bluuebunny/crossref_metadata_2025 huggingface dataset:
Volunteer Jerusalem Artichoke (Helianthus tuberosus) Interference and Control in Barley (Hordeum vulgare)
Authors: Wall David A. , Friesen George H.
Published: March 2018

Research conducted over 3 yr showed that volunteer Jerusalem artichoke was controlled effectively with clopyralid plus 2,4-D, dicamba plus 2,4-D, or 2,4-D alone applied postemergence at rates which did not injure spring barley. Glyphosate and paraquat applied preemergence to the crop did not reduce the number of Jerusalem artichoke shoots. Jerusalem artichoke which survived or escaped treatment was highly competitive with barley, as 4 to 6 surviving shoots/m2could reduce seed yield 20%.
No-Till Corn Production in a Living Mulch System
Authors: Echtenkamp Gerald W. , Moomaw Russell S.
Published: March 2018

Combinations of grass and legume mulches were planted in growing corn during the fall in 1985 and 1986, and the following spring no-till corn was planted into these living mulches. Mulch treatments consisted of a single species or grass plus legume mixtures. Fluazifop-P, 2,4-D, and atrazine were broadcast applied in late April to suppress the mulches and reduce their competition with corn. Chewings fescue and ladino clover competed least with dryland corn. Weed growth associated with chewings fescue and the ladino clover mulches was similar to that in the conventional disk-plant treatment, but corn yields were lower. Hairy vetch mulch was killed by 2,4-D. The winter rye mulch competed with corn and reduced yield.
Distribution of Blank Hexazinone Granules from Aerial and Ground Applicators
Authors: Feng Joseph C. , Sidhu Surindar S.
Published: March 2018

Variation in size and distribution patterns of granules of a blank hexazinone formulation were studied in both ground and aerial applications. Granule size ranged from 2.5 to 93 mg with 90% of the granules between 5 and 35 mg. The granule size frequency among weight classes did not change within a 5-m wide test swath from a truck-mounted applicator, indicating no impact on the distribution of active ingredient. The ground applicator did not produce a uniform deposition of granules. Average granule depositions were 11 ± 5 kg/ha and 16 ± 8 kg/ha for the target rates of 20 and 40 kg/ha, respectively. Aerial application with a helicopter-mounted bucket spreader produced a 27-m wide effective swath. Average deposition rates were 19 ± 5 kg/ha and 39 ± 9 kg/ha for the target rates 20 and 40 kg/ha, respectively. The optimal sample sizes for aerial application were estimated to be 27 and 50 samples for 40 (±10%) and 20 (±10%) kg/ha rates, respectively, with 90% certainty.
Duration and Intensity of Unicorn-Plant (Proboscidea louisianica) Interference with Cotton (Gossypium hirsutum)
Authors: Riffle Michael S. , Murray Don S. , Verhalen Laval M. , Weeks David L.
Published: March 2018

The duration and intensity of unicorn-plant interference on lint yield of cotton were evaluated in the field. Random densities of 5.5 ± 1.1 unicorn-plant/m2reduced lint yield by 41 kg/ha or about 5% for each week that unicorn-plant was present. Interference by 4, 8, and 12 weeds/10 m row decreased yield by 22, 49, and 56 kg/ha, respectively, for each week of weed interference. Each 1 kg/ha of unicorn-plant dry weight reduced lint yield by 0.26 kg/ha. Linear regression of weed dry weight could be used to predict cotton lint yield changes regardless of duration or intensity of weed interference.
Multiflora Rose (Rosa multiflora) Control with Metsulfuron
Authors: Derr Jeffrey F.
Published: March 2018

Multiflora rose was defoliated completely 320 days after spring foliar application of metsulfuron. Metsulfuron and 2,4-D plus dicamba spring foliar applied controlled multiflora rose equally. Metsulfuron applied to soil using a spotgun at 20 mg per m diam of multiflora rose in the spring resulted in 95% control 320 days later in one study but only 50% control in another. Control was less when lower rates of metsulfuron were soil-applied with a spotgun. Tebuthiuron spring soil-applied completely controlled multiflora rose. All spring-applied foliar and soil applications seemed to control multiflora rose better than fall treatments.
Red Rice (Oryza sativa) Control in Soybeans (Glycine max)
Authors: Nastasi Paolo , Smith Roy J.
Published: March 2018

In 1986 and 1987, imazethapyr at 0.11 or 0.14 kg ai/ha and metolachlor plus imazaquin at 1.4 plus 0.16 kg/ha, applied preplant incorporated, controlled greater than 85% of red rice in soybeans. Red rice was controlled similarly by standard herbicide treatments of alachlor at 2.8 kg ai/ha, metolachlor at 2.2 kg ai/ha, and alachlor plus imazaquin at 2.5 plus 0.14 kg ai/ha. Eighty-four percent or more of red rice was controlled with single postemergence herbicide treatments of DPX-Y6202-31 at 0.14 kg ai/ha or imazethapyr at 0.11 kg ai/ha or by sequential postemergence treatment of DPX-Y6202-31 (0.07 plus 0.07 kg ai/ha) or clethodim (0.1 plus 0.1 kg ai/ha). Soybean injury was insignificant, and yields from treated plots were superior or equal to those from untreated plots.
Cropping and Herbicide Systems for Red Rice (Oryza sativa) Control
Authors: Smith Roy J.
Published: March 2018

A cropping system of soybeans and rice grown in alternate years for 4 yr controlled red rice when combined with effective herbicide treatments applied to the soybean crop. Effective herbicide treatments in soybeans were preplant incorporated applications of alachlor, metolachlor, or alachlor plus trifluralin each followed by postemergence over-the-top applications of bentazon plus mefluidide, postemergence directed applications of paraquat, or sequential applications of postemergence over-the-top bentazon plus mefluidide and postemergence directed paraquat. Control of red rice in soybeans reduced red rice infestations in the subsequent rice crop. Red rice infestations were lower in rice grown the fourth year than in rice grown the second year. Postemergence over-the-top or directed herbicide treatments used alone or combined with preplant incorporated applications of trifluralin did not control red rice in soybeans with subsequent red rice infestations in the rice crop.
Glyphosate as Harvest Aid for Corn (Zea mays)
Authors: Alcantara Elifas N. , Wyse Donald L.
Published: March 2018

Glyphosate was evaluated as a preharvest treatment for enhancing corn kernel dry down and quackgrass control. Glyphosate at 0.4, 0.8, 1.3, and 1.7 kg ae/ha was applied to corn before physiological maturity (kernel moisture 44 to 47%) and at physiological maturity (kernel moisture 35 to 39%). Three weeks after treatment, grain moisture of plants treated at physiological maturity was 2.3 to 6.9% less than that of plants treated before physiological maturity which was 2.2 to 5.5% less than that of untreated plants. Glyphosate did not increase corn kernel drying effectively under high humidity conditions. Glyphosate applied to pre-physiologically-mature corn controlled quackgrass 49 to 64% in the fall of 1984 and 69 to 91% in the fall of 1985. None of the glyphosate treatments reduced corn yield. Glyphosate applied preharvest above the corn canopy may increase the rate of corn kernel drying and may control fall quackgrass in the northern corn belt.
Chemigation and Spray Application of Herbicides on Container-Grown Ornamentals
Authors: Caviness Darlene M. , Talbert Ronald E. , Klingaman Gerald L.
Published: March 2018

Metolachlor, oryzalin, and napropamide when chemigation-applied controlled large crabgrass more effectively than when spray applied in container-grown azalea, liriope, and Japanese holly. Oxadiazon and oxyfluorfen were equally effective as chemigation or spray applications. Azaleas were generally more susceptible to contact injury from sprays of oxadiazon and oxyfluorfen and large crabgrass interference than were holly and liriope.
Rose Rosette Disease on Multiflora Rose (Rosa multiflora) in Indiana and Kentucky
Authors: Hindal Dale F. , Amrine James W. , Williams Robert L. , Stasny Terry A.
Published: March 2018

Multiflora roses showing symptoms of rose rosette were found in nine counties in southern Indiana and two counties in northern Kentucky. The eriophyid mite, Phyllocoptes fructiphilus Kiefer (Acari: Eriophyidae), implicated as the vector of the rose rosette agent, occurred on most symptomatic material. Another eriophyid mite, P. rosarum Liro, was found on symptomatic material collected in Kentucky. Transmission of the causal agent into multiflora rose by shield budding and by P. fructiphilus was successful. The rose rosette agent appears to be spreading east and is established on multiflora rose in the Ohio Valley.
Fall-Applied Glyphosate for Canada Thistle (Cirsium arvense) Control in Spring Wheat (Triticum aestivum)
Authors: Carlson Steven J. , Donald William W.
Published: March 2018

Effects of repeated late-fall applications of the isopropylamine salt of glyphosate at 1.7 kg ae/ha plus 0.5% (v/v) surfactant on adventitious root buds, thickened propagative roots (> 1.3 mm diam), and shoot density of Canada thistle were studied in continuous hard red spring wheat over a 4-yr period. Glyphosate suppressed Canada thistle shoot density more quickly and to a greater extent than thickened root fresh weight or root bud number. A single fall application of glyphosate drastically decreased Canada thistle shoot density for 1 yr after treatment. However, shoot density was the same as the untreated control by 2 yr after a single fall treatment. Two consecutive late-fall applications of glyphosate in 2 yr decreased Canada thistle shoot density 94% in the fall 1 yr after the last treatment. Glyphosate reduced Canada thistle thickened root fresh weight 70% in the first fall 1 yr after a single fall treatment. However, 2 yr after a single fall application of glyphosate, root fresh weight equalled the controls. Two consecutive fall applications of glyphosate reduced thickened root fresh weight 77% 1 yr after the second treatment.
Economics of Herbicide use on Corn (Zea mays) and Soybeans (Glycine max) in Ontario
Authors: Stemeroff Marvin , Swanton Clarence J. , Hamill Allan S. , Brown Rudy H.
Published: March 2018

The productivity of herbicides used in corn and soybeans was calculated from field data collected in Ontario from 1967 to 1985. Combinations of preplant incorporated and preemergence treatments were selected and were evaluated to determine their effect on crop yield. Corn and soybean yields increased from herbicide use, thereby resulting in a positive net benefit to growers. Benefit/cost ratios for herbicide use in corn and soybeans were calculated to be 2.8/1 and 2.6/1, respectively, at an average price of $132/1000 kg for corn and $275/1000 kg for soybeans. The benefit/cost ratios varied with test location, method of herbicide application, and prevailing market price.
Loblolly Pine (Pinus taeda) Response to Weed Control in Central Louisiana
Authors: Haywood James D.
Published: March 2018

Herbaceous weed control was studied on a loblolly pine planting site in central Louisiana. Pine growth was enhanced without eradicating weeds; reducing weed biomass about 50% increased the mean inside bark volume of loblolly pine saplings 53% on the weeded treatments compared to the untreated control after five growing seasons in the field. Pines receiving both preplant weed control with glyphosate or disking and postplant weed control with a series of yearly treatments (1982, atrazine plus simazine; 1983, atrazine plus oxyfluorfen; 1984, hexazinone; and 1985, hexazinone) had 62% greater volume than pines on the preplant-only treatments. So, the best gains in loblolly pine volume required postplant weed control.
Effects of Ammonium Fertilizers and BCH 81508 S on Antagonism with Sethoxydim plus Bentazon Mixtures
Authors: Jordan David L. , York Alan C.
Published: March 2018

Field and greenhouse experiments were conducted to determine effects of adding (NH4)2SO4or urea ammonium nitrate containing 30% N (UAN) and/or substituting BCH 81508 S for crop oil with sethoxydim and sethoxydim plus bentazon applied to corn and large crabgrass. Control was similar with sethoxydim plus crop oil and sethoxydim plus BCH 81508 S. Adding (NH4)2SO4or UAN moderately improved control with sethoxydim in some experiments. Both (NH4)2SO4and UAN increased control when added to sethoxydim plus bentazon, with UAN being the more effective ammonium fertilizer. Large crabgrass control with sethoxydim plus bentazon was enhanced more with 1.4 and 2.8 kg/ha (NH4)2SO4than with 5.6 kg/ha. Substituting BCH 81508 S for crop oil with sethoxydim plus bentazon also increased corn and large crabgrass control. Adding ammonium fertilizers plus substituting BCH 81508 S for crop oil with sethoxydim plus bentazon eliminated antagonism on corn and partially alleviated antagonism on large crabgrass.
Soybean (Glycine max) Tolerance to Preemergence and Postemergence Herbicides
Authors: Griffin James L. , Habetz Robert J.
Published: March 2018

Field studies were conducted on a Crowley silt loam under weed-free conditions to determine herbicidal tolerance of ‘Centennial’ soybeans. Early season phytotoxicity and mature plant height reductions were caused by imazaquin at 140 g ai/ha applied preemergence (PRE) followed by imazaquin applied postemergence (POE) at both 140 (labeled rate) and 280 g/ha and for metribuzin plus chlorimuron at 360 plus 60 g ai/ha PRE followed by chlorimuron POE at 18 g/ha (double rate). Soybean yields, averaged across 3 yr, were reduced only for metribuzin plus chlorimuron PRE followed by chlorimuron POE at both 9 and 18 g/ha (10 and 15%, respectively).
Response of Sweet Corn (Zea mays) Endosperm Mutants to Chloracetamide and Thiocarbamate Herbicides
Authors: Bennett Mark A. , Gorski Stanley F.
Published: March 2018

Cold stress and field studies were conducted to determine the effects of alachlor, metolachlor, butylate plus dichlormid, and EPTC plus dichlormid on germination and seedling vigor of 30 sweet corn cultivars with three commercially important endosperm mutants (su, se, andsh2). Seedling emergence from cool soils was best when treated with EPTC plus dichlormid and alachlor and was decreased 11% by metolachlor and butylate plus dichlormid. Theseandsh2endosperm mutants were injured the most by the herbicides. Plant size was reduced by the thiocarbamate herbicides but not by the chloracetamides.
Effect of Herbicide Mixtures and Seeding Rate on Soft Red Winter Wheat (Triticum aestivum) Yield
Authors: Harrison S. Kent , Beuerlein James E.
Published: March 2018

A mixture of 2,4-D with either thiameturon, DPX-L5300, or DPX-R9674 controlled common chickweed in winter wheat better than 2,4-D alone. None of these herbicides affected wheat height, lodging, or yield. Similarly, no significant differences in wheat height or lodging occurred among seeding rates. Wheat sown near South Charleston, OH, at a seeding rate of 67 kg/ha yielded significantly less than that sown at 100 or 134 kg/ha; however, there was no difference in wheat yield among seedling rates at a second location near Columbus, OH.
Cowpea (Vigna unguiculata) Control in Soybean (Glycine max) With Acifluorfen, Chlorimuron, and Thiameturon
Authors: Jones James D. , Gossett Billy J. , Harris James R. , Toler Joe E.
Published: March 2018

Acifluorfen, chlorimuron, and thiameturon were compared in single and sequential treatments for cowpea control in soybean. Chlorimuron applied once at 8.8 g ai/ha at 14, 21, and 28 days after cowpea emergence controlled 80% or more of cowpea. Control was greater at 14 and 21 than at 28 days after emergence in one of three experiments. Cowpea control by chlorimuron was similar with single and sequential treatments. Soybean injury was lower, and soybean seed yields generally were higher with chlorimuron than with thiameturon or acifluorfen. Thiameturon and acifluorfen controlled less than 60% of cowpea. Three weedy cowpea cultivars responded the same to chlorimuron, but cowpea recovery was substantial in 1 of 3 yr.
Response of Cotton (Gossypium hirsutum) to Repeated Applications of Dinitroaniline Herbicides
Authors: Keeling J. Wayne , Abernathy John R.
Published: March 2018

Dinitroaniline herbicides have been used on the Texas Southern High Plains since the mid-1960s. Over this same period, cotton yields in this region have declined in spite of improved varieties and technology. Repeated applications of trifluralin and pendimethalin, each applied at 1x and 2x rates, were incorporated in 1983 through 1988. Variations in cotton stands, yields, and fiber quality were high due to environmental conditions. After six repeated applications, no reductions in cotton growth or yield were observed, even at the highest rates.
Potato (Solanum tuberosum) Yields and Weed Populations in Conventional and Reduced Tillage Systems
Authors: Wallace Russell W. , Bellinder Robin R.
Published: March 2018

Linuron, metribuzin, oryzalin, and dinoseb were evaluated for weed control in conventional (CT) and rye-stubble reduced-tillage (RT) systems for potatoes. Early season control of weeds was equivalent for all herbicides in both tillage systems. In 1985, redroot pigweed populations were significantly greater in RT than in CT control plots. Populations of common lambsquarters were equivalent, regardless of the tillage system. In 1986, the rye mulch reduced early emergence of both species in untreated RT plots when compared to the untreated CT controls. During both seasons, potato stands decreased 16% with RT. In 1985, total yields did not differ between tillage systems; however, in 1986, total potato yields in RT plots decreased an average of 22% compared to yields in CT plots.
Ozone-Metolachlor Interactions on Corn (Zea mays), Bean (Phaseolus vulgaris), and Soybean (Glycine max)
Authors: Mersie Wondimagegnehu , Mebrahtu Tadesse , Rangappa Muddappa
Published: March 2018

The potential interactive effects between metolachlor [0, 0.1, 0.5, and 1.0 ppm (w/w)] and the air pollutant ozone (O3) [0.2 and 0.4 ppm (v/v)], on growth of corn, bean, and soybean were examined under controlled conditions. At both concentrations, O3alone reduced corn and bean dry weights but only affected bean at 0.4 ppm (v/v). Shoot dry weight of corn was reduced by O3plus metolachlor more than expected, thus indicating synergism. The expected dry weights of bean and soybean treated with metolachlor plus O3were similar to or higher than expected, thus indicating additive or antagonistic interactions.
Weed Control with Clomazone Alone and with Other Herbicides
Authors: Westberg Dan E. , Oliver Lawrence R. , Frans Robert E.
Published: March 2018

The weed control spectrum of clomazone, the influence of clomazone on the performance of other herbicides, and the performance of tank mixtures containing clomazone were evaluated from 1985 through 1987. Clomazone applied preemergence at 280 g ai/ha controlled 90 to 100% of barnyardgrass, giant foxtail, goosegrass, large crabgrass, seedling johnsongrass, prickly sida, and velvetleaf. Clomazone at reduced rates was more effective applied preemergence than preplant-incorporated for 10 of 23 weed species. Clomazone enhanced imazaquin activity on entireleaf morningglory and sicklepod in 1986. A tank mixture of clomazone, imazaquin, and metribuzin at half the labeled rates reduced soybean injury, increased soybean yield, and controlled weeds as well as the mixture at labeled rates.
Dry Edible Bean (Phaseolus vulgaris) Response to Imazethapyr
Authors: Wilson Robert G. , Miller Stephen D.
Published: March 2018

Imazethapyr at 0.07 and 0.10 kg ai ha-1applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) was evaluated at two locations in 1988 and 1989 for safety to dry edible beans. Bean stunting, leaf crinkling, and interveinal chlorosis were evident from imazethapyr and varied from 1 to 57%. Imazethapyr significantly reduced bean height and delayed maturity. PPI and POST applications of imazethapyr at 0.07 and 0.10 kg ha-1did not reduce bean seed yields compared to yields of the untreated control. Bean cultivar by herbicide interactions were significant for bean injury but varied with year and location.
Runoff and Erosion Following Mechanical and Chemical Control of Creosotebush (Larrea tridentata)
Authors: Wood M. Karl , Garcia Eddie L. , Tromble John M.
Published: March 2018

Runoff and sediment yield were monitored from 1983 through 1986 on a range site dominated by creosotebush. The site was rootplowed and seeded, treated with tebuthiuron at 36 kg ai ha-1, or left untreated. Runoff from rootplowed and herbicide-treated plots was no different from untreated plots for 1 yr, but sediment yield from treated plots was lower than that from the untreated plots. Rootplowing and seeding increased sediment yield in the second year (1984), whereas treating with herbicide decreased sediment yield. Runoff and sediment yield during 1985 and 1986 were greatest from the untreated areas and least from the rootplowed and herbicide-treated areas. Total cover was nearly the same for each treatment. The untreated plots had 13% shrub cover; the others had none. Between shrubs in untreated plots, bare ground occupied large interconnected areas that contributed to the higher runoff and erosion rates.
DPX-V9360 Efficacy with Adjuvants and Environment
Authors: Nalewaja John D. , Woznica Zenon , Manthey Frank A.
Published: March 2018

Adjuvants enhanced DPX-V9360 control of green foxtail in the greenhouse and field as follows: methylated sunflower oil > petroleum oil > nonionic surfactant WK > nonionic surfactant X-77. DPX-V9360 applied at rates that controlled weeds did not injure corn. Green foxtail control with DPX-V9360 decreased as the amount of simulated rainfall after application increased from 0 to 4 mm and control increased as a 2 mm simulated rainfall was delayed up to 24 h. The influence of simulated rainfall differed with adjuvants, but adjuvants did not overcome the lower green foxtail control with simulated rainfall. DPX-V9360 was more phytotoxic to green foxtail and redroot pigweed at 95 to 100% than 45 to 50% relative humidity and at 20 or 30 C than 10 C after treatment.
Grass Weed Control for Soybean (Glycine max) on Clay Soil
Authors: Heatherly Larry G. , Elmore C. Dennis
Published: March 2018

Field studies were conducted for four consecutive years to determine if repeated applications of trifluralin (preplant incorporated), metolachlor (preemergence), and fluazifop (postemergence) herbicides alone or combined could be utilized in soybean to effectively control grass weed populations and maintain optimum yield in an irrigated environment where metribuzin plus dinoseb (preemergence) and 2,4-DB plus linuron (postemergence) were used as a standard weed control system. After repeated applications each year, all treatments maintained similar yields that were no different from yields obtained from the standard system. Grass weed infestation did not increase significantly in the treatment that received only the standard weed control herbicides over the duration of the study.
Bentazon for Annual Weed Control in Newly Seeded Alfalfa (Medicago sativaL.)
Authors: Harvey R. Gordon
Published: March 2018

Preplant-incorporated (PPI) herbicides were applied to suppress annual weeds in new seedings of alfalfa, then additional annual weed control and crop tolerance from selected bentazon treatments were evaluated. Bentazon applied at 0.8 kg ai ha-1without an adjuvant caused an average of 8% visual injury to newly seeded alfalfa but did not reduce first-harvest alfalfa yields. Bentazon improved common lambsquarters control in newly seeded alfalfa and reduced weed biomass in first-harvest forage. No significant difference in crop injury, weed control, alfalfa yield, or weed yield was observed when bentazon was applied at 0.6, 0.8, or 1.1 kg ha-1. Greater alfalfa injury occurred when bentazon was applied with 1.25% v/v oil-emulsifier mixture, than when applied alone or with 5% v/v 28% liquid nitrogen fertilizer (28% N). Ten alfalfa cultivars did not differ in sensitivity to bentazon applied early postemergence (POST) or POST.
The Influence of Terbufos on the Response of Five Corn (Zea mays) Hybrids to CGA-136872
Authors: Holshouser David L. , Chandler James M. , Smith Harold R.
Published: March 2018

Field experiments were established to investigate the influence of terbufos on the response of five corn hybrids to postemergence applications of CGA-136872. In 1987, Asgrow RX404, Dekalb DK656, Funk's G4673A, and Pioneer P3165 were tolerant to CGA-136872 when no soil insecticides were applied. In 1988, terbufos was applied at 1.1 kg ai ha-1in-furrow at planting. Injury was observed on all hybrids following CGA-136872 application in 1988. With the exception of Funk's G4307, all hybrids were tolerant to CGA-136872 in 1989 when no soil insecticide was used. When terbufos was applied in-furrow, injury increased with increasing herbicide rate for these hybrids.
Leaching of Oxyfluorfen in Container Media
Authors: Horowitz Menashe , Elmore Clyde L.
Published: March 2018

Bentgrass was used to bioassay oxyfluorfen in leaching experiments done in columns of soilless potting media and soils, with herbicide incorporated into the upper 2 to 4 cm. Depth of herbicide leaching increased in order in the following soils: peat and sand (1:1) mix, Stockton clay soil, Yolo fine sandy loam soil, and redwood bark and sand (3:1) mix. Depth of leaching was not related to soil organic matter content. Equilibration experiments showed that peat adsorbed 4 to 5 times more oxyfluorfen than redwood bark. Less leaching was observed in potting mixtures containing peat than bark. Raising the oxyfluorfen dose from 20 to 200 ppmw increased the depth of leaching and concentration of herbicide in the leachate, while a 10-fold increase in water volume had only a limited effect. Twenty ppmw of oxyfluorfen incorporated in the top of a peat-containing potting medium has a low risk of leaching out of the container.
Selective Application of Glyphosate for Control of Larkspurs (Delphiniumspp.)
Authors: Ralphs Michael H. , Mickelsen Larry V. , Evans John O. , Dewey Steven A.
Published: March 2018

Glyphosate effectively kills duncecap and tall larkspur on mountain rangelands but it is nonselective and kills all other vegetation it contacts. Two selective application methods to treat individual plants were compared to demonstrate their efficacy in controlling larkspur and their effect on associated plant species: (1) spot spray with glyphosate concentration at 2% product solution (0.8% ai); (2) hand held wiper applicator with glyphosate concentration at 33% production solution (13.5% ai). The two methods were equally effective in killing most of the larkspur plants, but the sprayer applicator was more rapid and easier to apply. Neither method adversely affected foliar cover of associated perennial species. Glyphosate must be applied to the entire plant to ensure its mortality.
Plant Protection Issues. I. A Commentary on New Weeds in the United States
Authors: Westbrooks Randy G.
Published: March 2018

New or recently introduced weeds are biological pollutants in our natural and agricultural ecosystems. Unlike chemical pollutants, new weeds left unchecked often proliferate and pose problems that may not become apparent until eradication is too expensive or impractical. Management strategies for weeds should include: 1. prevention (from entering foreign commerce); 2. exclusion (detection of weed contaminants in imported products at ports of entry); 3. detection, containment, and eradication of incipient infestations; and 4. perpetual control (of widespread species that cannot otherwise be addressed). Appropriate legislative authority, modern weed technology, funding, and a renewed commitment to the concept of prevention are needed to prevent the introduction of new weeds. A national initiative to prevent the establishment of new weeds would be beneficial by saving on future losses and perpetual control costs. Actions taken now will prevent the continued introduction and spread of new weeds in the United States.
Velvetleaf
Authors: Mitich Larry W.
Published: March 2018

Velvetleaf (Abutilon theophrastiMedicus. ♯ ABUTH), a large, vigorously competitive plant, produces thousands of long-lived seeds. Its hard-coated seeds germinate throughout the warm season, making control difficult. Seeds, adult plants, and decaying plant parts contain or produce allelopathic chemicals which aggravate the effects of velvetleaf on surrounding crop plants. Velvetleaf must be attacked with multiple strategies; reliance on single herbicides in the past has allowed velvetleaf to spread and even develop herbicide tolerance.
Insecticides Modify Cotton (Gossypium hirsutum) Response to Clomazone
Authors: York Alan C. , Jordan David L. , Frans Robert E.
Published: March 2018

Field experiments were conducted to determine if aldicarb, disulfoton, or phorate applied in-furrow at 0.84 or 1.12 kg ai ha–1affected cotton response to clomazone applied PPI or PRE at rates ranging from 0 to 1.12 kg ai ha–1. Disulfoton and phorate greatly reduced clomazone-induced chlorosis, stunting, and death of cotton seedlings. Compared with no insecticide or with dimethoate applied POST, aldicarb did not affect cotton response to clomazone. A clomazone rate by insecticide interaction was not observed for cotton yield. Clomazone reduced cotton yield at one of five locations. Insecticides affected yield at three locations, where highest yields were from cotton treated with aldicarb. In a separate experiment with 0.56, 1.12, and 2.24 kg ha–1of phorate applied in-furrow and 1.12 kg ha–1of clomazone applied PPI, phorate at all rates protected cotton from clomazone phytotoxicity.
Postemergence Control of Broadleaf Weeds in Tomato (Lycopersicon esculentum)
Authors: McGiffen Milton E. , Masiunas John B.
Published: March 2018

Greenhouse and field experiments were conducted to evaluate the control of eastern black nightshade and velvetleaf in tomato with bentazon, metribuzin, pyridate, and acifluorfen. Metribuzin controlled velvetleaf but not eastern black nightshade, whereas pyridate controlled eastern black nightshade but not velvetleaf. A combination of metribuzin + pyridate controlled both weeds, but caused tomato injury 4 wk after application. Bentazon neither controlled the weeds nor injured the crop. Acifluorfen controlled both eastern black nightshade and velvetleaf. Diammonium phosphate and oxysorbic (5 POE) improved bentazon and acifluorfen activity against velvetleaf. Although initial crop injury from some treatments applied prior to fruit initiation was severe, the crop recovered and there were no reductions in fruit weight compared with the control. However applying acifluorfen with oxysorbic (5 POE) during fruit development reduced yield 50%.
Economics of Johnsongrass (Sorghum halepense) Control in Soybeans (Glycine max)
Authors: Johnson William G. , Frans Robert E. , Parsch Lucas D.
Published: March 2018

Field trials were conducted from 1986 to 1988 at Clarkedale, AR, to evaluate selective POST grass herbicides for johnsongrass control in soybeans. Herbicide treatments were trifluralin PPI followed by single and sequential POST applications of fenoxaprop, fluazifop, quizalofop, or sethoxydim. In 1986, sequential applications of sethoxydim and fenoxaprop controlled more johnsongrass 4 WAT than single treatments. In 1987 and 1988, all herbicides except fenoxaprop controlled more than 79% of johnsongrass. The number of johnsongrass stems was reduced by cultural practices and herbicides after 2 yr. The lowest cost of control and the highest average net return over the 3-yr period was obtained with quizalofop.
Rhizome Johnsongrass (Sorghum halepense) Control in Corn (Zea mays) with Primisulfuron and Nicosulfuron
Authors: Camacho Rolando F. , Moshier Loren J. , Morishita Don W. , Devlin Daniel L.
Published: March 2018

In the greenhouse, soil applications of primisulfuron (40 g ai ha–1) reduced growth of emerged rhizome johnsongrass plants more than nicosulfuron (40 g ai ha–1). Both herbicides reduced growth more when applied to foliage only; a further decrease in growth did not occur for applications to both soil and foliage. Primisulfuron did not completely prevent regrowth of johnsongrass with any application method. Nicosulfuron prevented regrowth when applied to the foliage and to both soil and foliage. In single-year field studies in corn at four dryland sites and two irrigated sites, 50:50 split applications of primisulfuron (40 g ai ha–1) and nicosulfuron (35 g ai ha–1) approximately 2 wk apart provided the most consistent rhizome johnsongrass control compared with early or late single applications when visually rated 8 wk after the first application. Nicosulfuron treatments were more effective than primisulfuron treatments at both dryland sites the first year and at one of two dryland sites the second year. Primisulfuron and nicosulfuron at the irrigated site the first year were equivalent in efficacy. Nicosulfuron was more effective than primisulfuron at the irrigated site the second year. Primisulfuron or nicosulfuron treatments more than doubled corn yields at the dryland sites both years regardless of application timing. Split applications of primisulfuron or nicosulfuron provided the highest yields (approximately 80% increase over untreated plots) at the irrigated site the first year. All treatments provided equivalent yield increases (approximately 50%) the second year.
Growth and Development of Bigroot Morningglory (Ipomoea pandurata)
Authors: Horak Michael J. , Wax Loyd M.
Published: March 2018

Growth and development of bigroot morningglory was observed and quantified. Emergence occurred 75 ± 5 growing degree days (GDD) after seeding. Flower and seed production began 630 ± 20 GDD after emergence and continued until the first frost killed the shoots. Seedlings needed approximately 460 GDD of growth to become perennial. In the second year of growth, plants emerged in early May and flowered within 425 ± 50 GDD. Shoot dry weight accumulation in first-year plants was 3.5 g for the first 600 GDD after which a fifteenfold increase in dry weight occurred. Root growth followed the same pattern, however the large increase in dry weight occurred approximately 300 GDD later than that of the shoots. The root:shoot ratio was 0.2 to 0.3 for the first 900 GDD and increased to greater than 1.0 by the final harvest.
Buckbrush (Symphoricarpos orbiculatus) Control in Tall Fescue (Festuca arundinacea) Pastures
Authors: Defelice Michael S.
Published: March 2018

Field studies were established to evaluate several herbicides for buckbrush control in tall fescue pastures. Buckbrush was controlled most consistently by 2,4-D amine or low volatile ester, or package-mixes of 2,4-D plus dicamba or triclopyr. Two consecutive years of herbicide application was more effective for reducing buckbrush stem populations than one application.
Soil as Herbicide Carrier for Italian Ryegrass (Lolium multiflorum) Control in Wheat (Triticum aestivum)
Authors: Kinfe Birhanu , Peeper Thomas F.
Published: March 2018

The efficacy of herbicides applied broadcast by hand with a soil carrier or sprayed with water carrier were compared for Italian ryegrass control in winter wheat in central Oklahoma. Italian ryegrass was controlled 77 to 100% with BAY SMY 1500, chlorsulfuron, and CGA-131036 applied with both carriers. Metribuzin applied POST with 187 L ha–1water was less phytotoxic to Italian ryegrass and wheat than with 200 kg ha–1soil. All herbicides applied with 200 kg ha–1silt loam soil as carrier at two locations controlled Italian ryegrass 96 to 100%. Increasing herbicide rate, soil carrier quantity, or broadcasting soil-carried herbicide in two directions rather than one did not significantly improve herbicide efficacy over that of conventional spraying.
Common Lambsquarters (Chenopodium album) Control with Non-selective Herbicides
Authors: Higgins Jeffrey M. , Whitwell Ted , Toler Joe E.
Published: March 2018

Field experiments were conducted to compare the timing of non-selective herbicide application on common lambsquarters under reduced tillage culture after wheat harvest. Common lambsquarters was controlled more effectively with herbicides applied to plants that were allowed to recover from removal of topgrowth during wheat harvest. When herbicides were applied immediately after wheat harvest, only glufosinate (HOE-39866) at the low and medium rates provided greater than 70% control.
Effect of Acifluorfen on the Absorption, Translocation, and Metabolism of Chlorimuron in Certain Weeds
Authors: Westberg Dan E. , Coble Harold D.
Published: March 2018

Foliar absorption of14-chlorimuron at 6, 12, 24, and 48 h after application to common cocklebur was reduced when applied in combination with acifluorfen. A maximum reduction of 10% was observed at 48 h.14C translocation to meristematic tissue above the treated leaves also was reduced by acifluorfen in common cocklebur at 24 and 48 h after treatment. Absorption and translocation of14C-chlorimuron in sicklepod was not affected by acifluorfen. Thin layer chromatographic analysis of treated leaf extracts showed two metabolites in common cocklebur (Rfvalues of 0.0 and 0.42) and four metabolites in sicklepod (Rfvalues of 0.0, 0.16, 0.33, and 0.50). All metabolites were more polar than the parent compound (Rfvalue of 0.64). Addition of acifluorfen did not affect chlorimuron metabolism in common cocklebur but reduced metabolism in sicklepod. Absorption, translocation, and metabolism of acifluorfen in common cocklebur or sicklepod were not affected by the addition of chlorimuron.
Giant Ragweed (Ambrosia trifida) Control in Soybean (Glycine max)
Authors: Baysinger Jerry A. , Sims Barry D.
Published: March 2018

Two field experiments were established in 1988 and 1989 in southeast Missouri to evaluate several herbicides and herbicide combinations for giant ragweed control in soybean. In 1988, a timely rainfall was not received for soil-applied herbicides and giant ragweed control was less than 75%. However, in 1989 soil moisture was sufficient for uptake of soil-applied herbicides and early season giant ragweed control was generally greater than 80%. Chlorimuron, chlorimuron plus 2,4-DB, imazaquin plus 2,4-DB, acifluorfen followed by naptalam plus 2,4-DB, fomesafen, and imazethapyr applied to 2.5 to 5-cm giant ragweed controlled more than 85% in 1988. In 1989, all POST treatments except imazaquin controlled more than 81% of giant ragweed 2 wk after treatments. Imazethapyr controlled seedling giant ragweed at heights up to 12 to 25 cm. Giant ragweed regrowth and/or reinfestation and giant ragweed seed production occurred with all herbicide treatments.
Tank-mix Combinations for Weed Control in Stale Seedbed Soybean (Glycine max)
Authors: Bruff Stacey A. , Shaw David R.
Published: March 2018

Field experiments were established in 1989 and 1990 on silty clay and sandy loam soils to evaluate selective herbicides in combination with non-selective weed control measures in conventional and stale seedbed soybean production. Metribuzin PRE followed by chlorimuron POST controlled sicklepod better with paraquat than with glyphosate. A POST application of imazaquin increased sicklepod and pitted morningglory control by imazaquin PRE alone in a stale seedbed or tillage program. Pitted morningglory control with imazaquin PRE was lower with tillage than with glyphosate or paraquat combinations in a stale seedbed program. All metribuzin plus chlorimuron PRE treatments, whether conventional tillage or stale seedbed, controlled pitted morningglory more than 75%. Hemp sesbania control was above 80% with all metribuzin followed by chlorimuron or metribuzin plus chlorimuron PRE combinations, and less than 70% with all treatments containing imazaquin. Selective herbicides increased yield in stale seedbed when glyphosate or paraquat was added. Imazaquin PRE, imazaquin PRE followed by imazaquin POST, and metribuzin PRE followed by chlorimuron POST tank mixed with glyphosate or paraquat in a stale seedbed program increased yield compared with the same treatments used with tillage.
Petroleum Oil and Emulsifier Affect the Phytotoxicity of Imazethapyr
Authors: Manthey Frank A. , Matysiak Robert , Nalewaja John D.
Published: March 2018

Six commercial petroleum oil (PO) adjuvants differed in their enhancement of imazethapyr phytotoxicity to green foxtail and kochia but not to redroot pigweed, when imazethapyr was applied postemergence at 17 g ha–1. Imazethapyr at 5 g ha–1plus 27 combinations of three oils and nine emulsifiers reduced kochia growth by 61 to 88%. Optimum emulsifier concentration in a PO adjuvant ranged from 15 to 20% (v/v). All PO adjuvants tested produced fair to excellent oil-inwater emulsions with imazethapyr; however, emulsion stability did not correlate with weed control.
The Threshold Concept and its Application to Weed Science
Authors: Coble Harold D. , Mortensen David A.
Published: March 2018

The concept of thresholds has many applications in weed science, depending on the response being measured. The most common adjectives used to describe thresholds are damage, economic, period, and action. Damage threshold is the term used to define the weed population at which a negative crop yield response is detected. An economic threshold is the weed population at which the cost of control is equal to the crop value increase from control of the weeds present. Economic threshold may be used to describe short-term effects of weed interference occurring in a single growing season, or multiple-season effects including some cost associated with seed produced by uncontrolled plants. The term period threshold implies that there are times during the crop cycle in which weeds are more or less damaging than at others. Action threshold is the point at which some control action is initiated, and usually includes economic considerations along with other less tangible factors such as aesthetics, risk aversion, or sociological pressures. Regardless of the type, thresholds imply that weed effects are population dependent, and as such, allow some type of prediction to be made relative to the consequences of control decisions. One successful approach to the implementation of thresholds has been through the development of computerized decision-aid software. These programs allow users to compare economic and environmental consequences of potential control actions before committing to one particular decision.
Itchgrass–Stop the Trains?
Authors: Hall David W. , Patterson David T.
Published: March 2018

Itchgrass [Rottboellia cochinchinensis(Lour.) Clayton ♯ ROOEX] is a large aggressive annual in the Poaceae. This weedy grass is native to Southeast Asia. It now occurs also in tropical and subtropical areas of Australia and Africa and has been introduced into the West Indies and North, Central, and South America. It apparently was introduced into the United States at Miami, Fla. and Lafayette, La. in the early 1900s (1, 6, 7).
Sulfonylurea Herbicides Reduce Survival and Seed Production of Green and Yellow Foxtails (Setariaspp.)
Authors: Khan Mohammad , Donald William W.
Published: March 2018

Chlorsulfuron or metsulfuron applied POST at 10 g ai ha–1at the four-leaf stage prevented yellow foxtail from forming seed, whereas seed production per pot was 53 to 77% of untreated checks following POST tribenuron or CGA-131036 treatments in greenhouse experiments. Chlorsulfuron applied POST at the two- and four-leaf stage severely reduced total seed production of yellow foxtail primarily by increasing plant mortality, rather than only reducing seed production per plant. Chlorsulfuron at 10 g ha–1applied at the six- and eight-leaf stages decreased total seed production less than at the two earlier stages, by reducing both plant mortality and seed production per surviving plant. Yellow foxtail was much more susceptible than green foxtail to either chlorsulfuron or metsulfuron.
Leachability and Efficacy of Starch-Encapsulated Atrazine
Authors: Fleming Gwen F. , Wax Loyd M. , Simmons F. William
Published: March 2018

Controlled-release formulations have the potential to reduce atrazine leaching but may reduce herbicide bioavailability and weed control. This research was conducted to determine if starch-encapsulated atrazine produced by the extrusion process could be modified to provide an optimum rate of herbicide release for adequate weed control and reduced leaching potential in sandy soils. The dry flowable (DF) and six starch-encapsulated atrazine formulations of various mesh size (14 to 20 and 20 to 40), clay content (0 and 5%), and extruder processing speed (200 and 400 rpm) were evaluated. All starch encapsulations reduced the amount of atrazine leaching from the surface 5 cm of soil columns by an average of 68% compared with the dry flowable formulation. Compared with the larger starch granules (14 to 20 mesh) 8% more atrazine in the smaller granules leached from the surface 5 cm. Atrazine efficacy was measured using an oat bioassay conducted in the greenhouse. Smaller granules (20 to 40 mesh) provided equivalent efficacy to DF while large granules (14 to 20 mesh) did not. Extruder speed and clay content did not affect efficacy or leaching potential. This study indicates that finer starch granules should result in faster atrazine release and improved weed control while still reducing the leaching potential of atrazine.
Controlled Release Starch Granule Formulations Reduce Herbicide Leaching in Soil Columns
Authors: Boydston Rick A.
Published: March 2018

Experimental controlled release starch granules (CRSG) containing 5.3% a.i. (w/w) norflurazon or 6% a.i. (w/w) simazine retarded the leaching of both herbicides in loamy sand soil columns when compared to commercial formulations of norflurazon [80% (w/w) dry flowable] or simazine [90% (w/w) water dispersible granule]. Barley bioassays indicated norflurazon and simazine remained in the surface 0 to 2.5 cm of soil when applied as CRSG formulations and moved to a depth of 15 cm when applied as commercial dry formulations and leached with 6 cm of water. CRSG placed on pre-wetted soil columns began to release norflurazon by 7 d at 25 C or 14 d at 15 C, and subsequent leaching moved norflurazon beyond the top 2.5 cm of the soil column.
Interactions of Diphenylether Herbicides with Chlorimuron and Imazaquin
Authors: Wesley M. Todd , Shaw David R.
Published: March 2018

Field experiment were conducted to determine interactions of chlorimuron or imazaquin with fomesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with fomesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when low rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with fomesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai ha–1imazaquin was combined with 210 g ai ha–1fomesafen or 110 or 220 g ai ha–1lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai ha–1chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g ha–1imazaquin was combined with 110 g ha–1lactofen or 210 g ai ha–1acifluorfen; however, at higher rates of chlorimuron or imazaquin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.