bluuebunny/crossref_metadata_2025 huggingface dataset:
Herbicide-Resistant Sunflower (Helianthus annuus) Response to Soil Residues of ALS-Inhibiting Herbicides
Authors: Howatt Kirk A. , Endres Gregory J.
Published: July 2006

Sunflower lines developed to resist some acetolactate synthase (ALS)-inhibiting herbicides are susceptible to foliar applications of other ALS-inhibiting herbicides. Research was conducted to determine whether imidazolinone (IMI)- or sulfonylurea (SU)-resistant sunflower was affected by soil residues of imazethapyr, metsulfuron, or flucarbazone. In greenhouse experiments, IMI-sunflower displayed 60 and 66% injury 4 wk after emergence with incorporated soil residues of metsulfuron at 4.2 g ai/ha and flucarbazone at 30 g ai/ha, respectively, but response to imazethapyr at 35 g ai/ ha was not different from that of nontreated plants. Metsulfuron at 4.2 g/ha and flucarbazone at 30 g/ha resulted in 56 and 72% less biomass accumulation, respectively, of IMI-sunflower compared with that of nontreated plants. Incorporated soil residues of imazethapyr, metsulfuron, or flucarbazone did not cause significant injury or result in shorter plants or less biomass accumulation of SU-sunflower than nontreated sunflower in greenhouse experiments. In field experiments, nonincorporated residues of imazethapyr, metsulfuron, or flucarbazone did not induce visible chlorosis or significant stunting of IMI- or SU-sunflower compared with nontreated sunflower. Herbicide-resistant sunflower growing in soil with nonincorporated residues of imazethapyr, metsulfuron, or flucarbazone produced seed yield similar to sunflower growing in sulfentrazone-treated soil or nontreated soil.
Patch Management of Herbicide-Resistant Wild Oat (Avena fatua)
Authors: Beckie Hugh J. , Hall Linda M. , Schuba Barclay
Published: July 2006

A study was conducted at a 64-ha site in western Canada to determine how preventing seed shed from herbicide-resistant wild oat affects patch expansion over a 6-yr period. Seed shed was prevented in two patches and allowed to occur in two patches (nontreated controls). Annual patch expansion was determined by seed bank sampling and mapping. Crop management practices were performed by the grower. Area of treated patches increased by 35% over the 6-yr period, whereas nontreated patches increased by 330%. Patch expansion was attributed mainly to natural seed dispersal (nontreated) or seed movement by equipment at time of seeding (nontreated and treated). Extensive seed shed from plants in nontreated patches before harvest or control of resistant plants by alternative herbicides minimized seed movement by the combine harvester. Although both treated and nontreated patches were relatively stable over time in this cropping system, preventing seed production and shed in herbicide-resistant wild oat patches can markedly slow the rate of patch expansion.
Sicklepod (Senna obtusifolia) Control and Seed Production after 2,4-DB Applied Alone and with Fungicides or Insecticides
Authors: Lancaster Sarah H. , Jordan David L. , Spears Janet F. , York Alan C. , Wilcut John W. , Monks David W. , Batts Roger B. , Brandenburg Richard L.
Published: July 2006

Experiments were conducted during 1999, 2002, and 2003 to evaluate sicklepod control by 2,4-DB applied alone or in mixture with selected fungicides and insecticides registered for use in peanut. The fungicides boscalid, chlorothalonil, fluazinam, propiconazole plus trifloxystrobin, pyraclostrobin, or tebuconazole and the insecticides acephate, carbaryl, esfenvalerate, fenpropathrin, lambda-cyhalothrin, methomyl, or indoxacarb applied in mixtures with 2,4-DB did not reduce sicklepod control by 2,4-DB compared with 2,4-DB alone. The fungicide azoxystrobin reduced control in some but not all experiments. Sicklepod control was highest when 2,4-DB was applied before flowering regardless of fungicide treatment. Seed production and germination were reduced when 2,4-DB was applied 81 to 85 d after emergence when sicklepod was flowering. Applying 2,4-DB before flowering and at pod set and pod fill did not affect seed production.
Deep Tillage and Glyphosate-Reduced Redvine (Brunnichia ovata) and Trumpetcreeper (Campsis radicans) Populations in Glyphosate-Resistant Soybean
Authors: Reddy Krishna N.
Published: July 2006

Field studies were conducted during the years 2000 to 2003 at Stoneville, MS, to determine the efficacy of fall deep tillage and glyphosate applications on redvine and trumpetcreeper populations and soybean yield in glyphosate-resistant soybean. Fall deep (≈45 cm) tillage for 1, 2, and 3 yr reduced redvine density by 95, 88, and 97%, respectively, compared with shallow (≈15 cm) tillage, but deep tillage did not reduce trumpetcreeper density. Glyphosate applied preplant reduced trumpetcreeper density (25 to 44%), but not redvine density, compared to that with no glyphosate. Glyphosate early postemergence (EPOST) either alone (45 to 67%) or followed by (fb) late postemergence (LPOST; 59 to 83%) reduced density of trumpetcreeper, but not of redvine, compared to that with no herbicide. However, dry biomass of both vines was reduced with glyphosate EPOST or LPOST compared to that with no herbicide. Soybean yields were higher with deep tillage vs. shallow tillage, glyphosate preplant application vs. no glyphosate, and glyphosate EPOST either alone or fb LPOST vs. no herbicide. Redvine did not reestablish in 2003, which was after skipping fall deep tillage for 1 yr following three consecutive years of deep tillage compared with shallow tillage. It is possible to manage redvine infestations with fall deep tillage and trumpetcreeper infestations with glyphosate preplant and postemergence (POST) in-crop applications. Integration of fall deep tillage and glyphosate POST applications could be an effective strategy to manage combined infestations of these vines in glyphosate-resistant soybean.
Selective Creeping Bentgrass (Agrostis stolonifera) Control in Cool-Season Turfgrass
Authors: Beam Josh B. , Barker Whitnee L. , Askew Shawn D.
Published: July 2006

Creeping bentgrass infestations in cool-season turfgrass are unsightly and difficult to control. Field tests were conducted at Stoney Creek Golf Course in Wintergreen, VA, in 2002 and 2003 on a Kentucky bluegrass rough and at the Turfgrass Research Center in Blacksburg, VA, in 2003 on a perennial ryegrass lawn to determine the efficacy of imazaquin, isoxaflutole, and mesotrione for creeping bentgrass control and turfgrass tolerance. Isoxaflutole and mesotrione each applied in two sequential applications at 280 g ai/ha or three sequential applications at 170 or 60 g/ha and imazaquin in two sequential applications at 390 g/ha controlled bentgrass at least 92% 14 wk after initial treatment (WAIT) at all locations. Sequential applications were applied at 2-wk intervals. Isoxaflutole and mesotrione, regardless of rate or sequential treatment, injured turfgrass less than 20% at all rating dates and locations. Imazaquin in two sequential applications at 390 g/ha injured Kentucky bluegrass and perennial ryegrass greater than 50% at all locations 14 WAIT. Results indicate isoxaflutole or mesotrione could be used for selective bentgrass control in Kentucky bluegrass or perennial ryegrass.
Wheat Response to Simulated Drift of Glyphosate and Imazamox Applied at Two Growth Stages
Authors: Deeds Zacharria A. , Al-Khatib Kassim , Peterson Dallas E. , Stahlman Phillip W.
Published: July 2006

Field experiments were conducted at Hays and Manhattan, KS, in 2002 and 2003 to determine winter wheat response to simulated drift rates of glyphosate and imazamox. Glyphosate and imazamox at 1/100×, 1/33×, 1/10×, and 1/3× of usage rates of 840 g ae/ha glyphosate and 35 g/ha imzamox were applied individually to wheat in the early jointing or the early flower stages of growth. Wheat injury and yield loss increased as herbicide rate was increased, with minimal effect from either herbicide at the 1/100× rate, and nearly complete kill and yield loss of wheat from both herbicides applied at the 1/3× rate, regardless of growth stage at application. In general, wheat injury and yield reduction were greater from glyphosate than from imazamox. In addition, wheat injury and yield loss were greater from herbicide treatment at the jointing stage than at the flowering stage of development. Correlation analysis suggests that visual injury is an accurate indicator of yield reductions. Germination tests of harvested grain showed that the viability of the wheat seed was not reduced if plants survived the herbicide treatment and produced a harvestable seed.
Trifloxysulfuron Plus Pyrithiobac Mixtures for Broadleaf Weed Control in Cotton (Gossypium hirsutum)
Authors: Richardson Robert J. , Wilson Henry P. , Armel Gregory R. , Hines Thomas E.
Published: July 2006

Studies were conducted in 1999, 2000, and 2001 to evaluate broadleaf weed control in cotton from POST applications of trifloxysulfuron plus pyrithiobac. Trifloxysulfuron was applied at 2.5, 5, and 7.5 g ai/ha, and pyrithiobac was applied at 0, 17, and 35 g ai/ha in a factorial treatment arrangement. Cotton injury was affected by rates of both herbicides at 7 and 14 d after treatment (DAT) with injury ranging from 19 to 26%. Broadleaf weed control at 28 DAT from mixtures of the herbicides was generally commercially acceptable. Combinations of 17 or 35 g/ha pyrithiobac plus trifloxysulfuron controlled common ragweed, velvetleaf, common lambsquarters, annual morningglory species (ivyleaf morningglory, pitted morningglory, and tall morningglory), common cocklebur, spurred anoda, and jimsonweed at least 73% at 28 DAT. Trifloxysulfuron applied alone failed to control velvetleaf, spurred anoda, and jimsonweed. Cotton yield reflected weed control and yields increased with pyrithiobac rates. It is concluded that the spectra of the weeds controlled by trifloxysulfuron and pyrithiobac were highly complementary in these studies.
Weed Control in Sericea Lespedeza with Imazethapyr
Authors: Wehtje Glenn , Mosjidis Jorge A.
Published: July 2006

Field studies were conducted to determine the feasibility of using imazethapyr applied preemergence (PRE) and postemergence (POST) for weed control in sericea lespedeza. In the POST experiment, imazethapyr was applied at 0, 71, 142, and 213 g ai/ha to mature, recently mowed stands of sericea lespedeza. Regardless of rate, yellow nutsedge and cutleaf groundcherry control at 2 mo after treatment, as determined by weed foliage biomass relative to the nontreated plants, was 90 and 80%, respectively. Sericea lespedeza forage yield (weeds removed) was not reduced by POST-applied imazethapyr even at 213 g/ha. The same imazethapyr rates were used with newly seeded sericea lespedeza in the PRE-applied experiment. Imazethapyr at 71 g/ha provided at least 78% control of large crabgrass, stinkgrass, yellow nutsedge, sicklepod, and cutleaf groundcherry as well as maximum sericea lespedeza performance, as indicated by seedling height, weight, and stand count. Results indicated that imazethapyr can be used for either PRE- or POST-applied weed control in sericea lespedeza. However, margin of safety is greater with imazethapyr applied POST to mature stands than with PRE applications to germinating seeds.
Tall Ironweed (Vernonia altissimaNutt.) Control in Pastures with Fall-Applied Herbicides
Authors: Marshall Michael W. , Green Jonathan D. , Ditsch David C. , Turner J. Wade
Published: July 2006

Tall ironweed is a troublesome perennial weed that infests cool-season grass pastures in Kentucky. Field experiments were conducted in 2000 through 2003 to evaluate the efficacy of fall-applied herbicides on established tall ironweed following a midsummer mowing. Triclopyr-containing treatments showed the greatest suppression of tall ironweed 12 mo after treatment (MAT), across all years. With triclopyr at 0.56 and 0.63 kg/ha, tall ironweed control was 80% or greater in 2 of the 3 yr. Dicamba initially provided 87% control 8 MAT in 2 of 3 yr and declined to less than 60% 12 MAT. Tall ironweed shoot density was also reduced 66% or more 12 MAT with fall-applied triclopyr-containing treatments. In contrast, tall ironweed density increased approximately twofold in dicamba-treated plots between 8 to 12 MAT in all 3 yr. The impact of herbicide treatment on dry matter (DM) yield of spring-seeded red clover (Trifolium pratenseL.), tall ironweed, and forage grasses was also evaluated. Red clover DM yield in the herbicide-treated plots in 2002 showed no significant differences from the untreated control. However, red clover DM yield in 2003 was lowest for the two triclopyr + clopyralid treatments, indicating a decrease in DM production compared with that of the nontreated control. Results indicated that fall-applied triclopyr-containing herbicides following a midsummer mowing is an effective program for removing tall ironweed from grass pastures, but further research is needed to evaluate the establishment of red clover following herbicide treatment.
Evaluation of Sand Stockpiles as Potential Sources of Cranberry Weeds
Authors: Mason Joanne , Sandler Hilary A. , Hunsberger Laura K.
Published: July 2006

Sand stockpiles, located near commercial cranberry beds in Massachusetts, New Jersey, Washington, and Wisconsin, were sampled quarterly over a 2-yr period. Samples were collected from the surface and the interior of the piles. Utilizing a simple greenhouse germination bioassay, 74 plant species representing 23 plant families were identified across all locations and samples. Plant density varied by region and by sampling depth; species richness varied by region only. More seedlings germinated from samples taken from the surface of the stockpile compared with interior samples. Almost half of all species detected in either surface or interior samples were represented by only one seedling. Fifty-nine percent of the plant species from Massachusetts and New Jersey samples, and 79% and 96% of the plant species from Wisconsin and Washington, respectively, were considered to be weeds in cranberry production. Only one-third of the identified species had wind-blown seeds; seed dispersal was by other mechanisms in almost half of the species. This survey documented the weed management implications of spreading stockpiled sand on cranberry bogs for horticultural or pest management purposes. To minimize the introduction of additional weed problems, growers and integrated pest management consultants should evaluate the seedbank potential of a stockpile prior to application of the sand to the production area.
Corn (Zea maysL.) Response to Trifloxysulfuron
Authors: Porterfield Dunk , Wilcut John W.
Published: July 2006

Experiments were conducted in weed-free environments to determine corn tolerance to trifloxysulfuron applied PRE or POST, and to determine the potential for trifloxysulfuron applied PRE or POST to cotton to injure corn grown in rotation the following year. Trifloxysulfuron at 3.75, 7.5, or 15 g ai/ha applied PRE or POST resulted in 98% stand reduction of imidazolinone-tolerant (IT) corn and 100% stand reduction in conventional corn. No injury occurred to imidazolinone-resistant (IR) corn. A corn cultivar yield response was observed, with conventional nontreated corn yielding 8,850 kg/ha and greater than nontreated IT corn at 7,900 kg/ha. Nontreated IR corn yielded the least, at 6,400 kg/ha, and these yields were equivalent to trifloxysulfuron-treated IR corn at 6,590 kg/ha. Cotton treated with trifloxysulfuron PRE at any rate was injured less than 8%. Both trifloxysulfuron at 7.5 g/ha POST and pyrithiobac at 70 g ai/ha POST injured cotton 11% early in the season. Neither trifloxysulfuron nor pyrithiobac influenced weed-free cotton lint yields. When grown in rotation, corn was not injured by trifloxysulfuron or pyrithiobac applied the previous year to cotton, and yields were not influenced.
Trifloxysulfuron–Insecticide Combination Effects on Broadleaf Weed and Thrips (Frankliniella spp.) Control in Cotton
Authors: Miller Donnie K. , Downer Robert G. , Burris Eugene , Wilcut John W. , Cook Donald R.
Published: July 2006

Coapplication of herbicides and insecticides affords growers an opportunity to control multiple pests with one application given that efficacy is not compromised. Trifloxysulfuron was applied at 5.3 g ai/ha both alone and in combination with the insecticides acephate (370 g ai/ha), oxamyl (370 g ai/ha), lambda-cyhalothrin (34 g ai/ha), acetamiprid (45 g ai/ha), thiamethoxam (45 g ai/ha), endosulfan (379 g ai/ha), indoxacarb (123 g ai/ha), emamectin benzoate (11 g ai/ha), methoxyfenozide (67 g ai/ha), spinosad (75 g ai/ha), and pyridalyl (112 g ai/ha) to determine the effects of coapplication on control of some of the more common and/or troublesome broadleaf weeds infesting cotton. In addition, the insecticides acephate, oxamyl, lambda-cyhalothrin, thiamethoxam, and endosulfan, at the rates listed above, were applied either alone or in combination with trifloxysulfuron at 7.9 g/ha to assess the effects of coapplication on thrips control. Control of hemp sesbania (insecticides oxamyl and lambda-cyhalothrin), sicklepod (insecticides methoxyfenozide and pyridalyl), redroot pigweed (insecticides thiamethoxam, methoxyfenozide, spinosad, and pyridalyl), and smooth pigweed, Palmer amaranth, and common lambsquarters (all insecticides) with trifloxysulfuron may be reduced when coapplied with the indicated insecticides for each species. Control of pitted, tall, ivyleaf, and entireleaf morningglory with trifloxysulfuron was not affected by the insecticides evaluated. Coapplication of trifloxysulfuron with the insecticides evaluated also resulted in no negative effects on thrips control.
AMADS Increases the Efficacy of Glyphosate Formulations on Corn
Authors: Shaner Dale L. , Westra Phil , Nissen Scott
Published: July 2006

Greenhouse studies were conducted to determine the effect of 1-aminomethanamide dihydrogen tetraoxosulfate (AMADS) as a spray adjuvant on the efficacy of three different glyphosate formulations, the isopropylamine salt (glyphosate-IPA), potassium salt (glyphosate-K), and the acid of glyphosate dissolved in AMADS (glyphosate-A). All formulations were tested at multiple rates with and without AMADS (2% v/v) on greenhouse-grown corn, and growth inhibition was determined by measuring the elongation of the newest emerging leaf between 1 and 7 d after treatment. AMADS increased the efficacy of all three glyphosate formulations by threefold to fourfold. The IC50 values for glyphosate-IPA, glyphosate-K, and glyphosate-A without AMADS on corn were 77, 54, and 53 g ae/ha, respectively; and with AMADS the values were 20, 18, and 21 g/ha, respectively. AMADS was more effective than ammonium sulfate (2% w/v) in overcoming the antagonism of hard water (200 parts per million Ca+2) on glyphosate-K efficacy on corn. The rainfastness of glyphosate-IPA, glyphosate-A, and glyphosate-K was improved with AMADS.
Plant Response to Combinations of Mesotrione and Photosystem II Inhibitors
Authors: Abendroth Julie A. , Martin Alex R. , Roeth Fred W.
Published: July 2006

Photosystem II (PS II) inhibitors halt electron flow within the photosynthetic electron transport chain, thereby leading to increased oxidative stress. As a result, their addition to mesotrione, which inhibits carotenoid biosynthesis by inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), is complementary. Field and greenhouse experiments were conducted in 2002 and 2003 to investigate the joint action of POST mesotrione plus PS II inhibitor herbicide combinations. The joint action of mesotrione plus PS II inhibitors was investigated across five plant species, three PS II inhibitors, and two moisture environments to determine their influence on the joint action response. Rates of mesotrione evaluated ranged from 4.4 to 87.6 g ai/ha alone and in combination with reduced rates of atrazine, bromoxynil, and metribuzin. In the field, all combinations of mesotrione at 8.8, 17.5, and 35.0 g/ha plus atrazine, bromoxynil, or metribuzin were synergistic for necrosis 6 d after treatment (DAT) on sunflower. Addition of atrazine at 280 g/ha to mesotrione at 8.8 g/ha increased velvetleaf leaf necrosis by 18 to 47%. In the greenhouse, the addition of bromoxynil at 70 g/ha to mesotrione at 17.5 g/ha increased leaf necrosis by 23 to 34% and biomass reduction by 38 to 47%. Synergism on Palmer amaranth occurred similarly under both normal and dry moisture environments at application. Plant height at application was found to influence detection of synergism on the whole-plant level.
Weed Management withS-Metolachlor and Glyphosate Mixtures in Glyphosate-Resistant Strip- and Conventional-Tillage Cotton (Gossypium hirsutumL.)
Authors: Clewis Scott B. , Wilcut John W. , Porterfield Dunk
Published: July 2006

Five studies were conducted at Clayton, Rocky Mount, and Lewiston-Woodville, NC, in 2001 and 2002, to evaluate weed management, crop tolerance, and yield in strip- and conventional-tillage glyphosate-resistant cotton. Cotton was treated with two glyphosate formulations; glyphosate-IP (isopropylamine salt) or glyphosate-TM (trimethylsulfonium salt), early postemergence (EPOST) alone or in a mixture withS-metolachlor. Early season cotton injury was minimal (3%) with either glyphosate formulation alone or in mixture withS-metolachlor. Weed control and cotton yields were similar for both glyphosate formulations. The addition ofS-metolachlor to either glyphosate formulation increased control of broadleaf signalgrass, goosegrass, large crabgrass, and yellow foxtail 14 to 43 percentage points compared with control by glyphosate alone.S-metolachlor was not beneficial for late-season control of entireleaf morningglory, jimsonweed, pitted morningglory, or yellow nutsedge. The addition ofS-metolachlor to either glyphosate formulation increased control of common lambsquarters, common ragweed, Palmer amaranth, smooth pigweed, and velvetleaf 6 to 46 percentage points. The addition of a late postemergence-directed (LAYBY) treatment of prometryn plus MSMA increased control to greater than 95% for all weed species regardless of EPOST treatment, and control was similar with or withoutS-metolachlor EPOST. Cotton lint yield was increased 220 kg/ha with the addition ofS-metolachlor to either glyphosate formulation compared with yield from glyphosate alone. The addition of the LAYBY treatment increased yields 250 and 380 kg/ha for glyphosate plusS-metolachlor and glyphosate systems, respectively.S-metolachlor residual activity allowed for an extended window for more effective LAYBY application to smaller weed seedlings instead of weeds that were possibly larger and harder to control.
ALS-Inhibitor Resistance in Populations of Eastern Black Nightshade (Solanum ptycanthum) from Ontario
Authors: Ashigh Jamshid , Tardif François J.
Published: July 2006

Populations of eastern black nightshade suspected of being resistant to acetolactate synthase (ALS) inhibitors have been reported since 1999 in different locations in Ontario, Canada. This event has threatened the use of ALS inhibitors for control of this species. The objectives of this study were to evaluate the spectrum of resistance to different ALS-inhibiting herbicides and to examine the effectiveness of alternative modes of action herbicides. Growth room experiments were conducted to determine the response to imazethapyr and atrazine in seven suspected ALS inhibitor– resistant populations. One resistant and one susceptible population were further characterized for their response to ALS inhibitors and chloroacetamides. Seven populations were able to survive imazethapyr at 100 g ai/ha, while there was no resistance to atrazine. Compared to a susceptible (S) population, resistant (R) population SOLPT 1 had 726-, 31-, 6-, and 4-fold resistance to postemergence (POST) applied imazethapyr, imazamox, primisulfuron, and flumetsulam, respectively. Preemergence (PRE) application of imazethapyr, flumetsulam, cloransulam, nicosulfuron, prosulfuron, and rimsulfuron did not provide control of the R population, whereas they totally controlled the S population. The chloroacetamide herbicides metolachlor, dimethenamid, and flufenacet all provided at least 90% control of both R and S populations when applied PRE at the recommended field rates. The ALS inhibitors will not provide adequate control of these resistant populations, but acceptable control could be achieved with chloroacetamides or with atrazine.
Corn and Rice Response to Simulated Drift of Imazethapyr Plus Imazapyr
Authors: Bond Jason A. , Griffin James L. , Ellis Jeffrey M. , Linscombe Steven D. , Williams Bill J.
Published: July 2006

Field research was conducted for 2 yr to evaluate response of corn and rice to simulated drift rates of a commercial premix of imazethapyr plus imazapyr [3:1 (w/w)]. Drift rates of the imazethapyr plus imazapyr premix represented 0.8, 1.6, 3.2, 6.3, and 12.5% of the usage rate of 63 g ai/ha (0.5, 1, 2, 4, and 7.9 g/ha, respectively). The imazethapyr plus imazapyr premix applied to six-leaf corn at 7.9 g/ha reduced height 11% compared with the nontreated control 7 days after treatment (DAT) but did not affect corn height 14 and 28 DAT. Corn yield was equivalent regardless of imazethapyr plus imazapyr rate and ranged from 10,200 to 11,500 kg/ha. At 28 DAT, rice height was reduced 12% when 7.9 g/ha of the imazethapyr plus imazapyr premix was applied early postemergence (EPOST) at two- to three-leaf and 14 and 5% when the imazethapyr plus imazapyr premix at 7.9 and 4 g/ha, respectively, was applied late postemergence (LPOST) at panicle differentiation. Reductions in mature rice height of 11 and 6% were observed when the imazethapyr plus imazapyr premix was applied LPOST at 7.9 and 4 g/ha, respectively, and a 5% reduction was observed for 7.9 g/ha of the imazethapyr plus imazapyr premix applied EPOST. Application of the imazethapyr plus imazapyr premix EPOST at 7.9 g/ha delayed heading in only 1 yr, but heading was delayed both years when applied LPOST. Rice yield was reduced 39 and 16% when the imazethapyr plus imazapyr premix was applied LPOST at 7.9 and 4 g/ha, respectively, compared with a 9% yield reduction for 7.9 g/ha applied EPOST.
Control of Torpedograss (Panicum repens) with Trifloxysulfuron-Sodium in Bermudagrass (Cynodon dactylon×Cynodon transvaalensis) Turf
Authors: Stephenson Daniel O. , Brecke Barry J. , Unruh J. Bryan
Published: July 2006

Torpedograss is a serious problem in southern turfgrass, especially along the U.S. gulf coast. Studies were conducted in 1999, 2000, 2002, and 2003 to evaluate single and sequential applications of trifloxysulfuron-sodium for torpedograss control in bermudagrass turf. In 1999/2000, single applications of trifloxysulfuron-sodium at 75 g ai/ha provided at least 10% better torpedograss control than 25 g/ha 7 and 15 wk after initial treatment (WAIT). When evaluated 15 WAIT, sequential applications of trifloxysulfuron-sodium provided 87% control, similar to 84% control observed with quinclorac + diclofop-methyl, each applied at 840 g ai/ha. Both treatments controlled torpedograss better than a single trifloxysulfuron-sodium application (61%) in 1999/2000. Torpedograss control was less in 2002/2003 than in 1999/2000 because of high rainfall, which encouraged aggressive torpedograss growth and possible movement of trifloxysulfuron-sodium below its rooting zone. No differences were noted among trifloxysulfuron-sodium rates or number of applications in 2002/2003. Quinclorac + diclofop-methyl controlled torpedograss greater than trifloxysulfuron-sodium 15 WAIT in 2002/2003, but neither treatment provided greater than 45% control. These results suggest that trifloxysulfuron-sodium controls torpedograss when rainfall is not excessive.
Foliar vs. Root Sensitivity of Hairy Bittercress (Cardamine hirsuta) to Isoxaben
Authors: Wehtje Glenn , Gilliam Charles H. , Miller Michael E. , Altland James E.
Published: July 2006

It has been previously reported that POST-applied isoxaben can effectively control established hairy bittercress. Experiments were conducted to determine the relative importance of root vs. foliar entry of POST-applied isoxaben. At a common isoxaben rate of 0.56 kg/ha, foliar-only and foliar plus soil applications provided 10.5 and 23.3% control, respectively, as determined by fresh weight reduction. In contrast, soil-only application provided 47.0% control. Hairy bittercress foliar absorption of14C–isoxaben did not exceed 15% of the amount applied after 72 h. Therefore, the comparatively less effectiveness of foliar-only applications may be attributed primarily to limited absorption. Minimal isoxaben concentration required to inhibit root growth of hydroponically grown hairy bittercress was 0.0025 mg/L. Higher concentrations were required to produce a response in the foliage. Sorption of isoxaben by pine bark rooting substrate, typical of what is used in container nursery production, exceeded 99% of amount applied after 36 h. Even with 99% sorption, the probable concentration within the aqueous phase remains sufficient to inhibit hairy bittercress root growth. Additional studies with14C–isoxaben established that approximately 35% of the root-absorbed isoxaben was translocated into the foliage. Translocation from the roots into the foliage was reduced to 16% when the experiment was repeated during environmental conditions less favorable for vegetative growth (i.e., longer day length and higher temperature). Results indicate that the control of hairy bittercress with POST-applied isoxaben is likely the result of root absorption and root-growth inhibition. Expression of phytotoxicity within the foliage is also a component, but is dependent upon the root-absorbed isoxaben being translocated into the foliage. Extent of this translocation is dependent upon plant maturity and prevalent environmental conditions.
The Effects of Depth and Duration of Seed Burial on Viability, Dormancy, Germination, and Emergence of Ivyleaf Speedwell (Veronica hederifolia)
Authors: Mennan Husrev , Zandstra Bernard H.
Published: July 2006

Experiments were conducted to investigate the effects of depth and duration of burial on seasonal germination, primary and secondary dormancy, viability, and seedling emergence of ivyleaf speedwell (Veronica hederifoliaL.) seeds. The seeds were buried at 0, 5, 10, or 20 cm and retrieved from the field at monthly intervals. The exhumed seeds were germinated at 5 C. In the second experiment, seeds were stored in the laboratory after harvest and tested for germination at monthly intervals. In each experiment, nongerminated seeds were treated with triphenyltetrazolium chloride at monthly intervals to test their viability. The effects of stratification and burial depth on seedling emergence were observed for 1 yr. The seeds exhumed from the soil were dormant at the beginning of the experiment and exhibited dormancy/nondormancy/conditional dormancy cycling throughout the experiment. Depth of burial and time affected seed germination. Seeds retrieved from the soil surface germinated well initially, but germination decreased as depth of burial increased. In the dry storage experiment, seeds had a high level of primary dormancy, and viability decreased over time. Seedling emergence decreased when depth of burial increased. Seedlings emerged nonuniformly throughout the year and demonstrated typical winter annual characteristics.
Effects of Spring Wheat Seed Size and Reduced Rates of Tralkoxydim on Wild Oat Control, Wheat Yield, and Economic Returns
Authors: Xue Qingwu , Stougaard Robert N.
Published: July 2006

Spring wheat competitive ability has recently been demonstrated to co-vary with seed size. The objective of this study was to determine if spring wheat seed size would influence the effects of variable tralkoxydim rates on wild oat control, wheat yield, and economic returns. The factorial treatment arrangement consisted of three spring wheat seed size classes and five tralkoxydim rates. Wild oat density, panicles, and biomass decreased as spring wheat seed size and tralkoxydim rate increased, with the combined effect being additive. Wild oat variables decreased in a log-logistic manner as tralkoxydim rate increased during both years. However, tralkoxydim was less effective in 2000 than 2002, as indicated by the higher dosage required to reduce the wild oat variables by 50% (greaterI50values). In contrast, the effect of large seeded wheat in suppressing wild oat was more consistently expressed, with wild oat variables decreasing linearly as seed size increased. Wheat yield and economic returns increased exponentially as tralkoxydim rate increased. At the same time, wheat yield and economic returns were greater for wheat plants derived from large seed compared to those derived from small seed. Averaged over all other factors, adjusted gross returns of 578, 657, and 703 $/ha were realized for the small, medium, and large seed size classes, respectively. The combined use of large seeded wheat plus tralkoxydim applications provided greater wild oat control than did either single tactic. The use of large seeded wheat had a stabilizing effect that increased the consistency and durability of the weed management system while simultaneously improving economic returns.
Processing Tomato and Weed Response to Flufenacet plus Metribuzin
Authors: Sikkema Peter H. , Hamill Allan S. , Qaderi Mirwais M. , Doucet Colleen
Published: July 2006

Field experiments were conducted in 1998, 1999, and 2000 at two locations (Harrow and Ridgetown) in southwestern Ontario to determine the biologically effective rates (I90) of a commercial formulation of flufenacet plus metribuzin for weed control and processing tomato tolerance. At the proposed label use rate, flufenacet plus metribuzin provided excellent (≥90%) early-season (22 to 29 d after planting) control of velvetleaf, good (80 to 89%) control of barnyardgrass and redroot pigweed, and fair (60 to 79%) control of common lambsquarters. Flufenacet plus metribuzin provided fair late-season (59 to 97 d after planting) control of redroot pigweed and common lambsquarters and poor (≤59%) control of barnyardgrass and velvetleaf. At Harrow and Ridgetown, I90values for early-season weed control ranged from 70 to 1,300 g ai/ha and 50 to 1,900 g ai/ha, respectively. Flufenacet plus metribuzin provided poor weed control at Ridgetown. This result was not attributable to higher weed density or particular weed species but may have been caused by lack of rainfall and too low application rates for the medium-textured soil type. It is estimated that flufenacet plus metribuzin at 1,400 g/ha can control green foxtail season-long, whereas barnyardgrass and common lambsquarters would require 1,900 g/ha. Season-long control of velvetleaf and redroot pigweed would require application rates of 3,200 and 7,100 g/ha, respectively. Only slight early-season crop injury was observed, which was not reflected in yields. Optimum yields of tomatoes were obtained at Harrow at rates lower or slightly higher than the registered rates for corn and soybean. Tomato yields were higher at Harrow than at Ridgetown, which may have been due to differences in soil texture. Tomatoes grown in a medium-textured (Ridgetown) soil appeared to be less competitive against weeds than those grown in a coarse-textured soil (Harrow).
Assessment of Weed Control Strategies for Corn in the North-Central United States
Authors: Tharp Brent E. , Kells James J. , Bauman Thomas T. , Harvey R. Gordon , Johnson William G. , Loux Mark M. , Martin Alex R. , Maxwell Douglas J. , Owen Micheal D. K. , Regehr David L. , Warnke Jon E. , Wilson Robert G. , Wrage Leon J. , Young Bryan G. , Dalley Caleb D.
Published: July 2006

Field experiments were conducted across the north-central United States to determine the benefits of various weed control strategies in corn. Weed control, corn yield, and economic return increased when a preemergence (PRE) broad-spectrum herbicide was followed by (fb) postemergence (POST) herbicides. Weed control decisions based on field scouting after a PRE broad-spectrum herbicide application increased weed control and economic return. Application of a PRE grass herbicide fb a POST herbicide based on field scouting resulted in less control of velvetleaf and morningglory species, corn yield, and economic return compared with a PRE broad-spectrum herbicide application fb scouting. Cultivation after a PRE broad-spectrum herbicide application increased weed control and corn yield compared with the herbicide applied alone, but economic return was not increased. An early-postemergence herbicide application fb cultivation resulted in the highest level of broadleaf weed control, the highest corn yield, and the greatest economic return compared with all other strategies. Weed control based on scouting proved to be useful in reducing the effect of weed escapes on corn yield and increased economic return compared with PRE herbicide application alone. However, economic return was not greater than the PRE fb planned POST or total POST strategies.
Changes in Membrane Lipid Order With Capacitation in Rhesus Macaque (Macaca mulatta) Spermatozoa
Authors: Baumber Julie , Meyers Stuart A.
Published: July 2006

ABSTRACT: Lipophilic fluorescent dye merocyanine 540 is believed to stain cell membranes with increasing affinity as the lipid components become more disordered and has been associated with changes in membrane fluidity. The aim of this study was to determine whether membrane lipid disorder is associated with capacitation of macaque spermatozoa. To induce capacitation, spermatozoa from 5 rhesus macaques were incubated at 37°C (5% CO2 in air) for 2 hours in a modified Biggers‐Whitten‐Whittingham medium containing 30 mg/mL bovine serum albumin and 36 mmol/L NaHCO3. Caffeine (1 mmol/L) and dbcAMP (1.2 mmol/L) were added to the medium, and incubation was performed for an additional 30 minutes. Sperm motility was determined by computer‐assisted sperm analysis, and membrane lipid order and sperm viability was determined by flow cytometry with merocyanine (2.7 μmol/L) and Yo‐Pro‐1 (25 nmol/L), respectively. Tyrosine phosphorylation of proteins in sperm tail was immunohistochemically examined by means of anti‐phosphotyrosine (α‐PY; clone 4G10). Capacitation resulted in a significant increase in the amplitude of lateral head displacement and beat cross frequency (P < .005) and a significant decrease in linearity and straightness in capacitated spermatozoa (P < .005), compared with control spermatozoa, which suggests the expression of hyperactivated motility. Animals in which capacitation was induced had a significant increase in the number of spermatozoa showing tyrosine phosphorylation of tail proteins (P < .0001) and a significant increase in the intensity of merocyanine fluorescence (P < .0001), compared with control animals. The observed decrease in membrane lipid order after capacitation was induced was not associated with surface exposure of phosphatidylserine, as determined by flow cytometry with annexin V‐Alexa Fluor 488. Merocyanine may be a useful tool for investigating the role of the plasma membrane on capacitation and other cytotoxic events in macaque spermatozoa.
SAMMA Induces Premature Human Acrosomal Loss by Ca2+Signaling Dysregulation
Authors: Anderson Robert A. , Feathergill Kenneth A. , Waller Donald P. , Zaneveld Lourens J. D.
Published: July 2006

ABSTRACT:SAMMA is licensed for development as a contraceptive microbicide. Understanding mechanisms of its biological activity is prerequisite to designing more active second generation products. This study examined Ca2+involvement in SAMMA‐induced premature acrosomal loss (SAL) in noncapacitated human spermatozoa. SAMMA causes acrosomal loss (AL) in a dose‐dependent manner (ED50= 0.25 μg/mL). SAL requires extracellular Ca2+(ED50= 85 μM). SAL is inhibited by verapamil (nonspecific voltage‐dependent Ca2+channel blocker; IC50= 0.4 μM), diphenylhydantoin and NiCl2(T‐type [Cav3.x] channel blockers; IC50210 μM and 75 μM, respectively). Verapamil blockade of L‐type (Cav1.x) channels is use‐dependent; activated channels are more sensitive to inhibition. However, verapamil inhibition of SAL does not increase after repeated SAMMA stimulation. SAL is unaffected by 10 μM nifedipine (selective L‐type channel blocker). This contrasts to 40% inhibition (P< .001) of AL induced by 1 μM thapsigargin (Ca2+‐ATPase inhibitor; releases intracellular Ca2+stores, promotes capacitative Ca2+entry). SAL is unaffected by 1 μM BAPTA‐AM (intracellular Ca2+chelator), and 50 μM 2‐APB (blocks InsP3 receptors and store‐operated channels). This contrasts with thapsigargin‐induced AL, inhibited nearly 65% by BAPTA‐AM (P< .005) and 91% by 2‐APB (P, .001). The results suggest that SAL is mediated by Ca2+entry through channels pharmacologically similar to the T‐type (Cav3.2) class. This process appears distinct from that caused by physiological stimuli such as progesterone or zona pellucida‐derived proteins. SAMMA's contraceptive activity may be caused by induction of premature AL through dysregulation of Ca2+signaling.
A Novel Androgen Receptor Mutation Resulting in Complete Androgen Insensitivity Syndrome and Bilateral Leydig Cell Hyperplasia
Authors: Singh Rajender , Shastry Prabhakar K. , Rasalkar Avinash A. , Singh Lalji , Thangaraj K.
Published: July 2006

ABSTRACT:Androgens drive male secondary sexual differentiation and maturation. Mutations in the androgen receptor (AR) gene cause a broad spectrum of abnormal phenotypes in humans, ranging from mild through partial to complete androgen insensitivity. We have analyzed theARgene by using denaturing high‐performance liquid chromatography (DHPLC) and direct sequencing and have studied gonads histologically in a familial case of complete androgen insensitivity syndrome. Sequence analysis of theARgene showed a novel C2578T missense mutation, resulting in the replacement of a highly conserved leucine residue with phenylalanine (L859F) in ligand‐binding domain of the receptor. The residue L859, located in helix 10 of the androgen receptor, plays a significant role in overall architecture of ligand‐binding pocket. The mutation was absent from the father, normal brother of the patients, and 100 normal males recruited in this study as controls. The inheritance of the mutation in the family clearly shows that C2578T is the underlying mutation for the eventual phenotype in the patients. Histology of patient's gonads showed Leydig cell hyperplasia, with a few or no spermatogonium. It is thought thatARgene mutations result in hormonal imbalance, resulting in the high levels of luteinizing hormone (LH) and ultimately Leydig cell hyperplasia or tumor formation. In the present study, we have reported a rare familial case of Leydig cell hyperplasia despite consistently normal LH levels. The finding will help in giving counseling to this family and prevent the transmission of the mutated X chromosome to the coming generations.
Immunohistochemical Localization of Sperm‐Preserving Proteins in the Ram Reproductive Tract
Authors: Fernández‐Juan Marta , Gallego Margarita , Barrios Beatriz , Osada Jesús , Cebrián‐Pérez José A. , Muiño‐Blanco Teresa
Published: July 2006

ABSTRACT: Previously, we reported that the addition of seminal plasma proteins before cold‐shock treatment prevents sperm membrane injury, and that 2 proteins of approximately 14 (P14) and 20 (P20) kDa, the main components of fraction 6 isolated by exclusion chromatography, are responsible for this protective effect. The objective of the present study was to localize P14 and P20 in tissues of the ram reproductive tract to determine their origin. Antiserum generated against purified P14 and P20 reacted with proteins in seminal vesicles and vas deferens by Western blot analyses of protein tissue extracts. However, these antisera failed to detect P14 and P20 in testis, prostate, efferent ductules, bulbourethral glands, and epididymis (caput, corpus, and cauda). Immunohistochemical analyses by both indirect immunofluorescence and the avidin‐biotin complex technique confirmed that only seminal vesicles showed reactivity, restricted to the secretory cells, with both antibodies. Obtained results indicate that P14 and P20 are secreted specifically in the seminal vesicles. To further confirm that P14 and P20 are specifically expressed in seminal vesicles, we used Northern blot analyses to investigate the expression of both proteins in seminal vesicles and vas deferens. These assays corroborated again that P14 and P20 were specifically expressed in seminal vesicles. Consequently, we suggest referring to these 2 proteins as RSVP14 and RSVP20, respectively, according to their origin and molecular weight.
Reducing Estrogen Synthesis in Developing Boars Increases Testis Size and Total Sperm Production
Authors: At‐Taras Eeman E. , Berger Trish , McCarthy Megan J. , Conley Alan J. , Nitta‐Oda Barbara J. , Roser Janet F.
Published: July 2006

ABSTRACT: The abundant production of testicular estrogens and the presence of both ESR1 and ESR2 within boar testes are consistent with a role for estrogen in testicular development and/or function in this species. This study was aimed at determining the role of endogenous estrogen in the regulation of testicular development and function, including the effects on testis weight, histology, sperm production (detergent‐resistant spermatid numbers), Sertoli cell numbers, and Leydig cell volume in the boar. Twenty‐eight littermate pairs of boars were assigned to groups as follows: 1 boar from each pair was assigned to the control group (vehicle) and the other was assigned to treatment and received 0.1 mg/kg body weight of an aromatase enzyme inhibitor (letrozole) orally each week beginning at 1 week of age until castration at 2, 3, 4, 5, 6, 7, or 8 months of age. Testes were weighed and testicular parenchyma was recovered for determination of histology and detergent‐resistant spermatid numbers, and for determination of Sertoli cell number and Leydig cell volume by staining for GATA‐4 and 17‐α hydroxylase/17–20 lyase respectively. Testes of aromatase‐inhibited boars initially exhibited delayed lumen formation, lower testicular weight, fewer detergentresistant spermatids, and fewer Sertoli cells, but by 7 to 8 months, these boars had recovered and had larger testes, more detergentresistant spermatids per testis, and more Sertoli cells. Total Leydig cell volume increased in proportion to testis size. Reducing endogenous estrogen is consistent with a delay in testicular maturation/puberty that allows for a longer window for the proliferation of Sertoli cells and maturation of Leydig cells, resulting in larger testes and higher spermatid production.
Varicocele and Fertility: Relationship Between Testicular Volume and Seminal Parameters Before and After Treatment
Authors: Zucchi Alessandro , Mearini Luigi , Mearini Ettore , Fioretti Fabrizio , Bini Vittorio , Porena Massimo
Published: July 2006

ABSTRACT: Varicocele is a condition of varicosity and tortuosity of the pampiniform plexus that is often associated with a reduction in the volume of the affected testicle. Today there is much debate about how much the varicocele actually damages the reproductive system and the mechanism through which this occurs. Furthermore, it has not yet clearly been established if treatment is truly useful to restore testicular function. The goal of this study was to evaluate changes in the volume of the affected testis after treatment and to examine any correlations between volume and seminal parameters. We evaluated 43 patients with left idiopathic varicocele with ultrasound scan of the testis before and after surgery; testicular volume was obtained using the ellipsoid formula. We also examined semen parameters before and at an average time of 1 year after the procedure, using the WHO indications. We performed 2 statistical analyses, comparing changes in testicular volume before and after surgery, and volume with seminal parameters. Statistical analysis shows a significant increase of testicular volume after varicocele treatment (P < .05). Furthermore, the total number of spermatozoa and fast progressive spermatozoa rates significantly increased after surgery (respectively P < .05 and P < .01) (Figure 1). The Spearman correlation coefficient shows a good relationship between testicular volume and total number of spermatozoa (r = .445; P = .01). Our data point to the possibility that the affected testicle could benefit in terms of trophism and function after varicocele treatment. Ultrasound scan at follow‐up permits assessment of not only the presence of recurrence, but it is also useful for evaluating trophism.