A new extraction method for the HPLC-UV determination of metsulfuron in soil was developed and compared with NaHCO3 extraction and a lentil bioassay technique. The new procedure consisted of metsulfuron extraction using anion exchange membranes followed by a dichloromethane concentration of the membrane eluates. Three soils representing different landscape positions were spiked with metsulfuron to yield concentrations in the range of 0 to 40 μg kg−1 dry soil and were analyzed by the above procedures. At a given spike rate, the efficiency of the anion exchange membrane extraction was highest for the soil from the upper slope position and lowest for the soil from the lower slope position, indicating that the amount of ion-exchangeable sulfonylurea was affected by soil properties. Similar trends in degree of root growth inhibition were observed for lentil response to metsulfuron presence in soil; percent root growth inhibition was related to the landscape position as the amount of membrane-extractable metsulfuron. The percent shoot growth inhibition was not soil dependent and did not differ among soils. The efficiency of NaHCO3 extraction for metsulfuron did not vary with soil type; in the NaHCO3 method, because of the buffered alkaline nature of the extraction, differences in soil properties, particularly soil pH, would have less effect on metsulfuron recovery. Because of similar trends for the results of the membrane extraction method and a lentil root bioassay, anion exchange membrane extraction may provide useful information on bioavailable fractions of sulfonylurea herbicides in soil.

Field studies were conducted to determine the effect of early-season and early- plus late-season acetolactate synthase–resistant Helianthus annuus interference on Glycine max and H. annuus growth and yield at two sites in Missouri. Helianthus annuus densities of 3 plants m−2 were established shortly after G. max emergence in all plots except the weed-free check. To study early-season interference, H. annuus were removed with postemergence glyphosate (0.84 kg ae ha−1) 2, 4, 6, and 8 wk after planting (WAP) and kept weed-free for the rest of the growing season. Glycine max yields were not different with 2, 4, 6, or 8 wk of early-season interference at either location. To study early- plus late-season interference, H. annuus densities were established at 3 plants m−2. They were then removed 2, 4, 6, or 8 WAP with glyphosate and subsequently reestablished at the same density within 2 wk after removal by newly emerging and transplanted H. annuus. These H. annuus were allowed to remain in the field for the remainder of the growing season. This provided a weed-free period of approximately 2 wk during the growing season beginning 2, 4, 6, or 8 WAP. Season-long interference and no-interference treatments were also included. Glycine max yields were reduced 47 to 72% with season-long interference. Helianthus annuus vegetative dry matter was approximately 56% lower at Columbia than at Miami. Glycine max yields tended to increase as the weed-free period was delayed into the growing season. Early-season weed-free periods (2 to 4 and 4 to 6 WAP) allowed H. annuus to become re-established before G. max formed a canopy and resulted in larger amounts of H. annuus biomass and seed production as well as G. max yield losses of 15 to 80%. Re-establishment of H. annuus in 6 to 8 WAP and 8 to 10 WAP weed-free treatments generally resulted in the plants surviving for only a few weeks after establishment and not producing seed or reducing G. max yield.

Scanning electron microscopy (SEM) showed that EPTC (S-ethyl dipropylthiocarbamate) caused an aggregation of the epicuticular wax layer of corn (Zea mays L.). R-25788 (2,2-dichloro-N,N-diallylacetamide) prevented this aggregation when applied in combination with EPTC. Neither EPTC, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], nor R-25788 changed the weight of chloroform extractable epicuticular wax on corn leaves. EPTC apparently does not block lipid synthesis in corn as it does in other plant species. Thus R-25788 does not protect corn from EPTC or metolachlor by overcoming such a block. EPTC did affect wax arrangement on the leaf surface and caused an increase in the cuticular transpiration of corn and predisposed corn to injury from subsequent postemergence applications of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion). R-25788 protected corn against these deleterious effect.

Three herbicides, amine salt of 2,4-D [(2,4-dichlorophenoxy)acetic acid], glyphosate [N-(phosphonomethyl)glycine], and dicamba (3,6-dichloro-o-anisic acid) were applied for field bindweed (Convolvulus arvensis L.) control in grain/summerfallow or grain/legume rotations. After the first year all herbicide retreatments were made using 2,4-D amine. The 2,4-D treatment at 3.4 kg/ha gave 65% field bindweed control. Field bindweed control averaged 17% higher when the 2,4-D was applied in August rather than July. The 3.4-kg/ha rate gave 45% better field bindweed control than the 1.1 kg/ha rate. Dicamba at 6.7 kg/ha gave 90% field bindweed control and glyphosate at 4.5 kg/ha gave 86% control. Dicamba persisted in the soil for 1 to 3 yr after application and caused winter wheat (Triticum aestivum L.) and lentil (Lens culinaris Medik.) yield loss. Crop yields were highest more than 90% of the time from plots treated with 2,4-D or glyphosate.

Preliminary greenhouse studies indicated the presence of a synergistic interaction between low rates of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] or diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in combination with linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] or chlorbromuron [3-(4-bromo-3-chlorophenyl)-1-methoxy-1-methylurea]. In a 3-yr field study, moderate injury of cotton (Gossypium hirsutum L. ‘Stoneville 213’) with no yield reduction was observed with fluometuron or diuron at 1.68 and 1.12 kg/ha, respectively, but higher rates (5.04 and 3.36 kg/ha, respectively) caused injury and yield reductions. Soybean [Glycine max (L.) Merr. ‘Hill’] injury ratings during the second year indicated a synergistic interaction between residue from fluometuron at 5.04 kg/ha combined with linuron at 2.48 kg/ha or chlorbromuron at 3.85 kg/ha, and from diuron at 3.36 kg/ha combined with linuron at 2.48 kg/ha. These interactions were not apparent in soybean yield data. Soybean injury the third year ranged from 30 to 60% with single or repeated applications of linuron or chlorbromuron, although yields were not affected. Residual fluometuron and diuron from 2 yr of application at 5.04 and 3.36 kg/ha, respectively, injured soybeans, but did not reduce yields. Significant synergistic interactions were observed through injury and yield measurements after two annual applications of fluometuron at 5.04 kg/ha combined with linuron or chlorbromuron. A synergistic interaction was detected in soybean yields with chlorbromuron at 3.85 kg/ha preceded by two annual applications of diuron at 3.36 kg/ha. Such interactions may occur under field conditions, but are unlikely to be economically significant. Chemical analysis indicated little evidence of accumulation, even with repeated application of fluometuron or diuron at 5.04 and 3.36 kg/ha, respectively.

Field studies were conducted during 1983 and 1984 to determine the single and interactive effects of trifluralin, soybean thrips, and the sodium salt of acifluorfen on soybean. Increased soybean injury was observed in 1983 when acifluorfen at 0.6 kg ai/ha was applied to soybeans infested with soybean thrips versus plants where soybean thrips were controlled. Soybean injury measured by percent defoliation and visual injury ratings was reduced when thrips were controlled versus soybeans where thrips were not controlled with carbaryl at 0.9 kg ai/ha in 1983. Soybean thrips alone did not reduce soybean seed yield in this study. Acifluorfen reduced soybean photosynthetic rate, shoot weight, root weight, and seed yield. Trifluralin had no effect on soybean growth parameters measured in this study.

Napropamide [2-(α-napthoxy)-N,N-diethylpropionamide] inhibited root and shoot growth in corn (Zea mays L. ‘NC+ 59’) and tomato (Lycopersicon esculentum Mill. ‘Niagara VF315’) seedlings. Shoot growth was reduced less than root growth in both species. Corn roots were approximately 10 times more sensitive to napropamide than were tomato roots. Translocation of napropamide from the roots to the shoot of tomato occurred within 0.5 h and followed an apoplastic pattern. Little movement of napropamide from the roots to the shoots occurred in corn. Metabolism of napropamide was not evident in either species during an 8-h exposure. Absorption studies showed that total napropamide levels were 60% higher in corn root tissue than in tomato root tissue. The greater napropamide content in the corn roots was associated with a tightly bound fraction of the total napropamide influx.

Responses of soybeans [Glycine max (L.) Merr. ‘Bragg’] and red rice (Oryza sativa L.) to postemergence applications of mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] alone and in combinations were evaluated in greenhouse studies. Soybeans were tolerant to bentazon up to the highest tested rate of 2.0 kg/ha, but their height was reduced by mefluidide at 1.0 kg/ha. Soybeans were not injured by any tested combination of the two herbicides. Bentazon applied alone at rates of 5.0 kg/ha and above had a significant effect on red rice injury. Mefluidide applied at rates above 0.25 kg/ha severely reduced height and fresh weight of red rice. When these two herbicides were combined, a synergistic reaction occurred, and the combination was much more effective in controlling red rice than was either herbicide applied alone. The addition of a surfactant significantly increased the activity of the combination on red rice up to 0.25 kg/ha of mefluidide and at all rates of bentazon.

Field research was conducted in 1985 and 1986 to compare the efficacy of fluazifop and quizalofop on production of panicles and seeds of red rice. Single and first sequential treatments were applied to red rice in the early-tillering, midtillering, and panicle initiation stages of growth. Sequential treatments were applied 14 days after each earlier application to red rice in the midtillering, late-tillering, and early-heading growth stages, respectively. Both herbicides were applied singly or sequentially at 70, 140, and 280 g/ha. Sequential applications of fluazifop and quizalofop at 280 g/ha caused the greatest reduction of red rice panicle and seed production. Fluazifop at 280 g/ha applied sequentially reduced panicle production 75 to 80% and seed production 80%; 140 g/ha applied sequentially reduced seed production 83%. Quizalofop at 280 g/ha applied sequentially reduced panicle production 75 to 100% and seed production 91%. Sequential applications of either herbicide applied to red rice plants in the panicle initiation and early-heading growth stages were the most effective treatments.

The response of net photosynthetic rate to temperature and light, the rate of photorespiration, the compensation concentration for CO2, and the pathway of CO2 fixation in smooth pigweed (Amaranthus hybridus L.) were investigated using infrared gas analysis and 14CO2. Maximum net photosynthetic rates of whole shoots were 45 mg CO2 dm-2 hr-1 at 30 C and 7.8 klux. Intact whole shoots were not light saturated at 10 klux. The optimum temperature for net photosynthesis was between 30 C and 40 C. Photorespiration was low and the CO2 compensation concentration was 7 ppm. After a 5-sec exposure to 14CO2 in the light, label was detected in oxaloacetate, malate, and aspartate. It was concluded that smooth pigweed has the gross photosynthetic characteristics and CO2 fixation pathway typical of C4 or Hatch-Slack plants.

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4 (1H, 3H)-dione] effectively controlled herbaceous weeds in a loblolly pine (Pinus taeda L.) plantation in 1975. Pine seedling height increased as a result of weed control following 1 to 3 kg/ha applications but phytotoxic symptoms were evident. A 1976 field study indicated activated charcoal root coatings may reduce phytotoxic action. Hexazinone at 3 and 4 kg/ha applied to either the foliage or the soil was toxic to potted pine seedlings in 1976. The addition of surfactant to hexazinone treatments at 2, 3, and 4 kg/ha increased pine phytotoxicity to unacceptable levels. When hexazinone was applied to soil at 2, 3, and 4 kg/ha, activated charcoal root coatings reduced pine mortality to acceptable levels on Norfolk sandy loam. Charcoal was less effective on Madison clay loam. Pine tolerance on both soils was acceptable at 2 kg/ha.

The critical period for weed control for many crops has been well investigated and the results have been used to develop better weed management recommendations. However, research is limited on the critical period for weed control for alfalfa, a perennial crop with multiple harvests. With the advent of new, more effective POST herbicides for alfalfa, an understanding of the critical period may further enhance forage yield. The objective of this study was to determine the critical period for weed control in spring-seeded alfalfa. Alfalfa was seeded conventionally at two locations in Pennsylvania in the spring of 2004 and 2005; glyphosate and glyphosate-resistant alfalfa were used for weed management. A surrogate weed, Japanese millet, was seeded at three planting rates to simulate varied levels of weed density. In the analysis, the critical period for weed control was identified for the 2004 seedings, but not for 2005. In 2004, the critical period varied by location, but began at the 0.5 trifoliate alfalfa growth stage and ended at the 7 trifoliate growth stage. When identified, the critical period was similar for both first-harvest yield and first-year cumulative yield. Higher weed density caused the critical period to begin earlier than under lower weed densities, but weed density had no effect on when the critical period ended. Under moderate to heavy weed populations, the critical period for weed control can increase herbicide use efficiency and maximize alfalfa returns, although under low weed severity, the critical period may not exist.

Greenhouse and laboratory experiments were conducted to investigate the response of winter wheat, and two diclofop-methyl–sensitive (OR and KG) and four diclofop-methyl–resistant (EP, GT, RBG, and JB) Italian ryegrass biotypes to the experimental herbicide mixture AE F130060 03 (an 8.3:1.7 mixture of the experimental sulfonylurea herbicides AE F130060 00 and AE F115008 00). AE F130060 03 at 15 or 18 g ha−1 without the safener AE F107892 reduced biomass of winter wheat 10 to 14%, whereas applications made with AE F107892 did not reduce wheat biomass. AE F130060 03 at 15 or 18 g ai ha−1 was more effective than diclofop-methyl in reducing biomass of one diclofop-methyl–sensitive Italian ryegrass biotype and all four diclofop-methyl–resistant biotypes. However, differential responses to AE F130060 03 at 15 and 18 g ha−1 occurred among diclofop-methyl–resistant biotypes. AE F130060 03 at 15 or 18 g ha−1 reduced biomass of OR, KG, EP, and GT from 61 to 84% but reduced biomass of RBG and JB biotypes only 35 to 52%. Absorption, translocation, and metabolism experiments were conducted to further investigate differential response of diclofop-methyl–sensitive KG and diclofop-methyl–resistant JB to AE F130060 00. Absorption, translocation, and metabolism of AE F130060 00 in winter wheat treated with or without the herbicide safener AE F107892 were also included for comparison. Foliar absorption of [14C]AE F130060 00 was influenced only by plant species because Italian ryegrass biotypes absorbed at least three times more AE F130060 00 than did wheat 12, 36, and 72 h after treatment (HAT). No more than 9% of absorbed radioactivity translocated into shoots and roots of either species during the experiment. Greatest overall metabolism occurred in winter wheat treated with the safener AE F107892. Seventy-two HAT, relative amounts of parent AE F130060 00 in Italian ryegrass biotypes were nearly 1.8 times greater than that in wheat that received AE F107892 and nearly 1.5 times greater than that in unsafened wheat. However, obvious differences in herbicide metabolism between diclofop-methyl–sensitive KG and diclofop-methyl–resistant JB were not evident. We hypothesize that differential sensitivity to AE F130060 00 in these biotypes is most likely due to a less sensitive acetolactate synthase, although further research is required to confirm this hypothesis.

The foliar uptake of 4-amino-3,5,6-trichloropicolinic acid (picloram) and its phytotoxicity in mixtures with several phenoxy herbicides were studied using bean (Phaseolus vulgaris L. ‘Red Kidney’). The greatest accumulation of picloram occurred in the growing point, stem, and axillary buds. Transport from the treated leaf occurred within 6 hr and continued for at least 7 days. The effectiveness of herbicide combinations containing picloram was related to the particular plant part measured. A synergistic reduction in fresh and dry red kidney bean weight was obtained with (2,4-dichlorophenoxy) acetic acid (2,4-D) or 2-[(4-chloro-o-tolyl)oxy]propionic acid (mecoprop) when applied in combination with picloram, whereas 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) and picloram gave an antagonistic response. An investigation of the antagonistic reaction of 2,4-DB with picloram indicated that picloram prevented the movement of 2,4-DB, while 2,4-DB increased both the distribution and the amount of picloram translocated from the point of application.

The methyl ester of diclofop [2-(4-(2,4-dichlorophenoxy) phenoxy) propionic acid] was used in all of a series of experiments. When it was applied postemergence, it selectively controlled barnyardgrass [Echinochloa crus-galli (L.) Beauv.] in sugarbeets (Beta vulgaris L. ‘USH 9′). Tank-mixing diclofop with desmedipham [ethyl m-hydroxycarbanilate carbanilate (ester)] resulted in decreased control of barnyardgrass under greenhouse and field conditions. Losses in activity ranged from 10 to 80%. Delaying application of desmedipham following application of diclofop by 4 days in the greenhouse or in the field resulted in no reduction in barnyardgrass control. Increased rates of diclofop offset the antagonistic effect of desmedipham. Similar losses in activity occurred when Hoe-29152 {methyl-2-[4-(4-trifluoromethylphenoxy)phenoxy] propanoate} was tank-mixed with desmedipham.

Turnipweed [Rapistrum rugosum (L.) All.] and Mexican pricklepoppy (Argemone mexicana L.) are increasingly prevalent in the northern cropping regions of Australia. The effect of different densities of these two weeds was examined for their potential to cause yield loss in wheat (Triticum aestivum L.) through field studies in 2016 and 2017. There was 72% to 78% yield reduction in wheat due to competition from R. rugosum. Based on the exponential decay model, 18.2 and 24.3 plants m−2 caused a yield reduction of 50% in 2016 and 2017, respectively. Rapistrum rugosum produced a maximum of 32,042 and 29,761 seeds m−2 in 2016 and 2017, respectively. There was 100% weed seed retention at crop harvest. Competition from A. mexicana resulted in a yield loss of 17% and 22% in 2016 and 2017, respectively; however, plants failed to set seeds due to intense competition from wheat. Among the yield components, panicles per square meter and grains per panicle were affected by weed competition. The studies indicate a superior competitiveness of R. rugosum in wheat and a suppressive effect of wheat on A. mexicana. The results indicate that a wheat crop can be included in crop rotation programs where crop fields are infested with A. mexicana. High seed retention in R. rugosum indicates the possibility to manage this weed through seed catching and harvest weed seed destruction.

Common groundsel is an alien annual weed that has become increasingly troublesome in many crops in Ohio. Understanding the periodicity of seedling emergence and longevity of seeds buried in the soil may help growers devise more efficient strategies to control common groundsel. Studies were conducted to determine the dormancy status of common groundsel seeds over 24 mo, and to describe the effect of tillage and fertilizer on the pattern of seedling emergence and the rate of depletion of seeds from the soil seed bank. Common groundsel seeds were collected (June 2000 and 2002) from sites along a 700-km transect from Kentucky to Michigan (39°1′ and 43°36′N, respectively). Seeds were cleaned and placed in nylon mesh bags for burial in a common garden. Every month for the following 24 mo, replicate bags from each location were exhumed. Germination was tested under alternating temperatures of 20 and 10 C, for 14 and 10 h day/night, respectively. Germination response at each sampling date was similar regardless of seed source, but differed for the 2000 to 2002 and 2002 to 2004 experiments. Laboratory germination of seeds buried was initially high (98%) and declined rapidly to about 20% by midwinter. Germination increased to about 60% during the second summer, followed by a slow decline to 40% during winter and another rapid decline before the third summer. The rapid declines in germination were preceded by low soil temperatures (<5 C) and the germination peaks corresponded with periods of high soil temperatures (∼ 20 C). Results suggested that common groundsel follows a cycle of dormancy and nondormancy corresponding to decreases and increases, respectively, in soil temperature. During 2 yr of deep burial in undisturbed soil, 94% of the seeds germinated or died, suggesting that common groundsel seeds may not persist more than a few months in regularly disturbed soils.

Field trials were conducted to determine potato response to parts per trillion (ppt) per weight concentrations of sulfometuron in soil. The herbicide was applied to achieve targeted, 0-d soil concentrations of 0, 7.5, 15, 30, 60, 120, 240, 480, and 960 ppt. Russet Burbank potatoes were planted immediately after application using standard agronomic practices. Based on midseason visual evaluations, root and tuber injury occurred with 0-d concentrations of only 7.5 ppt. Concentrations at or above 120 ppt caused a significant increase in number of tubers with deformities compared with the control. By the end of the growing season, 0-d concentrations between 120 and 240 ppt resulted in higher percentages of tubers with deformities, such as cracks, knobs, or folds. Using logistic models fit to U.S. No. 1 tuber yield and net return data, doses of 74, 156, and 324 ppt are predicted to result in 5, 10, and 20% U.S. No. 1 yield reductions, respectively. The model predicted a 20% net return loss, approximately $160/ha, occurring at 262 ppt, which is near the 240 ppt concentration determined by standard ANOVAs and means comparisons with single degree of freedom contrasts causing significant tuber quality and yield reductions in our study. Growers using the 240 ppt concentration as an indicator of a no-effect level would encounter actual losses too great to withstand. This modeling approach provides an initial attempt at giving growers the tools necessary for assessing potential losses.

Velvetleaf has been a major concern of Southern cotton growers, yet information on its competitiveness and seed production in cotton is lacking. Experiments were conducted in 1997 and 1998 at the Central Crops Research Station in Clayton, NC, to evaluate density-dependent effects of velvetleaf interference and seed production dynamics in conventional tillage cotton. Velvetleaf at densities of up to 3.5 plants m−1 of row did not influence cotton height until at least 4 wk after planting. Velvetleaf height increased as plant density increased throughout the season in 1997, but it was not affected until 9 wk after planting in 1998. Because of differences in environmental conditions, velvetleaf and cotton achieved maximum height later in 1998 than in 1997; however, velvetleaf seed production and cotton yields were higher in 1998 than in 1997 regardless of velvetleaf density. Velvetleaf density had no effect on the fresh weight, dry weight, and stem diameter of velvetleaf plants in 1997. But in 1998, all these parameters decreased significantly with increasing velvetleaf density. Velvetleaf seed production in 1998 was nearly twice that in 1997. Averaged over velvetleaf densities, the greatest number of seed were produced between nodes 6 and 20 in 1997 and between nodes 1 and 10 in 1998. In both years, cotton yield loss increased with velvetleaf density. Maximum yield loss was 84% at 3.5 velvetleaf plants m−1 of row. Yield losses of 5 and 10% were caused by 0.2 and 0.4 velvetleaf plants m−1 of row (1,930 and 4,110 plants ha−1), respectively, in 1997 and by 0.03 and 0.08 velvetleaf plants m−1 of row (360 and 850 plants ha−1), respectively, in 1998. To understand better the applicability of these results, we hypothesized that environmental variation caused differences in measured responses between 1997 and 1998. Therefore, kriging methods were used to fit correlations between observed rainfall and growing degree days (GDD) each year at the experiment site. Results based on climate data from 4 yr at 110 sites indicated that inference space was higher for GDD than for rainfall. The conditions observed at the experiment site in 1997 were deemed most appropriate for the recommendations made in the surrounding area.

Glyphosate-resistant junglerice [Echinochloa colona (L.) Link] is a problematic weed in mungbean [Vigna radiata (L.) R. Wilczek] crops in Australia. Due to limited herbicide options in mungbean, there is an increased interest in developing integrated management strategies for the sustainable control of E. colona. Pot experiments were conducted in a screenhouse in 2017 and 2018 by growing E. colona plants (glyphosate-resistant [GR] and glyphosate-susceptible [GS] biotypes) alone (1 plant pot−1) and in competition with 4 and 8 mungbean plants pot−1. Both biotypes were developed from a single population using the clone method. The growth and seed production of both GR and GS biotypes were similar in response to mungbean competition. Averaged over biotypes, there was a reduction in the growth and seed production of E. colona as crop plants increased. Compared with the weed plants grown alone, crop interference reduced E. colona height by 17% to 19%, tiller numbers by 69% to 82%, total shoot biomass by 85% to 91%, and inflorescence numbers by 74% to 91%. When E. colona was grown with 8 mungbean plants pot−1, leaf weight ratio increased by 42% compared with plants grown alone. Compared with weed plants grown alone, mungbean interference (4 and 8 plants pot−1) reduced weed seed production by 85% to 95%. These reductions were similar for both biotypes (GR and GS), suggesting that there was no fitness penalty associated with resistance. The results of this study suggest that mungbean interference can reduce E. colona growth and seed production, but it should not be considered as a stand-alone strategy to manage E. colona and similar species in mungbean. These results also highlight the need for integrating crop competition with other management strategies to achieve complete and sustainable management of this weed.