bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Control Systems for Coffee Senna (Cassia occidentalis) in Cotton (Gossypium hirsutum)
Authors: Keeton Andrew , Murdock Edward C. , Stapleton Gregory S. , Toler Joe E.
Published: March 2018

Field experiments were established to evaluate coffee senna control in cotton with registered PRE, early POST-directed (EPD), and late POST-directed (LPD) herbicides and with pyrithiobac applied PRE and early POST. Fluometuron and norflurazon applied PRE controlled coffee senna 87 and 65%, respectively, 6 wk after planting (WAP). Methazole applied EPD controlled coffee senna 96% 2 wk after application, whereas fluometuron and MSMA applied EPD controlled 70 and 16%, respectively. LPD applications of cyanazine, diuron, and prometryn averaged only 45% control 8 WAP. MSMA applied LPD controlled coffee senna only 12%. Fluometuron and norflurazon applied PRE followed by methazole applied EPD and cyanazine applied LPD controlled coffee senna 98 and 99% 6 WAP, respectively. PRE, early POST, and PRE followed by early POST applications of pyrithiobac controlled coffee senna 88, 89, and 95% 6 WAP, respectively. Seed cotton yields were similar to weed-free cotton with all treatments except MSMA applied EPD and the LPD treatments, all of which provided unacceptable (12 to 49%) control 8 WAP.
Occurrence and Control of Triazine-Resistant Common Waterhemp (Amaranthus rudis) in Field Corn (Zea mays)
Authors: Anderson Daniel D. , Roeth Fred W. , Martin Alex R.
Published: March 2018

Triazine-resistant (TR) common waterhemp was reported and confirmed in Fillmore County, NE in 1990. A survey of 81 fields was conducted to characterize the occurrence of common waterhemp and grower practices. Sampled fields fell into three categories: suspected by growers to contain resistant plants (26 fields), randomly selected (28 fields), and adjacent to fields containing TR common waterhemp (27 fields). Resistant plants were found in 64% of all fields. Resistance was confirmed in 92% of the fields suspected by growers to contain resistant plants. Adjacent fields were no more likely to contain resistant plants than randomly chosen fields. Crop rotation did not significantly affect occurrence of resistance. Resistance was associated with the grower, indicating movement of resistant seed between fields via equipment. Atrazine, bromoxynil plus atrazine, and bentazon plus atrazine provided less than 75% postemergence control of TR common waterhemp, while primisulfuron, dicamba plus atrazine, primisulfuron plus dicamba, dicamba, 2,4-D ester, and metribuzin plus bentazon gave over 85% control.
Influence of Adjuvants on Efficacy of Clethodim
Authors: Jordan David L. , Vidrine P. Roy , Griffin James L. , Reynolds Daniel B.
Published: March 2018

Field experiments evaluated barnyardgrass, broadleaf signalgrass, and rhizomatous johnsongrass control with clethodim applied with Agri-Dex® crop oil concentrate at 1.0% v/v, the adjuvant Dash® at 1.0% v/v, the methylated seed oil Sun-It II® at 1.0% v/v, a blend of silicone surfactant plus methylated seed oil (Dyne-Amic® at 0.5% v/v) or nonionic surfactant (Kinetic® HV at 0.125% v/v), two silicone surfactants (Sylgard® 309 and Silwet L-77® surfactant) at 0.125% v/v, two other conventional nonionic surfactants (Latron AG-98™ and Induce®) at 0.25% v/v, and the acidified soya phospholipid LI-700®. When compared with the conventional nonionic or silicone-based surfactants and LI-700, clethodim at 70 g ai/ha controlled barnyardgrass more effectively when applied with Dash or Sun-It II. Broadleaf signalgrass and rhizomatous johnsongrass were controlled more effectively when clethodim was applied with Agri-Dex, Dash, Sun-It II, or Dyne-Amic. Clethodim at 70 g/ha applied with Dash or Sun-It II controlled grasses equally or greater than clethodim at 140 g/ha.
Influence of Surfactants and Ammonium Sulfate on Glyphosate Phytotoxicity to Quackgrass (Elytrigia repens)
Authors: De Ruiter Hans , Uffing Andre J. M. , Meinen Esther
Published: March 2018

Field and greenhouse experiments were conducted to investigate the influence of two cationic alkylamine surfactants, three nonionic surfactants, and ammonium sulfate on the performance of glyphosate (isopropylamine salt) against quackgrass. In the field experiments, the reinfestation of quackgrass in the year after treatment was zero or negligible in all plots that received the recommended rate of glyphosate (1.44 kg ae/ha). At one-fourth of the recommended rate (0.36 kg ae/ha) the glyphosate-adjuvant combinations also severely inhibited the reinfestation of quackgrass. At the low herbicide rate and without ammonium sulfate, lipophilic surfactants were less effective than more hydrophilic surfactants. In the greenhouse experiments, the glyphosate doses giving 50% response (ED50) were determined. Ranking of the surfactants according to the ED50for glyphosate demonstrated a similar result to that observed in the field experiment. Ammonium sulfate added to the glyphosate-surfactant combinations reduced the ED50for glyphosate 5-fold. The field and greenhouse experiments demonstrated that two hydrophilic nonionic surfactants enhance glyphosate efficacy against quackgrass to the same extent as the hydrophilic cationic tallowamine surfactant. These two nonionic surfactants have a relatively low toxicity to non-target organisms and may substitute the more toxic alkylamine surfactants.
Evaluation of a Rapid Method to Detect Terbufos Residue Levels in Corn (Zea mays) Seedlings
Authors: Castro-Escobar Antonio , Kells James J. , Penner Donald
Published: March 2018

Postemergence applications of nicosulfuron and primisulfuron may injure corn plants depending on the level of terbufos present in the young corn plants from application of terbufos for corn rootworm control. Field studies were conducted in 1992 and 1993 to evaluate the interaction of nicosulfuron and primisulfuron with terbufos and to relate terbufos levels, detected with a rapid detection kit, to injury. Terbufos was applied in-furrow at 0, 186, 375, and 750 g ai/100 m of row. Nicosulfuron was applied at 35 and 70 g ai/ha and primisulfuron at 40 and 80 g ai/ha when the corn was at the four-leaf stage. Prior to herbicide application, both fresh and frozen plant samples from each treatment were subjected to terbufos analysis. The correlation coefficient for terbufos detected in the shoot extract with observed herbicide injury to corn was r = 0.89 in 1992 and r = 0.94 in 1993. Injury ratings showed a greater correlation with terbufos levels than did corn shoot height. Thus, the rapid detection kit provided an efficient method to determine whether an injurious terbufos-herbicide interaction might occur.
Control of Annual Weeds with Glyphosate
Authors: Krausz Ronald F. , Kapusta George , Matthews Joseph L.
Published: March 2018

Field experiments were conducted from 1993 to 1995 to evaluate control of annual weeds with glyphosate applied at rates of 560 to 2800 g ai/ha in spray volumes of 93 and 187 L/ha. Glyphosate controlled 100% of giant foxtail, fall panicum, redroot pigweed, and velvetleaf (in 1993) regardless of rate, spray volume, or application timing. Ivyleaf morningglory, velvetleaf, and common lambsquarters control was greater with glyphosate applied early POST than late POST. Ivyleaf morningglory, velvetleaf, and common lambsquarters control increased as glyphosate rate increased with both spray volumes. Velvetleaf control with glyphosate applied late POST was greater with glyphosate in 187 L/ha water compared with 93 L/ha water.
Discovery Sessions: An Educational Approach to Explore Weed Management Alternatives
Authors: William Ray D. , Lev Larry S.
Published: March 2018

In the 1990s, citizens regard green lawns and golf courses with attitudes ranging from pleasure for their beauty to dismay caused by concerns for environmental consequences. Citizens concerned with environmental consequences describe fertilizers or pesticides that may be harmful to groundwater or other organisms while others worry about the harm caused by more bee stings or economic and aesthetic losses caused by unsightly weeds. Both sides of an issue can be supported by facts. The listener may have difficulty forming an opinion since many issues do not have a clearly right or wrong approach. How should educators deal with this sort of dilemma? Are learning methods available to explore people's values, data, assumptions, and practices?
Pesticide Residues in Foods: Recent Events and Emerging Issues
Authors: Winter Carl K.
Published: March 2018

Food safety concerns involving pesticide residues continue to receive widespread public, legislative, and scientific attention. The National Research Council's 1993 report Pesticides in the Diets of Infants and Children concluded that significant improvements in the U.S. government's pesticide risk assessment and food tolerance establishment procedures were needed. Strict interpretation of the Delaney Clause by the U.S. Ninth Circuit Court of Appeals has led to the projected elimination of several pesticide uses due to statutory, rather than scientific considerations. Congressional “solutions” to the Delaney problem may have broad impacts upon future pest management practices if adopted. Emerging issues include the safety of imported produce and the potential effects of trade agreements such as NAFTA and GATT upon U.S. pesticide residue standards.
Acetolactate Synthase Resistance in a Common Waterhemp (Amaranthus rudis) Population
Authors: Hinz John R. R. , Owen Micheal D. K.
Published: March 2018

Research was initiated to determine (a) whether a common waterhemp population was resistant to acetolactate synthase (ALS) inhibiting herbicides, (b) the percentage of the population that was ALS-inhibitor resistant, (c) the resistance mechanism, and (d) the effectiveness of a whole plant assay to detect ALS-inhibitor resistance. ALS-inhibitor resistance was confirmed in a common waterhemp population near Davis City, IA. The Davis City common waterhemp population was cross resistant to both imidazolinone and sulfonylurea herbicides, but not to lactofen. Approximately 10% of the Davis City common waterhemp population was sensitive to a rate of imazaquin 4 times the normal field rate. Davis City common waterhemp isolated ALS was much less sensitive to imazaquin and primisulfuron inhibition than was grain amaranth or an ALS-sensitive common waterhemp isolated ALS. Imazaquin I50values were 366.4 and 3.4 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. Primisulfuron I50values were 3.6 and 0.007 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. A whole plant ALS assay was developed that allowed for much more rapid detection of an ALS-resistant species and used less plant material than a conventional ALS assay.
Efficacy of Clomazone Applied at Various Timings in Soybean (Glycine max)
Authors: Langton Steven J. , Harvey R. Gordon , Albright John W.
Published: March 2018

Field studies conducted in 1991 to 1993 evaluated the efficacy of clomazone applied at various timings for weed control in soybean. Clomazone applied 45, 30, 15, or 0 days prior to planting (DPP) provided season-long control of velvetleaf and giant foxtail. In 1991 and 1992 clomazone alone 30 and 45 DPP failed to control redroot pigweed. Clomazone alone 45 DPP failed to control common lambsquarters. In 1991 and 1992 clomazone at 0.84 kg/ha plus metribuzin applied 45 DPP failed to control redroot pigweed. The addition of metribuzin plus chlorimuron to the above clomazone treatments resolved these weed control deficiencies. Weed control in 1993 was nearly complete across all clomazone treatments. In 1993 clomazone treatments which included metribuzin or metribuzin plus chlorimuron applied PPI or PRE reduced yield. Herbicide injury is the likely cause of this reduction because most treatments in 1993 provided 99% control of all weed species.
Control and Cross-Resistance of an Acetolactate Synthase Inhibitor-Resistant Palmer Amaranth (Amaranthus palmeri) Biotype
Authors: Gaeddert Jason W. , Peterson Dallas E. , Horak Michael J.
Published: March 2018

Over two years, acetolactate synthase (ALS)-inhibiting herbicides and herbicides with different mechanisms of action were tested individually and in combination for control of ALS-resistant Palmer amaranth in soybean. As expected, ALS-inhibiting herbicides did not control the resistant Palmer amaranth. Lactofen at 210 g/ha and acifluorfen at 560 g/ha gave the best postemergence control. Tank mixes of lactofen with either imazethapyr or chlorimuron plus thifensulfuron did not significantly increase control over lactofen alone. Sequential treatment with a soil-applied herbicide, either SAN 582 or pendimethalin, followed by lactofen postemergence, controlled weeds best (greater than 85%). The extent of cross-resistance of Palmer amaranth to ALS-inhibiting herbicides was determined in the greenhouse. Sixteen POST ALS-inhibiting herbicides were sprayed at ½, 1, 2, 4, and 8X field use rates on resistant and susceptible biotypes. All ALS-inhibiting herbicides at all rates controlled the susceptible biotype. The resistant biotype was cross-resistant to all ALS-inhibiting herbicides. Metsulfuron and imazapyr at 8X rates were the only treatments that provided 80% or greater control of the ALS-resistant Palmer amaranth. Chlorsulfuron and tribenuron were the only other herbicides that gave partial control at the highest rate. Control with these four herbicides decreased as the rate was decreased. Experimental results suggest that cultural practices and herbicides with different mechanisms of action will be required to manage this ALS-resistant Palmer amaranth biotype.
Management of Cogongrass (Imperata cylindrica) with Velvetbean (Mucuna pruriens var. utilis) and Herbicides
Authors: Udensi Udensi E. , Akobundu I. Okezie , Ayeni Albert O. , Chikoye David
Published: March 2018

Field experiments were conducted in 1992 to 1993 and in 1995 to 1996 in Ibadan, Nigeria, to assess the effect of velvetbean and herbicides on maize (corn) and cogongrass growth and to assess regrowth of the weed 1 yr after treatment. In 1992 and 1995 cover cropping with velvetbean and imazapyr and glyphosate application reduced cogongrass density as much as the handweeded control. The smothering effect of velvetbean was equivalent to that of glyphosate at 1.8 kg/ha but was less than imazapyr even at the lowest rate of 0.5 kg/ha. Addition of adjuvant did not improve the efficacy of either herbicide. Maize grain yield was higher in velvetbean plots than in fallow plots dominated by cogongrass. Velvetbean and herbicide effects on cogongrass 1 yr later (1993 and 1996) followed a similar trend as observed in the year of application. Annual weed density was highest in glyphosate plots, followed by imazapyr, and least in plots previously seeded to velvetbean. Maize grain yield was higher in herbicide plots (average yield of 3,170 and 1,920 kg/ha in 1993 and 1996, respectively) than in velvetbean plots (2,800 to 1,180 kg/ha in 1993 and 1996, respectively) and handweeded plots (2,890 and 723 kg/ha in 1993 and 1996, respectively). In 1996 the lowest maize yield was in handweeded plots without velvetbean, suggesting that weeding four times suppressed cogongrass density and biomass, but was not sufficient to minimize the subsequent competition from annual weeds. Uncontrolled cogongrass reduced maize yield to zero. These studies suggest that planting velvetbean for cogongrass control may be a better alternative for farmers without the resources to purchase herbicides.
Predicting Decreases in Canola (Brassica napus and B. rapa) Oil and Meal Quality Caused by Contamination by Brassicaceae Weed Seeds
Authors: Davis Jim B. , Brown Jack , Brennan Jeffrey S. , Thill Donn C.
Published: March 2018

Canola (edible rapeseed) crops are often infested by related weed species. This paper addresses effects that seeds from various Brassicaceae weeds may have on canola oil and meal quality. Seeds of common Brassicaceae weeds were collected from canola fields throughout northern Idaho. These were wild mustard, black mustard, birdsrape mustard, shepherd's-purse, flixweed, tumble mustard, and field pennycress. Collected seeds were physically described by weight, size, and shape and were analyzed for oil concentration, fatty acid composition, and glucosinolate concentration. Seed weights ranged from 0.1 to 2 g/1,000 seed. Oil concentration in the weed seeds ranged from 25 to 38%, with erucic acid levels ranging from less than 1 to 47%. Glucosinolate concentration in the mustard weed seeds was over 100 μmol/g oil-free meal, except for shepherd's-purse, which had only 3.4 μmol/g. Using these data, a simple model predicts that both canola oil and seed meal quality can be adversely affected by contamination with weed seeds. Increased erucic acid concentration in modeled admixtures was the most likely oil quality problem associated with weed seed contamination. Glucosinolate concentration in modeled admixtures was higher than acceptable only in those admixtures that also had erucic acid levels that exceeded canola quality standards. Canola-quality oil and seed meal can be maintained with conspicuous weed seed mixtures up to the 2% maximum allowed in U.S. No. 1 canola. However, canola-quality oil and seed meal was not achieved when a 5% weed seed mixture allowed in No. 2 canola was evaluated with the model.
Soybean (Glycine max) Response to Simulated Drift from Selected Sulfonylurea Herbicides, Dicamba, Glyphosate, and Glufosinate
Authors: Al-Khatib Kassim , Peterson Dallas
Published: March 2018

Field research was conducted to evaluate the response of soybean to various herbicides applied at rates to simulate drift damage. Dicamba, glyphosate, glufosinate, and the sulfonylurea herbicides CGA-152005, primisulfuron, nicosulfuron, rimsulfuron plus thifensulfuron, and CGA-152005 plus primisulfuron were applied to soybean at the two to three trifoliolate leaf stage in 1997 and 1998 atand ⅓ of the recommended use rates. The order of yield reduction after herbicide treatment was CGA-152005 > dicamba > CGA-152005 plus primisulfuron > rimsulfuron plus thifensulfuron > primisulfuron. Soybean yields were not reduced by glyphosate, glufosinate, and nicosulfuron. Applications of all herbicides at rates higher thanof the use rate caused injury symptoms within 30 d after treatment. However, soybean plants had partially or fully recovered by the end of the growing season. Therefore, early-season injury symptoms from herbicide drift are not reliable indicators for soybean yield reduction.
Herbicide Combinations for Weed Management in Glyphosate-Resistant Soybean (Glycine max)
Authors: Gonzini Lisa C. , Hart Stephen E. , Wax Loyd M.
Published: March 2018

Field experiments were conducted in 1995 and 1996 at DeKalb and Urbana, IL, to evaluate weed management systems in glyphosate-resistant soybean planted in rows 76 cm wide. These experiments compared weed control using preemergence (PRE) herbicides followed by glyphosate or postemergence (POST) tank-mix combinations of glyphosate and acetolactate-synthase-inhibiting herbicides with glyphosate applied alone at 0.63 kg ae/ha in single or sequential applications. Overall, the use of a tank-mix partner or a PRE herbicide followed by glyphosate improved weed control compared to a single application of glyphosate. However, weed control with these treatments was not better than with sequential applications of glyphosate. Control of giant foxtail exceeded 90% for single applications of glyphosate except at DeKalb in 1995 when late emergence of giant foxtail occurred after POST applications had been made. A PRE grass herbicide or a late postemergence (LPOST) application of glyphosate was necessary for season-long control of late-emerging giant foxtail. Tank-mixing glyphosate with imazethapyr, cloransulammethyl, and CGA-277476 or applying glyphosate LPOST following these herbicides improved giant foxtail control compared with these herbicides applied alone. A single application of glyphosate controlled common lambsquarters 88% or greater in two of three trials. At Urbana in 1995, a single application of glyphosate controlled common lambsquarters 78% compared to 88 to 96% control with PRE herbicides followed by glyphosate or sequential applications of glyphosate. Velvetleaf control with a single application of glyphosate ranged from 55 to 78%. A PRE application of chlorimuron + metribuzin, cloransulammethyl, or sulfentrazone followed by glyphosate POST, as well as sequential applications of glyphosate, consistently improved velvetleaf control compared to a single application of glyphosate. In some cases, adding glyphosate to a POST application of imazethapyr or CGA-277476 improved control of velvetleaf but decreased velvetleaf control when added to cloransulammethyl.
Fertilizer Placement Affects Jointed Goatgrass (Aegilops cylindrica) Competition In Winter Wheat (Triticum aestivum)
Authors: Mesbah Abdel O. , Miller Stephen D.
Published: March 2018

A 3-yr study was conducted in eastern Wyoming from 1995 to 1997 to evaluate the effect of fertilizer placement on jointed goatgrass competitiveness with winter wheat. Fertilizer placement methods consisted of applying 45 kg/ha of nitrogen (50% as urea and 50% as ammonium nitrate) in a deep band 5 cm below and 2.5 cm to the side of the wheat row, broadcasting on the soil surface, or injecting fertilizer by spoke wheel 10 cm deep and 5 cm to the side of the wheat row. Neither fertilizer placement nor jointed goatgrass presence affected winter wheat stand. Wheat yield reductions from jointed goatgrass competition were 7 and 10% higher with the broadcast than deep-band or spoke-wheel injection methods, respectively. Wheat spikes/plant, seeds/spike, 200-seed weight, and plant height were not influenced by fertilizer placement; however, the presence of 35 jointed goatgrass plants/m2reduced spikes/plant 21%, seeds/spike 12%, and 200-seed weight 6%. Jointed goatgrass populations were not influenced by fertilizer placement method; however, the number of spikes/plant was reduced 8 and 10%, joints/spike 3%, and biomass 15 and 21% by deep band or spoke wheel fertilizer placement.
Light Requirement in Rapid Diagnosis of Sulfonylurea-Resistant Weeds of Lindernia spp. (Scrophulariaceae)
Authors: Uchino Akira , Watanabe Hiroaki , Wang Guang-Xi , Itoh Kazuyuki
Published: March 2018

Sulfonylurea resistance has been found in Japan, and four of the nine resistant weeds are in the genus Lindernia (Scrophulariaceae). To develop appropriate control methods for these resistant weeds, a rapid method to diagnose sulfonylurea-resistant weeds was improved and applied to common falsepimpernel (L. procumbens), two varieties of low falsepimpernel (L. dubia var. dubia and var. major), and azetogarashi (L. micrantha). Illumination is crucial for diagnosis in Lindernia spp., and treatment with 7.5 or 75 ng ai/ml thifensulfuron-methyl produced clear results.
Evaluation of Glufosinate-Resistant Corn (Zea mays) and Glufosinate: Efficacy on Annual Weeds
Authors: Krausz Ronald F. , Kapusta George , Matthews Joseph L. , Baldwin John L. , Maschoff Jason
Published: March 2018

Field studies were conducted in 1996 and 1997 at Belleville and Pawnee, IL, to evaluate single and sequential applications of glufosinate on tolerance of glufosinate-resistant corn and annual weed control. Glufosinate caused 0 to 13% corn injury 7 days after treatment (DAT) and 0 to 6% corn injury 28 DAT. Injury was characterized as stunting with glufosinate. Glufosinate at 400 to 1,200 g ai/ha did not reduce final corn height or grain yield. At Pawnee in both years and at Belleville in 1996, a single application of glufosinate at 400 g/ha controlled giant foxtail, velvetleaf, ivyleaf morningglory, and common lambsquarters 85 to 100%. At Belleville in 1997, sequential applications of glufosinate provided greater weed control (87 to 100%) than a single application (0 to 63%) because of weed emergence after application. Weed control with a single application of glufosinate or with nicosulfuron plus bromoxynil was similar at both locations. Height and grain yield of glufosinate-resistant corn were not different from that of glufosinate-susceptible corn (isoline of glufosinate-resistant corn).
Imidazolinone Resistance in Smooth Pigweed (Amaranthus hybridus) Is Due to an Altered Acetolactate Synthase
Authors: Manley Brian S. , Singh Bijay K. , Shaner Dale L. , Wilson Henry P.
Published: March 2018

Seeds were collected from an imidazolinone-resistant (R) population of smooth pigweed near Marion, MD, and from an imidazolinone-susceptible (S) population near Painter, VA, and grown in the greenhouse. Acetolactate synthase (ALS) enzyme was extracted from both biotypes and assayed in the presence of CGA 152005, chlorimuron, halosulfuron, imazaquin, imazethapyr, nicosulfuron, primisulfuron, pyrithiobac, rimsulfuron, and thifensulfuron to determine if an altered ALS was the mechanism of resistance in the R biotype and to determine if this biotype was cross-resistant to other ALS inhibitor herbicides. The inhibitor concentration required to cause a 50% reduction in ALS activity (I50) was calculated for each herbicide. ALS from the R biotype was approximately 71-, 109,000-, and 9-fold more resistant to imazaquin, imazethapyr, and rimsulfuron, respectively, than that from the S biotype. ALS from the R biotype was approximately threefold more sensitive to pyrithiobac and thifensulfuron than that from the S biotype. R ALS was also slightly more tolerant to CGA 152005 and nicosulfuron and slightly more sensitive to primisulfuron and chlorimuron. ALS from both biotypes generally responded similarly to halosulfuron. Resistance in the R biotype was due to an altered form of ALS that is insensitive to the imidazolinone herbicides and rimsulfuron.
Use of Quinclorac Plus 2,4-D for Controlling Field Bindweed (Convolvulus arvensis) in Fallow
Authors: Enloe Stephen F. , Westra Philip , Nissen Scott J. , Miller Stephen D. , Stahlman Phillip W.
Published: March 2018

Field studies were conducted in Colorado, Kansas, and Wyoming to compare the use of quinclorac plus 2,4-D with picloram plus 2,4-D, dicamba plus 2,4-D, a glyphosate plus 2,4-D premix, and 2,4-D alone for control of field bindweed (Convolvulus arvensis) in a winter wheat (Triticum aestivum)-fallow rotation. Treatments were applied in late summer or fall each year for two, three, or four consecutive years at the beginning and end of each fallow period. Evaluations were taken 10 to 12 mo after treatment each year. Quinclorac plus 2,4-D and picloram plus 2,4-D consistently performed as well as or better than 2,4-D, dicamba plus 2,4-D, and glyphosate plus 2,4-D. Wheat yields increased when field bindweed was controlled during the fallow period. Strong correlations (r> −0.85) were obtained among visual field bindweed evaluation, biomass, and stand count data.
Weed Control in Soybean (Glycine max) with Flumetsulam, Cloransulam, and Diclosulam
Authors: Shaw David R. , Bennett Andrew C. , Grant Donald L.
Published: March 2018

Cloransulam postemergence (POST), diclosulam preemergence (PRE), and flumetsulam preplant incorporated (PPI) and POST were evaluated in six trials at two locations for control of sicklepod and pitted morningglory in soybean. Sicklepod control with cloransulam plus flumetsulam POST was equivalent to chlorimuron POST in seven of eight comparisons both 3 and 6 wk after treatment. Sicklepod control with cloransulam POST was equivalent to chlorimuron in only three of eight comparisons 3 wk after treatment, but late-season control was equivalent in five of six comparisons. Pitted morningglory control with cloransulam alone or in tank-mixture with flumetsulam POST was equivalent to chlorimuron in all comparisons. Control of sicklepod and pitted morningglory was greater in most comparisons when a POST application followed flumetsulam plus trifluralin PPI compared to only trifluralin PPI. In a total PRE stale seedbed system, where all treatments were tank-mixed with pendimethalin plus glyphosate, sicklepod control with all rates of flumetsulam and 26 or 35 g ai/ha diclosulam was equivalent to the standard treatment of imazaquin or metribuzin plus chlorimuron. None of the total PRE programs controlled sicklepod as well as when glyphosate was applied sequentially POST. Pitted morningglory was controlled 83 to 93% with 26 or 35 g/ha diclosulam, equivalent to imazaquin, metribuzin plus chlorimuron, or sequential glyphosate applications 8 wk after the PRE application. Increasing flumetsulam rate increased pitted morningglory control early season, but flumetsulam was not as effective as the other herbicides.
Important Considerations for RPA 201772 Utility
Authors: Sprague Christy L. , Penner Donald , Kells James J.
Published: March 2018

Greenhouse and laboratory studies were conducted to examine certain characteristics of RPA 201772 and how they may affect its utility.14C-RPA 201772 was used to determine the stability of RPA 201772 in various pH spray solutions over time. After 24 h, degradation of RPA 201772 was 20, 36, and 93% in spray solutions adjusted to pH 4.0, 7.0, and 10.0, respectively. The major metabolite was diketonitrile (DKN), which is herbicidally active. In addition, 9 and 15% of the RPA 201772 had degraded into an inactive benzoic acid derivative at pH 7.0 and 10.0, respectively. The differences in herbicidal activity of RPA 201772 and its metabolite DKN were also evaluated. Corn seeds and velvetleaf seeds readily imbibed RPA 201772, but only low levels of DKN were imbibed. Preemergence (applications of RPA 201772 and DKN were equally active on corn and velvetleaf. Further studies determined that the principal sites of uptake of RPA 201772 by corn was roots and seeds for four different corn hybrids. Another study determined that light was required for RPA 201772 activity. Corn shoots from seeds germinated under 14 h of light exhibited rate-dependent injury, while corn germinated and grown in the darkness was not injured.
Time of Application of Cloransulam for Giant Ragweed (Ambrosia trifida) Control in Soybean (Glycine max)
Authors: Franey Rebecca J. , Hart Stephen E.
Published: March 2018

Field experiments were conducted at Dekalb, IL, in 1996 and 1997 to determine the optimum application timing and rate of cloransulam for giant ragweed (Ambrosia trifida) control in soybean (Glycine max). Cloransulam treatments included preplant incorporated (PPI) and preemergence (PRE) applications of 35 g ai/ha and early postemergence (EPOST), postemergence (POST), and late postemergence (LPOST) applications of 18 or 27 g ai/ha. Cloransulam applied at 18 g/ha was also combined with lactofen at 70 g ai/ha at each POST application timing. At 60 d after LPOST, cloransulam applied PPI provided 68% giant ragweed control in 1996 and 1997 compared to PRE applications, which provided 95 and 25% giant ragweed control, respectively. The reduction in giant ragweed control with PRE applications of cloransulam in 1997 was likely due to insufficient rainfall for activation. Cloransulam applied at 18 g/ha EPOST provided 87 and 88% giant ragweed control, respectively, in 1996 and 1997. Cloransulam applied POST provided 97 and 82% giant ragweed control, respectively, in successive years. Delaying cloransulam application until LPOST reduced giant ragweed control to 53 and 47%, respectively, in 1996 and 1997 compared to EPOST and POST. At EPOST and POST application timings, increasing the rate of cloransulam to 27 g/ha or adding lactofen did not improve giant ragweed control. However, giant ragweed control was improved by at least 20% by increasing the rate of cloransulam to 27 g/ha at LPOST. Similarly, applying cloransulam in combination with lactofen improved giant ragweed control by at least 15% at LPOST.
Glyphosate Tank Mixtures with SAN 582 for Burndown or Postemergence Applications in Glyphosate-Tolerant Soybean (Glycine max)
Authors: Scott Robert , Shaw David R. , Barrentine William L.
Published: March 2018

Field experiments were conducted to evaluate postemergence (POST)-applied tank mixtures of 560, 1,120, and 1,680 g ai/ha glyphosate with or without 1,120 g ai/ha SAN 582 (proposed name, dimethenamid) as burndown treatments or POST in glyphosate-tolerant soybean. SAN 582 was not antagonistic with glyphosate at the glyphosate rates evaluated. In the burndown study, glyphosate controlled horseweed 98% or more and curly dock 82% or more with or without SAN 582. However, broadleaf signalgrass emerged after the burndown treatments were applied. All tank mixtures that included SAN 582 controlled broadleaf signalgrass 84 to 96%, 6 wk after treatment. In the glyphosate-tolerant soybean study, glyphosate controlled barnyardgrass and johnsongrass present at the time of application 89% or more, regardless of rate. Tank mixtures of SAN 582 with glyphosate controlled late-season flushes of barnyardgrass through residual activity of the SAN 582. Applying SAN 582 with glyphosate improved soybean yield 500 kg/ha over glyphosate applied alone.
Effect of Soil-Applied Atrazine and Pendimethalin on Velvetleaf (Abutilon theophrasti) Competitiveness in Corn
Authors: Schmenk Richard , Kells James J.
Published: March 2018

Field studies were conducted in 1992 and 1993 to determine the effect of atrazine and pendimethalin on velvetleaf competitiveness in corn. The three factors included in this research were herbicide, velvetleaf density (zero or nine plants per meter of row), and treatment (treated with herbicide or untreated). Herbicide treatments consisted of atrazine (0.6 and 1.1 kg/ha) or pendimethalin (0.6 and 1.1 kg/ha) applied preemergence. In 1992 and 1993, both atrazine and pendimethalin applied at 1.1 kg/ha greatly reduced velvetleaf growth and seed production and prevented velvetleaf from reducing corn yield. Both atrazine and pendimethalin applied at 0.6 kg/ha reduced velvetleaf growth and seed production in 1993, but only atrazine prevented yield loss in 1992. In the absence of velvetleaf, corn yield was not affected by either herbicide. These results indicate that sublethal exposure to atrazine or pendimethalin can significantly reduce velvetleaf competitiveness in corn.
Quantification of Viral Disease Incidence in Corn (Zea mays) as Affected by Johnsongrass (Sorghum halepense) Control
Authors: Eberwine John W. , Hagood Edward S. , Tolin Sue A.
Published: March 2018

Field and laboratory experiments were conducted to evaluate the effect of postemergence johnsongrass control on incidence of maize chlorotic dwarf virus (MCDV) and maize dwarf mosaic virus (MDMV) in corn and to confirm the presence and movement of the blackfaced leafhopper, the insect vector of MCDV. Corn plants surrounded by MCDV- and MDMV-infected rhizomatous johnsongrass were either treated or not treated with nicosulfuron at 35 g ai/ha. Corn tissue samples were taken at the time of treatment and 4, 9, 14, and 21 d after treatment and the presence of MCDV and MDMV was determined by enzyme-linked immunosorbent assay (ELISA). Virus incidence in treated experimental units was higher at the later sampling dates relative to the nontreated. Earlier differences in incidence of MCDV and MDMV double infection in corn were detected where johnsongrass was controlled. Movement of the insect vector of MCDV was observed within the experimental area after johnsongrass was controlled, but was not significantly different from that in nontreated areas.
Control of Perennated Bermudagrass (Cynodon dactylon) and Johnsongrass (Sorghum halepense) in Sugarcane (Saccharumspp. hybrids)
Authors: Richard Edward P.
Published: March 2018

In two separate field experiments conducted over time, at-planting preemergence (PRE) applications of sulfometuron at 110 to 150 g ai/ha followed by March applications of sulfometuron at 30 g/ha or metribuzin at 2,580 g ai/ha at the start of the initial (plant cane) growing season controlled more bermudagrass and johnsongrass emerging in sugarcane from rhizome and stolon pieces than standard at-planting followed by March applications of atrazine at 2,240 g ai/ha (no control), metribuzin at 2,580 g ai/ha, or pendimethalin at 2,240 g ai/ha. Treatments containing at-planting applications of imazapyr at 280 g ai/ha or thiazopyr at 560 g ai/ha did not provide levels of control similar to sulfometuron. Crop injury in excess of 10% occurred only when imazapyr at 280 g/ha (18 to 42%) or sulfometuron at 30 g/ha (11 to 32%) was applied in March to emerging sugarcane. Sugarcane stalk numbers, stalk heights, and ultimately cane and sugar yields were increased when compared to the standards with all sulfometuron treatments and when thiazopyr was applied at planting and again in March.
Annual Grass Control by Glyphosate plus Bentazon, Chlorimuron, Fomesafen, or Imazethapyr Mixtures
Authors: Gimenez Agustin E. , York Alan C. , Wilcut John W. , Batts Roger B.
Published: March 2018

The isopropylamine salt of glyphosate at 420, 560, and 840 g ae/ha applied alone or mixed with the sodium salt of bentazon at 840 g ai/ha, chlorimuron at 9 g ai/ha, the sodium salt of fomesafen at 350 g ai/ha, or the ammonium salt of imazethapyr at 70 g ae/ha was evaluated for control of large crabgrass and broadleaf signalgrass. Neither grass was controlled by bentazon, fomesafen, or chlorimuron. Imazethapyr controlled large crabgrass and broadleaf signalgrass 30 and 72%, respectively, 3 weeks after treatment (WAT). Glyphosate at all rates controlled both grasses 100%. Control 3 WAT was unaffected by mixing bentazon, chlorimuron, fomesafen, or imazethapyr with glyphosate. Broadleaf signalgrass control 1 WAT was reduced 4 to 15% by mixing bentazon with glyphosate.
Soybean (Glycine max) Response to Thifensulfuron and Bentazon Combinations
Authors: Hart Stephen E. , Roskamp Gordon K.
Published: March 2018

Field studies were conducted in 1995 and 1996 at three locations in Illinois to determine soybean response to combinations of thifensulfuron and bentazon. Thifensulfuron was applied at 2.2 to 8.8 g ai/ha alone or in combination with 280 to 560 g/ha of bentazon. Soybean injury 30 d after treatment ranged from 0 to 22% when thifensulfuron was applied alone at 2.2 g/ha. Increasing thifensulfuron rate to 8.8 g/ha increased soybean injury to a range of 12 to 44%. Soybean grain yield was significantly reduced compared to the yield of untreated soybean when thifensulfuron was applied at 4.4 and 8.8 g/ha in two of five and four of five experiments, respectively. The addition of bentazon to thifensulfuron consistently reduced soybean injury and stunting. In many cases, increasing the bentazon rate to 420 g/ha decreased soybean injury from thifensulfuron to a greater extent than 280 g/ha. In cases where thifensulfuron decreased soybean yield, the addition of 420 or 560 g/ha of bentazon restored yields to levels that were not lower than untreated soybeans. These studies demonstrate that thifensulfuron at 2.2 to 8.8 g/ha in combination with bentazon at 420 g/ha may be safely applied to soybean for broadleaf weed control.
Pluchea lanceolata: A Noxious Perennial Weed
Authors: Inderjit  , Foy Chester L. , Dakshini K.M.M.
Published: March 2018

Pluchea lanceolata(DC.) C. B. Clarke # PLULA is an aggressive, pernicious, rhizomatous evergreen weed in the Asteraceae. In other literature,P. lanceolataOliv. & Hiern has also been mentioned (Anonymous 1992, pp. 731 and 1147). With heavy root branches and dense subterranean parts,P. lanceolatais a common weed of sandy and saline tracts of the dry plains of the northwestern parts of India (Dakshini and Sabina 1981; Inderjit 1993; Rice 1995). It also occurs in North Africa, Afghanistan, and Pakistan (Nasir and Ali 1972; Oliver 1885). In India, it occurs both in cultivated and uncultivated areas. It causes considerable damage to winter and summer season crops. The control measures through conventional methods such as deep plowing, burning of aboveground parts, and herbicides are found to be unsuccessful. This rapidly spreading perennial weed apparently cannot be used for forage because of its disagreeable bitter taste (Anonymous 1976). Allelopathy has been reported as a probable cause ofP. lanceolatainterference (Inderjit and Dakshini 1990, 1992b, 1994a, 1994b, 1996a, 1996b; Inderjit et al. 1996).
The Effect of Phenological Stage on Detectability of Yellow Hawkweed (Hieracium pratense) and Oxeye Daisy (Chrysanthemum leucanthemum) with Remote Multispectral Digital Imagery
Authors: Lass Lawrence W. , Callihan Robert H.
Published: March 2018

Many upland pastures and forest meadows in the western United States contain significant infestations of yellow hawkweed and oxeye daisy. Documentation of infestations is necessary in order to plan and assess control tactics. Previous work with an airborne charge coupled device (CCD) with spectral filters indicated that flowering yellow hawkweed with at least 30% cover was detectable at 1 m resolution. A single image of a large area may not capture all plants in the flowering phase and multiple images are costly. The objective of this paper was to assess the accuracy of images recorded at different phenological stages. We compared three methods of classification: unsupervised classification of a three principal component analysis image, supervised classification of a three principal component analysis image, and supervised classification of a composited image consisting of four bands and normalized difference near infrared (NIR)/red band. Regardless of the classification method, images of yellow hawkweed and oxeye daisy in full bloom had lower classification error than at early bloom or post bloom. The percent error for yellow hawkweed classification was about twice as high at post bloom as at full bloom, but varied slightly depending on the method of classification and cover class. The ability to detect discrete colonies of yellow hawkweed was not affected by phenological stage, but the ability to measure the area of each cluster differed among stages. Less than one-third fo the pixels classified as yellow hawkweed or oxeye daisy in the early bloom image remained in the same class in the full bloom image. About half the pixels in the full bloom image remained in the 90 to 100% cover class at the post bloom image. Seasonal growth of the grasses masked some yellow hawkweed and oxeye daisy plants, and accounted for differences in classification among phenological stages.
Efficacy and Economics of Cultivation for Weed Control in Potato (Solanum tuberosum)
Authors: Eberlein Charlotte V. , Patterson Paul E. , Guttieri Mary J. , Stark Jeffrey C.
Published: March 2018

A 3-year study was conducted in irrigated potato to compare weed control efficacy and economics of hilling plus one or two cultivations with the standard treatment of hilling plus a preemergence application of pendimethalin plus metribuzin. Trials were conducted under both weedy and weed-free conditions. Common lambsquarters and redroot pigweed were present in weedy treatments each year; significant populations of hairy nightshade and green foxtail also were present one year. When weed populations were low or moderate (< 45 plants/m2), total weed biomass in the hilling plus one cultivation treatment was reduced 98 to 99% relative to the weedy control, and U.S. No. 1 tuber yields were equal to the standard treatment. However, when weed populations were high (145 plants/m2), hilling plus one cultivation and hilling plus two cultivations provided only 30% and 61% reduction in weed biomass, respectively, and U.S. No. 1 tuber yields were 35% and 13% less, respectively, than the standard treatment. The standard treatment provided 99% reduction in total weed biomass each year, and yields were equal to the weed-free, hill plus no cultivation control. Net return was $37 to $100/ha higher for the hilling plus one cultivation treatment compared to the standard treatment when weed populations were moderate or low, but was $808/ha less than the standard treatment when weed populations were high.
Weed Management in No-Tillage Bromoxynil-Tolerant Cotton (Gossypium hirsutum)
Authors: Culpepper A. Stanley , York Alan C.
Published: March 2018

An experiment was conducted at four locations in North Carolina during 1994 and 1995 to evaluate weed control, cotton yield, fiber quality, and net returns in no-tillage bromoxynil-tolerant cotton. The experiment focused on using bromoxynil or pyrithiobac sodium applied early POST over-the-top as alternatives to fluometuron plus MSMA applied early POST directed. Fluometuron plus MSMA was more effective than bromoxynil or pyrithiobac sodium on tall morningglory, large crabgrass, goosegrass, and broadleaf signalgrass. Bromoxynil and fluometuron plus MSMA were similarly effective on common lambsquarters, common ragweed, and eclipta and more effective than pyrithiobac sodium. Pyrithiobac sodium and fluometuron plus MSMA were similarly effective on smooth pigweed and Palmer amaranth and more effective than bromoxynil. Prickly sida control by bromoxynil and pyrithiobac sodium was equal to or greater than control by fluometuron plus MSMA. All early POST herbicides controlled pitted morningglory similarly. Regardless of the early POST herbicides used, fluometuron applied PRE and cyanazine plus MSMA applied late POST directed increased control of most weeds and increased cotton yield and net returns. Bromoxynil and pyrithiobac sodium effectively substituted for fluometuron plus MSMA only in systems that included fluometuron applied PRE and cyanazine plus MSMA applied late POST directed. Effects of herbicide systems on cotton fiber quality were minor.
Imazethapyr, Alone or with Other Herbicides for Weed Control During Alfalfa (Medicago sativa) Establishment
Authors: Darwent A. Lloyd , Cole Dan , Malik Najib
Published: March 2018

During the establishment of alfalfa, POST applications of imazethapyr at 50 g/ha, following PPI applications of trifluralin at 1,100 g/ha, consistently provided ≥ 80% control of wild oat, volunteer canola, and shepherd's-purse with no crop injury. POST applications of the same rate of imazethapyr without PPI applications of trifluralin provided similar volunteer canola and shepherd's-purse control, but ≥ 80% wild oat control was achieved only 25% of the time. Imazethapyr, alone or following trifluralin, did not control common groundsel. Broadleaf weed control from imazethapyr at 50 g/ha tank mixed with fluazifop-P at 125 g/ha or sethoxydim at 200 g/ha was not reduced compared to imazethapyr alone. However, the probability of controlling wild oat by ≥ 90% was reduced from 83% to 0 when the same rate of imazethapyr was tank mixed with fluazifop-P, compared to fluazifop-P alone. Tank mixtures of imazethapyr at 50 g/ha and sethoxydim controlled wild oat only slightly less than sethoxydim alone. First cut and total herbage yields, obtained 1 yr after alfalfa establishment, increased where treatments effectively controlled broadleaf weeds and wild oat, compared to check plots. Second cut herbage and seed yields, also obtained 1 yr after alfalfa establishment, were not affected by any of the treatments.
Effects of Herbicides on Grass Seed Production and Downy Brome (Bromus tectorum)
Authors: Whitson Tom D. , Majerus Mark E. , Hall Reginald D. , Jenkins Jay D.
Published: March 2018

Control of downy brome in cool-season perennial grasses grown for seed production must be done prior to seed harvest, because downy brome seeds cannot be separated from cool-season grass seeds. Field experiments were conducted near Powell, WY, and Bridger, MT, to evaluate several herbicides for control of downy brome from 1992 through 1994 in western wheatgrass, slender wheatgrass, beardless wild rye, thickspike wheatgrass, and meadow bromegrass. When fall-applied, only metribuzin at 0.4 kg/ha and oxyfluorfen plus metribuzin at 1.1 plus 0.3 kg/ha controlled 98 and 95% of the downy brome, respectively, without affecting grass seed viability or seed yield. Early spring applications of paraquat at 0.8 kg/ha controlled 100% of the downy brome, but suppressed perennial grasses. Glyphosate applied in early spring at 0.3 kg/ha controlled 48% of the downy brome, but suppressed perennial grasses. Seed yield reductions occurred when thickspike wheatgrass and meadow brome were treated with glyphosate at 0.3 kg/ha.