bluuebunny/crossref_metadata_2025 huggingface dataset:
Fall-applied Herbicides for Canada Thistle (Cirsium arvense) Root and Root Bud Control in Reduced-till Spring Wheat
Authors: Donald William W.
Published: March 2018

Several sequences of POST herbicides applied each year in fall alone, in spring alone, or both in fall and again in spring controlled Canada thistle stands in spring wheat by severely decreasing root biomass and the numbers of adventitious root buds to a depth of 50 cm over four years. These treatments included dicamba applied at 1.7 or 2.2 kg ae ha–1for the first two successive falls followed in wheat by either chlorsulfuron at 30 g ai ha–1plus nonionic surfactant, MCPA plus bromoxynil at 280 plus 280 g ha–1, or 2,4-D amine at 560 g ha–1applied annually for each of four consecutive years from the start. Chlorsulfuron at 30 g ha–1applied alone in spring for each of four years also reduced and prevented Canada thistle root growth as effectively as a sequence of fall-applied dicamba followed by spring-applied chlorsulfuron in spring wheat.
Green Foxtail (Setaria viridis) Competition with Spring Wheat (Triticum aestivum)
Authors: Peterson Dallas E. , Nalewaja John D.
Published: March 2018

Yield reductions due to green foxtail competition with hard red spring wheat varied with environment in field experiments conducted in 1984, 1985, and 1986 at Oakes, Langdon, Prosper, and Fargo, North Dakota. Wheat yield reductions ranged from 0 to 47% from 720 green foxtail plants per m2. Inclusion of early season temperature and precipitation, soil texture, and foxtail density into multiple regression analysis of wheat yield reductions significantly increased the coefficient of determination to 0.62 compared with 0.12 for regression based on green foxtail density alone. Wheat yield reduction decreased as green foxtail seeding was delayed after wheat seeding in 1986. Wheat yield generally decreased as time of diclofop application was delayed from 2 to 6 wk after wheat emergence in 1986.
Differential Competitiveness of Sulfonylurea Resistant and Susceptible Prickly Lettuce (Lactuca serriola)
Authors: Alcocer-Ruthling Mauricio , Thill Donald C. , Shafii Bahman
Published: March 2018

Repeated use of sulfonylurea herbicides in continuous, no-till winter wheat selected for a herbicide resistant biotype of prickly lettuce in Idaho. Greenhouse experiments were conducted to compare the relative competitiveness and growth rate of sulfonylurea herbicide resistant (R) and susceptible (S) prickly lettuce. The S biotype of prickly lettuce produced 31% more aboveground biomass than the R biotype averaged over all densities. Both biotypes were equally competitive when analyzed for both inter- and intrabiotype competition. In relative growth rate studies, regression analysis showed that the S biotype accumulated biomass 52% faster than the R biotype. The results of this study showed that the S biotype was superior to the R biotype in biomass production and growth rate, but competitiveness appeared to be equal for both biotypes. Other fitness parameters must be measured before fitness differences between biotypes can be determined.
Activated Carbon Reduces Tobacco (Nicotiana tabacum) Injury from Soil-Applied Herbicides
Authors: Yelverton Fred H. , Worsham A. Douglas , Peedin Gerald F.
Published: March 2018

Five field experiments were conducted during 1987–89 to determine the effectiveness of using activated carbon in transplant water to reduce injury to tobacco from herbicides incorporated before transplanting. Herbicides used were dicamba, chlorimuron, atrazine, lactofen, flumetralin, pendimethalin, pebulate, and imazaquin. Activated carbon was applied in the transplant water at a rate of 9 kg ha–1in 1987 and 18 kg ha–1in 1988 and 1989. Measurements taken were visual stunting ratings, yield, grade index, fresh and dry weights of roots and shoots, and percent sugars and total alkaloids in cured leaves. Activated carbon consistently reduced phytotoxicity of imazaquin and chlorimuron. As much as four- and two-fold yield increases were obtained when imazaquin and chlorimuron, respectively, were applied in conjunction with activated carbon. Less consistent results were obtained in reducing the phytotoxic effects of dicamba, atrazine, and flumetralin. Phytotoxicity without activated carbon was not consistently obtained with lactofen, pendimethalin, or pebulate.
A Method for Assessing the Efficacy of a Biocontrol Agent on Dandelion (Taraxacum officinale)
Authors: Burpee Lee L.
Published: March 2018

The efficacy of nine granular formulations of a bioherbicide containing the fungusSclerotinia sclerotiorum(Lib.) de Bary was determined by assessing vegetative growth from tap roots of treated plants after incubation in a controlled environment. Plants treated with formulations 0788-03 or 0788-04 did not produce new petioles and leaves from tap roots after 96 h at 23 C and 100% relative humidity.
Optimization of Weed Management Systems: The Role of Ecological Models of Interplant Competition
Authors: Kropff M. J. , Lotz L.A.P.
Published: March 2018

The strategy to optimize weed management systems with a minimum use of herbicides includes both the adaptation of crop management practices and well designed decision making systems, based on postemergence observations of weed infestations. Both strategies require thorough quantitative insight into the crop weed ecosystem, which can be provided by systems analysis, using process based models. These models also can be applied to similar systems like intercropping. For practical application, however, a simple measure of weed infestation and a simple model which relates weed infestation to yield loss are required. Recent progress in model development is discussed. An alternative empirical model that predicts yield loss from the relative leaf area of the weeds shortly after crop emergence, seems to be a useful approach for prediction of yield loss shortly after crop emergence. The use of systems approaches at different levels of detail for bridging the gap between research and practical application is discussed.
Participatory Research and Extension Strategies for Sustainable Agricultural Systems
Authors: Doll Jerry D. , Francis Charles A.
Published: March 2018

Conventional strategies for developing component technologies are being challenged by the complexities of today's agricultural environment. The needs for support of adaptive research, for sufficient field sites to evaluate location specificity of technologies, and for testing components as parts of total farm systems are not easily met within the confines of the experiment station. On-farm research strategies involve the farmer and rancher in project design, field implementation, collection and evaluation of data, and interpretation of results. Farmer presentations in extension meetings and field tours involve these cooperators in the demonstration and technology sharing process. Farmers in Nebraska and Wisconsin have applied this process to research nitrogen levels in continuous and rotated cereals, the use of allelopathic chemicals from rye(Secale cerealeL.) to reduce herbicide costs in soybean [Glycine max(L.) Merr.] production, on other alternative weed management strategies, and strip cropping to reduce soil erosion and meet government program compliance requirements. Useful in a wide range of ecological and economic circumstances, participatory methods using farming systems research and extension strategies have global applications.
Addressing Real Weed Science Needs with Innovations
Authors: Gressel Jonathan
Published: March 2018

Weed science is responsible for reducing weed competition with crops, within constraints, allowing food production for a growing world population. We have been successful, but with an increasing reliance on the fantastic arsenal of herbicides. Heavy herbicide usage and the concomitant loss of control due to changing weed species spectra, as well as evolved herbicide resistance, along with cancellations of registrations, limit chemical options. Old “innovations” such as well-conceived rotations and various mechanical procedures partly alleviate chemical dependency. We must try innovative, meaningful herbicide mixtures, whether synergistic or additive, mixtures of crop varieties, more competitive varieties, including allelopathic varieties, which could all help to lower chemical dependency. Three cases where innovative genetic-engineering coupled with chemistry seem to be needed are: (a) for the control of parasitic higher plant weeds such as broomrapes (Orobanchespp.), dodders (Cuscutaspp.), witchweeds (Strigaspp.) that cannot be controlled by mechanical or selective chemical means with a sufficient margin of user error; (b) for the control of weeds in wheat (Triticumspp.) that are evolving multiple and cross resistances toallwheat-selective herbicides; and (c) to replace the majors-triazine and chloroacetamide herbicides in corn (Zea maysL.) that are under attack and where many local restrictions and cancellations have been imposed. We need better replacements than the resistance-prone inhibitors of acetolactate-synthase and acetyl-CoA-carboxylase. Much of the long-term innovative planning and research must come from the public sector as no one else seems willing to fill the needs.
Banded Herbicide Applications and Cultivation in a Modified No-till Corn (Zea mays) System
Authors: Eadie Allan G. , Swanton Clarence J. , Shaw James E. , Anderson Glen W.
Published: March 2018

The acceptance of no-till crop production systems has been limited due to expected problems with weed management. Field experiments were established at two locations in Ontario in 1988 and one location in 1989. Band or broadcast applications of preemergence (PRE) combinations of high or low label rates of atrazine with or without metolachlor or inter-row cultivation, were evaluated for their effectiveness in controlling annual weeds in no-till corn. At each location, different herbicide and cultivation combinations were required to achieve adequate weed control. Corn grain yield was equivalent regardless of whether herbicides were applied as a band or broadcast treatment at all three sites. At two of the three sites, one cultivation combined with herbicides applied as a band was adequate to maintain weed control and corn grain yields. Selective application of herbicides in bands represented an approximate 60% reduction in total herbicide applied into the environment. The integration of a shallow post-plant inter-row cultivation combined with the soil conservation attributes of no-till, would enhance the sustainability of a modified no-till corn production system.
Phytotoxicity of Fumonisin B1on Weed and Crop Species
Authors: Abbas Hamed K. , Boyette C. D.
Published: March 2018

Fumonisin B1(FB1) sprayed on intact jimsonweed plants at 10 to 200 μg ml–1caused chlorosis and necrosis on three- to four-leaf plants and reduced their height and biomass. Excised leaves of jimsonweed were necrotic on both surfaces after treatment with FB1at 10 to 200 μg ml–1. The degree of damage increased with the concentration of FB1. The minimum amount of FB1that damaged excised leaves was 0.05 μg. The symptoms of toxicity on sensitive plants varied with concentration of FB1. Symptoms observed included: chlorosis (creeping cucumber), necrosis (jimsonweed and common sunflower), black leaf lesions (sicklepod), curl of tissues (soybean), stunting, defoliation (hemp sesbania and northern jointvetch), and death (prickly sida, spurred anoda, northern jointvetch, and jimsonweed). Monocots (barley, bermudagrass, corn, johnsongrass, rice, sorghum, and wheat) were not visibly affected by FB1. This is the first evidence of the phytotoxic properties of fumonisin B1against a wide variety of weeds and crop cultivars.
History of Herbicide-Tolerant Crops, Methods of Development and Current State of the Art – Emphasis on Glyphosate Tolerance
Authors: Kishore Ganesh M. , Padgette Stephen R. , Fraley Robert T.
Published: March 2018

Weed management is an integral part of agriculture; weeds lower both productivity and quality of agricultural products. A combination of mechanical, chemical, biological, and cultural methods is expected to deliver a sustainable weed management program for the next two decades. While chemical methods offer the most cost effective means of weed management, crop selectivity has hampered the use of the best chemicals for weed management. Recent progress in gene technology has facilitated the introduction and expression of genes to confer a wide range of traits to crop plants. Application of this technology has resulted in the development of crop plant genotypes that are resistant to a specific herbicide. This article describes the progress that has been made by our group toward the introduction of glyphosate tolerance to crop plants. Glyphosate [N-(phosphonomethyl)glycine] kills plants due to inhibition of the biosynthesis of aromatic compounds via the shikimate pathway. Our approach for introduction of glyphosate tolerance is based on insertion and expression in plants of a gene encoding a glyphosate-tolerant 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, a key enzyme of the shikimate pathway. The wild type enzyme present in plants is susceptible to inhibition glyphosate; variants of EPSP synthase have been produced that are less susceptible to inhibition by glyphosate. Expression of genes encoding these variants has been shown to confer glyphosate tolerance to plants. The degree of glyphosate tolerance is related to the tolerance characteristics of the EPSP synthase variant, its substrate activity, targeting to the plastid, and the level of expression of the variant gene. The tissue specificity of expression of the variant EPSP synthase has also been shown to be critical since glyphosate is a systemic herbicide and is translocated to many growing points within the plant. Our studies on glyphosate tolerance have substantially enhanced our understanding of the mode-of-action of glyphosate, the shikimate pathway, and protein sorting within plant cells, as well as developmental and tissue specific expression of genes in plants. Commercial use of glyphosate tolerance technology is expected to affect positively, the weed management arsenal available to the farmers, the sustainability of farm land and groundwater, and promote the use of a “soft” herbicide.
Environmental Concerns with the Development of Herbicide-Tolerant Plants
Authors: Goldburg Rebecca J.
Published: March 2018

Development of herbicide-tolerant plants is the focus of considerable research. Some projects aim to increase herbicide use or promote use of particularly environmentally damaging chemicals, and thus may lead to environmental degradation. Other projects aim to develop herbicide-tolerant plants that allow substitution of newer less environmentally damaging chemicals for older more damaging ones. To the extent they divert research dollars from development of other weed control strategies, these projects may also jeopardize environmentally sound weed control. The paper concludes with policy recommendations concerning a) public sector research priorities, b) planting of herbicide-tolerant trees in forests, and c) regulation of herbicide-tolerant crops.
Models and Modeling in a Regulatory Setting: Considerations, Applications, and Problems
Authors: Russell Mark H. , Layton Raymond J.
Published: March 2018

Computer based simulation models are increasingly being used to predict the environmental fate of crop protection chemicals. Some considerations that need to be given in selecting appropriate models for regulatory purposes include model applicability, validation, capability, ease of use, and documentation. Problems commonly encountered in modeling include limited accuracy, lack of defined objectives and standard modeling practices, and misuse of models and results. Models will continue to play an important role in the regulation of crop protection chemicals. It is important that regulators and industry agree on appropriate models and practices, and that regulatory decisions are not based solely on model results but take into account all available data.
The Role of Sensitivity Analysis in Groundwater Risk Modeling for Pesticides
Authors: Fontaine Don D. , Havens Patrick L. , Blau Gary E. , Tillotson Patricia M.
Published: March 2018

Two methods were used to obtain the sensitivity of chemical leaching depth to variations in the input parameters of the Pesticide Root Zone Model (PRZM). First a Plackett-Burman (PB) screening design was used to vary 35 PRZM inputs over seven ranges around a nominal value. Six of the seven ranges were approximately 0.1, 0.25, 0.5, 1.0, 5.0, and 15%, the seventh range was chosen to cover a range appropriate for a soybean herbicide applied preemergence in the Midwestern region defined by the USDA–SCS land resource region M. Next, Fourier amplitude sensitivity testing (FAST) was then used to vary from 19 to 25 parameters over four of the ranges previously tested. For the smaller parameter ranges the two methods typically gave equivalent results but the PB method required far fewer simulations. For the simulation of the Midwestern region where some parameter varied by larger amounts the relative magnitudes of the sensitivity coefficients obtained by the two methods were similar but the magnitude of the coefficients obtained using FAST were smaller than those obtained using PB.
The Weather Factor: Incorporating Weather Variance Into Computer Simulation
Authors: Williams J. R. , Richardson C. W. , Griggs R. H.
Published: March 2018

The effect of weather variation on pesticide losses was estimated with the Erosion-Productivity Impact Calculator (EPIC) model. Weather variations had little effect on pesticide loss from a hypothetical site near Memphis, TN, but the effect was more dramatic and in the expected direction at Des Moines, IA. Atrazine losses at Des Moines were reduced by lowering relative humidity or rainfall intensity. Increasing the CO2 level from 300 to 660 ppm slightly increased atrazine losses. Results from these two sites are very limited and only serve to demonstrate modeling potential for addressing weather/pesticide problems. Further, more comprehensive studies are needed to better estimate pesticide loss sensitivity to weather variation.
The Usda-Ars Pesticide Properties Database: A Consensus Data Set for Modelers
Authors: Herner Albert E.
Published: March 2018

The ARS Pesticide Properties Database (PPD) is a compendium of chemical and physical properties of a collection of widely used pesticides. At present, there are 92 compounds in the database and we have focused on 19 of the most important properties impacting on groundwater and atmospheric quality. The PPD relies upon experimentally determined data points. With the help of the National Agricultural Chemicals Association (NACA) we have been communicating directly with manufacturers to obtain the original experimental data with which they characterize pesticide properties and fulfill requirements for federal and state regulations. This provides the basis for the PPD which is augmented with data from the scientific literature. Features of the PPD are: 1. 19 parameters are provided for each pesticide. 2. References are given for all data. 3. When there are several values for a given property, all are cited. 4. All data have been verified and provide the latest, most reliable figures available.
Interactions Between Primisulfuron and Selected Soil-Applied Insecticides in Corn (Zea mays)
Authors: Biediger Darrin L. , Baumann Paul A. , Weaver Dave N. , Chandler James M. , Merkle Morris G.
Published: March 2018

Field experiments were conducted at two locations in 1989 and 1990 to investigate possible interactions between POST applications of primisulfuron and selected soil-applied carbamate and organophosphate corn insecticides. Insecticides were applied in-furrow at planting, at recommended use rates. Primisulfuron was applied POST to corn in the three- or five-leaf stage at 0, 20, 40, or 80 g ai ha-1. Combinations of primisulfuron with disulfoton, fonofos, isozophos, or terbufos resulted in foliar and root injury, plant height reductions, and yield losses. No foliar or root injury, plant height reductions, or yield losses were observed from combinations of primisulfuron and carbaryl, carbofuran, chlorpyrifos, or diazinon. Differences among and within the experiments are attributed to edaphic and environmental conditions at the time of primisulfuron application.
Seeding Arrangement on Winter Wheat (Triticum aestivum) Grain Yield and Interaction with Italian Ryegrass (Lolium multiflorum)
Authors: Appleby Arnold P. , Brewster Bill D.
Published: March 2018

Studies were conducted to determine whether cross-seeding of winter wheat, while maintaining an equal seeding rate per hectare, would increase wheat grain yields and help the wheat compete more effectively against Italian ryegrass than conventional seeding. Wheat was seeded at rates of 50, 100, and 150 kg ha-1 in conventional parallel rows or cross seeded in a grid pattern. Ryegrass was seeded at densities of 0, 20, 100, and 200 plants per m-2. Cross-seeded wheat yielded less grain than single-seeded wheat in 1990 in the absence of ryegrass; there were no differences in 1991. Cross seeding did not reduce competition from Italian ryegrass. Ryegrass was highly competitive against wheat, especially in 1990. Even 20 plants per m-2 reduced grain yield by an average of 38%. Wheat seeding rate had essentially no effect on grain yield in 1990, but the higher seeding rates reduced yields in 1991 because of extensive lodging. In 1991, wheat grain yields were higher in the cross-seeded plots than the single-seeded plots at the two high wheat seeding rates and highest ryegrass densities. Cross seeding does not appear promising as an aid to controlling ryegrass in Pacific Northwest wheat.
Control of Bigroot Morningglory (Ipomoea pandurata)
Authors: Horak Michael J. , Wax Loyd M.
Published: March 2018

Herbicide efficacy was examined in the greenhouse on bigroot morningglory seedlings and on established plants in the field. Dicamba (0.14 kg ae ha-1) and 2,4-D (0.28 kg ae ha-1) alone or combined, glyphosate (2.24 kg ai ha-1), fluroxypyr (0.28 kg ae ha-1), and triclopyr (0.42 kg ae ha-1) controlled more than 90% of bigroot morningglory seedlings. Fluroxypyr (0.56 kg ha-1), triclopyr (0.84 kg ha-1), and 2,4-D (0.56 kg ha-1) alone or combined with dicamba (0.28 kg ha-1) reduced established stands in the field at least 50% within the season of application, whereas clopyralid (0.56 kg ha-1) did not provide acceptable control. Glyphosate (2.24 kg ha-1) was among the best treatments for long term control at all locations.
Seed Biology of Sulfonylurea-Resistant and -Susceptible Biotypes of Prickly Lettuce (Lactuca serriola)
Authors: Alcocer-Ruthling Mauricio , Thill Donald C. , Shafii Bahman
Published: March 2018

The persistence of herbicide-resistant biotypes within a given weed population can be highly correlated with the longevity of its seed in the soil and its reproductive ability. This study compared seed longevity of sulfonylurea-susceptible (S) and -resistant (R) biotypes of prickly lettuce in soil at three depths and two locations. Seed longevity in soil was not different between R and S biotypes. Seed longevity was longer when seed were buried compared to seed placed on the soil surface. A field study on seed production showed that prickly lettuce plants produced an average of 14 flower heads and 181 seed per day. Average seed weight was 0.6 mg. No differences were observed in the fecundity or seed viability between the R and S biotypes. However, seed from R biotype plants germinated as fast or faster than seed from S biotype plants.
Effects of Various Adjuvants on Sethoxydim Activity
Authors: Harker K. Neil
Published: March 2018

Field experiments were conducted at the Lacombe Research Station from 1989 to 1991 to determine the influence of various adjuvants on sethoxydim activity. In all experiments sethoxydim was applied at 100 g ai ha-1to green foxtail, wheat, wild oat, and barley seeded in a canola crop. Of the four grass species, green foxtail was the most susceptible and barley was the least susceptible to sethoxydim. CC 16255 was the most effective adjuvant followed by either of two sources of ammonium sulphate (liquid or granular) and then Merge. Liquid and granular forms of ammonium sulphate were equally effective in enhancing sethoxydim activity. Several other adjuvants, including Enhance, Savol, and XE 1167, were moderately effective in the enhancement of sethoxydim activity. Adding Canplus 411 to Merge was not usually beneficial, but additions of Canplus 411 to Enhance often increased sethoxydim activity compared with sethoxydim and Enhance alone. Agral 90 and LI-700 were of little or no value as adjuvants with sethoxydim.
Nonlinear Regressions for Analyzing Growth Stage and Quinclorac Interactions
Authors: Chism William J. , Birch Jeffrey B. , Bingham S. Wayne
Published: March 2018

Control of southern crabgrass by quinclorac was influenced by plant growth stage. A three-parameter nonlinear regression was used to describe the influence of quinclorac concentration on each growth stage and to compare growth stages. A SAS® program for these comparisons is described. Pseudo R2values for fit were above 0.98 for all tests. Flowering crabgrass plants had the highest GR50value (50% growth reduction on a dry weight basis) whereas preemergence, three- to five-true-leaf, and two- to four-tiller stages were lower.
Response of Soybean to Combinations of Clomazone, Metribuzin, Linuron, Alachlor, and Atrazine
Authors: Salzman Frederick P. , Renner Karen A.
Published: March 2018

Field observations in 1986 indicated that increased injury to soybean could occur from clomazone plus metribuzin and clomazone plus linuron compared with metribuzin or linuron alone. Field experiments to measure this response were conducted in 1988, 1989, and 1990 at two locations in Michigan. Atrazine at 0, 1120, 2240, and 3360 g ha-1was applied the year previous to soybean planting to determine if atrazine residues in the soil influenced soybean response. Herbicide treatments in soybean included clomazone, metribuzin, linuron, alachlor, clomazone plus metribuzin or linuron, alachlor plus metribuzin or linuron, and an untreated control. Additive and synergistic responses in soybean to clomazone plus linuron and clomazone plus metribuzin, regardless of atrazine application rate, occurred in some field environments. Experiments in the greenhouse demonstrated that soybean shoot weight was reduced synergistically from clomazone plus metribuzin compared with either herbicide alone, and the response was greater on a soil with 2.5% organic matter compared with a soil with 4.4% organic matter. Clomazone plus metribuzin reduced leaf area and shoot dry weight, regardless of placement, while leaf area and shoot dry weight were reduced more when clomazone plus linuron- and atrazine plus metribuzin-treated soil was placed in the same zone as the soybean seed. The synergistic interaction in soybean to clomazone plus metribuzin occurred under both cool and warm temperature regimes in growth chamber studies.
Influence of Growth Stage on Rice (Oryza sativa) Tolerance to Triclopyr
Authors: Street Joe E. , Baldwin John L. , Mueller Thomas C.
Published: March 2018

Field studies were conducted from 1985 to 1989 on a Sharkey clay to examine injury to a semi-dwarf rice cultivar, ‘Lemont’, from triclopyr or triclopyr plus propanil. Triclopyr applied in the booting stage reduced yield two of three years, with the observed yield reduction possibly caused by epinasty of the rice flag leaf. Triclopyr application to three- to four-leaf rice caused hyponasty. Triclopyr did not reduce plant height, seed weight, germination, or total milling yield. Triclopyr plus propanil caused more leaf burn that triclopyr alone, but yields were not reduced compared with the untreated control. This research indicated that triclopyr and triclopyr plus propanil can be used in rice production with the semi-dwarf cultivar, Lemont, with the potential to minimize drift to non-target crops due to the greater flexibility in application timing compared with 2,4-D application.
Field Bindweed (Convolvulus arvensis) Control with Various Herbicide Combinations
Authors: Westra Philip , Chapman Philip , Stahlman Phillip W. , Miller Stephen D. , Fay Peter K.
Published: March 2018

Dicamba, 2,4-D, picloram, and commercially available premixes of glyphosate plus 2,4-D or glyphosate plus dicamba were evaluated alone and in combination for field bindweed control in a winter wheat-fallow system in Colorado, Wyoming, Kansas, and Montana. Approximately one year after application, herbicide mixtures containing picloram at 0.14 or 0.28 kg ai ha-1provided the best control. In five of seven locations, the control provided by picloram in herbicide mixtures was greater than the control provided by glyphosate plus 2,4-D, 2,4-D, or dicamba when these products were mixed with picloram. Glyphosate plus 2,4-D or glyphosate plus dicamba premixes, or 2,4-D added to dicamba were less effective for long-term control of field bindweed than mixtures containing 0.14 kg ai ha-1or more of picloram. Under drought conditions in Kansas in 1988, picloram did not control field bindweed as well as in Colorado, Wyoming, or Montana where rainfall was normal.
Prodiamine Controlled Florida Betony (Stachys floridana) in Leatherleaf Fern (Rumohra adiantiformis)
Authors: Stamps Robert H.
Published: March 2018

Field and container studies were conducted to determine effects of prodiamine on Florida betony and leatherleaf fern. Effects of Florida betony competition on leatherleaf fern frond yield and quality were also determined. Seed germination and growth and flowering of established Florida betony decreased with increasing prodiamine application rates; 4.5 kg ai ha-1or higher prevented seed germination and eliminated or nearly eradicated established betony one year after treatment. Prodiamine treatments up to 6.7 kg ai ha-1did not affect leatherleaf fern growth, frond yield (number, fresh weight) or quality (color, size, vase life). When leatherleaf fern and Florida betony were grown together in containers for 7 mo, fern frond yield and quality were reduced.
Varietal Tolerance of Rice (Oryza sativa) to Bromoxynil and Triclopyr at Different Growth Stages
Authors: Pantone Dan J. , Baker John B.
Published: March 2018

This study was conducted to determine the tolerance of three cultivars of rice (‘Lemont’, ‘Mars', and ‘Tebonnet’) to bromoxynil and triclopyr. The effects of two rates of application (the labeled rate and twice the labeled rate) at three different growth stages (two- to three-leaf stage, four- to five-leaf stage, and panicle initiation) on percent visible injury rating and percent grain yield reduction of rice were investigated. Percent visible injury ratings for triclopyr averaged across all rates and application times, were 15, 16, and 25% (LSD = 3%) for Tebonnet, Mars, and Lemont, respectively, whereas ratings for bromoxynil were 11, 8, and 7% injury (LSD = 2%). Tebonnet was more tolerant than Lemont to triclopyr with an average percent grain yield reduction, across treatments, of 6% compared with 9% for Mars and 12% for Lemont (LSD = 4%). Bromoxynil did not decrease the average yield of any of the three cultivars.
Sweet Cherry (Prunus avium) Response to Simulated Drift from Selected Herbicides
Authors: Al-Khatib Kassim , Parker Robert , Fuerst E. Patrick
Published: March 2018

This study evaluated the response of sweet cherry to different herbicides applied at rates simulating drift. Chlorsulfuron, thifensulfuron, bromoxynil, 2,4-D, glyphosate, and a combination of 2,4-D and glyphosate were applied on one side of one- and two-year-old established cherry trees at 1/3, 1/10, 1/33, and 1/100 of the maximum rate for small grain production. The order of herbicide phytotoxicity was chlorsulfuron > 2,4-D > glyphosate > 2,4-D + glyphosate > thifensulfuron > bromoxynil. Trees recovered from injury caused by all treatments except higher rates of chlorsulfuron, 2,4-D, and glyphosate. The herbicides caused characteristic symptoms, but some resembled disease, mineral deficiency, and environmental stress symptoms. Therefore, any allegations about herbicide drift based on chronic symptoms should be supported by analysis of plant tissue.
Phenology and Distribution of Red Horned Poppy (Glaucium corniculatum) in Oklahoma
Authors: Baughman Todd A. , Peeper Thomas F. , Baker Thomas K. , Weeks David L.
Published: March 2018

A survey conducted to determine the distribution of red horned poppy in western Oklahoma identified infestations in 14 Oklahoma and 3 Texas counties. Soil pH from infested fields ranged from 7.0 to 8.5. Red horned poppy grew as an annual, germinating in fall, spring, or summer. Plants that emerged in the fall survived −25 C, flowered in April and produced mature seed in June. Plants that emerged in April, flowered in June and produced mature seed in July. Corolla color varied from red to yellow with time of anthesis.
Remote Sensing of Broom Snakeweed (Gutierrezia Sarothrae) with Noaa-10 Spectral Image Processing
Authors: Peters Albert J. , Reed Bradley C. , Eve Marlen D. , McDaniel Kirk C.
Published: March 2018

Low-spatial resolution satellite imagery from the NOAA-10 polar-orbiting meteorological satellite was analyzed to determine if central New Mexico grasslands infested by broom snakeweed could be discriminated from unaffected areas. Distinctive phenological characteristics of broom snakeweed, including an early season growth flush and late season flowering, enable moderate to heavily infested areas to be separated from grasslands having few or no weeds present. The procedure used shows promise as a tool for locating and monitoring brown snakeweed and other weeds growing on shortgrass prairie.
Grain Rye Residues and Weed Control Strategies in Reduced Tillage Potatoes
Authors: Lanfranconi Luis E. , Bellinder Robin R. , Wallace Russell W.
Published: March 2018

Experiments were conducted to evaluate the effect of tillage, rye residue levels, and control strategies on weed suppression and potato yield. Reduced tillage (RT) yields in 1989 were lower than in conventional tillage (CT) due to high hairy galinsoga populations. However, in 1990, potato yields were greater in RT when early emerging weeds were suppressed. Increasing residue levels up to 2300 kg ha-1had no effect on weeds or yields in either year. In a separate study, preemergence herbicides (linuron plus metolachlor, 1.7 kg ai ha-1each) applied 10 d after planting (DAP) in reduced tillage controlled weeds for 6 wk, but efficacy decreased after hilling. Metribuzin applied postemergence (0.19 kg ai ha-1) 7 d after hilling controlled late germinating weeds. Potato yields were greatest when the preemergence herbicides were applied.
The Nettles
Authors: Mitich Larry W.
Published: March 2018

Nettles belong to the genus Urtica, in the Urticaceae, which includes about 30 species of herbs, shrubs, and trees of world-wide distribution (3, 12). These species have recognizable similarities but vary considerably in height - from 0.3 to 0.66 m to 2.6 or 3 m tall (15). Nettles have a peculiar notoriety. As the 17th century herbalist Nicholas Culpeper (5) wrote, “Nettles are so well known, that they need no description, they may be found by feeling for them in the darkest night.”
Summary of Outcomes and Recommendations from the First International Weed Control Congress
Authors: Combellack J. Harry , Friesen George
Published: March 2018

This “Outcomes Paper” was developed in response to one of the objectives of the First International Weed Control Congress:
Effective Kill of Trifluralin-Susceptible and -Resistant Green Foxtail (Setaria viridis)
Authors: Beckie Hugh J. , Morrison Ian N.
Published: March 2018

The response of susceptible (S) and resistant (R) green foxtail biotypes to increasing dosages of trifluralin, applied PPI in rapeseed and preemergence incorporated (PEI) in wheat, was investigated in field experiments in 1989 and 1990. Differences in response between the biotypes to PPI- and PEI-trifluralin were 7- and 12-fold, respectively, based on density and shoot biomass determinations 4 wk after emergence. Nine- and 14-times higher dosages of PPI- and PEI-trifluralin, respectively, were required to reduce R-seed production by 50% than to reduce S-seed production by the same amount. At the recommended trifluralin dosage in rapeseed (1.4 kg ha−1), the density of S-plants 4 wk after emergence was reduced by 84% compared with untreated plots, whereas the density of R-plants was reduced by only 4%. The effective kill (seed yield reduction) was 99% and 42%, respectively. At the recommended dosage in wheat (0.9 kg ha−1), the density of S-plants 4 wk after emergence was reduced by over 99% compared with less than 36% for R-plants. The effective kill was 97% and 14%, respectively. Based on determination of effective kill, the selection pressure of trifluralin on green foxtail is greater when the chemical is applied PPI in rapeseed than when applied PEI in wheat, even though initial density reductions are less in the former than the latter.
Effect of MSMA on Entireleaf Morningglory (Ipomoea Hederacea var. Integriuscula) Control with Postemergence Herbicides
Authors: Jordan David L. , McClelland Marilyn R. , Frans Robert E. , Kendig J. Andrew
Published: March 2018

Experiments were conducted from 1989 through 1991 to determine the effect of MSMA on efficacy of fluometuron, cyanazine, oxyfluorfen, lactofen, methazole, diuron, and linuron applied POST to entireleaf morningglory. In one set of experiments, applications were made at the cotyledon to three-leaf and four- to six-leaf stages of weed growth. In another set of experiments, applications were made at only one growth stage. Cyanazine, MSMA, or cyanazine plus MSMA were the most efficacious treatments, especially when application was delayed until the four- to six-leaf stage. Adding MSMA to all of the herbicides increased control of entireleaf morningglory, with the magnitude of improvement increasing as the application timing was delayed.
Perennial Sowthistle (Sonchus arvensis) Interference in Soybean (Glycine max) and Dry Edible Bean (Phaseolus vulgaris)
Authors: Zollinger Richard K. , Kells James J.
Published: March 2018

Field experiments were conducted in 1987 and 1988 to examine interference from a natural population of perennial sowthistle on soybean and dry edible bean. In 1987, an average of 78 and 90 perennial sowthistle shoots per m2in 71-cm (wide) crop row spacing reduced soybean and dry edible bean yield by 49% and 36%, respectively. In 1988, a year of less precipitation, an average density of 96 and 88 shoots per m2reduced soybean and dry bean yield by 87% and 83%, respectively. One cultivation 5 wk after planting increased crop yield and decreased perennial sowthistle density compared with no cultivation. Perennial sowthistle reduced seed weight, germination percentage, and seedling growth rate of seed produced by both crops. In the presence of perennial sowthistle, one cultivation resulted in improved seed quality compared with no cultivation.
DPX-PE350 Does Not Interact with Early-Season Insecticides in Cotton (Gossypium Hirsutum)
Authors: Jordan David L. , Frans Robert E. , McClelland Marilyn R.
Published: March 2018

Cotton tolerance of DPX-PE350 applied POST alone, mixed with acephate, carbaryl, or dimethoate applied at 220, 1100, or 280 g ai ha−1, respectively, or following aldicarb, disulfoton, or phorate applied in the seed furrow at 1.0, kg ai ha−1 was evaluated. DPX-PE350 at 170 g ae ha−1 did not adversely affect seed cotton yield, fiber length, fiber length uniformity, or micronaire but did decrease fiber strength. The insecticides did not alter cotton response to DPX-PE350. Entireleaf morningglory was controlled 92, 95, and 96% with DPX-PE350 applied POST at 56, 110, and 170 g ha−1, respectively. Mixing acephate, carbaryl, or dimethoate with DPX-PE350 did not affect control.
Wine Grape (Vitis viniferaL.) Response to Simulated Herbicide Drift
Authors: Al-Khatib Kassim , Parker Robert , Fuerst E. Patrick
Published: March 2018

Chlorsulfuron, thifensulfuron, bromoxynil, 2,4-D, glyphosate, and a combination of 2,4-D plus glyphosate were applied on newly planted and established ‘Lemberger’ wine grape at 1/3, 1/10, 1/33, and 1/100 of the maximum labelled rate in wheat or fallow to simulate exposure to drifted herbicides. All herbicides produced symptoms on grape but the most severe symptoms were with 2,4-D and the least severe with bromoxynil. Newly planted grape was more sensitive to herbicides than established grape. Although established grape recovered from injury caused by all treatments except 2,4-D and the highest rate of chlorsulfuron and glyphosate, newly planted grape recovered only from lower rates of bromoxynil. All herbicides resulted in diagnostic symptoms, but other symptoms were very similar to those caused by other stresses.
Selectivity of Pronamide and Trifluralin in Belgian Endive (Cichorium intybus)
Authors: Mersie Wondimagegnehu , Elliott Joycelyn
Published: March 2018

Field studies were conducted to determine the selectivity and efficacy of pronamide alone or with sethoxydim and trifluralin, in Belgian endive. Pronamide at 1.68 with sethoxydim or alone or at 2.24 kg ai ha−1controlled weeds better than trifluralin at 0.6 or 1.0 kg ai ha−1in the field. Pronamide at 2.24 kg ha−1was the best at controlling grass and broadleaf weeds season-long. In nutrient culture studies, Belgian endive roots were injured at 5 mg L−1of pronamide, whereas redroot pigweed and green foxtail were inhibited at 0.5 and 0.1 mg L−1, respectively. Shoot weights showed similar differences but were less sensitive than roots.
Horse Purslane (Trianthema portulacastrum) Control in Peanut (Arachis hypogaea)
Authors: Grichar W. James
Published: March 2018

Field experiments in 1988 and 1989 evaluated five POST herbicides alone or combined for horse purslane control in peanut. Acifluorfen, acifluorfen plus bentazon, pyridate plus 2,4-DB, and lactofen controlled more than 75% when rated up to 26 days after treatment (DAT). However at 67 DAT, acifluorfen alone, acifluorfen plus bentazon or 2,4-DB, or lactofen applied EPOST controlled horse purslane greater than 60% in 1988. In 1989, only 2,4-DB or pyridate plus 2,4-DB controlled horse purslane at least 70% at 116 DAT. Pyridate alone did not control horse purslane adequately.
Preemergence Herbicide Effects on Bermudagrass (Cynodon dactylon) Interference in Sugarcane (Saccharumspp. hybrids)
Authors: Richard E. P.
Published: March 2018

The effect of annual spring PRE applications of fenac, metribuzin, and terbacil on the competitiveness of sugarcane with bermudagrass during a 3-yr crop cycle was evaluated. For each herbicide treatment, bermudagrass was allowed to interfere with sugarcane during the growing season for 0, 1 (plant-cane crop only), 2 (plant-cane and first-ratoon crops), or 3 (plant-cane through second-ratoon crops) yr. Predicted total yields of cane from the three harvested crops was 3600 kg ha−1higher on average in plots maintained free of bermudagrass and treated with metribuzin than where fenac and terbacil were applied. Bermudagrass biomass increased with each growing season. Greatest biomass production occurred in the fenac plots and the smallest in terbacil plots. Bermudagrass did not reduce the predicted total yields of cane where metribuzin or terbacil was applied. With fenac, predicted total cane yields were 4, 7, and 11% lower than the weed-free control where bermudagrass interference was allowed for 1, 2, and 3 yr, respectively. Season-long bermudagrass interference in the fenac plots reduced actual cane yields 10% (plant-cane crop), 6% (first-ratoon crop), and 14% (second-ratoon crop) when compared with plots maintained free of bermudagrass for the entire growing season.
Weed and Corn (Zea mays) Responses to a Hairy Vetch (Vicia villosa) Cover Crop
Authors: Hoffman Melinda L. , Regnier Emilie E. , Cardina John
Published: March 2018

Field studies were conducted in 1990 and 1991 to determine the effects of corn planting date and hairy vetch control method on the efficacy of fall-planted hairy vetch as a weedsuppressive cover crop for no-till corn. Glyphosate controlled hairy vetch when applied at the early bud growth stage (April), but hairy vetch residue provided no weed control compared to the weedy check. Mowing was not an effective means of suppressing hairy vetch at the early bud stage. Untreated hairy vetch reduced weed biomass 96% in 1990 and 58% in 1991 but reduced yield over 76% in April-planted corn. There was no competition of untreated hairy vetch with corn when corn planting was delayed until May or June (mid- or late-bloom growth stages of hairy vetch). Corn planted in May into untreated hairy vetch yielded similarly to corn planted in a no-cover weed-free check.
Sequential Herbicide Treatments for Large Crabgrass (Digitaria sanguinalis) and Goosegrass (Eleusine indica) Control in Bermudagrass (Cynodon dactylon) Turf
Authors: Johnson B. Jack
Published: March 2018

Preemergence (PRE) and postemergence (POST) herbicides were sequentially applied to common bermudagrass over a two-year period to determine the lowest herbicide rates required to maintain acceptable large crabgrass and goosegrass control. Large crabgrass control was consistently higher in late August when MSMA at 2.2 kg ha−1was applied to plots previously treated with dithiopyr at 0.3 kg ha−1(99%) in 1991, and either pendimethalin at 1.1 kg ha−1(95%) or oxadiazon at 1.1 kg ha−1(94%) in 1992 than when either herbicide was applied alone (≤ 79%). Goosegrass control was also higher in late August when MSMA plus metribuzin at 2.0 + 0.14 kg ha−1was applied to plots treated with pendimethalin at 1.7 kg ha−1(71%) in 1991, with oxadiazon at ≤ 2.2 kg ha−1(≤ 89%) in 1992, and with dithiopyr at 0.4 kg ha−1(≤ 96%) both years than when the herbicides were applied alone. Diclofop at 1.1 kg ha−1applied alone as POST controlled ≥ 96% goosegrass throughout the two-year period.
Economic Assessments of Serrated Tussock (Nassella trichotoma) as a Pasture Weed
Authors: Vere David T. , Auld Bruce A. , Campbell Malcolm H.
Published: March 2018

Weeds reduce the livestock production from pastures and impose control costs on producers and governments. Economic assessments of pasture weed problems are required on and beyond the farm for planning private and public weed control. This requirement has several dimensions that can be used to demonstrate the economic effect of weeds and encourage weed control by the private and public sectors. This paper discusses the economic problems of pasture weeds and the procedures for multi-level economic assessments with a major pasture weed in Australia as an example, and demonstrates the important private and social economic benefits from controlling this weed.
Enhanced Activity of Nicosulfuron in Combination with Soil-Applied Insecticides in Corn (Zea mays)
Authors: Rahman Anis , James Trevor K.
Published: March 2018

Field experiments were conducted to determine the occurrence and the extent of interaction among four soil-applied organophosphate insecticides and the sulfonylurea herbicide nicosulfuron applied POST to corn. Nicosulfuron was damaging to corn when the crop was planted with terbufos, phorate, or fonofos applied into the open furrow. Terbufos was the most damaging and also caused damage when applied as a 17-cm band prior to or after closing the furrow, with or without incorporation. Phytotoxic symptoms appeared within 3 d of application of nicosulfuron and damage increased as the rate was increased from 53 g ai/ha to 140 g ai/ha. However, despite severe damage of up to 50% recorded in some terbufos combinations, all plants had completely recovered within 4 wk and none of the treatments had any effect on grain yield or crop maturity. No damage resulted from nicosulfuron when corn was planted with the insecticide chlorpyrifos. Efficacy data of nicosulfuron on the main weeds present are also reported.