bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluazifop-P Reduces Strawberry (Fragariaxananassa) Tolerance to Terbacil
Authors: Jensen Klaus I. N. , Doohan Douglas J. , Specht Eric G.
Published: March 2018

Greenhouse and field experiments were conducted to characterize a synergistic interaction between fluazifop-P and terbacil in strawberry (FragariaxananassaDuchesne). In the greenhouse, injury from foliar terbacil applications generally increased two- or more fold when 75 or 150 g/ha fluazifop-P was applied foliarly 24 h later to either a terbacil tolerant (‘Veestar’) or sensitive (‘Kent’) strawberry cultivar. Synergism also occurred when terbacil was applied as a soil drench and fluazifop-P was applied 5 d later. There was little difference in effect between tank-mixed and sequential applications made 0.5 and 20 min apart. Increased injury was also observed with intervals up to 6 d between applications in the greenhouse, and the order of herbicide application did not affect injury level. Similar results were obtained in field experiments on newly planted ‘Honeoye’ and ‘Cavendish’ strawberry. An interval of 6 d or more between terbacil and fluazifop-P application is suggested to minimize the risk of increased crop injury.
Interaction of Graminicides Applied in Combination with Pyrithiobac
Authors: Snipes Charles E. , Allen Ralph L.
Published: March 2018

Field experiments were conducted from 1992 through 1994 to determine the effect of selected graminicides when applied in combination with pyrithiobac for johnsongrass control in cotton. Quizalofop-P, clethodim, sethoxydim, and fluazifop-P were applied at rates recommended for rhizome johnsongrass control with or without pyrithiobac at 70 g ae/ha. At 14 DAT johnsongrass control without pyrithiobac was more than 85% for all graminicides all years except sethoxydim in 1993. When graminicides were applied in combination with pyrithiobac, johnsongrass control was 86% or less and was lower than when each respective graminicide was applied alone. At 21 DAT, similar differences were apparent. Seed cotton yield, determined only one year, was not affected by reductions in johnsongrass control when either quizalofop or clethodim were used in combination with pyrithiobac. Pyrithiobac applied alone controlled johnsongrass 20 to 44% 14 DAT depending on year.
Tolerance of Direct-seeded Pepper (Capsicum annuum) Under Plastic Mulch to Herbicides
Authors: Cavero Jose , Zaragoza Carlos , Gil-Ortega Ramiro
Published: March 2018

Tolerance of direct-seeded pepper under clear plastic mulch to herbicides applied pre- and post-emergence was investigated in 1991 and 1992. Weed control of herbicides applied preemergence was also studied. Paprika cultivar ‘Buketen’ and canning cultivars ‘Piquillo de Lodosa’ and ‘Pico de Mendavia’ were seeded in the field in Zaragoza, Spain, in a loamy soil. Percent emergence, plant mortality after the postemergence treatment, dry weight of plants, and fruit weight were recorded. Pepper was tolerant to diphenamid and napropamide applied preemergence but these herbicides did not control broadleaf weeds. Clomazone, when applied preemergence resulted in chlorotic seedlings and at 2 kg ai/ha reduced the final stand, but was selective when applied at the 6 to 8-leaf stage of the crop. Pepper was tolerant to diethatyl-ethyl when applied preemergence. However, diethatyl-ethyl applied postemergence caused severe phytotoxicity symptoms, and when mixed with diphenamid, fruit ripeness in 1992 was delayed. Weed control during the crop emergence period was better when diethatyl-ethyl was used mixed with diphenamid or napropamide.
Use of Incorporated and Non-incorporated Granular Trifluralin for Annual Grass Control in Barley (Hordeum vulgare), Wheat (Triticum aestivum), and Canola (Brassica napus)
Authors: Kirkland Kenneth J.
Published: March 2018

The comparison of incorporation vs no incorporation on a mid-October application of the granular formulation of trifluralin to control infestations of wild oat and green foxtail was evaluated in spring barley, wheat, and canola in west central Saskatchewan over a 3 yr period. Incorporation treatments consisted of: no incorporation, one incorporation in fall, one incorporation in fall and a second in spring, one incorporation in fall and two additional incorporations in spring. All treatments eliminated green foxtail. In all three crops wild oat panicle counts were equivalent from incorporated and non-incorporated trifluralin. Wild oat fresh weights in crops grown on stubble were similar for incorporated and non-incorporated trifluralin. In fallow crops, wild oat fresh weight reductions were greater in three of nine site years with incorporation. There was little difference in crop yields from incorporated and non-incorporated trifluralin.
Interactions of Sethoxydim and Corn (Zea mays) Postemergence Broadleaf Herbicides on Three Annual Grasses
Authors: Young Bryan G. , Hart Stephen E. , Wax Loyd M.
Published: March 2018

Greenhouse and laboratory studies were conducted to determine the effect of 22 postemergence corn broadleaf herbicide combinations on the efficacy of sethoxydim applied to giant foxtail, large crabgrass, and shattercane. Eighteen combinations caused a reduction in sethoxydim efficacy on at least one grass species. Dicamba, atrazine plus dicamba, atrazine plus bentazon, bromoxynil, primisulfuron, CGA-152005 plus primisulfuron, MON 12000, and flumetsulam plus clopyralid plus 2,4-D (NAF-73) were evaluated further on the efficacy and foliar absorption of sethoxydim applied to giant foxtail, large crabgrass, and shattercane. In timing studies, applying all herbicide combinations at 7 or 3 d before sethoxydim application eliminated significant antagonistic interactions. However, applying NAF-73, primisulfuron, or CGA-152005 plus primisulfuron 1 d prior resulted in a reduction in sethoxydim efficacy on at least one grass species. Dicamba, atrazine plus dicamba, and atrazine plus bentazon decreased14C-sethoxydim absorption 9 to 63% across grass species. Replacing crop oil concentrate (COC) with DASH increased sethoxydim absorption when applied with these herbicides but not to the full extent of sethoxydim applied alone with DASH. Sethoxydim efficacy was retained or improved with DASH when applied with dicamba, atrazine plus dicamba, atrazine plus bentazon, or bromoxynil. When primisulfuron, CGA-152005 plus primisulfuron, MON 12000, or NAF-73 was applied with14C-sethoxydim no effect on sethoxydim absorption was observed. DASH was less effective than COC at restoring sethoxydim efficacy when applied with these herbicides.
Integration of Glyphosate and Quizalofop with Tillage for Quackgrass (Elytrigia repens) Management in Continuous Annual Crop and Legume Plowdown Rotations
Authors: Darwent A. Lloyd , Clayton George W. , Drabble James C. , Mills Peter F. , Wolynetz Mark S.
Published: March 2018

A field study was conducted from 1987 to 1992 to determine the effectiveness of several treatments consisting of combinations of glyphosate and/or quizalofop with tillage to control quackgrass in legume plowdown and continuous annual crop rotations. The treatments were imposed on the quackgrass in 1987 and/or 1988, evaluated in 1989 (cycle 1), reimposed on the same plots in 1990 and/or 1991 and re-evaluated in 1992 (cycle 2). Where continuous barley was grown, glyphosate applied at 0.45 kg/ha before seeding in 1987 (cycle 1) and 1990 (cycle 2), and combined with fall tillage in the first two years of each cycle, reduced quackgrass shoot density and rhizome dry weight by more than 96%. In a legume plowdown rotation, consisting of barley underseeded to red clover followed by plowdown and barley in subsequent years, quackgrass was reduced by a similar amount by glyphosate at 0.45 kg/ha applied in 1987 and 1990 before seeding or in 1988 and 1991 at 5 d before or 6 wk after red clover plowdown. Quackgrass reduction from all of these treatments was as effective as the labelled rate of glyphosate (0.90 kg/ha) applied at the same times, and also as effective as glyphosate applied at 0.45 kg/ha in combination with tillage in a year of fallow. Without fall tillage the efficacy of glyphosate applied before seeding was reduced. Quizalofop at 0.20 kg/ha applied to canola in a rotation of canola followed by two years of barley, reduced quackgrass, but was less effective than glyphosate treatments with fall tillage. Reducing quackgrass populations resulted in significant increases in crop yields.
A Seedling Bioassay for Assessing the Response of Wild Oat (Avena fatua) Populations to Triallate
Authors: O'Donovan John T. , Rashid Abdur , Van Nguyen Hai , Newman Jeff C. , Khan Aziz , Johnson C. Ian , Blackshaw Robert E. , Harker K. Neil
Published: March 2018

Germinated seeds of wild oat populations that were susceptible (S) or resistant (R) to triallate at the recommended soil-applied rate (1.7 kg/ha) were treated with six triallate concentrations on filter paper in petri dishes. Measurement of shoot length 8 d after treatment provided an accurate indication of differences among populations, and was more reliable than determining shoot fresh weight. ED50values (herbicide concentrations that reduced shoot length by 50% relative to untreated controls), derived from nonlinear regression analysis, indicated four and five levels of response to triallate among eight S and seven R populations, respectively. The ED50values varied from 0.11 to 11 ppm a.i. triallate for the most susceptible to the most resistant populations, respectively. Routine testing of wild oat samples suspected of resistance, at triallate concentrations of 0.5 or 1 ppm in the petri dish bioassay, effectively identified populations that had become resistant to the recommended soil-applied rate.
Using the In Vivo Acetolactate Synthase (ALS) Assay for Identifying Herbicide-Resistant Weeds
Authors: Lovell Sarah Taylor , Wax Loyd M. , Simpson David M. , McGlamery Marshal
Published: March 2018

An in vivo ALS assay was used to differentiate between susceptible and resistant kochia biotypes from Idaho and Montana. Experiments were also conducted using this assay to determine the effect of the timing of herbicide application on ALS activity in resistant and susceptible cocklebur biotypes from Mississippi. When treated with chlorsulfuron, resistant kochia biotypes demonstrated 160-and 170-fold resistance at the whole plant level for the Idaho and Montana biotypes, respectively, compared to susceptible biotypes. Using the in vivo ALS assay, the Idaho and Montana biotypes showed 70- and 490-fold resistance, respectively, based on I50values. The biotypes also demonstrated a low level of cross-resistance to imazethapyr using the in vivo technique. Resistant cocklebur biotypes showed approximately 200-fold resistance to imazaquin compared with susceptible biotypes. This research demonstrated that the in vivo assay can be used effectively to identify resistant biotypes 6 and 24 h after treatment, and to determine the extent of cross-resistance.
Effect of Nicosulfuron Mixtures and Time of Application on Peanut (Arachis hypogaea) Cultivars
Authors: Littlefield Terry A. , Colvin Daniel L. , Brecke Barry J. , McCarty Lambert B.
Published: March 2018

Field experiments were conducted near Marianna, Trenton, and Archer, FL in 1990 and 1991 to investigate the effect of nicosulfuron mixtures and time of application on five peanut cultivars. Nicosulfuron at 54 g ai/ha was applied alone or in mixture with 2,4-DB at 280 g ai/ha 5 weeks after planting (WAP), 9 WAP, or 5 plus 9 WAP. Injury was greater from early and sequential nicosulfuron applications while a single application 9 WAP typically did not cause significant injury or reduce peanut yield. The 5 WAP and 5 plus 9 WAP applications often caused early visible injury and sometimes reduced peanut yield. When peanut yields were compared, ‘Florigiant’ was the most sensitive cultivar while ‘Southern Runner’ and ‘Valencia’ were more tolerant to nicosulfuron. ‘Sunrunner’ and ‘NC-7’ were intermediate in tolerance to nicosulfuron. In several instances, the addition of 2,4-DB to nicosulfuron reduced initial crop injury and ameliorated yield losses resulting from nicosulfuron applied alone.
Nitrogen Carrier and Surfactant Increase Foliar Herbicide Injury in Winter Wheat (Triticum aestivum)
Authors: Stahlman Phillip W. , Currie Randall S. , El-Hamid Mosad A.
Published: March 2018

A three-year field study in west-central Kansas investigated the effects of combinations of spray carrier, nonionic surfactant (NIS), triasulfuron, and/or 2,4-D on winter wheat foliar injury and grain yield. Herbicides applied in water without NIS caused little or no foliar injury in two of three years. Urea-ammonium nitrate (UAN) at 112 L/ha (40 kg N/ha) alone or as a carrier for herbicides caused moderate to severe foliar injury in all three years. Adding NIS to UAN spray solutions increased foliar injury, especially with the tank mixture of triasulfuron + 2,4-D. Effects of triasulfuron + NIS or 2,4-D applied in UAN were additive. Foliar injury was related inversely to temperature following application. Foliar injury was most evident 4 to 7 d after application and disappeared within 2 to 3 wk. Diluting UAN 50% with water lessened foliar injury in two of three years, especially in the presence of NIS, regardless of whether herbicides were in the spray solution. Treatments did not reduce wheat grain yield in any year despite estimates of up to 53% foliar injury one year.
Evaluation of Glufosinate on Rice (Oryza sativa) Transformed with the BAR Gene and Red Rice (Oryza sativa)
Authors: Sankula Sujatha , Braverman Michael P. , Jodari Farman , Linscombe Steven D. , Oard James H.
Published: March 2018

Glufosinate at 1.1 and 2.2 kg/ha injured ‘Koshihikari’ rice lines that were transformed with the BAR gene from 0 to 53%. However, transgenic ‘Gulfmont’ rice was not injured. Rice yields of transgenic ‘Gulfmont’ lines and six of nine ‘Koshihikari’ lines were not affected by 2.2 kg/ha glufosinate. In field studies, flooding reduced the efficacy of glufosinate in controlling red rice, and greenhouse tests determined that glufosinate efficacy was reduced when red rice was submerged between 25 and 50% of its height. Plant heights and dry weights of red rice increased as flood water depth increased at all rates of glufosinate.
Interaction of Glyphosate and 2,4-DB for the Control of Selected Morningglory (Ipomoeaspp.) Species
Authors: Wehtje Glenn , Walker Robert H.
Published: March 2018

Interaction of glyphosate and 2,4-DB was evaluated in greenhouse and laboratory studies with respect to control of four species of annual morningglory. The greenhouse study included smallflower, pitted, palmleaf, and ivyleaf morningglory at three growth stages: seedling, juvenile, and vining. A series of glyphosate rates (0.28 to 1.26 kg ae/ha) and 2,4-DB (0.022 and 0.045 kg ae/ha) were applied alone, and in all possible two-way tank mixtures. Morningglory response to both glyphosate and 2,4-DB applied alone was species- and growth stage-dependent. All combinations were either additive or synergistic for control of pitted, palmleaf, and ivyleaf morningglory. Response of smallflower morningglory ranged from antagonistic to synergistic. Absorption and translocation of14C-2,4-DB was independent of the addition of glyphosate in all four species. By contrast, absorption of foliar-applied14C-glyphosate and translocation of14C from treated leaves to other plant parts were enhanced by the addition of 2,4-DB in all species except palmleaf morningglory. In palmleaf morningglory,14C-glyphosate absorption and translocation were independent of the addition of 2,4-DB. Absorption and translocation data were in agreement with greenhouse studies.
Annual Grass Control in Corn (Zea mays) with Primisulfuron Combined with Nicosulfuron
Authors: Rabaey Thomas L. , Harvey R. Gordon
Published: March 2018

Efficacy of primisulfuron and reduced rates of nicosulfuron on woolly cupgrass, wild-proso millet, and giant foxtail in field corn was evaluated in 1994 and 1995. Nicosulfuron was applied at 18, 27, and 36 g ai/ha alone and with 20 g ai/ha primisulfuron. Woolly cupgrass control from nicosulfuron at 18 and 27 g/ha was less than control from 36 g/ha (79% and 84% vs. 90%, respectively). Woolly cupgrass control was 5% greater when primisulfuron was combined with nicosulfuron at 27 and 36 g/ha than when nicosulfuron was applied alone. Corn grain yields were similar among all nicosulfuron plus primisulfuron treatments applied to control woolly cupgrass in 1994. In 1995, corn grain yield was increased 900 kg/ha when primisulfuron was combined with nicosulfuron at 18 g/ha compared to nicosulfuron applied at the same rate alone. Wild-proso millet control 3 WAT with nicosulfuron at 18 g/ha was less than control with nicosulfuron at 36 g/ha. Wild-proso millet control 8 WAT with nicosulfuron alone was greater than when nicosulfuron at any rate was applied with primisulfuron. No differences in corn grain yields were observed across nicosulfuron rates or combinations with primisulfuron to control wild-proso millet either year. Giant foxtail control and corn grain yield were not affected by nicosulfuron rate or combined applications of nicosulfuron and primisulfuron either year.
Perspectives on Glyphosate Resistance
Authors: Bradshaw Laura D. , Padgette Stephen R. , Kimball Steven L. , Wells Barbara H.
Published: March 2018

The lack of evolution of weed resistance to the herbicide glyphosate has been considered from several perspectives. Few plant species are inherently resistant to glyphosate. Furthermore, the long history of extensive use of the herbicide has resulted in no verified instances of weeds evolving resistance under field situations. Unique properties of glyphosate such as its mode of action, metabolism, chemical structure and lack of residual activity in soil may explain this observation. Selection for glyphosate resistance of crops using intense whole plant and cell/tissue culture techniques, including mutagenesis, has had only limited success and is unlikely to be duplicated under normal field conditions. Information obtained in the development of glyphosate-resistant crops suggests that target-site alterations that decrease the herbicidal activity of glyphosate also may lead to reduced survival of a weed. In addition, the complex manipulations that were required for the development of glyphosate-resistant crops are unlikely to be duplicated in nature to evolve glyphosate-resistant weeds.
Turf Safety and Effectiveness of Dithiopyr and Quinclorac for Large Crabgrass (Digitaria sanguinalis) Control in Spring-Seeded Turf
Authors: Reicher Zachary J. , Weisenberger Daniel V. , Throssell Clark S.
Published: March 2018

There are limited options for controlling large crabgrass in spring-seeded cool-season turf. The objective of this experiment was to evaluate the safety and effectiveness of dithiopyr and quinclorac to control large crabgrass in spring-seeded Kentucky bluegrass and perennial ryegrass stands. Quinclorac at 0.84 kg/ha and dithiopyr at 0.56 kg/ha were applied separately at various times prior to seeding and after emergence of Kentucky bluegrass and perennial ryegrass. Quinclorac applied once at 2, 4, 8, or 12 weeks after emergence (WAE) or split-applied preplant incorporated (PPI) + 12 WAE will give season-long control of large crabgrass with no injury to spring-seeded Kentucky bluegrass or perennial ryegrass. Quinclorac applied PPI or 0 WAE is safe to use in spring seedings, but it will not provide season-long control of large crabgrass. Dithiopyr applied 2 or 4 WAE will control large crabgrass season-long while not injuring spring-seeded Kentucky bluegrass or perennial ryegrass. However, dithiopyr applied PPI or 0 WAE will severely limit germination of desirable turf, and dithiopyr applied 8 or 12 WAE will not control mature crabgrass.
Evaluation of Soil-Applied Herbicides in Sequential Programs with CGA-277476 in Soybean (Glycine max)
Authors: Palmer Eric W. , Shaw David R. , Holloway J. C.
Published: March 2018

Soil-applied herbicides alone or followed by postemergence (POST) applications of CGA-277476 were evaluated for season-long weed control in soybean. Common cocklebur, hemp sesbania, and pitted morningglory control was not consistently improved with a soil-applied herbicide followed by a POST application of 79 g ai/ha CGA-277476. However, in locations with heavy weed pressure, a tank-mix of chlorimuron + metribuzin + trifluralin or imazaquin + pendimethalin followed by CGA-277476 improved common cocklebur, hemp sesbania, and pitted morningglory over CGA-277476 alone. Sequential application of CGA-277476 following SAN 582 improved weed control over SAN 582 alone. When weed pressure was not severe, there were no differences in control from CGA-277476 alone or following soil-applied herbicides. A POST application of CGA-277476 following soil-applied herbicides did not consistently improve soybean yield over CGA-277476 alone. Yield from soybean treated with SAN 582 was improved when CGA-277476 was applied. In contrast, when chlorimuron + metribuzin + trifluralin or imazaquin + pendimethalin were applied at planting, yield was similar with or without POST application of CGA-277476.
Weed Management in Soybean (Glycine max) with Preplant-Incorporated Herbicides and Cloransulam-Methyl
Authors: Askew Shawn D. , Wilcut John W. , Langston Vernon B.
Published: March 2018

Cloransulam-methyl applied postemergence (POST) following various preplant-incorporated (PPI) herbicides was evaluated in four experiments for weed control in North Carolina soybean over a 2-yr period at three locations. Acifluorfen plus bentazon or chlorimuron alone applied POST injured soybean more than cloransulam-methyl when following any soil-applied herbicide. When following trifluralin PPI, cloransulam-methyl controlled common ragweed, entireleaf morningglory, and pitted morningglory comparable to acifluorfen plus bentazon or chlorimuron. Common lambsquarters and prickly sida control was higher when acifluorfen plus bentazon was applied POST following trifluralin PPI compared to trifluralin PPI followed by cloransulam-methyl or chlorimuron. Acifluorfen plus bentazon or chlorimuron POST controlled yellow nutsedge and smooth pigweed more than cloransulam-methyl POST when following trifluralin PPI. When trifluralin was applied PPI in mixtures with chlorimuron plus metribuzin, flumetsulam, or imazaquin, control of most species was similar regardless of POST treatment used. Soybean treated with cloransulam-methyl yielded 250 kg/ha more than treatments with chlorimuron when these herbicides followed trifluralin plus flumetsulam or trifluralin plus imazaquin. Net returns with different herbicide systems followed trends similar to soybean yield.
Biologically Effective Dose and Selectivity of SAN 1269H (BAS 662H) for Weed Control in Corn (Zea mays)
Authors: Sikkema Peter H. , Knezevic Stevan Z. , Hamill Allan S. , Tardif François J. , Chandler Kevin , Swanton Clarence J.
Published: March 2018

Field experiments were conducted in 1996 and 1997 at five locations in southwestern Ontario to develop dose-response curves for SAN 1269H (SAN 835H plus dicamba) for weed control and crop tolerance in corn. SAN 1269H controlled wild buckwheat (Polygonum convolvulusL.), common ragweed (Ambrosia artemisiifoliaL.), common lambsquarters (Chenopodium albumL.), pigweeds (Amaranthus retroflexusL. andA. powelliiS. Wats.), barnyardgrass [Echinochloa crus-galli(L.) Beauv.], and yellow foxtail [Setaria glauca(L.) Beauv.]. Biologically effective doses of SAN 1269H (BAS 662H) were 440, 430, 180, and 40 g/ha for yellow foxtail, barnyard grass, wild buckwheat, and common ragweed, respectively. The biologically effective dose (that which provides 90% reduction in weed dry matter) for common lambsquarters was 560 g/ha when SAN 1269H was applied preemergence (PRE) and 110 g/ha when applied postemergence (POST). When applied PRE at a rate of 420 g/ha, pigweed was controlled, whereas only 85 g/ha was required when applied POST. Grain yield increased with dose of SAN 1269H and did not differ with time of application. Temporary crop injury was observed when SAN 1269H was applied at the four- to six-leaf growth stage. Optimum corn yields were achieved with doses of 100 to 250 g/ha.
Weed Management in Glufosinate-Resistant Corn (Zea mays)
Authors: Culpepper A. Stanley , York Alan C.
Published: March 2018

An experiment was conducted at five locations in North Carolina to compare management systems utilizing glufosinate applied postemergence (POST) in glufosinate-resistant corn with standard systems of metolachlor plus atrazine preemergence (PRE) or nicosulfuron plus atrazine POST Glufosinate alone and both standard systems controlled common ragweed and prickly sida at least 98%, whereas sicklepod control was < 20% late in the season. Late-season control of common lambsquarters, smooth pigweed, pitted morningglory, and tall morningglory was generally less with glufosinate alone than with the standard systems. However, late-season control of common lambsquarters, smooth pigweed, pitted morningglory, tall morningglory, and sicklepod by mixtures of glufosinate plus atrazine was at least 99, 100, 89, 93, and 81%, respectively, and was equal to or greater than control by either standard. Broadleaf signalgrass, large crabgrass, and fall panicum were controlled similarly by glufosinate and the standards. Goosegrass control by glufosinate was similar to control by nicosulfuron plus atrazine, but it was less than control by metolachlor plus atrazine. Metolachlor applied PRE or atrazine mixed with glufosinate increased goosegrass control to that achieved with metolachlor plus atrazine. Mixing atrazine with glufosinate did not affect fall panicum control, but metolachlor PRE followed by glufosinate controlled fall panicum as well as the standards. Cultivation or ametryn applied at layby increased control when PRE or POST herbicides alone controlled weeds less than about 90%. Ametryn was generally more effective than cultivation. Glufosinate POST followed by ametryn at layby controlled sicklepod > 90% and other species > 95% late in the season. Corn yield and net returns were similar in the glufosinate and standard systems.
Purple Nutsedge (Cyperus rotundus) and Sicklepod (Senna obtusifolia) Response to Glyphosate Mixtures with ALS-Inhibiting Herbicides
Authors: Rao A. Subrahmanyeswara , Reddy Krishna N.
Published: March 2018

Greenhouse studies were conducted to evaluate potential interactions among glyphosate mixtures with five acetolactate synthase (ALS)-inhibiting herbicides (chlorimuron, imazamox, imazaquin, MON 12,000, or pyrithiobac) for the control of purple nutsedge and sicklepod at two growth stages. Herbicides were tested alone at 0.5X and 1X rates (1X being suggested use rate for these herbicides) and in combination with glyphosate at 560 (0.5X) and 1,120 (1X) g ai/ha on 3-wk-old plants and at 1,120 g/ha on 6-wk-old plants. Glyphosate alone at 1,120 g/ha gave complete control of purple nutsedge and at least 78% control of sicklepod regardless of growth stage. In 3-wk-old purple nutsedge plants, three of the 20 herbicide combinations were antagonistic and 17 combinations were additive, whereas all five combinations were additive in 6-wk-old plants. In sicklepod, eight combinations were antagonistic and 12 combinations were additive in 3-wk-old plants, and all five combinations were antagonistic in 6-wk-old plants. In 3-wk-old plants, the glyphosate (0.5X) plus imazaquin (0.5X) combination resulted in highest antagonism in purple nutsedge control (79%), and the combination of glyphosate (0.5X) plus imazamox (0.5X) resulted in highest antagonism in sicklepod control (54%). These results indicate that mixing chlorimuron, imazamox, imazaquin, MON 12,000, or pyrithiobac with glyphosate does not increase glyphosate efficacy on purple nutsedge or sicklepod.
Influence of Fertilizer Particle Size on Efficacy of Dithiopyr, Prodiamine, Oryzalin, and Oxadiazon for Southern Crabgrass (Digitaria ciliaris) Control
Authors: Kelly Steven T. , Coats G. Euel
Published: March 2018

A commercial fertilizer (40-0-0, N-P-K) was screened into seven particle size fractions (23, 58, 165, 465, 1,310, 3,728, or 10,606 particles/g) and coated with dithiopyr (0.345%, wt/wt), prodiamine (0.689%), oryzalin (3.28%), or oxadiazon (2.76%). Dithiopyr and oryzalin provided best southern crabgrass control with a fertilizer size of 465 particles/g or greater, whereas prodiamine controlled southern crabgrass greatest using a size fraction at least 165 particles/g. Southern crabgrass control with oxadiazon was not as dependent on particle size, with all fraction sizes of 58 or 165 particles/g or greater controlling southern crabgrass equally in 1995 or 1996, respectively.
Annual Weed Control by Glyphosate in Glyphosate-Resistant Soybean (Glycine max)
Authors: Ateh Comfort M. , Harvey Robert G.
Published: March 2018

Control of natural infestations of common lambsquarters and giant foxtail in 1993, 1994, and 1995 and of velvetleaf in 1994 and 1995 by postemergence application of glyphosate to glyphosate-resistant soybean planted in narrow (20 cm) and wide (76 cm) rows was evaluated. Planting glyphosate-resistant soybean in narrow rows and applying reduced rates of glyphosate when common lambsquarters, giant foxtail, and velvetleaf were at their actively growing stage 3 to 18 cm, 5 to 28 cm, and 3 to 20 cm tall, respectively, resulted in > 90% control. The effect of time of herbicide application was greater than the rate of herbicide application, especially within the wide-row soybean plantings. Applying imazethapyr in combination with glyphosate did not improve weed control or soybean yield compared with glyphosate alone.
Weed Management and Net Returns With Transgenic, Herbicide-Resistant, and Nontransgenic Cotton (Gossypium hirsutum)
Authors: Culpepper A. Stanley , York Alan C.
Published: March 2018

Weed management systems were compared in bromoxynil-resistant, glyphosate-resistant, and nontransgenic cotton. A standard system of pendimethalin preplant incorporated (PPI), fluometuron preemergence (PRE), fluometuron plus MSMA early postemergence-directed (POST-DIR), and cyanazine plus MSMA late POST-DIR in combination with cultivation controlled broadleaf signalgrass, large crabgrass, common lambsquarters, jimsonweed, pitted morningglory, prickly sida, sicklepod, and smooth pigweed 98 to 100% late season. Weed control, cotton yield, and net returns were similar when pyrithiobac or bromoxynil plus MSMA postemergence (POST) replaced fluometuron plus MSMA POST-DIR. Fluometuron PRE had little to no effect in bromoxynil systems. Glyphosate POST to three- to four-leaf-stage cotton followed by cyanazine plus MSMA late POST-DIR and cultivation controlled weeds 96 to 100%. Glyphosate POST followed by glyphosate POST-DIR and cultivation controlled pitted morningglory and large crabgrass 89 to 90% and other species at least 94%. Yields and net returns at one location were similar for glyphosate applied twice or glyphosate POST followed by cyanazine plus MSMA POST-DIR and the standard system. Pendimethalin plus fluometuron in glyphosate systems did not increase yield or net returns. At a location severely infested with large crabgrass, pendimethalin plus fluometuron in glyphosate systems increased yield 37 to 44% and net returns 85 to 108%, respectively, when glyphosate was applied to cotton at the three-to four-leaf stage, but not if glyphosate was applied to cotton at the one-leaf stage. Yield and net returns were similar when bromoxynil-resistant, glyphosate-resistant, and nontransgenic cotton were treated using the standard system.
Differential Response of Ajuga (Ajuga reptans), Wintercreeper (Euonymus fortunei), and Dwarf Burning Bush (Euonymus alatus‘Compacta’) to Root- and Shoot-Applied Isoxaben
Authors: Salihu Sydha , Derr Jeffrey F. , Hatzios Kriton K.
Published: March 2018

Hydroponics and sand culture studies evaluated the effects of isoxaben rate (0.84, 1.69, and 3.39 kg/ha) and application type (root only, shoot only, and root plus shoot) on the growth of ajuga, wintercreeper, and dwarf burning bush. Similar responses were exhibited by the three species tested in both hydroponics and sand culture studies. Based on shoot weight reductions, dwarf burning bush was one to three times more sensitive than wintercreeper, which was the most tolerant of the three species, and ajuga was five to 20 times more sensitive than wintercreeper. Isoxaben applied to the root system at all three rates injured ajuga root tips and foliage and reduced root weight by approximately 40% and shoot weight by 20 to 30%. Isoxaben applications to ajuga foliage damaged the roots and leaves and caused over 30% reductions in shoot and root weights at the highest rate tested. Isoxaben applied to dwarf burning bush roots caused less than 20% shoot injury, reduced root weight by 8 to 18%, and reduced shoot weight by less than 10%. Application to dwarf burning bush foliage caused 20 to 30% injury, but only slight reductions in root and shoot weights were observed. No visible injury was observed in wintercreeper from any isoxaben application. However, root treatment reduced wintercreeper root weight by approximately 15%, and shoot treatment reduced shoot weight by 6 to 10% at the highest isoxaben rate tested. Application of isoxaben to both roots and foliage of wintercreeper resulted in similar reductions in shoot and root weights compared to root or shoot exposure alone. Shoot application to wintercreeper affected root growth, and root treatment reduced shoot growth.
Effect of Temperature and Cultivar on the Response of Broccoli and Collard (Brassica oleracea) to Oxyfluorfen
Authors: Harrison Howard F. , Peterson Joseph K.
Published: March 2018

Growth chamber studies were conducted to investigate the effect of temperature, cultivar, and leaf wax content on the response of broccoli and collard to oxyfluorfen. Broccoli cultivars grown under cool temperatures (15/10 C) were more susceptible to preemergence (PRE) application of oxyfluorfen, and broccoli and collard cultivars grown at cool temperatures were more susceptible to postemergence (POST) application of oxyfluorfen than cultivars grown under warm temperatures (25/20 C). Differences between the tolerant cultivar ‘Pinnacle’ and the susceptible cultivar ‘Packman’ in response to PRE oxyfluorfen application were more distinct at warm temperatures than at cool temperatures. Although the broccoli and collard cultivars used in the POST study varied in leaf wax content, differences in wax content did not appear to be as important as other genetic factors in the differential response to POST oxyfluorfen application between cultivars.
Absorption, Translocation, and Metabolism of Chlorimuron and Nicosulfuron in Imidazolinone-Resistant and -Susceptible Smooth Pigweed (Amaranthus hybridus)
Authors: Manley Brian S. , Hatzios Kriton K. , Wilson Henry P.
Published: March 2018

The absorption, translocation, and metabolism of the ethyl ester of chlorimuron and nicosulfuron in resistant (R) and susceptible (S) smooth pigweed (Amaranthus hybridus) were investigated. R and S smooth pigweed seedlings (5 to 10 cm tall) were treated with foliar-applied14C-labeled chlorimuron and nicosulfuron and harvested at 3, 6, 24, and 72 h after application. Chlorimuron absorption increased with time in both populations of smooth pigweed and was higher in the R accession only at 6 h after application. Nicosulfuron absorption did not increase with time in the R accession, and after 6 h, there were no differences between the R and S accessions. Absorbed chlorimuron and nicosulfuron were translocated to shoots and leaves above and below the treated leaf, but not into the roots in both accessions. Translocation of chlorimuron and nicosulfuron out of the treated leaf was also similar in the two accessions. Metabolism of14C-chlorimuron occurred more rapidly in the R accession with approximately 68% remaining as chlorimuron at 3 h after application. At the same time period, 81% of the absorbed radioactivity remained as chlorimuron in the S accession. Metabolism of14C-chlorimuron at 24 and 72 h after application was greater in the S than the R accession of smooth pigweed. Metabolism of14C-nicosulfuron was similar in the two accessions and did not increase with time. Rapid herbicide metabolism may explain the twofold level of crossresistance of the R accession of smooth pigweed to chlorimuron at the whole plant level.
Adjuvant Effects on CGA-248757 and Flumiclorac Efficacy and Crop Tolerance
Authors: Fausey Jason C. , Penner Don , Renner Karen A.
Published: March 2018

Adjuvants influence weed control and crop tolerance provided by postemergence (POST) herbicides. Adjuvant effects on weed control and corn and soybean tolerance with CGA-248757 and flumiclorac applied alone and soybean tolerance with CGA-248757 and flumiclorac applied in combination with imazethapyr or CGA-277476 were evaluated. Velvetleaf control in the greenhouse and common lambsquarters, redroot pigweed, and common ragweed control in the greenhouse and field with CGA-248757 and flumiclorac were increased by the addition of an adjuvant. However, corn and soybean tolerance to these herbicides was not affected by adding an adjuvant. Laboratory studies suggest enhanced weed control from the addition of an adjuvant resulted from an increase in CGA-248757 and flumiclorac foliar absorption. In greenhouse studies, velvetleaf, common lambsquarters, and redroot pigweed control with CGA-248757 plus imazethapyr; velvetleaf control with flumiclorac plus imazethapyr; redroot pigweed and common ragweed control with CGA-248757 plus CGA-277476; and velvetleaf, redroot pigweed, and common ragweed control with flumiclorac plus CGA-277476 increased by adding an organosilicone adjuvant when compared with adding a nonionic surfactant (NIS). However, in field evaluations of CGA-248757 or flumiclorac plus imazethapyr, the addition of NIS or an organosilicone adjuvant resulted in equivalent soybean injury, common lambsquarters and redroot pigweed control, and soybean yield. Yet in tank mixtures of CGA-248757 or flumiclorac plus CGA-277476, the addition of an organosilicone adjuvant increased redroot pigweed control and soybean yield compared to adding NIS.
Influence of Herbicide Application Rate, Timing, and Interrow Cultivation on Weed Control and Corn (Zea mays) Yield in Glufosinate-Resistant and Glyphosate-Resistant Corn
Authors: Tharp Brent E. , Kells James J.
Published: March 2018

Field trials were conducted in 1996 and 1997 to determine the influence of glufosinate and glyphosate application rates, application timings, and interrow cultivation on weed control and corn yield. Glufosinate-ammonium rates ranged from 0.18 to 0.41 kg ai/ha, while rates for the isopropylamine salt of glyphosate ranged from 0.21 to 0.84 kg ae/ha. Increasing rates of glufosinate and glyphosate often improved weed control. Control of many of the weed species was improved by delaying herbicide application timing. Weed control was most consistent from late postemergence (LPOST) applications of glufosinate at 0.41 kg ai/ha or glyphosate at 0.84 kg ae/ha. Corn yields were reduced due to incomplete weed control when the lowest rate of glufosinate was applied. Weed control from early postemergence (EPOST) glufosinate and glyphosate applications followed by cultivation was similar to weed control from LPOST glufosinate and glyphosate applications without cultivation. Interrow cultivation following glufosinate or glyphosate application did not affect corn yield.
Differential Tolerance of Broccoli (Brassica oleracea) Cultivars to Preemergence Application of Oxyfluorfen
Authors: Harrison Howard F. , Farnham Mark W.
Published: March 2018

The tolerance of 10 broccoli cultivars to preemergence (PRE) applications of oxyfluorfen was evaluated in greenhouse and field experiments. Differences in tolerance among cultivars were expressed as differences in seedling injury ratings and growth and stand reduction. The cultivars ‘Pinnacle’ and ‘Mercedes’ were most tolerant, ‘Embassy’ and ‘Early Dawn’ were least tolerant, and other cultivars were intermediate in tolerance. Broccoli seedling weights and stand counts averaged across 10 cultivars and oxyfluorfen application rates of 0.125, 0.25, and 0.5 kg/ha were 70 and 81% of control, respectively, for the two fall-planted experiments and 39 and 50% of control, respectively, for the spring-planted experiment. Differences in tolerance among cultivars were less distinct in the cooler spring than in the warmer fall season. Oxyfluorfen application that caused stand and early growth reduction did not always affect broccoli head weight or quality or delay harvest.
Discovery of a Primisulfuron-Resistant Shattercane (Sorghum bicolor) Biotype
Authors: Anderson Daniel D. , Roeth Fred W. , Martin Alex R.
Published: March 2018

Shattercane seeds were collected in 1992 from 16 fields in southeastern and south-central Nebraska that had been treated for 3 consecutive yr with primisulfuron or nicosulfuron. Approximately 11,200 plants, from a total of 16,000 seeds (1,000 per field) planted, were evaluated for primisulfuron resistance in greenhouse screening. A single resistant plant was found. No other primisulfuron resistance was found in evaluating an additional 1,718 plants from the remaining seeds collected in 1992 from the field where the original resistant plant was found. Shattercane seeds were collected in 1993 and 1994 from that field. All 17,038 plants from these collections were killed by primisulfuron. A field assessment of 118 descendents of the original resistant plant (S1progeny) produced three responses to primisulfuron at an approximate 1:2:1 ratio: (1) death; (2) some interveinal chlorosis; or (3) no visible injury or symptoms. Discovery of this resistant shattercane biotype indicates the potential for selection of primisulfuron-resistant shattercane populations under field conditions.
HERB and MSU-HERB Field Validation for Soybean (Glycine max) Weed Control in Mississippi
Authors: Rankins Alfred , Shaw David R. , Byrd John D.
Published: March 2018

In 1994, herbicide efficacy and competitive index databases were adjusted in the soybean herbicide recommendation program HERB to best reflect data for Mississippi. Field experiments were conducted to compare efficacy and economics of postemergence herbicides recommended by HERB and MSU-HERB. The study was conducted utilizing four locations over 2 yr, which provided different soil types, weed spectra, and environmental conditions with which to evaluate weed control from herbicides recommended by these programs. HERB and MSU-HERB agreed on an herbicide recommendation in 62% of the modeling runs. Herbicides recommended by both software versions were generally effective for controlling the predominant weed species at each location. In instances where there was a significant difference in herbicide efficacy between herbicides recommended by HERB and MSU-HERB, improved weed control resulted from herbicides recommended by MSU-HERB. In 1994, excellent moisture conditions enabled soybean to gain a significant competitive advantage over weeds and, as a result, yield loss predictions after treatment were overestimated in most instances. Conversely, 1995 environmental conditions better represented average Mississippi growing conditions, and yield loss predictions after treatment were more accurate. Yield loss prediction accuracy of HERB versions was related to the length of interference between soybean and weeds. Thus, prediction accuracy of HERB and MSU-HERB was similar. Soybean yield increase and net economic gain following MSU-HERB recommendations was as high or higher than following HERB recommendations.
Herbicide Programs for Red Rice (Oryza sativa) Control in Soybean (Glycine max)
Authors: Askew Shawn D. , Street Joe E. , Shaw David R.
Published: March 2018

A study was conducted in 1994 and 1995 at two Mississippi locations to evaluate preplant incorporated (PPI) and preemergence (PRE) applications of alachlor, clomazone, SAN 582, metolachlor, pendimethalin, and trifluralin, and postemergence (POST) applications of AC 263,222 and imazethapyr alone or followed by clethodim late postemergence (LPOST) for red rice control in soybean. Applications of 110 g ai/ha clethodim increased red rice control when following any earlier herbicide application at one location that harbored a high natural infestation. In 1 yr at one location, red rice seedhead suppression from PPI and PRE herbicide applications alone was greater than 95% due to high activity from herbicides and drought conditions during red rice seedhead development. Early postemergence (EPOST) applications of 30 g ae/ha AC 263,222 suppressed at least 95% of red rice seedheads, regardless of year, location, or clethodim LPOST application. At one location, any treatment where 110 g/ha clethodim followed an earlier herbicide application suppressed red rice seedheads at least 95%. Compared to the nontreated control, only AC 263,222 injured soybean (30%) and reduced soybean yield (200 kg/ha).
Effect of Sulfonylurea Herbicides on Early Development of Egyptian Broomrape (Orobanche aegyptiaca) in Tomato (Lycopersicon esculentum)
Authors: Hershenhorn Joseph , Plakhine Dina , Goldwasser Yaakov , Westwood James H. , Foy Chester L. , Kleifeld Yeshaiahu
Published: March 2018

The effect of the sulfonylurea herbicides, bensulfuron, chlorsulfuron, nicosulfuron, primisulfuron, rimsulfuron, thifensulfuron, and triasulfuron, on seed germination and radicle elongation of the parasitic plant, Egyptian broomrape, was tested in vitro without a host plant. These herbicides applied to the seeds at the preconditioning and germination stages significantly reduced radicle elongation of the parasite. Chlorsulfuron, rimsulfuron, and triasulfuron were further tested in polyethylene bags, where the parasite was able to parasitize tomato roots. Chlorsulfuron and triasulfuron applied at 2.5 and 25 μM ai and rimsulfuron at 5.0 μM ai, at the preconditioning and germination stages, almost completely inhibited parasite development, but at lower concentrations the parasite partially recovered 26 days after application. Chlorsulfuron inhibited parasite development for 34 d. Chlorsulfuron, triasulfuron, and rimsulfuron damaged parasite organs and caused rapid death of Egyptian broomrape tubercles when applied after the parasite had completed attachment to host roots. However, chlorsulfuron and triasulfuron at 25 μM ai were toxic to the tomato plants.
Weed Control in Wide- and Narrow-Row Soybean (Glycine max) with Imazamox, Imazethapyr, and CGA-277476 plus Quizalofop
Authors: Nelson Kelly A. , Renner Karen A.
Published: March 2018

Field experiments were conducted at East Lansing and Clarksville, MI, to evaluate the efficacy of imazamox, imazethapyr, and CGA-277476 plus quizalofop applied postemergence in wide- (76-cm) and narrow- (19-cm) row soybean. Soybean injury from all herbicides was minimal 14 days after treatment (DAT), except for CGA-277476 at 79 g ai/ha plus 69 g ai/ha quizalofop, which caused 30% soybean injury at the Clarksville location. Adding 4 g ai/ha CGA-248757 to 65 g ai/ha CGA-277476 plus quizalofop reduced common ragweed control, but increased redroot pigweed control in wide rows compared to 79 g ai/ha CGA-277476 plus quizalofop. Imazamox at 35 and 45 g ai/ha provided greater common ragweed and common lambsquarters control than imazethapyr at 70 g ai/ha 28 DAT. All herbicide treatments controlled velvetleaf. Common ragweed and common lambsquarters control by all herbicide treatments was enhanced in narrow- compared to wide-row soybean 56 DAT as was redroot pigweed control by CGA-277476 treatments. Total weed biomass and soybean yield in wide-row soybean treated with imazamox at 45 g/ha was not different from the hand-weeded control. In narrow-row soybean, soybean yield was equal to the hand-weeded control for 35 and 45 g/ha imazamox and 70 g/ha imazethapyr. Postemergence herbicide treatments resulted in less weed biomass and greater soybean yield in narrow- compared to wide-row soybean.
Poison-Hemlock (Conium maculatum L.)
Authors: Mitich Larry W.
Published: March 2018

The genus Conium is comprised of two or three temperate species of biennial herbs with highly divided leaves and compound umbels of small white flowers. All parts of C. macula tum have long been recognized as being highly poisonous; it was the plant used to kill Socrates in BC 399 (Gledhill 1985; Holm et al. 1997; Hyam and Pankhurst 1995). Conium is a member of the Umbelli ferae or Apiaceae, the carrot family, which accommodates 300 genera and between 2,500 and 3,000 species.