bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Drift Retardant Adjuvants on Spray Droplet Size of Water and Paraffinic Oil Applied at Ultralow Volume
Authors: Hanks James E
Published: March 2018

Adjuvants were evaluated to determine the effect on increasing spray droplet size and reducing the amount of spray dispensed in small driftable size particles when applying water and paraffinic oil at ultralow volume. Spray solutions were applied with an air-assist system at liquid flow rates of 28 and 56 ml/min and atomized with 14, 28, 42, 56, and 84 kPa of air pressure. Water and paraffinic oil were applied alone and with two drift retardant adjuvants mixed individually in each. The two water soluble adjuvants were mixed at concentrations of 0.25, 0.50, 0.75, 1.0, and 2.0%; oil soluble adjuvants were applied at 0.125, 0.25, and 0.50%. Adjuvants used in water and oil were effective at increasing droplet size and reducing the amount of liquid dispensed in small driftable size particles. Effectiveness of the adjuvants decreased as air pressures increased, with water soluble adjuvants being more susceptible to air pressure. Volume median diameters > 200 μm with water could be achieved without adjuvants; whereas with oil, an adjuvant was required.
Carpeted Roller Application of Herbicides for Larkspur (Delphiniumspp.) Control
Authors: Bunderson F. Brent , Ralphs Michael H. , Evans John O. , Call Christopher A. , Nielsen Darwin B.
Published: March 2018

A carpeted roller applicator and broadcast sprayer were compared for application of glyphosate, metsulfuron, and picloram to control duncecap and tall larkspur on mountain range sites in southern Idaho and central Utah, respectively. Glyphosate was the most effective herbicide, controlling 96% of both larkspur species when applied by the sprayer and 78% when applied by the roller. There was no difference in larkspur control between application methods using metsulfuron or picloram. Application of herbicides by the carpeted roller was less detrimental to forbs compared to the sprayer, and the roller application of glyphosate did not reduce grass cover. Grass cover doubled following treatments with picloram and metsulfuron.
Comparing Techniques for Quantifying Haloxyfop Absorption and Translocation in Johnsongrass (Sorghum halepense)
Authors: Peregoy Robert S. , Kitchen Lynn M. , Griffin James L. , Braverman Michael P.
Published: March 2018

In comparing laboratory techniques, absorption and translocation of14C-haloxyfop was not affected by droplet size or treatment area. Treatment with haloxyfop prior to application of14C-haloxyfop resulted in 27% less translocation of radiolabel from the treated leaf and 43% less acropetal translocation compared with plants receiving only the radiolabeled herbicide. Leaf washing with distilled water, distilled water plus haloxyfop, distilled water plus surfactant, distilled water plus haloxyfop plus surfactant, 100% ethanol, 100% methanol, or methanol:water (1:1 v/v) removed similar amounts of radiolabel, while chloroform removed more. Considering some of the differences found with these techniques, pretreatment with nonlabeled herbicide should be routine practice and water used as the standard solvent.
Weed Control in Rice (Oryza sativa) with Quinclorac and Bensulfuron Coating of Granular Herbicides and Fertilizer
Authors: Braverman Michael P.
Published: March 2018

Weed control with thiobencarb, molinate, or fertilizer granules coated with quinclorac or bensulfuron was evaluated in 1992 and 1993. With thiobencarb or fertilizer granules, less than 55% control of 4-leaf junglerice was obtained, regardless of additional herbicide coating. Coating thiobencarb or fertilizer granules with quinclorac at 550 g ai/ha increased junglerice control, but was not satisfactory. Molinate granules at 4.4 kg ai/ha controlled junglerice at least 81% and improved rice yields over fertilizer or thiobencarb granules. Fertilizer coated with bensulfuron at 111 g ai/ha controlled ducksalad 86 to 96%.
Response of Soybean (Glycine max) and Rice (Oryza sativa) in Rotation to AC 263,222
Authors: Grymes Charles F. , Chandler James M. , Nester Paul R.
Published: March 2018

Field studies were conducted in 1991 and 1992 to evaluate the response of soybean and the subsequent rice crop to AC 263,222 applied alone and in tank mixtures with imazethapyr or imazaquin. In 1991, 18, 36, and 70 g ai/ha of AC 263,222 visibly stunted soybean 9, 19, and 35%, respectively. Adding imazethapyr at 36 g/ha or imazaquin at 70 g/ha to AC 263,222 in a tank mixture did not increase soybean response compared to AC 263,222 alone. Soybean yield was not reduced by any treatment. In 1992, 14 g/ha of AC 263,222 alone or in tank mixtures damaged soybean 38% or greater. In one study, rice was injured the year following application of AC 263,222 alone and in tank mixtures. Rice yield was reduced by 70 g/ha of AC 263,222 alone and by 36 g/ha of AC 263,222 when tank mixed with 36 g/ha of imazethapyr.
Weed Control Efficacy and Pinto Bean (Phaseolus vulgaris) Tolerance to Early Season Mechanical Weeding
Authors: Vangessel Mark J. , Wiles Lori J. , Schweizer Edward E. , Westra Phil
Published: March 2018

An integrated approach to weed management in pinto bean is needed since available herbicides seldom adequately control all weed species present in a field. A two-year study was conducted to assess weed control efficacy and pinto bean tolerance to mechanical weeding from a rotary hoe or flex-tine harrow at crook, unifoliolate, and trifoliolate stages of bean development. Weed control was similar for both implements and all timings in 1993. In 1994, mechanical weeding at trifoliolate and both crook and trifoliolate stages controlled more weeds than at other growth stages, regardless of type of implement. Using the flex-tine harrow reduced pinto bean stand, but results based on growth stage were not consistent each year. Damage to pinto bean hypocotyls and stems was observed with the flex-tine harrow used at both crook and trifoliolate stages in 1994. Rotary hoeing did not reduce pinto bean stand or cause injury. Yield and seed weight did not differ among treatments in either year.
Use of Remote Sensing for Detecting and Mapping Leafy Spurge (Euphorbia esula)
Authors: Everitt James H. , Anderson Gerald L. , Escobar David E. , Davis Michael R. , Spencer Neal R. , Andrascik Roger J.
Published: March 2018

Leafy spurge is a troublesome, exotic weed in the northern Great Plains of the United States. Leafy spurge produces showy yellow bracts during June that give this weed a conspicuous appearance. A study was conducted to determine the feasibility of using remote sensing techniques to detect leafy spurge in this phenological stage. Study sites were located in North Dakota and Montana. Plant canopy reflectance measurements showed that leafy spurge had higher visible (0.63- to 0.69-μm) reflectance than several associated plant species. The conspicuous yellow bracts of leafy spurge gave it distinct yellow-green and pink images on conventional color and color-infrared aerial photographs, respectively. Leafy spurge also could be distinguished on conventional color video imagery where it had a golden yellow image response. Quantitative data obtained from digitized video images showed that leafy spurge had statistically different digital values from those of associated vegetation and soil. Computer analyses of video images showed/that light reflected from leafy spurge populations could be quantified from associated vegetation. This technique permits area estimates of leafy spurge populations. Large format conventional color photographs of Theodore Roosevelt National Park near Medora, ND were digitized and integrated with a geographic information system to produce a map of leafy spurge populations within the park that can be useful to monitor the spread or decline of leafy spurge.
Edible Weeds in Morocco
Authors: Tanji Abbes , Nassif Fatima
Published: March 2018

Morocco has a large number of edible weeds, but seventeen are mostly eaten by the population, collected for sale in different provinces, or even exported. Eight weeds have edible shoots while the others have edible stems, fruits, roots, flowers, or petioles. Thirteen weed species are marketed either seasonally or throughout the year and generate money for the people. Morocco's tassel grapehyacinth bulbs and products extracted from pennyroyal mint are exported. Further research should focus on the nutritive value of these weeds and their economic role in the country.
Wildfire Suppression—A Paradigm for Noxious Weed Management
Authors: Dewey Steven A. , Jenkins Michael J. , Tonioli Robert C.
Published: March 2018

The spread of noxious weeds on rangeland and forests in the United States has been described as a raging biological wildfire. This analogy applies to aspects of spread, impact, and control of weeds. Patterns and means of spread are similar. Noxious weeds and wildfires can dramatically change natural plant communities, alter distribution and species composition of wildlife populations, damage watersheds and increase soil erosion, and adversely affect recreation and aesthetic values. Wildfire management involves prevention, early detection, timely control, and site rehabilitation; elements which are also the foundation of sound weed management. Principles and practices associated with wildfire suppression can be used to illustrate many weed science fundamentals, and to improve weed management programs. Federal land management agencies are directed to train employees in effective weed management and to increase public awareness about noxious weeds. Most agency employees are familiar with wildfire management; knowledge which could be useful in teaching weed management principles. Fire prevention could serve as a model to promote greater public awareness of the impact of noxious weeds and the need for weed prevention and early detection.
Effects of Ultra-low Volume Application on Herbicide Efficacy Using Oil Diluents as Carriers
Authors: Bohannan Daren R. , Jordan Thomas N.
Published: March 2018

The efficacy of postemergence herbicide applications was evaluated in the greenhouse and the field in 1993 and 1994, using variables of carrier volume and diluent type. Ultra-low volume (ULV) applications of herbicides using an air-assisted sprayer calibrated at a volume of 9.4 L/ha were compared to 94 and 187 L/ha applications with a conventional hydraulic system. In greenhouse studies, reduced rates of sethoxydim, clethodim, fluazifop-P, and quizalofop were used to compare the effects of carrier types and volumes on their efficacy to yellow foxtail. All herbicides applied in oil diluents at 9.4 L/ha, with the exception of fluazifop-P and quizalofop applied in soybean oil, provided better yellow foxtail control than when applied in water at 94 and 187 L/ha. Sethoxydim and clethodim applied at 25 and 16% of the recommended rate, respectively, provided over 90% control in both petroleum oil and methylated seed oil. Reduced rates of glyphosate in petroleum oil or soybean oil were more effective at reducing bermudagrass growth than in water or methylated seed oil. Activity of glyphosate in methylated seed oil was no more effective than in water. Field experiments were conducted to study the efficacy of ULV applications of sethoxydim, clethodim, fluazifop-P, imazethapyr, and bentazon. Rates of the postemergence grass herbicides could be reduced by applying them at ULV in oil diluents while maintaining annual grass control equal to that achieved with higher herbicide rates in larger volumes of water. Control of annual grasses and annual broadleaf weeds with bentazon and imazethapyr applied at ULV were inconsistent and did not provide acceptable weed control. This may be partially due to the poor suspension of these herbicides in oil carriers.
Surfactants and Oil Adjuvants with Nicosulfuron
Authors: Nalewaja John D. , Praczyk Tadeusz , Matysiak Robert
Published: March 2018

Nicosulfuron is used with surfactant or oil adjuvant to enhance postemergence efficacy. Yellow foxtail fresh weight reduction from nicosulfuron varied from 10 to 92% depending upon surfactant in greenhouse experiments. Oil adjuvants differed in enhancement of nicosulfuron phytotoxicity to yellow foxtail or large crabgrass with methylated canola oil being most effective, followed by vegetable oils, and petroleum mineral oil as least effective. Percentage and type of surfactant used as an emulsifier in an oil adjuvant was important to nicosulfuron phytotoxicity especially when applied with the less effective oils, but was of minimal importance when applied with methylated canola oil. Adjuvant effectiveness was directly related to nicosulfuron absorption. These data indicated that recommendations for adjuvants to maximize nicosulfuron phytotoxicity should be limited to specific products.
Short-Term Split Application Effects of Grass-Specific Herbicides on Quackgrass (Elytrigia repens) Under Field Conditions
Authors: Harker K. Neil
Published: March 2018

Field experiments were conducted at the Lacombe Research Station from 1989 to 1991 to determine if short-term, split applications of grass-specific herbicides would improve quackgrass control relative to single applications. Quackgrass infested plots were planted to canola the first year and barley the following year. Glyphosate applied at 880 g/ha controlled quackgrass to a greater extent and for a longer time period than any of the grass-specific herbicides. In contrast to glyphosate, none of the grass-specific herbicides controlled quackgrass 1 yr after treatment. Quackgrass control with sethoxydim or fluazifop-P was usually similar when applied as single or short-term, split applications. In contrast, quizalofop often provided better quackgrass control and higher crop yields when short-term, split applications were compared to a single application with the same total amount of quizalofop. However, the extent of increased quackgrass control is difficult to justify due to increased application costs and inconvenience.
Compatibility and Efficiency of In-Row Cultivation for Weed Management in Corn (Zea mays)
Authors: Vangessel Mark J. , Schweizer Edward E. , Lybecker Donald W. , Westra Phil
Published: March 2018

Information on the effects of multiple weed management tactics in corn is needed to develop integrated weed management systems. The effectiveness and compatibility of an in-row cultivator as compared to a standard interrow cultivator used with reduced rates of a soil-applied herbicide, rotary hoeing, and/or a bioeconomic model for POST herbicide selection was examined. Weed control with a single rotary hoeing at corn emergence controlled annual weeds similarly to two rotary hoeings. One-third recommended use rate of alachlor controlled weeds similarly to a two-thirds rate. Reduced rates of alachlor controlled more weeds than rotary hoeing over 2 yr. The in-row cultivator required early-season weed control (rotary hoeing or reduced alachlor rate) for optimum efficacy. The in-row cultivator provided better weed control than the standard cultivator while the cost of operating the two cultivators was similar. Thus, the in-row cultivator was more efficient than the standard cultivator. Furthermore, less intensive early-season weed control was required with the in-row cultivator for maximum weed control as compared to the standard cultivator. Rotary hoeing plus the in-row cultivator provided similar weed control to other weed management tactics that required both soil-applied and POST herbicides. Gross margin was influenced more by corn yield than cost of weed management tactics.
Comparison of Conventional and Alternative Nursery Weed Management Strategies
Authors: Calkins James B. , Swanson Bert T.
Published: March 2018

Soil cultivation (3 to 5 times/yr) and herbicide management (oxadiazon, 3.92 kg ai/ha), agricultural standards for reducing weed competition, were compared to three alternative nursery field management systems regarding weed suppression: ‘Norcen’ bird's-foot trefoil companion crop, ‘Wheeler’ winter rye cover crop/mulch, and grass sod (80% ‘Eton’ perennial ryegrass and 20% ‘Ruby’ red fescue). Field management treatment had a significant effect on observed weed populations. Weed densities were also subject to yearly variations caused by climate and endogenous weed life cycles. Herbicide management (oxadiazon) consistently provided the best control of undesired vegetation (0.3 weeds/m2) followed by the grass sod (0.7 weeds/m2), Wheeler rye cover crop/mulch (1.7 weeds/m2), Norcen bird's-foot trefoil companion crop (8.6 weeds/m2), and cultivated (55.7 weeds/m2) treatments, respectively. Although the grass sod treatment provided excellent control of undesired vegetation, as an alternative to cultivation and herbicide use, it proved to be excessively competitive with the nursery crop. The bird's-foot trefoil treatment quickly became infested with broadleaf weeds the eradication of which proved difficult. The Wheeler winter rye cover crop/mulch field management system provided acceptable weed control combined with other beneficial effects on the plant/soil environment. Results support the effectiveness of Wheeler winter rye and perhaps other allelopathic cover crop/mulch systems in controlling undesired vegetation in horticultural field production systems.
Tolerance of Four Seeded Common Bermudagrass (Cynodon dactylon) Types to Herbicides
Authors: Johnson B. Jack
Published: March 2018

The tolerance of four established seeded common bermudagrass types to PRE and POST herbicides was evaluated. Pendimethalin at 3.4 kg ai/ha, oryzalin at 3.4 kg ai/ha, and dithiopyr at 0.8 kg ai/ha suppressed the quality of bermudagrass 8 to 16% more than oxadiazon at 4.5 kg ai/ha and prodiamine at 0.8 kg ai/ha. When interactions of PRE herbicide by bermudagrass cultivars occurred, oxadiazon, prodiamine, and pendimethalin suppressed the quality of ‘common’ and ‘Sahara’ 18 to 20% more than ‘Tropica’; oryzalin suppressed the quality of common and Sahara 11 to 18% more than Tropica; and dithiopyr suppressed the quality of common and Sahara 9% more than Tropic and ‘Cheyenne.’ The quality of Cheyenne treated with either oxadiazon, prodiamine, or pendimethalin was generally intermediate to the other cultivars. When POST herbicides by bermudagrass cultivar interactions occurred, MSMA plus metribuzin applied at 2.2 + 0.1 kg ai/ha injured common and Sahara an average of 10 to 12% higher than Tropica during 1993 and 1994. Diclofop applied at 1.1 kg ai/ha and dicamba applied at 0.6 kg ae/ha injured common 9 to 12% higher than Tropica. There was no difference in injury to cultivars when treated with 2,4-D plus mecoprop plus dicamba at 1.1 + 0.6 + 0.1 kg ae/ha. In general, Tropica was affected least by PRE and POST herbicide treatments, while common and Sahara cultivars were affected the most.
Herbicide Resistance: Where are we? How did we Get here? Where are we Going?
Authors: Shaner Dale L.
Published: March 2018

The first significant cases of herbicide-resistant weed populations were to the triazines in the 1970s. In the last 10 years there has been an increase in the number of weed populations that have become resistant to an array of herbicides. In some of these cases, like rigid ryegrass in Australia, a multitude of resistant biotypes has evolved with different mechanisms of resistance. If the present trend continues, the number of herbicides effective on certain weed species may diminish rapidly. To counteract this trend, industry has organized a number of intercompany working groups to specifically address the development of resistance and to implement plans to manage resistance. University and extension along with industry personnel across the world have begun educating growers on resistance management. However, this effort needs to be intensified to find new solutions for controlling weeds through the use of integrated weed management practices that incorporate new and established herbicides with cultural, mechanical, and biological control methods. The challenge is to develop cost effective, environmentally sustainable programs for weed control while maintaining the present efficiency in food and fiber production so that needs of an ever expanding human population can be met.
Predicting the Evolution and Dynamics of Herbicide Resistance in Weed Populations
Authors: Maxwell Bruce D. , Roush Mary Lynn , Radosevich Steven R.
Published: March 2018

Herbicide resistance jeopardizes the usefulness of valuable chemical tools and, therefore, weed management in many crop systems. Models must be developed to evaluate management tactics that prevent, delay, or reduce resistance. The complexity of biological processes involved in herbicide resistance also requires models to focus research and to integrate experiments. A population model was developed that improves upon previous attempts to predict herbicide resistance dynamics. The model incorporates plant population demographics with the Hardy-Weinberg concept for gene segregation. The model simulates the evolution, spread, and subsequent dynamics of resistance in the presence and absence of a herbicide. Analysis of model simulations identified two sets of biological processes as key factors in the evolution and dynamics of herbicide-resistant weed populations. These are processes that influence ecological fitness and gene flow. Several options are suggested as examples for the management of resistant weed populations.
Effect of AC 222,293 Soil Residues on Rotational Crops
Authors: Fellows Gary M. , Fay Peter K. , Carlson Gregg R. , Stewart Vern R.
Published: March 2018

AC 222,293, a postemergence herbicide for wild oat control in wheat, barley, and sunflower, was applied at five rates at three locations in Montana in the spring of 1985. Twelve and 11 crops were seeded into treated soil in 1985 and 1986, respectively. Sugarbeet, lentil, and rape were injured by residual levels of AC 222,293 14 months after application. Injury was significantly greater at one location, indicating herbicide bioavailability varied by location. Soil pH was correlated negatively with crop injury, indicating the herbicide persists longer on lower pH soils.
Herbicide Combinations for Postemergent Weed Control in Safflower (Carthamus tinctorius)
Authors: Blackshaw Robert E. , Derksen Douglas A. , Muendel H.-Henning
Published: March 2018

Greenhouse and field studies were conducted to examine the interaction of sethoxydim or fluazifop-P tank mixed with chlorsulfuron or thiameturon for selective weed control in safflower. Under greenhouse conditions, the addition of chlorsulfuron to sethoxydim or fluazifop-P slightly improved the control of green foxtail above that achieved with either herbicide alone. Control of wild oat and wild mustard was similar with the tank mixes and each herbicide alone. In the field, control of wild oat with sethoxydim or fluazifop-P was not altered by adding chlorsulfuron or thiameturon in tank mixes. Similarly, control of common lambsquarters and wild mustard with chlorsulfuron or thiameturon was not affected by adding either sethoxydim or fluazifop-P in tank mixes. Plant height, date of flowering, seed yield, and quality data indicated that safflower tolerated these herbicides applied alone or in combination. Sethoxydim or fluazifop-P tank mixed with chlorsulfuron or thiameturon provide a postemergent alternative for selective control of grass and broadleaf weeds in safflower.
Significance and Distribution of Herbicide Resistance
Authors: Holt Jodie S. , Lebaron Homer M.
Published: March 2018

Herbicide-resistant weed species have become widespread in recent years. Fifty-five weed species, including 40 dicots and 15 grasses, are known to have biotypes resistant to the triazine herbicides. One or more resistant species have arisen in 31 states of the United States, four provinces of Canada, 18 countries in Europe, and Israel, Japan, Australia, and New Zealand. Resistance to other classes of herbicides is more restricted in distribution and recent in detection but is becoming more widespread. Trifluralin resistance has spread in the southeastern United States and has been detected in Canada, while 11 species with biotypes resistant to paraquat have been reported around the world. Diclofop-methyl-resistant weed species are problems in cereal production in Australia and have been found in Oregon, South Africa, and the United Kingdom. Resistance to the substituted ureas also is present in the United Kingdom, West Germany, and Hungary. Within the last 2 yr, biotypes of at least four weed species resistant to the sulfonylurea herbicides have arisen following several annual applications of these herbicides in wheat. Some resistant biotypes have multiple resistance to different classes of herbicides, which greatly exacerbates the threat of resistance. Herbicide resistance has reached the level where more concerted efforts are needed in research, education, and development of effective management strategies to preserve herbicides as essential tools of agricultural technology.
Mechanisms of Paraquat Resistance
Authors: Fuerst E. Patrick , Vaughn Kevin C.
Published: March 2018

Ten weed species have developed resistance to paraquat. Evidence supporting two potential mechanisms of resistance has been reported in several species. Resistance may be due to the rapid sequestration of paraquat thus reducing levels of paraquat at the site of action in the chloroplast; alternatively, resistance may be due to the rapid enzymatic detoxification of superoxide and other toxic forms of oxygen.
Modelling the Effectiveness of Herbicide Rotations and Mixtures as Strategies to Delay or Preclude Resistance
Authors: Gressel Jonathan , Segel Lee A.
Published: March 2018

Herbicide-resistant populations have evolved only in monoculture and/or monoherbicide conditions at predictable rates for each compound and weed. No populations of triazine-resistant weeds have appeared in corn where rotations of crops and herbicides or herbicide mixtures were used. This is due to the greatly reduced competitive fitness of the resistant individuals, which could be expressed only during rotational cycles, and also to the greater sensitivity of resistant individuals to other herbicides, pests, and control practices (“negative cross-resistance”). The model presented here describes how an understanding of all of these factors can provide strategies to decrease the frequency of the resistant individuals during rotation. Rotations or mixtures may not delay the rate of appearance of resistance to inhibitors of acetolactate synthase (ALS), where the fitness of resistant biotypes is claimed to be near normal. The best way to delay resistance to ALS inhibitors is to use those compounds with less persistence so that the selection pressure will be lowered. Too little is known about the frequency of resistance to other herbicides with target-site resistance–to dinitroanilines, to acetyl CoA carboxylase inhibitors, or to those situations where a single enzyme system confers resistance to a broad spectrum of seemingly unrelated herbicides.
Dandelion (Taraxacum officinale) Use by Cattle Grazing on Irrigated Pasture
Authors: Bergen Peter , Moyer James R. , Kozub Gerald C.
Published: March 2018

Hereford cows and their spring-born calves grazed an irrigated grass pasture containing about 13% dandelion based on dry weight yield. Grazing treatments were 1) no grazing, 2) 4 days of grazing just before clipping, and 3) long-term grazing just before clipping. In clippings taken in June and July after the grazing treatments, the percentage dandelion in the forage was similar in all three grazing treatments, indicating that cattle used dandelion as readily as grass. The protein and mineral contents of dandelion were at appropriate levels to meet the established requirements of beef cattle.
Effects of Additives on Efficacy, Uptake, and Translocation of Chlorimuron Ethyl Ester
Authors: Fielding Robert J. , Stoller Edward W.
Published: March 2018

Effects of a 28% N solution containing urea and ammonium nitrate (28% UAN) and a nonionic surfactant on efficacy, uptake, and translocation of chlorimuron ethyl ester in soybean and broadleaf weeds were investigated. Chlorimuron applied postemergence at 8.8 and 13 g ai/ha with either nonionic surfactant at 0.25% (v/v), 28% UAN at 9.4 L/ha, or nonionic surfactant plus 28% UAN controlled weeds better than without additives. Chlorimuron with nonionic surfactant and with 28% UAN controlled weeds similarly but with 28% UAN injured soybeans least. Chlorimuron with nonionic surfactant plus 28% UAN controlled velvetleaf best but injured soybeans most. Less than 2% of applied14C-chlorimuron was absorbed in velvetleaf 84 h after treatment (HAT) when no additive was present, but adding nonionic surfactant, 28% UAN, and nonionic surfactant plus 28% UAN resulted in 21, 9, and 32% uptake, respectively, 84 HAT. Nonionic surfactant plus 28% UAN also increased translocation (primarily acropetal) of the14C. Adding 28% UAN increased14C-chlorimuron uptake in velvetleaf grown at low fertility but had no effect under high fertility.
Chemical Control of Giant Burreed (Sparganium eurycarpum) in Wild Rice (Zizania palustris)
Authors: Clay Sharon A. , Oelke Ervin A.
Published: March 2018

The response of giant burreed to bentazon, propanil, 2,4-D (amine salt), and 2,4-D plus crop oil (0.5% v/v) was evaluated at the 2-aerial-leaf stage of wild rice. Bentazon, 2,4-D, and 2,4-D plus crop oil at 1.1 kg/ha or more in 1984, and propanil and 2,4-D plus crop oil at 4.5 kg/ha in 1985 reduced giant burreed dry weight. Generally, herbicide rates above 1.1 kg/ha injured wild rice and reduced yields compared to weed-free controls. None of the study treatments resulted in effective giant burreed control without unacceptable injury to wild rice.
Preplant-Postemergence Herbicides for Legume Cover-Crop Control in Minimum Tillage Systems
Authors: Griffin James L. , Dabney Seth M.
Published: March 2018

Field studies were conducted to compare preplant-postemergence-applied paraquat, glyphosate, SC-0224, and HOE-39866 on subterranean clover, crimson clover, and hairy vetch cover crops. Subterranean clover control with paraquat at 1.1 kg ai/ha was about 80 and 100% when applied in early April and early May, respectively, regardless of spray volume (190 vs. 370 L/ha). Glyphosate and SC-0224 at 1.7 and 2.8 kg ai/ha applied in April controlled about 53% of subterranean clover. Subterranean clover control with HOE-39866 at 0.8 kg ai/ha applied in April was excellent. Paraquat at 0.6 kg ai/ha and HOE-39866 at 0.8 kg/ha regardless of application time controlled both crimson clover and hairy vetch. Grain sorghum and soybean yields following the legume cover crops generally were similar for the herbicide treatments.
Behavior of Dinitroaniline Herbicides in Soils
Authors: Weber Jerome B.
Published: March 2018

The behavior and dissipation of 26 dinitroaniline herbicides in soils are reviewed. Some of the compounds also are referred to as dinitrotoluidines, -benzen(e)amines, -benzenediamines, -cumidines, -benzenesulfonamides, -acetophenones, and sulfonylsulfilimines. All dinitroanilines are sorbed to soil particles, particularly to organic or humic substances, and are nearly immobile in soils. Soil K values range from 7 to 117 and KOCvalues range from 80 to 471 000. Compounds with vapor pressures greater than 50 × 10-6mm of Hg at ambient temperatures were reported to volatilize and diffuse through, and out of, the soil in significant amounts, depending on temperature and moisture conditions. Greater losses occurred from warm, moist soils than from cool, dry soils. Photodecomposition of dinitroanilines on soil surfaces was low but occurred when the chemicals were present in the vapor state or in aqueous solutions. Bioavailability of the chemicals decreased as organic matter contents of the soils increased. Dinitroaniline herbicides were degraded primarily by soil microorganisms, and fungi were the major organisms involved. Degradation proceeded faster under anaerobic conditions than under aerobic conditions and faster under warm, moist conditions than under cool, dry conditions. Half-life values for dinitroanilines ranged from 7 to 27 days under anaerobic conditions and from 19 to 132 days under aerobic conditions. The chemicals did not affect most soil microflora; and any significant effects reported were of short duration.
Combining Cultural Practices and Herbicides to Control Wild-Proso Millet (Panicum miliaceum)
Authors: Harvey R. Gordon , McNevin Gregory R.
Published: March 2018

Field studies evaluated the effects of crop, crop rotation, planting date, row spacing, no-till planting, and herbicides on wild-proso millet control. Benefin and EPTC reduced wild-proso millet biomass in new seedings of alfalfa, and the combination of herbicides and forage harvest prevented wild-proso millet seed production in that crop. Wild-proso millet seedling populations were reduced and corn yields increased when corn followed 1 to 4 yr of alfalfa. Apparent effectiveness of herbicides in corn increased after cropping with alfalfa. Germination of buried wild-proso millet seed decreased approximately 90% after 54 months which is equivalent to 4-yr prior cropping to alfalfa. Wild-proso millet control and field and sweet corn yields increased when the crops were planted late season (May 17) rather than early season (April 27). Planting sweet corn in rows spaced 76 cm rather than 108 cm apart also increased sweet corn yields. EPTC plus dichlormid (EPTC+) plus cyanazine always controlled wild-proso millet equal to or better than EPTC+alone. When field corn was planted no-till into killed alfalfa sod, combinations of pendimethalin plus simazine and pendimethalin plus cyanazine provided the best wild-proso millet control and corn yields. But the following year when corn was no-till planted into corn stubble of the identical plots, wild-proso millet control from the same treatments tended to be lower and corn yields were reduced.
Yarrow – the Herb of Achilles
Authors: Mitich Larry W.
Published: March 2018

Common yarrow (Achillea millefolium L. ♯3 ACHMI) was called Achillea by the ancient Greeks (4), referring to the all-but-invulnerable Achilles who stormed Troy around 1200 B.C. According to legend (12), the centaur physician Chiron taught Achilles the benefits of this plant; the warrior then used yarrow to stanch the wounds of his compatriots during the siege of Troy. In fact, Achilles' knowledge of this herb may have provided him with the invulnerability which catapulted him into legend. Since the time of Achilles and the Trojan War more than 3000 yr ago, yarrow has been used to heal wounds and cure other ailments. Yarrow's legendary curative powers have a basis in chemical fact, as we will see.
Biology of Host Range Testing for Biocontrol of Weeds
Authors: Weidemann Gregory J. , Tebeest David O.
Published: March 2018

The determination of host range is an important component in developing a plant pathogen for use as a bioherbicide. The safety of non-target economic and wild plants must be assured before experimental release and commercial use. In contrast to other methods of weed control, the genetic variability and genetic stability of both the weed and the biological control agent must be considered. Schemes to determine host range generally assume a close phylogenetic relationship between the weed host and its co-evolved pathogens. Therefore, testing generally is based on inoculation of genetically related plant species and progresses to more distantly related species until the host range is circumscribed. Several potential weaknesses in these schemes will be illustrated with examples using specific biological control agents. Future tests must place greater emphasis on testing taxa representing the full range of genetic diversity within the biogeographic area of intended use.
Control of Venice Mallow (Hibiscus trionum) in Corn (Zea mays) and Onions (Allium cepa)
Authors: Westra Philip , Pearson Calvin H. , Ristau Randall
Published: March 2018

Postemergence herbicides alone and in combination were evaluated for Venice mallow control in corn and onion in Colorado during 1986 and 1987. Season-long control of 88 to 98% in corn was obtained with bromoxynil plus cyanazine or atrazine; 2,4-D amine plus dicamba or bromoxynil; or linuron, bromoxynil, or dicamba applied alone. Oxyfluorfen plus bromoxynil in a split application controlled Venice mallow 80 to 99% all season in onions. Uncontrolled Venice mallow caused higher yield reductions in onions than in corn.
Low-Rate Applications of Herbicides in Conventional and Reduced Tillage Potatoes (Solanum tuberosum)
Authors: Wallace Russell W. , Bellinder Robin R.
Published: March 2018

Linuron, metribuzin, oryzalin, and metolachlor were applied at recommended (1X) and two-thirds (0.67X) rates to evaluate control of redroot pigweed and common lambsquarters in conventional and rye-stubble reduced-tillage potato production systems. Regardless of tillage, common lambsquarters control was satisfactory during both seasons at both rates of linuron, metribuzin, and oryzalin. Redroot pigweed control by these three herbicides, although excellent in 1988, was poor in RT plots during 1987. Yields did not differ between tillage systems. Reduced weed control with metolachlor during both seasons, and possible crop injury with linuron in 1987 resulted in significant yield reductions.
Enhancement of Soybean (Glycine max) Injury and Weed Control by Thifensulfuron-Insecticide Mixtures
Authors: Ahrens William H.
Published: March 2018

Combinations of thifensulfuron with carbaryl, chlorpyrifos, malathion, and methomyl caused soybean injury that exceeded the expected injury based on effects of herbicide and synergists applied alone. Thifensulfuron-induced injury and growth reductions generally increased as insecticide rates increased from 140 to 560 g ai ha-1. TBPT and fenarimol also synergistically enhanced thifensulfuron injury in soybeans. Yellow foxtail control by thifensulfuron was enhanced slightly by all insecticides except carbaryl. Insecticides did not enhance kochia control by thifensulfuron.
Weed Control by Subterranean Clover (Trifolium subterraneum) Used as a Living Mulch
Authors: Enache Adrian J. , Ilnicki Richard D.
Published: March 2018

Subterranean clover as a living mulch was evaluated for weed control and its effect on field corn silage and grain yield in 1986 to 1988. Treatments included combinations of subterranean clover living mulch, rye dead mulch, and no mulch with three superimposed tillage practices (conventional, minimum, and no-tillage). Results indicated that subterranean clover living mulch effectively controlled ivyleaf morningglory. Little control of fall panicum was obtained in 1986; however, living mulch combinations effectively controlled fall panicum in 1987 and 1988. Weed biomass was reduced significantly by all living mulch combinations, but all other combinations resulted in higher weed biomass than living mulch. Corn silage and grain yields from the no-tillage plus living mulch treatment were comparable to or higher than those obtained with the conventional tillage plus no mulch treatment.
Effect of Duration of Green Foxtail (Setaria viridis) Competition on Potato (Solanum tuberosum) Yield
Authors: Wall David A. , Friesen George H.
Published: March 2018

The effects of different periods of green foxtail competition on the components of potato yield were investigated. Delaying the removal of green foxtail for 2 wk following crop emergence reduced total and marketable tuber yield by 19 and 29%, respectively, when averaged over 2 yr. Similarly, the number and average weight of marketable tubers were reduced by 24 and 6%, respectively. The proportion of unmarketable tubers comprising the total yield increased as the duration of weed competition was increased. Successively longer periods of green foxtail competition further decreased the measured parameters.
Non-Phenoxy Herbicides for Perennial Broadleaf Weed Control in Cool-Season Turf
Authors: Neal Joseph C.
Published: March 2018

Field experiments were conducted to compare non-phenoxy herbicides with 2,4-D for broadleaf plantain, dandelion, and white clover control in cool-season turf. Herbicides tested were BAS 514, chlorflurenol, clopyralid, dicamba, triclopyr, and 2,4-D, alone and in combinations. Broadleaf plantain was controlled by 2,4-D and by clopyralid plus triclopyr at 0.21 plus 0.63 kg ae ha-1. Dandelion was controlled by 2,4-D, BAS 514 at 0.84 kg ha-1, and by the combination of clopyralid plus triclopyr at 0.16 plus 0.47 kg ha-1. Chlorflurenol, clopyralid, dicamba, or triclopyr did not control dandelion. White clover was controlled by all herbicides except 2,4-D. The combination of clopyralid plus triclopyr was the only non-phenoxy treatment which controlled broadleaf plantain, dandelion, and white clover.
Differential Tolerance of Winter Wheat (Triticum aestivum) to Cyanazine and Triazinone Herbicides
Authors: Baker Thomas K. , Peeper Thomas F.
Published: March 2018

Field experiments were conducted to evaluate the tolerance of 79 winter wheat cultivars to cyanazine, BAY SMY 1500, and metribuzin. When known, the pedigree of the more cyanazineand BAY SMY 1500-tolerant hard red winter cultivars included ‘Hope’ and/or ‘Cheyenne’ parentage. However, the cultivars more sensitive to BAY SMY 1500, notably those with ‘Vona’ parentage, were not consistently sensitive to cyanazine. Visible injury on the hard red and soft red winter cultivars did not consistently indicate yield reductions. The soft red winter cultivars, compared to the hard red winter cultivars, were generally more sensitive to cyanazine than BAY SMY 1500.
Russian Thistle (Salsola iberica) and Kochia (Kochia scoparia) Control in Dryland Corn (Zea mays)
Authors: Blackshaw R. E.
Published: March 2018

Field studies were conducted in 1987, 1988, and 1989 at Lethbridge, Alberta to determine suitable herbicides for the control of Russian thistle and kochia in field corn grown in a dryland cropping system. Soil-applied atrazine or cyanazine provided inconsistent control of these weeds under dryland conditions. Combining inter-row tillage or 2,4-D applied postemergence with soil-applied atrazine improved the consistency of weed control over years. Postemergence atrazine and dicamba plus 2,4-D controlled Russian thistle and kochia in all years. Corn yields reflected the level of weed control attained with each treatment. The suitability of the various treatments for weed control in corn grown under dryland crop production systems is discussed.
Weed Science in the 1990s: Will It be Forward or in Reverse?
Authors: Lebaron Homer M.
Published: March 2018

Dr. Homer M. LeBaron is Senior Research Fellow in the New Technology and Basic Research Department of CIBA-GEIGY Corporation, where He has the responsibility for coordinating and directing outside basic research on all of CIBA-GEIGY agricultural products. He has been employed in various R&D positions with Geigy and CIBA-GEIGY for 27 years. From 1960 to 1964, Dr. LeBaron was employed as a plant physiologist at the Virginia Tech Experiment Station in Norfolk, Virginia, mainly researching weed problems in vegetables and fruit crops.

LeBaron was born May 13, 1926 in Southern Alberta, Canada, the third in a family of 10 children, and grew up on a diversified irrigation farm. He obtained his B.S. and M.S. degrees from Utah State University in 1955 and 1957. He received his Ph.D. degree from Cornell in 1960.

LeBaron, in addition to WSSA, is a member of the American Society of Agronomy, American Chemical Society, Entomological Society of America, American Phytopathological Society, CAST, Sigma Xi, Aquatic Plant Management Society, European Weed Research Society, and all of the regional weed science societies.

He has held numerous positions in several of these and other scientific societies. Homer served as president of NEWSS in 1969–70 and as president of the SWSS in 1986–87. He served on several WSSA committees, including the Executive Board of Directors. In 1978, Dr. LeBaron was elected a Fellow in the WSSA, and received the Distinguished Service Award in the SWSS in 1984.

He is author of over 70 scientific publications, and has been editor and author of five books on herbicide and pesticide resistance and biotechnology. He is currently serving on the parent Herbicide Resistance Action Committee (HRAC) under GIFAP, as well as on the ALS/AHAS Inhibitors Resistance Working Group and as Chairman of the Triazine Resistance Working Group. He is on the Planning Committee and Co-Chair of the Weed Resistance Management Working Group within the International Organization for Pest Resistance Management (IOPRM). In addition to his busy professional schedule, Dr. LeBaron has always been involved in church and community affairs. He has 7 children and 20 grandchildren.
Efficacy and Economic Analysis of Texas Panicum (Panicum texanum) Management Systems in Corn (Zea mays)
Authors: Johnson W. Carroll , Mullinix Benjamin G.
Published: March 2018

Studies on the efficacy and economic analysis of Texas panicum management systems in corn were conducted in Georgia on a loamy sand soil in 1987, 1988, and 1989. Management systems that included butylate, EPTC, atrazine plus tridiphane, atrazine plus pendimethalin, atrazine plus trifluralin, paraquat, or ametryn acceptably control Texas panicum. Corn yields were not affected significantly by the Texas panicum management systems. Overall net returns calculated for corn production indicated that systems which included postemergence applications of atrazine, pendimethalin, trifluralin, paraquat, ametryn, or cultivation alone gave the highest net returns. Systems which included butylate, EPTC, or tridiphane frequently had significantly lower net returns.
Velvetleaf (Abutilon theophrasti) Interference with Cotton (Gossypium hirsutum)
Authors: Smith Brenda S. , Murray Don S. , Weeks David L.
Published: March 2018

Field experiments were conducted to evaluate the critical period for velvetleaf interference with cotton and to assess the reliability of using weed growth variables as predictors of cotton lint yield losses. An inverse linear relationship existed between velvetleaf dry weight and cotton lint yield. The relationship between the number of velvetleaf main-stem nodes or velvetleaf height with cotton lint yield was best described by quadratic regression equations. Weed dry weight appeared to be the most accurate predictor followed by weed height and by number of velvetleaf main-stem nodes. A nonlinear equation best described percent lint yield loss as a function of critical-period interference intervals.
Effect of Paraquat on Yield and Market Grade of Peanut (Arachis hypogaea) Genotypes
Authors: Knauft David A. , Colvin Daniel L. , Gorbet Daniel W.
Published: March 2018

Experiments were conducted for two years at one location and one year at a second location to determine the effects of paraquat on a range of peanut genotypes. Paraquat caused yield reductions of most Valencia-, Spanish-, and runner-market types as compared with hand-weeded checks. Virginia-market types were less affected by paraquat treatment. Most grade characteristics were adversely affected by paraquat. Because the paraquat treatments increased the proportion of other kernels, the herbicide may be affecting yield and grade by delaying maturity.
A Tractor Mounted Sampler for Obtaining Large Soil Columns
Authors: Walker David S. , O'Dell J. David , Wolt Jeff D. , Rhodes G. Neil , Graveel John G.
Published: March 2018

A tractor mounted sampler was constructed which allows large soil columns to be obtained rapidly and with minimal physical effort. The machine utilizes the hydraulic system of a tractor to push a steel sampling cylinder containing 30.5-cm id. polyvinyl chloride (PVC) pipe into the soil, after which the hydraulic cylinder is retracted to pull the pipe and enclosed soil from the ground. Columns 68 cm in length were taken with a hydraulic cylinder pressure of approximately 10 MPa. Soil separated evenly at the bottom of the columns, and compaction was measured to be approximately 5%. This is a relatively simple and rapid method for obtaining large soil columns for use in pesticide leaching studies.