Abstract: The response of littleseed canarygrass biotypes to isoproturon, pendimethalin, and diclofop-methyl was evaluated in India, in pot studies and the field during the winters of 1991 to 1992 and 1992 to 1993. Some biotypes of littleseed canarygrass were resistant to isoproturon but cross-resistance to pendimethalin and diclofop-methyl was not confirmed. The resistant biotype required a higher dose of diclofop-methyl than the susceptible biotype. Variations in the response of littleseed canarygrass biotypes were not due to isoproturon formulation. Resistant biotypes required 2 to 8 times more isoproturon than a susceptible biotype for the same level of control. Diclofop-methyl at 1.0 kg ai/ha applied at the 2- to 3-leaf stage of littleseed canarygrass in pot experiments and PRE pendimethalin at 1.5 kg ai/ha in field trials controlled resistant biotypes. Field surveys of the affected areas revealed that resistance in littleseed canarygrass is more prevalent in rice-wheat rotations compared to other crop sequences. Control of littleseed canarygrass with isoproturon dropped from 78 to 21% from 1990 to 1993.

Abstract: Field experiments were conducted from 1989 to 1992 to determine whether no-tillage corn grown in 38-cm rows and a 2× population could improve weed control relative to 76-cm rows and 1× population under reduced-herbicide options. A standard treatment including 1.12 kg ai/ha of atrazine plus 2.24 kg ai/ha of metolachlor was compared with a treatment including the same herbicides applied at 25% of the standard rates. Both treatments included 0.56 kg ai/ha of paraquat which controlled annual weeds established at the time of application. Weed control was less in the 25%-herbicide treatment than in the standard treatment in two of four years when corn was grown in 76-cm rows with a l× population. The 25%-herbicide treatment provided weed control and grain yields similar to the standard treatment in each year when corn was grown in 38-cm rows with a 2× population. Weed control was poor and yield was reduced when no herbicides were applied regardless of row spacing or population. The leaf canopy of corn in the 38-cm row/2×-population treatment reduced light transmittance 1 wk earlier than corn in the 76-cm row/1×-population treatment.

Abstract: Fall-planted rapeseed and sudangrass were evaluated for weed control in potato during a two-year study. Rapeseed incorporated in the spring in a loamy sand soil reduced weed density 85 and 73% in 1992 and 1993, respectively, and reduced weed biomass 96 and 50% in 1992 and 1993, respectively, in following potato crops compared to potato after fallow. Potato following rapeseed yielded 25% and 17% more total tuber weight than potato following sudangrass in 1992 and fallow in 1993, respectively. In greenhouse trials, rapeseed tissue added to a loamy sand soil at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and longspine sandbur by 90 and 83%, respectively. Similarly, white mustard tissue added at 20 g fresh weight per 400 g dry soil reduced biomass of hairy nightshade and green foxtail by 83 and 70%, respectively.

Abstract: Seeds of suspected herbicide-resistant Palmer amaranth and common waterhemp were collected in Clay County and Douglas County, KS, respectively. An experiment was established in a greenhouse to determine if these species had developed resistance to imazethapyr and thifensulfuron. Imazethapyr was applied pre- (PRE) and postemergence (POST) at 1×, 2×, 4×, and 8× the suggested use rate (70 g/ha), and thifensulfuron was applied POST at 1×, 2×, 4×, and 8× the suggested use rate (4.5 g/ha). Both species had developed resistance to all rates of these herbicides. The occurrence of resistance at the Clay County site (Palmer amaranth) fit the typical pattern for the development of herbicide resistance, i.e., multiple applications of the same class of herbicide for several years. However, the Douglas County (common waterhemp) site had a limited history of use of ALS-inhibiting herbicides and did not follow typical models of resistance development.

Abstract: Bioherbicides are biological control agents applied in similar ways to chemical herbicides to control weeds. The active ingredient in a bioherbicide is a living microorganism and it is applied in inundative doses of propagules. Most commonly the microorganism used is a fungus and its propagules are spores or fragments of mycelium; in this case the bioherbicide is also referred to as a mycoherbicide. Commercial bioherbicides first appeared on the market in the USA in the early 1980s with the release of the product DeVine® in 1981 and in the next year, the release of the product Collego®. In spite of considerable public research effort and many promising candidate organisms, only one other bioherbicide product, BioMal®, has been registered (in Canada) since then. Furthermore none of these products are currently commercially available for a variety of reasons that will be discussed below.

Abstract: A synthetic data set was created by incorporating results from previously published papers on antagonistic and synergistic herbicide interactions between two herbicides applied as a tank mixture or sequentially, and then analyzed on the basis of various properties of the herbicides and target plants. Generally, interactions between herbicides were antagonistic more frequently than synergistic. This trend held no matter whether the interacting herbicides were absorbed by the same or different parts of the plant, had the same or different translocating abilities, had the same or different modes of action, and regardless of whether the target plants were annual or perennial plants, or crops or weeds. Antagonistic interactions occurred much more frequently when the target plants were monocot than dicot, and in the Compositae, Gramineae, or Leguminosae than in the Chenopodiaceae or Convolvulaceae families.

Abstract: Propanil-resistant barnyardgrass was reported in Poinsett County, AR, in 1990. Greenhouse studies were initiated to determine the distribution of propanil-resistant barnyardgrass in the state and to characterize the resistance. Barnyardgrass seeds were obtained in 1991 and 1992 from fields in 19 of the 38 rice producing counties in Arkansas where propanil treatment at recommended rates gave unsatisfactory barnyardgrass control. Barnyardgrass seedlings from the various sources were treated with propanil at 4.5 kg ai/ha and seedling injury response was compared to the response of seedlings collected from known resistant and susceptible barnyardgrass populations. Propanil-resistance of varying levels was confirmed in 115 (16 counties) out of the 138 Arkansas barnyardgrass seed sources. Propanil I 50 values (rate of herbicide required to provide 50% injury/control) were determined to be 14, 20, and 39 kg/ha for slightly, moderately, and highly resistant barnyardgrass, respectively. A resistance factor of 20x was found in the highly resistant barnyardgrass category. Development of resistance was highly correlated with crop rotations where rice was grown one out of two, or two out of three years. Nomenclature: Propanil, N-(3,4-dichlorophenyl)propanamide, barnyardgrass, Echinochloa crus-galli (L.) Beauv. #4 ECHCG; rice, Oryza sativa L.

Abstract: Acifluorfen, lactofen, chlorimuron, thifensulfuron, imazethapyr, and imazaquin were evaluated for control of Palmer amaranth, common waterhemp, redroot pigweed, and tumble pigweed at three application timings in field and greenhouse experiments. Results from field studies indicated that most herbicides provided greater than 90% control of common waterhemp, redroot pigweed, and tumble pigweed regardless of time of application. Palmer amaranth was the most difficult species to control, and only thifensulfuron and imazethapyr provided greater than 80% control at all application timings. In the greenhouse experiment, herbicides were applied when pigweeds averaged 10 cm, 20 cm, and 30 cm in height. Results were similar to the field experiment, except that common waterhemp was more difficult to control

Abstract: Yellow hawkweed infests permanent upland pastures and forest meadows in northern Idaho. Conventional surveys to determine infestations of this weed are not practical. A charge coupled device with spectral filters mounted in an airplane was used to obtain digital images (1 m resolution) of flowering yellow hawkweed. Supervised classification of the digital images predicted more area infested by yellow hawkweed than did unsupervised classification. Where yellow hawkweed was the dominant ground cover species, infestations were detectable with high accuracy from digital images. Moderate yellow hawkweed infestation detection was unreliable, and areas having less than 20% yellow hawkweed cover were not detected.

Abstract: Grass and broadleaf herbicides are available for effective, single-application total postemergence weed control in corn. Field experiments were conducted in 1992 and 1993 on sites with dense natural weed infestations to determine the effects of weed interference prior to herbicide application on corn yield. Nicosulfuron plus bromoxynil was applied at 5-, 10-, 15-, or 20-cm weed canopy heights in plots with or without weed interference. Crop injury was more severe when herbicides were applied to smaller corn. Herbicide applications made to 5-, 10-, or 15-cm tall weeds provided nearly complete weed control. Weed interference did not reduce corn height or grain yield when postemergence applications were made to weeds 10 cm or less in height. Weed interference reduced corn height and grain yield in 1992 when applications were made to 15-cm tall weeds even though weed control was nearly complete. Weed control was incomplete and corn height and grain yield were reduced when applications were delayed until weeds were 20 cm tall. Nomenclature: Bromoxynil, 3,5-dibromo-4-hydroxybenzonitrile; nicosulfuron, 2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide; corn, Zea mays L. 'Pioneer 3753.'

Abstract: Greenhouse studies were conducted to determine the response of purple and yellow nutsedge to selective soil placement of 5 cm of soil treated with MON-12037 above and/or below the nutsedge tubers. MON-12037 at 53 g/ai ha applied as a foliar, soil, or foliar + soil application also were evaluated. MON-12037 placement above, below, or above+below the nutsedge tuber decreased shoot number, shoot dry weight, shoot regrowth dry weight, and root-tuber dry weight production in both species, 30 and 60 d after treatment. MON-12037 applied as a foliar, soil, and foliar + soil treatment was effective in reducing purple nutsedge shoot regrowth dry weight to less than 5% of the non-treated control. Yellow nutsedge shoot regrowth dry weight from the foliar + soil and soil-only applications was less than 1% of the non-treated control

Abstract: Imazethapyr and bentazon were applied with petroleum oil adjuvant in a factorial arrangement to weed species in greenhouse and field research to determine if postemergence weed control by imazethapyr was antagonized when bentazon was tank-mixed. Tank-mixing 840 g/ha of bentazon with 13 or 27 g/ha of imazethapyr increased redroot pigweed and eastern black nightshade dry weight as compared to Colby's expected values in the greenhouse. However, weed control was not reduced in field studies. Subsequent greenhouse studies indicated that soil interception and resulting root uptake of imazethapyr increased redroot pigweed control. Bentazon decreased foliar absorption of 14C-imazethapyr by 15% and translocation of 14C from the treated leaf by more than 50% compared to 14C-imazethapyr applied alone. Nomenclature: Bentazon, 3-(1 -methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2- dioxide; imazethapyr, 2-(4,5-dihydro-4-methyl-4-methyl-4-(1-methylethyl)-5-oxo-lH-imidazol-2-yl)- 5-ethyl-3-pyridinecarboxylic acid; eastern black nightshade (Solanum ptycanthum Dun.) #3 SOLPT; concluded that reduced quackgrass (Elytrigia repens (L.) Nevski) control was due to inhibited absorption of 14C- sethoxydim by quackgrass in the presence of the sodium salt of bentazon. Conversely, pitted morningglory (Ipo- moea lacunosa L.) control increased synergistically with combinations of imazaquin 1 2-(4,5-dihydro-4-methyl-4- (1 - methylethyl)-5-oxo- 1H-imidazol-2-yl)-3-quinoline- carboxylic acid) and imazethapyr (15). An increase in morningglory control was also observed when imazapyr { (?)-2- (4,5-dihydro-4-methyl-4-( 1 -methylethyl)-5 -oxo- IH-imidazol-2-yl)-3-pyridinecarboxylic acid) was ap- plied in combination with either imazaquin or imazethapyr (14, 20).

Abstract: Field studies were conducted to determine rhizomatous johnsongrass and barnyardgrass control with clethodim, quizalofop-P-ethyl, fluazifop-P, sethoxydim, fenoxaprop-ethyl, and quizalofopP-tefuryl applied alone and with lactofen, imazaquin, chlorimuron, and fomesafen. Graminicides applied alone controlled johnsongrass and barnyardgrass 83 to 99%. Of the graminicides evaluated, clethodim was the most susceptible to decreased grass control in mixture with broadleaf herbicides. Imazaquin and chlorimuron were most antagonistic of the broadleaf herbicides toward the activity of graminicides. Clethodim mixed with imazaquin reduced johnsongrass control as much as 64% and mixed with chlorimuron reduced barnyardgrass control as much as 52%. Quizalofop-P-tefuryl was least affected by broadleaf herbicides and fomesafen was least antagonistic in mixture with graminicides

Abstract: AAL-toxin, produced by Alternaria alternata, was investigated for its phytotoxic effects on 86 crop and weed species. On susceptible tomato leaf discs, AAL-toxin caused electrolyte leakage and chlorosis at 0.01 μM in 24 h. Plants tested exhibited a range of response. AAL-toxin damaged sensitive plants at 5 μM while other plants showed minimal damage at > 1000 μM. Cotton and the important weeds, Canada thistle, field bindweed, and velvetleaf were largely unaffected. Monocots tested were largely immune.

Abstract: A method was developed and tested for in vivo assay of acetolactate synthase (ALS). The method used foliar application of 1,1-cyclopropanedicarboxylic acid (CPCA) to inhibit ketol-acid reductoisomerase, the enzyme immediately following ALS in biosynthesis of branched-chain amino acids, thereby causing accumulation of acetolactate. Since the amount of acetolactate accumulation is a function of carbon flux through ALS, quantification of acetolactate accumulation determined ALS activity. Accumulation of acetolactate in soybean leaves resulted from CPCA rates as low as 15 g/ha and occurred within 1.5 h. Accumulation rates in soybean leaflets declined with leaf age from 84 μg/h/g tissue at 3 d to 17 μg/h/g tissue at 7 d. Foliar application of CPCA also caused acetolactate accumulation in corn, grain sorghum, velvetleaf, common cocklebur, and smooth pigweed. The ability of the in vivo assay to quantify the reduction in ALS activity following applications of ALS-inhibiting herbicides was validated by comparing ALS activity following thifensulfuron application to «Williams 82» soybean, which has a sulfonylurea-sensitive ALS, and «Asgrow 3200» soybean, which has a sulfonylurea-insensitive ALS. Thifensulfuron reduced ALS activity in Williams 82 soybean to 0, 0.8, 3.3, and 15.6% of the CPCA control at 6, 12, 24, and 48 HAT, but ALS activity in Asgrow 3200 soybean was reduced only to 34, 40, 57, and 88% of the CPCA control

Abstract: Adjuvants were evaluated to determine the effect on increasing spray droplet size and reducing the amount of spray dispensed in small driftable size particles when applying water and paraffinic oil at ultralow volume. Spray solutions were applied with an air-assist system at liquid flow rates of 28 and 56 ml/min and atomized with 14, 28, 42, 56, and 84 kPa of air pressure. Water and paraffinic oil were applied alone and with two drift retardant adjuvants mixed individually in each. The two water soluble adjuvants were mixed at concentrations of 0.25, 0.50, 0.75, 1.0, and 2.0%; oil soluble adjuvants were applied at 0.125, 0.25, and 0.50%. Adjuvants used in water and oil were effective at increasing droplet size and reducing the amount of liquid dispensed in small driftable size particles. Effectiveness of the adjuvants decreased as air pressures increased, with water soluble adjuvants being more susceptible to air pressure. Volume median diameters > 200 μm with water could be achieved without adjuvants; whereas with oil, an adjuvant was required.

Abstract: Plant growth regulators paclobutrazol and flurprimidol were evaluated for suppression of Poa annua spp. reptans, a perennial biotype of annual bluegrass, in a creeping bentgrass green. Paclobutrazol at 0.6 kg ai/ha applied on Mar. 15, followed by 0.3 kg/ha on Apr. 29, 0.6 kg/ha on Oct. 1, and 0.3 kg/ha on Nov. 12 for each of 2 yr suppressed P. annua spp. reptans 28% approximately 4 mo after the final treatment. When paclobutrazol was applied at 0.3 kg/ha in each of four applications during the same period, suppression was similar to that with the higher rate 1 and 2 mo after final treatment but declined to 7% by 4 mo. Suppression of P. annua spp. reptans from flurprimidol applied four times during each of 2 yr was 22 to 27% 1 mo after final treatment but no suppression was noted 2 mo after the final treatment. Maximum creeping bentgrass injury was less than 20% when either paclobutrazol or flurprimidol was applied in the spring. However, creeping bentgrass injury was approximately 30% in the fall when either chemical was applied in the spring and repeated in October at 0.6 kg/ha

Abstract: Morocco has a large number of edible weeds, but seventeen are mostly eaten by the population, collected for sale in different provinces, or even exported. Eight weeds have edible shoots while the others have edible stems, fruits, roots, flowers, or petioles. Thirteen weed species are marketed either seasonally or throughout the year and generate money for the people. Morocco's tassel grapehyacinth bulbs and products extracted from pennyroyal mint are exported. Further research should focus on the nutritive value of these weeds and their economic role in the country.

Abstract: Literature concerning interactions between herbicides and insects is reviewed. Herbicides can be toxic to insects or can affect them indirectly, such as by destroying food supplies, but they usually can be used with proper application timing without affecting insects adversely. Herbicides and biocontrol insects can interact either favorably or unfavorably depending on the life cycle stage of weed and insect, effect on predatory insects, changes in food quality, mobility of the biocontrol insect, and impact of herbicides on weed growth. Thus, interactions between a biocontrol insect and herbicide can be antagonistic, additive, complementary, or synergistic. Split-plot techniques to evaluate these interactions at an early stage of insect establishment are proposed to improve weed biocontrol.

Abstract: Field and greenhouse studies were performed to examine the influence of various surfactants with glyphosate on whole plant efficacy. Relationships were examined between glyphosate phytotoxicity and surfactant properties, including ionic form, degree of ethoxylation, and hydrophobe composition. Cationic tertiary amine surfactants enhanced glyphosate performance in both field and greenhouse studies. Nonionic allinol and octoxynol surfactants were not effective in combination with glyphosate. In field studies, glyphosate efficacy increased with increasing surfactant ethylene oxide (EO) content. Soybean and velvetleaf responded similarly to glyphosate-surfactant spray applications, as both demonstrated significant linear and quadratic relationships between increasing surfactant ethoxylation and phytotoxicity, while common lambsquarters showed a significant linear relationship only. Cationic surfactants were evaluated in the greenhouse and a significant quadratic regression of glyphosate phytotoxicity to common lambsquarters on increasing surfactant ethoxylation indicated an optimum surfactant EO content of about 10 moles. Both tertiary and quaternary ethoxylated fatty amines were effective with glyphosate in decreasing common lambsquarters' fresh weight. Fatty amine hydrophobe composition did not correlate with glyphosate phytotoxicity to common lambsquarters. Nomenclature: Glyphosate, N-(phosphonomethyl)glycine; common lambsquarters, Chenopodium album L. # 3 CHEAL; velvetleaf, Abutilon theophrasti Medicus # ABUTH; soybean, Glycine max (L.) Merr. 'Elgin.'

Abstract: The first significant cases of herbicide-resistant weed populations were to the triazines in the 1970s. In the last 10 years there has been an increase in the number of weed populations that have become resistant to an array of herbicides. In some of these cases, like rigid ryegrass in Australia, a multitude of resistant biotypes has evolved with different mechanisms of resistance. If the present trend continues, the number of herbicides effective on certain weed species may diminish rapidly. To counteract this trend, industry has organized a number of intercompany working groups to specifically address the development of resistance and to implement plans to manage resistance. University and extension along with industry personnel across the world have begun educating growers on resistance management. However, this effort needs to be intensified to find new solutions for controlling weeds through the use of integrated weed management practices that incorporate new and established herbicides with cultural, mechanical, and biological control methods. The challenge is to develop cost effective, environmentally sustainable programs for weed control while maintaining the present efficiency in food and fiber production so that needs of an ever expanding human population can be met.

Abstract: Five sulfonylurea herbicides were applied to Typic Boroll soil with pH 8.0 and 2% organic matter in the field and growth chamber to assess their residual effects on following crops. Under irrigated conditions, triasulfuron at 22 g/ha reduced the growth of alfalfa, canola, corn, lentil, pea, potato, and sugarbeet the year after application but caused no injury after two years. Alfalfa GR50 (rate required to reduce growth by 50%) values immediately after application of chlorsulfuron, triasulfuron, and metsulfuron were < 2.2 g/ha and similar in the growth chamber and field. Alfalfa and canola GR50 values immediately after thifensulfuron application in the growth chamber were ≥ 90 g/ha. Alfalfa, canola, flax, and sugarbeet GR50 for tribenuron in the growth chamber were < 4 g/ha. Crop response curves developed by growth chamber experiments could replace many of the multiple site and crop field experiments now required to develop recropping guidelines for residual herbicides.

Abstract: Field studies were conducted from 1991 to 1994 to investigate the effectiveness of reduced rates of bentazon in tank-mixtures with imazethapyr, thifensulfuron, or HOE 075032 for improved control of redroot pigweed and common lambsquarters in navy bean. Tank-mixtures of bentazon at 600 g ai/ha plus imazethapyr at 25 g/ha or HOE 075032 at 5 to 15 g/ha controlled both redroot pigweed and common lambsquarters. These rates represent an approximate 45% reduction in total amount of active ingredient needed to control these weeds compared with full label rates. Bentazon tank-mixtures with 2 or 4 g/ha of thifensulfuron controlled these weeds but caused severe injury and delayed crop maturity. In greenhouse studies, the GR 25 for HOE 075032 in navy bean was > 90 g/ha, while in soybean it was 16 to 24 g/ha.

Abstract: Problems with insecticide resistance have long plagued the field of economic entomology. Genetic, biochemical, and ecological information on insects has been used to develop strategies to slow the rate of insecticide resistance evolution. Documented cases of herbicide resistance have increased dramatically over the past 10 yr. This paper compares some aspects of insect and weed biology that can be used in determining whether or not resistance management strategies developed for insects are likely to be useful in combating herbicide resistance. Differences between insects and weeds in terms of genetic architecture, mating systems, and population structure lead to differences in the expected efficacy of some resistance management strategies. Because of the localized population structure of some weeds, it may be easier to get farmers to participate in herbicide resistance management programs and avoid a tragedy of the commons. A review of the herbicide resistance literature reveals a number of areas of basic research on ecology and genetics of weeds that could help in designing more appropriate resistance management programs.

Abstract: Increased crop densities and postplant tillage were evaluated as nonchemical methods to supplement metribuzin for improved broadleaf weed control in dry pea and lentil. The effects of 50, 100, and 150% of recommended 220 kg/ha pea and 67 kg/ha lentil seeding rates and two dates of rotary hoeing and harrowing on pea, lentil, and broadleaf weeds were studied with and without metribuzin for two years. Under favorable growing conditions, crop competition gave 72 and 99% weed control in pea and 33 and 70% weed control in lentil with the 50 and 150% seeding rates. Under less favorable conditions, control was 21 to 39% with the low and high pea and lentil seeding rates. At recommended seeding rates, metribuzin gave greater than 90% control in either crop or year. Postplant tillage 12 to 27 d after planting slightly reduced crop densities in three tillage treatments in one year, but not the second. Postplant tillage did not affect crop yield or improve weed control. In all studies, pea was similar to or more competitive than lentil in suppressing broadleaf weeds. Because neither non-chemical practice significantly improves weed control, changes are not recommended for weed management in pea and lentil

Abstract: A large crabgrass population (PW2) that demonstrated resistance to fluazifop-P and sethoxydim was identified in Wisconsin during 1992. Dose-response experiments were conducted in the greenhouse to determine the level of resistance of a PW2 large crabgrass accession to aryloxyphenoxypropionate (APP), cyclohexanedione (CHD), and other herbicide chemistries relative to a large crabgrass accession (A310) which was susceptible to APP and CHD herbicides. Based on shoot dry biomass reduction, the PW2 accession was 337- and 59-fold resistant to sethoxydim and fluazifop-P, respectively, relative to the A310 accession. Resistance of the PW2 accession to fenoxaprop, haloxyfop, quizalofop, and diclofop ranged from 18- to 29-fold. The PW2 accession was only 7-fold resistant to clethodim. Both large crabgrass accessions were susceptible to imazethapyr and linuron. These results suggest that APP and CHD herbicides will be ineffective for the management of the PW2 accession. An integrated approach including cultural, mechanical, and alternative chemical methods, should be implemented for the management of the PW2 accession and to prevent additional resistance problems.

Abstract: Field experiments conducted at three locations in Georgia during 1991 and 1992 evaluated AC 263,222 and imazethapyr rates alone at 18, 36, 54, or 72 g ai/ha and in mixture for a total of 36, 54, or 72 g/ha of herbicide applied early-POST for weed control, peanut injury, and yield An application of AC 263,222 at 72 g/ha controlled (> 90%) Ipomoea morningglories, sicklepod, smallflower morningglory, and yellow nutsedge in all experiments and coffee senna and Florida beggarweed at Chula in 1991 Bristly starbur was controlled at least 90% with AC 263,222 at 72 g/ha at Tifton in 1991, but less than 62% at Chula in 1991 Imazethapyr applied at 72 g/ha controlled coffee senna, Ipomoea morningglories, and smallflower morningglory at least 85%, but did not control Florida beggarweed or sicklepod and provided inconsistent bristly starbur and yellow nutsedge control Bristly starbur and yellow nutsedge control was increased with several AC 263,222 plus imazethapyr mixtures High peanut yields comparable to the standard were indicative of the AC 263,222 rate applied whether alone or in mixture with imazethapyr

Abstract: Nicosulfuron is used with surfactant or oil adjuvant to enhance postemergence efficacy. Yellow foxtail fresh weight reduction from nicosulfuron varied from 10 to 92% depending upon surfactant in greenhouse experiments. Oil adjuvants differed in enhancement of nicosulfuron phytotoxicity to yellow foxtail or large crabgrass with methylated canola oil being most effective, followed by vegetable oils, and petroleum mineral oil as least effective. Percentage and type of surfactant used as an emulsifier in an oil adjuvant was important to nicosulfuron phytotoxicity especially when applied with the less effective oils, but was of minimal importance when applied with methylated canola oil. Adjuvant effectiveness was directly related to nicosulfuron absorption. These data indicated that recommendations for adjuvants to maximize nicosulfuron phytotoxicity should be limited to specific products.

Abstract: Field experiments evaluated barnyardgrass, broadleaf signalgrass, and rhizomatous johnsongrass control with sethoxydim, clethodim, fluazifop-P, quizalofop-P, and fenoxaprop applied alone and with bentazon or chlorimuron when crop oil concentrate or BCH 815 was used. Bentazon strongly antagonized sethoxydim and clethodim. BCH 815 partially reduced the antagonism with sethoxydim and clethodim compared with crop oil concentrate. Chlorimuron was most antagonistic towards fluazifop-P, fenoxaprop, and quizalofop-P, and BCH 815 did not reduce antagonism. Additional experiments evaluated Italian ryegrass control with diclofop applied alone and with bromoxynil, metribuzin, 2,4-D amine, or tribenuron plus thifensulfuron with these adjuvants. The amine formulation of 2,4-D and tribenuron plus thifensulfuron reduced Italian ryegrass control with diclofop, irrespective of the adjuvant.