rates. Increased herbicide rates generally resulted in reduced plant height and vigor and increased plant injury. Cultivars tolerant to the three herbicides included Cumberland, Essex, FFR 560, NAPB 420, and Pixie.
Control of Virginia Creeper (Parthenocissus quinquefolia): Effects of Carrier Volume on Toxicity and Distribution of Triclopyr
Authors: Tworkoski Thomas J. , Young Roger S. , Sterrett John P.
Published: March 2018

The butoxyethyl ester of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was more effective than either the triethylamine salt formulation or an equivalent combined rate of the butoxyethyl esters of triclopyr plus 2,4-D [(2,4-dichlorophenoxy)acetic acid] (1:2, w/w) for the control of Virginia creeper [Parthenocissus quinquefolia(L.) Planch. # PRTQU]. Carrier volume did not affect14C-triclopyr absorption and distribution, but control generally was greater after high carrier-volume application (281 L/ha) because the dense Virginia creeper canopy was thoroughly penetrated. In orchards, Virginia creeper was controlled by triclopyr ester at 0.6 kg ae/ha through the second season after treatment if foliage was covered thoroughly.
Selective Control of Japanese Honeysuckle (Lonicera japonica)
Authors: Regehr David L. , Frey David R.
Published: March 2018

Japanese honeysuckle (Lonicera japonicaThunb. # LONJA) vines can smother young trees, presenting problems in nursery, parkland, and woodlot management. The tardy-deciduous nature of honeysuckle provides an application window for its selective control with glyphosate [N-(phosphonomethyl)-glycine] or dichlorprop [(±)-2-(2,4-dichlorophenoxy)propanoic acid] plus 2,4-D [2,4-dichlorophenoxy)acetic acid] immediately after fall defoliation of hardwood species. Glyphosate at 1.5% v/v (5.4 g ae/L) applied in December killed mature, woody honeysuckle vines and eliminated most regrowth from basal and subterranean buds 28 months after treatment. Dichlorprop plus 2,4-D at 1.5% v/v (3.6 g ae/L of each herbicide), when applied shortly after the first freezing temperatures in October, was as effective as glyphosate but was less effective when applied in December. Tuliptree (Liriodendron tulipiferaL.), American beech (Fagus grandifoliaEhrh.), and Scotch pine (Pinus sylvestrisL.) suffered minimal and temporary injury from these herbicides.
Effects of Rainfall on Foliar Herbicides Applied to Seedling Johnsongrass (Sorghum halepense)
Authors: Bryson Charles T.
Published: March 2018

The effects of rainfall on the efficacy of 11 foliar-applied herbicides were evaluated for their control of seedling johnsongrass [Sorghum halepense (L.) Pers. # SORHA] in greenhouse experiments during 1984 and 1985 at Stoneville, MS. Time intervals between herbicide application and rainfall (at 1.27 cm in 10 ± 0.5 min) ranged from 5 to 60 and 30 to 240 min depending on herbicide classification. In general, the phosphonic acid herbicides glyphosate [N-(phosphonomethyl)glycine] and SC-0224 (trimethylsulfonium carboxymethylaminomethylphosphonate) at 0.99 kg ai/ha required rain-free periods ≥240 min to control seedling johnsongrass effectively. The selective postemergence grass herbicides generally required ≥60 min to control seedling johnsongrass effectively when control without rainfall was ≥85%. Among the selective herbicides tested, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanoic acid} and DPX-Y6202 {ethyl[2-[4-(6-chloro-2-quinoxalinyl)oxy] phenoxy] propionic acid} at 0.06 kg ae/ha required the shortest time between herbicide application and rainfall to be effective. As herbicide rates were reduced, the effects of rainfall increased.
Effect of Paraquat Plus Prescribed Burning on Eastern Redcedar (Juniperus virginiana)
Authors: Engle David M. , Stritzke Jimmy F. , Claypool P. Larry
Published: March 2018

Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) was evaluated as a pretreatment for eastern redcedar (Juniperus virginiana L. # IUPVI) before spring burning in tallgrass prairie. Wetting sprays of paraquat at 0.3 g ai/L or 0.6 g/L were applied to crowns of small (0.8 to 1.5 m), medium (1.5 to 2.5 m), and large (2.5 to 5.0 m) eastern redcedar trees in August 1983 and 1984 before prescribed burns in the springs of 1984 and 1985. Paraquat alone at the 0.6 g/L concentration killed about 90% of the crown of small trees but as little as 30% of the crown of large trees. Paraquat pretreatments increased post-fire damage to small- and medium-size trees and partially compensated for light fine fuel loading.
Weed Control in Water- and Dry-seeded Rice,Oryza sativa
Authors: Smith Roy J.
Published: March 2018

Herbicides were applied as single, sequential, or tank mixture treatments at different growth stages and rates and were compared with standard treatments for control of barnyardgrass, bearded sprangletop, elipta, spreading dayflower, and aquatic weeds in water- or dry-seeded rice. In water-seeded rice, thiobencarb granules applied alone or sequentially selectively controlled bearded sprangletop and aquatic weeds in the 1- to 4-leaf stages better than standards of propanil alone or mixed with bentazon. Fenoxaprop plus bentazon selectively controlled 1- to 4-leaf bearded sprangletop but failed to control 1- to 4-leaf aquatic weeds. In dry-seeded rice, treatments of fenoxaprop applied to tillering rice after earlier applications of preemergence thiobencarb or postemergence applications of propanil selectively controlled barnyardgrass, bearded sprangletop, eclipta, or spreading dayflower better than standards of propanil alone or mixed with thiobencarb. Fenoxaprop alone or in tank mixtures with other herbicides applied early postemergence either injured rice or failed to control weeds. Esprocarb applied preemergence controlled weeds but injured rice while early postemergence treatments of propanil plus esprocarb performed better than standard herbicide treatments.
A Mycoherbicide Integrated with Fungicides in Rice,Oryza sativa
Authors: Khodayari Khosro , Smith Roy J.
Published: March 2018

Field experiments were conducted to determine the effect of selected rice pesticides on the mycoherbicideColletotrichum gloeosporioides(Penz.) Sacc. f. sp.aeschynomene(designated as C.g.a.) for northern jointvetch control in dry-seeded rice. Sequential treatments of pencycuron at 0.56 kg ai/ha, SN-84364 at 0.40 kg ai/ha applied 7 and 14 days after C.g.a., or pencycuron sprayed sequentially after a tank mixture of C.g.a. plus actifluorfen did not reduce infectivity of C.g.a. Also, propiconazol at 0.60 kg ai/ha or pencycuron applied 7 days before and after C.g.a. did not reduce fungus development on northern jointvetch. Sequential treatments of benomyl at 0.56 kg ai/ha or propiconazol applied 7 and 14 days after C.g.a. reduced pathogen activity on northern jointvetch.
Techniques for Selection of Glyphosate-Tolerant Field Pea, Pisum sativum, Cultivars
Authors: Yenne Samuel P. , Thill Donald C. , Letourneau Duane J. , Auld Dick L. , Haderlie Lloyd C.
Published: March 2018

The tolerance of several field pea cultivars to glyphosate was compared in the laboratory and greenhouse, using root, foliar, and tissue culture exposure techniques. Pea cultivar response among glyphosate exposure techniques did not always agree. However, the cultivar ‘Alaska’ was consistently one of the most susceptible cultivars regardless of exposure technique. ‘Melrose’ was one of the most tolerant cultivars, especially when its roots and cells were exposed to glyphosate. The response of ‘Frogel’, ‘Glacier’, and other cultivars varied among glyphosate-exposure techniques.
Metribuzin and Chlorimuron Mixtures for Preemergence Broadleaf Weed Control in Soybeans,Glycine max
Authors: Green Jerome M. , Obrigawitch Timothy T. , Long James D. , Hutchison James M.
Published: March 2018

Metribuzin and the ethyl ester of chlorimuron were evaluated alone and in combination for preemergence broadleaf weed control in soybeans. Neither herbicide alone controlled all broadleaf weeds tested, but combinations showed both complementary and additive action. Two field studies quantified these interactions on broadleaf weeds and showed that low rates of either herbicide alone controlled Pennsylvania smartweed and redroot pigweed. Metribuzin was more effective than chlorimuron in controlling prickly sida and hemp sesbania, while chlorimuron was more effective on common cocklebur, sicklepod, and ivyleaf and pitted morningglories. Additive action was most important on velvetleaf, sicklepod, annual morningglories, and hemp sesbania. Because the components were both additive and complementary, a range of mixture rates and ratios were more effective for weed control than either herbicide alone.
An Eradication Plan for Plant Invasions
Authors: Zamora David L. , Thill Donald C. , Eplee Robert E.
Published: March 2018

An eradication plan is needed to counteract the increasing number of invasions by new plant species and the cost of resulting control programs. An eradication plan includes early detection of new species, assessment of the invader's noxious potential, surveys, understanding of the invader's biology, and technology incorporated into a strategy to eliminate the species and to revegetate invasion sites. Early detection increases the probability of successfully eradicating invading plants. Key factors in determining a plant's noxious potential are similarities among the climates of the invaded area and endemic population, the plant's history of spread, and its ability to germinate. Surveys are necessary to detect new species and to assess their threat. Reliable surveys depend on using proper methods and tactics. Population dynamics indicate the stage of a plant's life cycle most vulnerable to eradication treatments, the time to deplete viable propagules from the soil, and the strategy to stop spread. Eradication technology is based on a plant's population dynamics and must eliminate every plant from an infestation. The survey data, population dynamics, and eradication technology are combined into an eradication strategy that must stop spread, prevent reproduction, and deplete viable propagules from the soil. An effective eradication strategy specifies where and when to apply treatments, quarantine measures, criteria to assess progress, steps to prevent further invasions, and cost appraisals.
Tolerance of Transplanted Muskmelon(Cucumis melo)to Oxyfluorfen Applied Preemergent
Authors: Masiunas John B. , Weller Stephen C.
Published: March 2018

Field studies were conducted to determine if oxyfluorfen alone or combined with other herbicides could be applied between black polyethylene mulch without injuring muskmelon. Oxyfluorfen at rates up to 1.1 kg ai/ha did not injure muskmelon provided adequate rain or irrigation occurred to incorporate the oxyfluorfen thereby minimizing vapors that could injure muskmelon. Using this practice, muskmelon yields from oxyfluorfen-treated plots were the same as yields from untreated cultivated plots.
Response of Tall Fescue (Festuca arundinacea) to Plant Growth Regulators and Mowing Frequency
Authors: Johnson Billy J.
Published: March 2018

Mefluidide, Mon 4620, paclobutrazol plus mefluidide, and flurprimidol plus mefluidide temporarily injured and discolored tall fescue without reducing shoot density. Mefluidide at 0.43 kg ai/ha and Mon 4620 at 2.8 kg ai/ha suppressed vegetative growth of mowed grass 4 weeks while unmowed grass was suppressed for 8 weeks. Mefluidide at 0.14 kg/ha with either flurprimidol at 1.1 kg ai/ha or paclobutrazol at 1.1 kg ai/ha suppressed vegetative growth of mowed tall fescue for 5 and 6 weeks, respectively. Combination treatments also suppressed the growth of nonmowed tall fescue 8 to 10 weeks. Mowing effectively suppressed seedheads for 12 weeks when the grass was mowed at 3 and 6 weeks, while mowing only once at 4 weeks did not. Seedhead suppression was not improved with weekly mowing compared with two mowings. Mowing influenced the performance of plant growth regulators on vegetative growth and seedhead control but not plant injury, quality, or shoot density.
Identification of Efficacious Adjuvants for Sethoxydim and Bentazon
Authors: Wanamarta Gunawan , Penner Donald , Kells J. J.
Published: March 2018

Experimental adjuvants were tested to maximize herbicidal activity of sethoxydim on quackgrass and of bentazon on common lambsquarters. Efficacious adjuvants were identified by measuring the14C-herbicide droplet spread and absorption, as influenced by various adjuvants, on the target weed. The absorption and droplet spreadability of sethoxydim and bentazon on quackgrass and common lambsquarters leaves were increased or were decreased depending on the type of adjuvant used. No correlation was found between sethoxydim droplet spread and absorption on quackgrass. With bentazon, the relationship between these two factors was greater. Thus, measurement of droplet spread, as affected by adjuvants, was useful only as a screening technique for bentazon. Blending surfactants with paraffinic oil or soybean oil to form a crop oil concentrate changed the efficacy of the surfactant compared to the surfactant by itself. Surfactants most effective as components of paraffinic-oil based crop oil concentrate were different from surfactants ideal for inclusion with soybean oil-based crop oil concentrate. Thus, the effectiveness of a crop oil concentrate depends on herbicide, surfactant, and oil types. In the field, several of the superior adjuvants identified in the laboratory enhanced sethoxydim and bentazon activity on grass and broadleaf weeds.
Clomazone Dissipation in Two Montana Soils
Authors: Gallandt Eric R. , Fay Peter K. , Inskeep William P.
Published: March 2018

Clomazone is effective as a chemical fallow herbicide; however, its soil residual properties in the Northern Great Plains are unknown. Clomazone was applied to soil at 0.6, 1.1, and 2.2 kg ai/ha at two locations in Montana in the spring of 1986. Soil samples were taken at each location at monthly intervals for 6 months. Residual levels of the herbicide were estimated by measuring the percent chlorosis by height in oat leaves. Clomazone at 2.2 kg ai/ha applied to a loam soil dissipated to levels below 0.1 mg/kg in 3 months and applied to a silty clay loam soil dissipated to 0.2 mg/kg 6 months after application. Half-lives (t½), determined from first-order rate plots, were 33 and 37 days in the Willow Creek loam and Bozeman silty clay loam, respectively. Thus, clomazone residue from labeled-use rates should not inhibit wheat in a wheat-fallow-wheat cropping system in Montana.