bluuebunny/crossref_metadata_2025 huggingface dataset:
Antagonism of Johnsongrass (Sorghum halepense) Control with Fenoxaprop, Haloxyfop, and Sethoxydim by 2,4-D
Authors: Mueller Thomas C. , Witt William W. , Barrett Michael
Published: March 2018

Johnsongrass control in the field was greater with fenoxaprop or haloxyfop than with sethoxydim in 1985 and 1986. Johnsongrass control was reduced under field and greenhouse conditions by adding a dimethylamine salt of 2,4-D. Generally, the antagonism was overcome by increasing the rate of fenoxaprop, haloxyfop, or sethoxydim. Sethoxydim showed less antagonism from 2,4-D than did fenoxaprop or haloxyfop in the greenhouse.
Johnsongrass (Sorghum halepense) and Pitted Morningglory (Ipomoea lacunosa) Control with Imazaquin and Imazethapyr
Authors: Riley Dennis G. , Shaw David R.
Published: March 2018

Imazaquin and imazethapyr were applied postemergence to soybeans for control of 8- to 12-leaf rhizome johnsongrass and pitted morningglory in the field. At 8 weeks, johnsongrass control was 70% with 70 g ai/ha imazaquin plus 105 g ai/ha imazethapyr but was no more than 50% with a single application of either herbicide. Imazaquin at 70 g/ha plus imazethapyr at 35 g/ha interacted synergistically to provide 90% pitted morningglory control, while 140 g/ha imazaquin controlled 77%. Imazaquin at 70 g/ha with imazethapyr from 18 to 105 g/ha controlled both weed species equal to or better than that obtained with 140 g/ha imazaquin.
Desiccation of Field Bindweed (Convolvulus arvensis) in Alfalfa (Medicago sativa) Seed Fields with Glyphosate
Authors: Packer Douglas S. , Krall James M.
Published: March 2018

The effect of glyphosate applied as a desiccant to field bindweed-infested alfalfa in the final year of seed production was examined in field experiments near Lovelock, NV. Glyphosate at 2.5 and 5.0 kg ae/ha flat fan applied was equal to and/or superior to dinoseb for desiccation of foliage, respectively. Alfalfa seed yield and quality following glyphosate treatment were similar to that of dinoseb-treated alfalfa. Glyphosate treatment reduced some alfalfa and field bindweed stands. A beneficial interaction between low-volume control droplet application (CDA) and glyphosate was not evident.
Control of Triazine-Resistant Smooth Pigweed (Amaranthus hybridus) and Common Lambsquarters (Chenopodium album) in No-till Corn (Zea mays)
Authors: Hagood Edward S.
Published: March 2018

Field experiments were established to evaluate preemergence and postemergence herbicides for control of triazine-resistant smooth pigweed and common lambsquarters in no-till corn. When applied preemergence, alachlor in the microencapsulated formulation controlled smooth pigweed better than the emulsifiable concentrate formulation and better than either metolachlor or pendimethalin. These herbicides applied preemergence did not control common lambsquarters consistently. Pendimethalin controlled both triazine-resistant species when applied as a sequential treatment of a preemergence and an early postemergence application. Control of triazine-resistant smooth pigweed and common lambsquarters was excellent when dicamba was applied early postemergence in treatments containing alachlor, metolachlor, or pendimethalin applied preemergence and/or early postemergence. Thiameturon and CGA-131036 controlled triazine-resistant smooth pigweed with acceptable crop tolerance. Thiameturon also controlled common lambsquarters, but control was unacceptable with CGA-131036.
Preemergence Weed Control in a Conservation Tillage Cotton (Gossypium hirsutum) Cropping System on Sandy Soils
Authors: Keeling J. Wayne , Abernathy John R.
Published: March 2018

Field experiments were established on a loamy fine sand to evaluate weed control in a conservation tillage system where cotton was planted into sorghum stubble. Preemergence herbicides for Palmer amaranth and volunteer sorghum control in cotton included methazole, dipropetryn, prometryn, metolachlor, and metolachlor plus dipropetryn or prometryn. Dipropetryn controlled both weeds without crop injury. Above 1.7 kg ai/ha, methazole provided effective control but injured the crop. Prometryn was less effective than dipropetryn or methazole against Palmer amaranth and controlled <40% volunteer sorghum. Metolachlor unacceptably injured cotton. Cotton yields were excellent when both weeds were controlled.
Survey of Winter Wheat (Triticum aestivum) Stubble Fields Sprayed with Herbicides After Harvest in 1986
Authors: Wicks Gail A. , Popken Donald H. , Lowry Stephen R.
Published: March 2018

A survey of 146 fields was conducted to investigate herbicide performance in winter wheat-producing areas of southwestern Nebraska during August and September of 1986. Only 55% of the fields received an excellent rating for weed control and stubble quality; one third rated as unacceptable. Weed control after wheat harvest was improved by planting ‘Bounty 310’, ‘Siouxland’, ‘Vona’, and ‘Centura’ winter wheat cultivars rather than ‘Mustang’, ‘Hawk’, ‘Pioneer 2656’, and ‘Wings'. Fertilizing winter wheat in the fall, planting wheat at the optimum date, high wheat stem density, using a winter wheat-corn-fallow rotation, not spraying herbicides after wheat harvest on days that it rained or air temperature exceeded 35 C, and spraying weeds when they were small also improved weed control in wheat stubble. Nine months after wheat harvest, fields treated with atrazine before July 16 had more volunteer wheat than fields treated later.
Sand Sagebrush (Artemisia filifolia) and Brittle Pricklypear (Opuntia fragilis) Control
Authors: Wilson Robert G.
Published: March 2018

Experiments were conducted at Bridgeport, NE, during 1983 through 1987 to select alternatives for silvex and 2,4,5-T for sand sagebrush and brittle pricklypear control. Of the six herbicides examined, the butoxyethyl ester of 2,4-D at 2.2 kg ae/ha was equivalent to the propylene glycol butyl ether ester of silvex or 2,4,5-T for sand sagebrush control. The potassium salt of picloram at 0.3 kg ae/ha was equal to silvex for brittle pricklypear control.
Plant Growth Regulators Suppress Established Orchard Sod and Dandelion (Taraxacum officinale) Population
Authors: Miller Stephen S. , Eldridge B. Joe
Published: March 2018

Several plant growth regulators applied to established sod driveways in an apple orchard suppressed growth of the ground cover sufficiently to eliminate one to three mowings. MH at 4.5 or 6.7 kg ai/ha applied spring and fall reduced the growth of a single species sod cover crop, ‘Kentucky 31’ tall fescue, the year after treatment. MH at both rates also reduced the dandelion population growing in the mixed species orchard sod. Paclobutrazol or EPTC applied in the spring before or during initial grass growth reduced dry matter production in the fescue sod cover crop and the number of mowings compared to the mowed and non-mowed control plots.
Difficulty in Controlling Duncecap Larkspur (Delphinium occidentale)
Authors: Ralphs Michael H. , Turner David L.
Published: March 2018

Duncecap larkspur was not killed by triclopyr, picloram, or clopyralid applied once at recommended rates. Triclopyr at 1.1, 1.7, 2.2, and 4.6 kg ae/ha applied twice to the same plots in two consecutive years reduced duncecap larkspur density from 29 to 64%. However, the higher rates of triclopyr left 2 plants/m2, an unacceptable level for preventing cattle poisoning.
Preemergence Weed Control in Row Middles of Polyethylene-Mulched Cauliflower (Brassica oleracea)
Authors: Gilreath James P. , Botts Daniel A. , Stall William M. , Dusky Joan A.
Published: March 2018

Four experiments were conducted in 1985 and 1986 at three locations to assess weed control efficacy and phytotoxicity of several preemergence herbicides applied between beds (row middles) of polyethylene-mulched cauliflower grown on raised beds. Efficacy of most herbicide treatments varied among the four experiments; however, 4.5 kg ai/ha diethatyl and tank mixes of oxyfluorfen with cinmethylin consistently controlled weeds best. Plant stand, yield, and cauliflower curd size were not affected by treatment for any of the varieties used at any of the locations.
Release Rate of Three Herbicides from Controlled-Release Tablets
Authors: Gorski Stanley F. , Reiners Stephen , Ruizzo Michael A.
Published: March 2018

Six, 9, and 12-mm diam dicalcium phosphate tablets were evaluated for their release of acetochlor, metolachlor, and metribuzin. Greenhouse bioassays with Italian ryegrass demonstrated that herbicides from the smaller tablets did not control grass as long as from the larger tablets. Italian ryegrass was controlled within a 5- to 7-cm diam circle around the 12-mm diam tablet and a 5-cm diam circle around the 6-mm diam tablet. All tested herbicides responded in a similar fashion. Six-mm diam tablets released metolachlor for 11 weeks, while the 12-mm tablet was active for 28 weeks.
Herbicide Effects on Tensile Strength and Rooting of Bermudagrass (Cynodon dactylon) Sod
Authors: Sharpe Sam S. , Dickens Ray , Turner David L.
Published: March 2018

The objective of this study was to determine how selected herbicides affect sod tensile strength and rooting of mature and immature turfs of ‘Tifway’ bermudagrass. Both immature and mature turf had 100% ground cover, but only mature turf had tensile strength adequate for harvesting and handling. Sod tensile strength at 2, 4, and 8 weeks after application generally was unaffected by herbicide treatment, although imazapyr killed bermudagrass top growth. Root number and root length initially were depressed by imazapyr, bensulide, napropamide, sethoxydim, and sulfometuron at most rates and intervals tested. Eight weeks after treatment, root length, root number, and sod tensile strength for all treatments, except those with imazapyr, were similar to that of the untreated control.
Horseweed (Conyza canadensis) Control in Conservation Tillage Cotton (Gossypium hirsutum)
Authors: Keeling J. Wayne , Henniger C. Gary , Abernathy John R.
Published: March 2018

Horseweed is a major weed in conservation tillage production systems. Herbicides were evaluated for horseweed control at two growth stages, rosette and 10- to 15-cm tall. Horseweed was controlled at the rosette stage with the 2,4-D ester, 2,4-D amine, dicamba, 2,4-D plus glyphosate, and glyphosate. Higher rates were needed for control at the 10- to 15-cm stage. Paraquat did not effectively control horseweed at any stage.
Response of Tall Fescue (Festuca arundinacea) to Plant Growth Regulator Application Dates
Authors: Johnson Billy J.
Published: March 2018

Mon 4620 at 2.8 kg ai/ha, paclobutrazol plus mefluidide at 1.1 plus 0.4 kg ai/ha, and flurprimidol plus mefluidide at 1.1 plus 0.4 kg ai/ha were applied on four dates to determine their influence on highly maintained tall fescue turf. Seedhead suppression was good to excellent by Mon 4620 applied March 1 or 18 and by paclobutrazol plus mefluidide and flurprimidol plus mefluidide applied anytime from March 1 until April 1. None of the plant growth regulators (PGRs) suppressed seedheads effectively when applied April 15 when the grass was near the end of the rapid growth cycle and just before seedhead emergence. Vegetative growth of mowed tall fescue was suppressed for 8 weeks in 1987 when PGRs were applied March 1 immediately after full green-up. Application dates were not as important in 1988 as in 1987. Tall fescue was injured the least by Mon 4620 applied in March and by flurprimidol plus mefluidide applied on March 18. Paclobutrazol plus mefluidide injured the turf severely regardless of application date.
Bermudagrass
Authors: Mitich Larry W.
Published: March 2018

Bermudagrass [Cynodon dactylon(L.)Pers. #3CYNDA] probably originated in tropical Africa; however, Australia, Eurasia, the Indo-Malaysian area, and the Bengal region of India/Bangladesh also have been proposed as its home (11). Although many early writers believed that bermudagrass started in India, most improved strains ofCynodonhave been developed from Africian stock (15).
Principles of Weed Threshold Research
Authors: Oliver Lawrence R.
Published: March 2018

Competitive and economic thresholds are distinctive and important concepts to weed scientists. The producer is most concerned about the economic threshold because of its importance in production decisions. The three additive research techniques to determine competitive weed thresholds are removal or plant-back, paired plot, and area of influence. Each method has advantages and disadvantages and must be conducted in a specific manner in the field. The area of influence technique is the most accurate for determining the influence of a single weed. Data must be reported in a usable form such as percent yield reduction. An example calculation for determining the two weed thresholds is illustrated with common cocklebur in soybeans. Generally, the economic threshold is one-half to one-third the competitive threshold.
Insect and Weed Interactions on Bell Peppers (Capsicum annuum)
Authors: Prank J. Ray , Schwartz Paul H. , Bourke John B.
Published: March 2018

Two years of field research were conducted to determine the additive effects of weed cover and insects on pepper production. When weeds covered less than 10% of test plots, the natural insect populations reduced the marketable fruit yield of bell peppers 32% in 1983 and 22% in 1984. When weeds covered 72 or 94% of the test plots, foliage damage due to insects was from 5.8 to 12.1%, respectively. The high percent weed cover and insects reduced yield 99%. The average fresh weight of pepper foliage approached zero as weed cover approached maximum. Foliar levels of iron and aluminum were reduced greatly in peppers grown in competition with a 100% weed cover. The level of boron, copper, phosphorus, and potassium in pepper foliage increased as percent weed cover increased.
Interactions of Carbaryl and Dimethoate with Sethoxydim
Authors: Byrd John D. , York Alan C.
Published: March 2018

Field experiments were conducted to determine the effects of tank-mix and sequential postemergence (POE) applications of the insecticides carbaryl and dimethoate with sethoxydim on large crabgrass control and cotton tolerance. Large crabgrass control was similar with sethoxydim and sethoxydim-dimethoate tank mixtures. Although tank mixing carbaryl with sethoxydim reduced control, it was not reduced when carbaryl was applied 2 days before or 2 days after applying sethoxydim. Neither the insecticides nor sethoxydim applied alone or as tank mixtures injured cotton or affected lint yield, percent lint, fiber length, fiber length uniformity, fiber strength, or micronaire.
Effect of AC 94,337 on Young Grain Sorghum (Sorghum bicolor) and Rotational Crops
Authors: Dale Jim E.
Published: March 2018

Greenhouse experiments were conducted to determine effects of AC 94,377, seed depth, and commercially applied seed protectants on emergence and early growth of grain sorghum. Mean height of grain sorghum was increased by 500 to 2000 ppmw AC 94,377 but not by 250 ppmw. Emergence and fresh weight of grain sorghum was not affected. Plants arising from seeds without protectants were taller and heavier than those with protectants intact. Soybean sown in soil containing AC 94,377 at 0.6 to 2.5 kg ai/ha was injured; however, soybean grew normally if seeds were not sown until at least 1 week after applying AC 94,377. Cotton was not injured by AC 94,377.
Herbicide Control of Locoweeds: A Review
Authors: Ralphs Michael H. , Ueckert Darrell N.
Published: March 2018

Locoweed poisoning of livestock is the most widespread poisonous plant problem in the western United States. This paper presents a historical review of control methods to reduce locoweed plant density. Hand grubbing, the most common method of control before phenoxy herbicides, was practical in small pastures considering the number of livestock saved. Trials in the 1950s indicated that 2,4-D and 2,4,5-T generally controlled locoweeds effectively if applied when plants were actively growing and soil moisture was not limiting plant growth. Picloram, dicamba, clopyralid, and triclopyr provide more consistent control than 2,4-D and 2,4,5-T when applied at less than optimum environmental conditions.
Efficacy ofColletotrichum coccodesand Thidiazuron for Velvetleaf (Abutilon theophrasti) Control in Soybean (Glycine max)
Authors: Hodgson Richard H. , Wymore Lee A. , Watson Alan K. , Snyder Robert H. , Collette Anne
Published: March 2018

The plant pathogenic fungusColletotrichum coccodes(Cc) and the plant growth regulator thidiazuron (TDZ) were evaluated in Maryland and Quebec for velvetleaf control in ‘Williams' and ‘Maple Arrow’ soybean. TDZ was applied at 0, 0.1, 0.2, 0.3, and 0.4 kg ai/ha alone or was combined with Cc at 109spores/m2when velvetleaf was at the 1- to 2-leaf (Trial 1) or 4- to 6-leaf (Trial 2) growth stages. Velvetleaf control increased with TDZ rate, and TDZ combined with Cc further increased control. TDZ reduced velvetleaf biomass and height, and Cc increased velvetleaf mortality. In Quebec, Cc also reduced the biomass of velvetleaf treated in Trial 1 and interacted positively with TDZ at this growth stage. Cc nearly halved the rates of TDZ required for 90 and 75% mortality of velvetleaf treated at the 1- to 2-leaf and 4- to 6-leaf stages to 0.09 and 0.12 kg/ha, respectively, in Quebec. Cc similarly lowered the rate of TDZ required for 75% stand reduction of velvetleaf in Trial 1 to 0.17 kg/ha in Maryland. Cool wet weather in Quebec contrasted with warm, dry weather in Maryland. Soybean biomass and yield were increased significantly by treatment with TDZ plus Cc in Trial 1 at both locations.
Changes in Rangeland Canopy Cover Seven Years After Tebuthiuron Application
Authors: Whitson Thomas D. , Ferrell Mark A. , Alley Harold P.
Published: March 2018

Tebuthiuron was evaluated at two Wyoming locations for its effects on big sagebrush control and associated vegetation, Big sagebrush was controlled with tebuthiuron at 0.6 to 1.1 kg ai/ha. Green needlegrass, prairie junegrass, blue grama, and Douglas rabbitbrush were unaffected by tebuthiuron treatments. Western wheatgrass and downy brome increased at different study locations and were dominant grass species at the end of 7 yr.
Wild Oat (Avena fatua) Infestations and Economic Returns as Influenced by Frequency of Control
Authors: O'Donovan John T.
Published: March 2018

In continuous wheat or barley or in a canola/barley rotation, wild oat control every year over 4 yr maintained wild oat seedling populations at 3 plants/m2 or less. Failure to control wild oats annually increased wild oat populations (>200 plants/m2 by the fourth year) in continuous wheat dramatically, while in the other two cropping systems, populations increased to only 40 plants/m2 or less by the fourth year. In the continuous wheat and in the canola/barley rotation, wild oat control every year generally provided the best economic returns when prices and costs were averaged over 4 yr; in continuous barley, the average return was better when wild oats was controlled only in the second or third years rather than every year.
Interference of Common Lambsquarters (Chenopodium album) in Transplanted Tomato (Lycopersicon esculentum)
Authors: Bhowmik Prasanta C. , Reddy Krishna N.
Published: March 2018

Field studies were conducted in 1982 to 1984 to determine the effects of common lambsquarters on growth, yield, and nutrient concentration of transplanted tomato. Common lambsquarters densities ranged from 16 to 64 plants/m tomato row and fresh weight ranged from 26 360 kg/ha at 16 plants/m to 46 000 kg/ha at 64 plants/m row. Common lambsquarters did not affect tomato shoot dry weight at the vegetative stage but decreased the weight at the early fruit stage. Season-long interference of common lambsquarters reduced marketable tomato fruit number and also, marketable fruit weight ranging from 17% at 16 plants/m to 36% to 64 plants/m row. Concentrations of N in tomato leaves were unaltered at vegetative and flowering stages but decreased regardless of common lambsquarters density at early fruit and harvest stages. Weed density did not alter concentrations of P, K, and Ca in tomato leaves.
Naptalam as a Safener Against Chloramben in Cucumber (Cucumis sativus)
Authors: Knerr Larry D. , Hopen Herbert J.
Published: March 2018

Naptalam at 6.7 kg ae/ha applied with chloramben at 2.0 to 4.5 kg ae/ha was a safener for chloramben phytotoxicity to cucumber as expressed by increased dry weight in the greenhouse and yield in the field, but the protection was inadequate to be commercially acceptable. Naptalam applied in seed coatings also protected cucumber from chloramben phytotoxicity in the greenhouse but were ineffective in the field. Delaying chloramben application 24 to 72 h after naptalam application in the field increased the safening effect to a level that may be commercially acceptable. The safening effect was only to cucumber as effective weed control was achieved with chloramben and naptalam.
Johnsongrass (Sorghum halepense) Control in Soybeans (Glycine max) with Postemergence Herbicides
Authors: Vidrine Paul R.
Published: March 2018

Antagonism was evaluated among four grass and seven broadleaf herbicides applied postemergence for seedling and rhizome johnsongrass control in soybeans. Imazaquin and chlorimuron were most antagonistic to grass herbicides. Haloxyfop and quizalofop were least affected by the addition of broadleaf herbicides. Johnsongrass control was reduced 11 to 46% when grass herbicides were applied with broadleaf herbicides and were evaluated 3 and 12 weeks after treatment (WAT).
Response of Early-Maturing Cabbage (Brassica oleraceavar.capitata) to Metolachlor
Authors: Bellinder R. R. , Wilcox-Lee D. , Senesac A. , Warholic D. T.
Published: March 2018

The effect of three rates of metolachlor on ‘Prime Time’ and ‘Tastie’, early maturing, fresh-market cabbage was evaluated in two geographically distinct regions of New York in 1986 and 1987. Metolachlor, when applied at 1.1, 1.7, and 2.2 kg ai/ha either pretransplant or 48 h after transplanting, caused no observable negative effects on either cabbage variety in either year when grown on sandy loam soils on Long Island. On a central New York silt loam soil, injury from metolachlor at 1.7 and 2.2 kg/ha applied post-transplant was negligible and transient. Metolachlor applied post-transplant caused a delay in maturity of Tastie cabbage in both years but not Prime Time; however, total yields equalled those of the weed-free controls with both varieties. Metolachlor applied pretransplant frequently caused excessive and persistent injury and often reduced cabbage yields.
Control of Leafy Spurge (Euphorbia esula) With Growth Regulator-Herbicide Combinations
Authors: Ferrell Mark A. , Whitson Thomas D. , Alley Harold P.
Published: March 2018

Field and greenhouse studies were conducted to evaluate the following growth regulators: ABG-3034, a cytokinin, benzylaminopurine (BAP); alkanolamine salt of 2,4-D; gibberellic acid (GA); isopropylamine salt of glyphosate; kinetin; napthaleneacetic acid (NAA); and PP333, an experimental antigibberellin compound, and the herbicides: dimethylamine salt of dicamba and potassium salt of picloram alone and combined on the growth and control of leafy spurge. The results of greenhouse and field studies show that growth regulators did not enhance the performance of herbicides in controlling leafy spurge.
Common Dandelion – the Lion's Tooth
Authors: Mitich Larry W.
Published: March 2018

From ancient times to the present, common dandelion (Taraxacum officinale Weber in Wiggers ♯3TAROF) has been considered one of the most delectable of garden vegetables. People have carried the seeds from place to place for cultivation since before written history (9). According to legend, Theseus ate a dandelion salad after killing the Minotaur. Romans ate the plant as did the Gauls and Celts when the Romans invaded the North (9). The Anglo-Saxon tribes of Britain and the Normans of France continued to use the plant as food and as medicine to control scurvy and as a diuretic; it was planted in the medicinal gardens of monasteries (9).
Confirmation of Trifluralin-resistant Green Foxtail (Setaria viridis) in Manitoba
Authors: Morrison Ian N. , Todd Barry G. , Nawolsky Ken M.
Published: March 2018

Dose-response experiments showed that three samples of green foxtail collected from fields in southern Manitoba where trifluralin had not controlled the weed in 1987 were resistant to the herbicide. GR50values indicated that the resistant populations were about 5 times more resistant to trifluralin than susceptible populations, about twice as resistant as wild oat, and about equally resistant as wheat. An additional 33 samples collected in 1988 from southwestern Manitoba where trifluralin has been used for nearly 20 yr in both cereal and oilseed crops were resistant to trifluralin.
Dodder (Cuscutaspp.) Control in Established Alfalfa (Medicago sativa) with Glyphosate and SC-0224
Authors: Dawson Jean H.
Published: March 2018

Glyphosate and SC-0224 at 75 or 150 g ae/ha, applied to alfalfa foliage after field dodder and largeseed dodder were parasitically well established, controlled dodder selectively. Glyphosate applied at any time over a range of developmental stages stopped the growth of dodder. Control was best when the herbicides were applied when alfalfa was 20 to 30 cm tall, when maximum length of dodder shoots was 30 to 60 cm, and while host and parasite were both vegetative and growing vigorously. Later application allowed dodder to injure alfalfa before being controlled, and earlier application sometimes allowed dodder to recover and suppress alfalfa before the hay was cut.
Response of Soybean (Glycine max) Cultivars to Metribuzin in the Field and Greenhouse
Authors: De Weese W. W. , Wax L. M. , Carlson W. C. , Ciarletta J. A.
Published: March 2018

Experimental objectives were to assess metribuzin tolerance of predominately privately developed soybean cultivars and to evaluate a greenhouse screening procedure. In field results in 1982, ‘Vinton 81’, ‘Northrup King 1884’ and ‘L77-1863’ soybean cultivars were extremely sensitive to metribuzin at 0.56 kg/ha, averaging 34% injury. The other 45 cultivars showed no significant injury at the 0.56 kg/ha rate, from 9 to 46% injury at 1.4 kg/ha, and 18 to 72% injury at 2.2 kg/ha. In greenhouse hydroponic studies, these same three soybean cultivars were killed, while the other 45 cultivars were injured from 15 to 82%. A good agreement of greenhouse and field data was determined, with a correlation coefficient of r = 0.82.
Sodium Bicarbonate Antagonism of Sethoxydim
Authors: Nalewaja John D. , Manthey Frank A. , Szelezniak Edward F. , Anyska Zbigniew
Published: March 2018

Research was conducted to determine the influence of water carrier quality on grass control from sethoxydim. Water from a well near Halliday, ND, where sethoxydim failed to control grasses, contained 650 mg/L sodium and 1650 mg/L bicarbonate. Both sodium bicarbonate and sodium carbonate when included in the sethoxydim spray reduced grass species control in the greenhouse and field. Sodium carbonate in the spray generally was more antagonistic than sodium bicarbonate to sethoxydim toxicity to grasses. The antagonism from sodium bicarbonate at 6000 mg/L was overcome by diammonium sulfate or ammonium nitrate at 2.8 kg/ha or a 28% nitrogen liquid fertilizer at 9.4 L/ha in the sethoxydim spray. These compounds also overcame sodium carbonate and partly overcame the antagonism of sethoxydim by bentazon. Three commercial adjuvants for use with sethoxydim differed in their effect on wheat and oats control with sethoxydim alone or with bentazon.
A Comparison of Herbicide Sprays and Pellets for Control of Broadleaf Weeds in Pastures
Authors: Mayeux Herman S.
Published: March 2018

Picloram was applied broadcast on kleingrass pastures in the spring either as sprays or as pellets containing 2, 5, or 10% ae. The carrier in 5 and 10% pellets was inert clay, but 2% pellets were formulated with sufficient ammonium sulfate to contain 14.4% N. Dry formulations of picloram (10% ae), dicamba (5% ae), and tebuthiuron (20% ai) were compared to sprays at equal rates in a coastal bermudagrass pasture. Picloram was more effective as a spray than as pellets in two of five experiments. Few differences in weed control were observed with 2, 5, and 10% picloram pellets. Picloram applied up to 3 kg ae/ha as 2% pellets did not reduce kleingrass standing crop and up to 29 kg/ha of N as ammonium sulfate applied with or without picloram did not increase kleingrass production. None of the herbicides controlled weeds during the year following application.
Synergistic Mixes of DPX-A7881 and Clopyralid in Canola (Brassica napus)
Authors: Blackshaw Robert E.
Published: March 2018

The interaction of DPX-A7881 and clopyralid applied as tank mixtures was studied under controlled environment and field conditions on several commonly occurring weeds in canola. Control of wild mustard and wild buckwheat was not affected by mixing these herbicides. DPX-A7881 controlled wild mustard, and clopyralid controlled wild buckwheat independently of the other herbicide. However, redroot pigweed and common lambsquarters were controlled better with DPX-A7881 plus clopyralid than with either herbicide alone. The herbicides interacted in an additive to synergistic manner on redroot pigweed depending on the rate of each herbicide. DPX-A7881 and clopyralid interacted synergistically at all rates on common lambsquarters. Plant height, date of flowering, seed yield, and quality data all indicated that canola completely tolerated DPX-A7881 and clopyralid applied alone or in combination.
Biology and Control of Jointed Goatgrass (Aegilops cylindrica), a Review
Authors: Donald William W. , Ogg Alex G.
Published: March 2018

Jointed goatgrass is a winter annual grass weed which is believed to have been introduced into North America as a contaminant in winter wheat seed. Although jointed goatgrass was first discovered in some states early in the 20th century, changing wheat production practices during the past 25 yr have encouraged its spread and increase. Winter wheat producers in the western United States are concerned about the lack of adequate selective control measures for this weed. Jointed goatgrass and wheat share the D chromosome in common and have similar growth habits. Jointed goatgrass lowers winter wheat yield by competing for growth requirements, reducing harvesting efficiency, and lowering crop quality by contaminating harvested grain. Jointed goatgrass is well adapted to stubble-mulch or reduced tillage crop production, particularly in regions where climate limits cropping options to the winter wheat-fallow rotation or continuous wheat. This review summarizes jointed goatgrass seed germination, dormancy, physiology, yield loss estimates in winter wheat, and both herbicidal and non-chemical methods of managing jointed goatgrass.
Ammonium Sulfate Enhancement of Glyphosate and SC-0224 Control of Johnsongrass (Sorghum halepense)
Authors: Salisbury Clay D. , Chandler James M. , Merkle Morris G.
Published: March 2018

Ammonium sulfate enhanced the initial control of johnsongrass by glyphosate and SC-0224 applied in the fall or summer. Glyphosate at 0.42 kg ha-1in combination with ammonium sulfate at 3.33 kg ha-1provided levels of fall johnsongrass control and spring regrowth control comparable to glyphosate at 0.84 kg ha-1. Spring applications to mixed populations of seedling and rhizome johnsongrass showed that ammonium sulfate added to glyphosate or SC-0224 afforded little enhancement of herbicide efficacy. Glyphosate or SC-0024 at 0.42 kg ha-1applied in combination with logarithmically decreasing rates of ammonium sulfate demonstrated reduced weed control with ammonium sulfate rates above 9.7 kg ha-1.
Grass Weed Management Systems in Grain Sorghum (Sorghum bicolor)
Authors: Walker Robert H. , Norris Bobby E. , McGuire John A.
Published: March 2018

Field experiments in 1984 and 1985 near Headland, AL involved the influence of 18 integrated weed management systems incorporated from nine herbicide-tillage systems (H-T) and two row patterns on control of large crabgrass and Texas panicum, crop yield, and net returns in grain sorghum. The conventional-tillage system plus herbicide combinations; alachlor preplant incorporated (PPI), atrazine postemergence (POST), and paraquat POST directed, provided 90% or greater control of large crabgrass throughout the season and high sorghum yields in one of two years; and 90% or greater control of Texas panicum from mid-June through mid-August and high sorghum yields in both years. Results in 1984 and 1985 similar to those above were obtained with strip tillage plus herbicide combinations; alachlor PPI, atrazine POST, and paraquat POST directed; alachlor PPI and tridiphane plus atrazine POST; and tridiphane plus atrazine POST and paraquat POST directed. Row patterns did not consistently influence control of large crabgrass, Texas panicum, or sorghum yield. Economic net returns ranged from – $20 to $210 per hectare for the large crabgrass control systems in 1984; however, low sorghum yields in 1985 resulted largely in negative returns. Similar net returns were obtained in the Texas panicum experiment.
Factors that Influence Germination and Mycoherbicidal Activity ofAlternaria cassiae
Authors: Daigle Donald J. , Cotty Peter J.
Published: March 2018

The influences of pH, surfactants, and nutrients on germination were investigated to develop a basis for improvement ofAlternaria cassiaemycoherbicide formulations. In vitro results indicated that a formulation with a pH of approximately 6.5 containing 0.1 to 1% Tween 80, 0.02 M potassium phosphate buffer, and 1% dehydrated potato dextrose broth best promoted germination. Sicklepod plants at the 2 to 3 true-leaf stage were sprayed with test solutions, incubated in the dark at 100% relative humidity (28 C) for 6 h, and placed in a growth chamber maintained at 30 C. Assessment of the plants after 2 d indicated that the ability of the formulation components to induce germination ofAlternaria cassiaein vitro corresponded well with their ability to improve infection of sicklepod seedlings.
Variables Affecting the Use of Positive Displacement Pumps to Apply Herbicides in Ultralow Volume
Authors: Hanks James E. , McWhorter Chester G.
Published: March 2018

Water and paraffinic oils were used to determine variables that affect positive displacement pumps used to meter liquid flow in an air-assist spray system. Components needed to construct an air-assist spray system were described for use in spray chambers and on a tractor for field application of herbicides in ultralow volume (ULV). The flow rate of the pump varied less than 2% for the water and oil as the pump setting was varied from 0 to 100% of the pump's capacity. Linear relationships were shown for both liquids as the voltage input varied from 4 to 13 volts. Air pressures to 100 kPa and liquid temperatures to 35 C did not affect flow rate of the pump. Volume median diameter of the spray droplets decreased from 295 μm to 77 μm and 159 μm to 85 μm for water and paraffinic oil, respectively, as the air pressure was adjusted from 14 to 110 kPa.
Narrow Row Spacing and Canopy Formation Reduces Weed Resurgence in Soybeans (Glycine max)
Authors: Yelverton Fred H. , Coble Harold D.
Published: March 2018

In 1982 and 1983, effects of soybean row spacing and irrigation on weed resurgence following postemergence herbicide applications were evaluated. Also, ‘Forrest’ and ‘Ransom’ cultivar effects and early and late planting date influences on weed resurgence were evaluated in 1982 and 1983, respectively. In both years, as row spacing increased, weed resurgence increased. Photosynthetically active radiation measurements indicated the amount of weed resurgence coincided closely with the differing amounts of light penetrating to the soil surface. Irrigation, planting date, and cultivars showed no significant effect on weed resurgence. In 1982, a significant cultivar by row spacing interaction was obtained. In 1983, the late planting date showed a trend for less weed resurgence under irrigated conditions, although the difference was not significant. Soybean canopy measurements indicated development was greater under irrigation.
Decreasing Rates of Nonselective Herbicides in Double-Crop No-Till Soybeans (Glycine max)
Authors: Moseley Carroll M. , Hagood Edward S.
Published: March 2018

Experiments were conducted in 1988 and 1989 at four sites in Virginia to test weed control efficacy in double-crop, no-till soybean production systems with reduced rates of nonselective herbicides. Chlorimuron plus linuron at 0.04 plus 0.46 kg ha-1gave more than 94% control of five weed species, but only 81 to 86% control of three weed species. Tank mix additions of reduced rates of either glyphosate, HOE-0661 or paraquat to the chlorimuron plus linuron treatment increased large crabgrass and common ragweed control.
Biology and Control of Black Nightshade (Solanum nigrum) in Cotton (Gossypium hirsutum)
Authors: Keeley Paul E. , Thullen Robert J.
Published: March 2018

A 4-yr study (1985, 1987, 1988, 1989) was conducted on the same field plots at Shafter, CA to evaluate the efficacy of prometryn in controlling black nightshade on planting beds of cotton. Two rates (1.7 and 2.2 kg ai ha–1) were applied at two times (mid March before the preplant irrigation and early April at cotton planting) each year. Incorporation of prometryn into moist planting beds with a powered rotary tiller operated at 10 cm deeper resulted in excellent control of black nightshade under low to moderate weed pressure in 1985 and 1987. Control of nightshade with early and late applications of 1.7 kg ha–1of prometryn under high weed pressure in 1988 was only 70% at harvest, and yield losses of cotton averaged 25%. Yields of cotton treated with 2.2 kg ha–1of prometryn in 1988 were not significantly different from weed-free plots. Only the late application of 2.2 kg ha–1of prometryn prevented significant cotton losses under extreme weed pressure in 1989. Cotton yield losses with the other prometryn treatments ranged from 78 to 100%. Losses of cotton in weedy-check plots that received only cultivation ranged from 22% in the absence of rain or irrigation at cotton planting in 1987 to as much as 100% when rain fell in 1988 or plots were irrigated at planting in 1989. Plots hoed one time 4 wk after cotton planting yielded an average of 84% as much seed cotton as weed-free plots. In an attempt to determine why the efficacy of prometryn declined between 1985 and 1989, several experiments were conducted in 1988 to 1990 to discover reasons for this poor control of nightshade. Because efforts failed to provide evidence for the movement of the herbicide with water, the development of weed resistance to prometryn, or accelerated degradation of this herbicide in soil, increasing weed seed populations in soil were believed to have contributed greatly to the declining nightshade control from prometryn. The fact that prometryn applied and incorporated into flat soil provided excellent control of nightshade in 1990 under sprinkler irrigation indicated that both soil moisture and incorporation techniques limited activity of prometryn in planting beds in 1988 and 1989. Incomplete control of nightshade plus good soil moisture at planting contributed to the high weed populations in 1988 and 1989.
Effects of Herbaceous Weeds on Fourth Year Water Relations and Gas Exchange of Loblolly Pine
Authors: Green Thomas H. , Mitchell Robert J. , Paliwal Kailash C. , Pathre Uday V. , Zutter Bruce R. , Gjerstad Dean H.
Published: March 2018

Stands of four-year-old loblolly pines grown with and without herbaceous competition were compared to determine whether early increases in soil moisture and plant water status had been maintained throughout the first four years. Non-weeded stands tended to have greater soil moisture than weeded stands, although these differences were never statistically significant (P > 0.05). Plant water potential was remarkably similar between treatments, as were photosynthesis and stomatal conductance. The increase due to weed control in foliage production early in stand development apparently caused a depletion in available soil moisture to levels similar to non-weeded stands. Therefore, the direct benefit of increased soil resources with weed control is short lived.
Interference Between Soybean (Glycine max) and Jimsonweed (Datura stramonium) in Indiana
Authors: Henry William T. , Bauman Thomas T.
Published: March 2018

Interference between jimsonweed and soybean was investigated. Jimsonweed growing within the soybean row had little influence on vegetative characteristics of soybean during the first 12 wk of the growing season. The influence of an individual jimsonweed plant was first detected 10 wk after planting and extended 20 cm within the row. At harvest, interference extended 50 cm from individual jimsonweed plants, and yield within the 1.2 m of row surrounding a single jimsonweed plant was reduced 12%. Jimsonweed spaced 60 cm apart within the row reduced yield 18%. Soybean interference with jimsonweed growth increased steadily during the season, reducing the size of jimsonweed plants within the soybean row 80 to 93% compared with jimsonweed plants free of soybean interference. Jimsonweed grown within the soybean rows produced an average of 4900 seeds per plant whereas jimsonweed grown crop-free produced nearly 69 000 seeds per plant.
Uptake, Translocation, and Metabolism of Quinclorac in Two Grass Species
Authors: Chism William J. , Bingham S. Wayne , Shaver Richard L.
Published: March 2018

Research was conducted to determine the role of uptake, distribution, and metabolism of quinclorac in differential sensitivity of southern crabgrass and Kentucky bluegrass. At 0.5 h, quinclorac uptake was 85% in southern crabgrass and 66% in bluegrass. Uptake and distribution differed between species. By 128 h, Kentucky bluegrass had uniformly distributed quinclorac and exuded 17% into the nutrient solution. Metabolism of quinclorac was limited to less than 3.6% of the applied14C in the two species, at 128 h. Selectivity of quinclorac may be influenced by differences in uptake, distribution, and exudation by the roots but not by metabolism.
Using Reduced Rates of Postemergence Herbicides in Soybeans (Glycine max)
Authors: Devlin Daniel L. , Long James H. , Maddux Larry D.
Published: March 2018

Eight field studies were conducted in soybeans at seven locations in Kansas over a 3-yr period to examine the efficacy of using reduced rates of the herbicides acifluorfen, bentazon, chlorimuron, and tank mixes of acifluorfen and bentazon. POST applications of these herbicides at 1/2X rates at 2 wk after planting (WAP) resulted in broadleaf weed control similar to that obtained from standard treatments of 1X rates applied at 4 WAP at six of seven studies with acifluorfen, bentazon, and acifluorfen plus bentazon and at five of seven studies with chlorimuron. One-quarter rates applied 2 WAP were equivalent to standard treatments for broadleaf weed control in four of seven studies with acifluorfen and chlorimuron, five of seven studies with bentazon, and six of seven studies with acifluorfen plus bentazon. One cultivation at 4 WAP, increased the broadleaf weed control with all herbicide treatments.
Effects of Nicosulfuron on Quackgrass (Elytrigia repens) Control in Corn (Zea mays)
Authors: Bhowmik Prasanta C. , O'Toole Betsey M. , Andaloro John
Published: March 2018

Four field experiments were conducted during 1988 and 1989 to determine the effects of POST application of nicosulfuron on quackgrass control in conventional field corn. A single application of nicosulfuron at 35 to 70 g ha–1applied to four- to six-leaf quackgrass controlled over 90% of quackgrass five weeks after treatment. Nicosulfuron at 35 g ha–1applied at the one- to three-leaf stage was not as effective as the same rate applied at the four- to six-leaf stage. When nicosulfuron at 35 g ha–1was applied to four- to six-leaf quackgrass, over 80% of the quackgrass regrowth was controlled one year later. Nicosulfuron did not injure ‘Agway 584S’ corn at the highest rate (140 g ha–1) tested and did not reduce silage or grain yield.
Estimating the Life of Short-lived, Cyclic Weeds with Markov Processes
Authors: Torell L. Allen , McDaniel Kirk C. , Williams Kent
Published: March 2018

Some annual weeds, perennial herbs, and suffrutescent half shrubs are unique in that their populations are cyclic in nature and relatively short-lived. This variability presents a confounding factor that makes management decisions about control of these weeds difficult. This paper presents a procedure, using Markov processes, that gives additional information for managing cyclic weed populations. The Markov chain model is used to evaluate the interyear patterns of broom snakeweed survival when growing on New Mexico rangeland.
Effectiveness of Bensulide in Controlling Two Annual Bluegrass (Poa annua) Subspecies
Authors: Callahan Lloyd M. , McDonald Ellen R.
Published: March 2018

Studies were conducted to determine the effectiveness of 11 multiple treatment combinations of bensulide in controlling a perennial and an annual subspecies of annual bluegrass. Bensulide controlled 97% of the annual subspecies with annual applications of 11 kg ai ha–1(Jan.) + 6 kg ha–1(Feb.) + 6 kg ha–1(Mar.) totaling 92 kg ha–1in 4 yr. The annual subspecies appeared to have a germination period from mid November to early January. None of the bensulide treatments controlled the perennial subspecies acceptably. The common occurrence of these two subspecies in mixed stands may account for the erratic weed control reported by many researchers. Bentgrass showed good tolerance to bensulide totals over 4 yr of 160 kg ha–1applied in a U.S. Golf Association rootzone green.
Weed Thresholds: The Space Component and Considerations for Herbicide Resistance
Authors: Maxwell Bruce D.
Published: March 2018

As an extension of weed threshold models in which crop losses are based on weed density, an alternative model for grass weeds in cereal crops is proposed that incorporates the theoretical importance of selection for herbicide resistance, initial weed population frequency, and weed seed dispersal. Simulations suggest optimum weed population levels (thresholds) for maintaining genotypes that are susceptible to control practices and which minimize crop yield reductions. Weed population frequency, in combination with dispersal and competitive traits may determine optimum weed management strategies/Model simulations indicate that understanding how agricultural practices select for “weedy” traits (e.g. herbicide resistance, competitive ability, dispersal potential) may be important in determining weed density thresholds.
Case History for Weed Competition/Population Ecology: Velvetleaf (Abutilon theophrasti) in Corn (Zea mays)
Authors: Sattin Maurizio , Zanin Giuseppe , Berti Antonio
Published: March 2018

According to Grime's model, velvetleaf can be classified as a competitive-ruderal species. Its biological and ecological characteristics make it particularly competitive and persistent in cultivated fields. Herbicide control is difficult and, once established, it is almost impossible to avoid seed production. The economic threshold, on a single year basis, varies between 0.3 and 1.7 plants m–2. When the competitive relationships and their effects are evaluated, it is very difficult to apply a weed management system based on a single-season threshold. When one considers the agronomic implications of the ecological characteristics of velvetleaf over a longer period, it can be concluded that the use of a single-season economic threshold is probably not the best management strategy.