The prolific seed production and polyploidy of annual bluegrass allow for the rapid development of herbicide resistance. Ethofumesate-resistant annual bluegrass plants were identified in the 1990s in grass seed production in Oregon, but their prevalence and distribution are not well documented. Therefore a dose–response experiment was initiated to determine the potential level of ethofumesate resistance in seed production systems. Seeds from 55 annual bluegrass populations were obtained from three sources: seed production fields (31 populations), the seed cleaning process (6 populations), and seed testing lots prior to retail distribution (18 populations). Additionally, two populations, one with known ethofumesate resistance and one with known susceptibility, were identified in preliminary testing and used as controls in this experiment. Seed from each collected population was increased. Individual seedlings were then transplanted into separate cone-tainers, grown to a size of 2 to 3 tillers in the greenhouse, and then sprayed using a compressed air track spray chamber with 10 doses of ethofumesate at 0, 0.56, 1.1, 2.8, 5.6, 8.4, 11.2, 16.8, 22.4, and 44.8 kg ai ha−1, with 0.84 to 2.2 kg ha−1 as the label application rate for perennial ryegrass. The resistant to susceptible ratio of populations across all sources ranged from 0.5 to 5.5. The most resistant populations found in production fields, seed cleaning, and seed testing lots had the effective dose necessary to kill 50% of the population (ED50) of 12.1, 9.4, and 13.1 kg ha−1, respectively. Furthermore, 68% of the populations found in production fields had ED50 higher than 6 kg ha−1, indicating common annual bluegrass resistance in grass seed production. As such, growers should implement integrated weed management strategies, as herbicides alone will likely be ineffective at controlling annual bluegrass.

Ethofumesate is a broad-spectrum, soil-applied herbicide used to control broadleaf and grass weeds in sugarbeet crops. Ethofumesate is commonly applied preemergence at rates ranging from 1.25 to 4.2 kg ai ha−1, or applied postemergence (POST), up to 0.38 kg ai ha−1. The Generic Crop Science company has developed a new Ethofumesate 4SC label that has increased ethofumesate POST rates up to 4.48 kg ha−1 in sugarbeet with more than two true leaves per plant. Field and greenhouse experiments were conducted in 2018 and 2019 to evaluate sugarbeet tolerance and herbicide efficacy. Field tolerance experiments indicated sugarbeet stature from ethofumesate applied POST at 0.28, 0.56, and 1.12 kg ha−1 was the same as that of the nontreated control, but ethofumesate at 2.24 kg ha−1 reduced sugarbeet stature, although that rate did not affect yield components. Ethofumesate applied POST at 4.48 kg ha−1 reduced sugarbeet stature and affected sugarbeet yield components. Ethofumesate applied alone POST provided weed control of up to 85%, 76%, and 84% on common lambsquarters, redroot pigweed, and waterhemp, respectively, in field efficacy experiments. Mixing ethofumesate at 1.12 kg ha−1 with glyphosate does not provide a second effective herbicide for POST control of common lambsquarters or redroot pigweed, but it does provide residual control of these weeds when at least one-half inch of penetrating rainfall occurs, following application. In greenhouse experiments, ethofumesate alone or ethofumesate plus glyphosate applied to common lambsquarters, redroot pigweed, or waterhemp at heights of less than 2.5 cm provided the best combination of burndown and soil residual control compared with weeds that were 2.5 to 5 cm tall. Ethofumesate applied POST at 1.12 kg ha−1 plus glyphosate provided the best combination of tolerance and efficacy, especially on waterhemp.

Sugarbeet growers only recently have combined ethofumesate, S-metolachlor, and dimethenamid-P in a weed control system for waterhemp control. Sugarbeet plant density, visible stature reduction, root yield, percent sucrose content, and recoverable sucrose were measured in field experiments at five environments between 2014 and 2016. Sugarbeet stand density and stature reduction occurred in some but not all environments. Stand density was reduced with PRE application of S-metolachlor at 1.60 kg ai ha–1 and S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ai ha–1 alone or followed by POST applications of dimethenamid-P at 0.95 kg ai ha–1. Sugarbeet visible stature was reduced when dimethenamid-P followed PRE treatments. Stature reduction was greatest with ethofumesate at 1.68 or 4.37 kg ha–1 PRE and S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ha–1 PRE followed by dimethenamid-P at 0.95 kg ha–1 POST. Stature reduction ranged from 0 to 32% 10 d after treatment (DAT), but sugarbeet recovered quickly and visible injury was negligible 23 DAT. Although root yield and recoverable sucrose were similar across herbicide treatments and environments, we caution against the use of S-metolachlor at 0.80 kg ha–1 + ethofumesate at 1.68 kg ai ha–1 PRE followed by dimethenamid-P at 0.95 kg ha–1 in sugarbeet.

Sugarbeet, grown for biofuel, is being considered as an alternate cool-season crop in the southeastern United States. Previous research identified ethofumesate PRE and phenmedipham + desmedipham POST as herbicides that controlled troublesome cool-season weeds in the region, specifically cutleaf evening-primrose. Research trials were conducted from 2014 through 2016 to evaluate an integrated system of sweep cultivation and reduced rates of ethofumesate PRE and/or phenmedipham+desmedipham POST for weed control in sugarbeet grown for biofuel. There were no interactions between the main effects of cultivation and herbicides for control of cutleaf evening-primrose and other cool-season species in two out of three years. Cultivation improved control of cool-season weeds, but the effect was largely independent of control provided by herbicides. Of the herbicide combinations evaluated, the best overall cool-season weed control was from systems that included either a 1/2X or 1X rate of phenmedipham+desmedipham POST. Either rate of ethofumesate PRE was less effective than phenmedipham+desmedipham POST. Despite improved cool-season weed control, sugarbeet yield was not affected by cultivation each year of the study. Sugarbeet yields were greater when treated with any herbicide combination that included either a 1/2X or 1X rate of phenmedipham+desmedipham POST compared with either rate of ethofumesate PRE alone or the nontreated control. These results indicate that cultivation has a very limited role in sugarbeet grown for biofuel. The premise of effective weed control based on an integration of cultivation and reduced herbicide rates does not appear to be viable for sugarbeet grown for biofuel.

Sugarbeet, grown for biofuel, is being considered as an alternate cool-season crop in the southeastern U.S. coastal plain. Typically, the crop would be seeded in the autumn, then grow through the winter and be harvested the following spring. Labels for herbicides registered for use on sugarbeet grown in the traditional sugarbeet production regions do not list any of the cool-season weeds common in the southeastern United States. Field trials were initiated near Ty Ty, GA, to evaluate all possible combinations of ethofumesate applied PRE, phenmedipham+desmedipham applied POST, clopyralid POST, and triflusulfuron POST for cool-season weed control in sugarbeet. Phenmedipham+desmedipham alone and in combination with clopyralid and/or triflusulfuron effectively controlled cutleaf eveningprimrose, lesser swinecress, henbit, and corn spurry when applied to seedling weeds. Ethofumesate PRE alone was not as effective in controlling cool-season weeds compared to treatments containing phenmedipham+desmedipham POST. However, ethofumesate PRE applied sequentially with phenmedipham+desmedipham POST improved weed control consistency. Clopyralid and/or triflusulfuron alone did not adequately control cutleaf eveningprimrose. Triflusulfuron alone effectively controlled wild radish. In the 2013–2014 and 2014–2015 seasons, December-applied POST herbicides did not injure sugarbeet. However, in the 2015–2016 season POST herbicides were applied in late October. On the day of treatment, the maximum temperature was 25.4 C, which exceeded the established upper temperature limit of 22 C for safe application of phenmedipham+desmedipham, and sugarbeet plants were severely injured. In the southeastern United States, temperatures frequently exceed 22 C in early autumn, which may limit phenmedipham+desmedipham use for controlling troublesome cool-season weeds of sugarbeet in the region. Weed control options need to be expanded to compensate for this limitation.

Twelve sequential herbicide treatments were compared to cycloate (S-ethyl N-ethylthiocyclohexanecarbamate), a standard treatment, for control of annual weeds in sugarbeets (Beta vulgaris L.) in three field experiments conducted from 1971 through 1977. At harvest, seven sequential treatments had less than 10 annual broadleaf weeds per 30 m of row, whereas there were 40 broadleaf weeds per 30 m of row for the cycloate treatment. Four of these sequential treatments had significantly higher root yields and net returns than the cycloate treatment. Dependent on the sequential treatment and year, tonnage was increased 7.3 to 20.3 t/ha, and net returns $150 to $515/ha above those with cycloate. The most effective sequential treatment for control of weeds was a preplanting mixture of 2.2 kg/ha of ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] plus 1.7 kg/ha of diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} followed by a postemergence mixture of 0,6 kg/ha each of desmedipham [ethyl m-hydroxycarbanilate carbanilate (ester)] plus phenmedipham (methyl m-hydroxycarbanilate m-methylcarbanilate). This sequential herbicide treatment increased root yields by an average of 20.3 t/ha and net returns by $515/ha above those with cycloate.

Preplant applied herbicides were compared for their effect on three varieties of sugarbeets when seeds were planted at six depths during 1987 through 1989. More sugarbeet seedlings emerged and at a faster rate as the depth of seeding decreased from 4.5 to 1.6 cm. Herbicide injury to sugarbeet seedlings increased as depth of seeding increased from less than to greater than 2.5 cm. Herbicide treatments reduced sugarbeet stand and decreased early season sugarbeet height but had little effect on root yield or sucrose content.

A field experiment was conducted for 2 yr near Scottsbluff, NE, to evaluate the growth and yield response of nine commercial sugarbeet cultivars to five postemergence herbicide mixtures applied two times. Sugarbeet cultivars varied in their response to herbicides. Three of the five postemergence herbicide mixtures reduced sugarbeet leaf area at 9 wk after planting (WAP), while two treatments had no significant effect. Root yield reductions from herbicide treatments ranged from 3 to 11% averaged over the nine cultivars. Two applications of desmedipham plus phenmedipham at 180 plus 180 g/ha reduced root yield 3% compared to untreated plots. Two applications of clopyralid at 100 g/ha, triflusulfuron at 18 g/ha, or ethofumesate at 160 g/ha plus desmedipham plus phenmedipham resulted in a 17, 29, and 22% reduction in leaf area at 9 WAR respectively, and a 6, 8, and 6% reduction in root yield, respectively, compared to untreated plots. Sethoxydim at 280 g/ha plus desmedipham plus phenmedipham did not cause additional sugarbeet injury.

Two field studies, a seeded study and a golf course study, were conducted to compare competition among creeping bentgrass, annual bluegrass, and roughstalk bluegrass when subjected to common weed control practices and foliar applications of iron and magnesium. A research site was selected for the seeded study and divided into 10 whole plots receiving irrigation at either 50 or 100% evapotranspiration deficit. Each whole plot was further divided into subplots receiving one of seven treatments: bensulide, ethofumesate, trinexapac-ethyl, foliar Mg, foliar Fe, foliar Mg plus foliar Fe, and control. The site was seeded to a mixture of creeping bentgrass, annual bluegrass, and roughstalk bluegrass in September 1995, and treatments began in March 1996. Annual bluegrass was reduced 29% in plots treated with foliar Fe and 65% in plots treated with foliar Fe plus foliar Mg. Roughstalk bluegrass was significantly reduced in seeded plots treated with foliar iron (50%), plant growth regulator (75%), and foliar iron plus foliar magnesium (100%). Annual bluegrass and roughstalk bluegrass proportions were not affected by irrigation regime. In a second study, the most effective treatment, foliar magnesium plus foliar iron, was tested on a working golf course fairway and on a practice putting green beginning April 1997 and ending November 1997. Treatments on the golf course fairway and practice putting green were ineffective due to the established, perennial nature of the annual bluegrass biotypes on these sites. Further research is required to improve the efficacy of nutritional treatments on these perennials.

Bermudagrass growing in a creeping bentgrass green is a severe problem where both grasses are grown. An experiment was conducted to determine the effects of multiple flurprimidol-herbicide applications on tolerance of bentgrass and on suppression of three bermudagrass cultivars in bentgrass. Application of 1.4 kg ai ha–1 flurprimidol on April 15 and 0.8 kg ha–1 repeated on June 1 injured creeping bentgrass 44% in 1988 and 22% in 1989. Bermudagrass was suppressed from the two flurprimidol applications until mid-June in 1988. Growth in 1989 was not influenced by number of applications since bermudagrass was suppressed only until late May. Application of 0.8 + 54 kg ai ha–1 flurprimidol plus siduron on April 15 and 0.4 + 27 kg ha–1 on June 1 injured creeping bentgrass 23 to 28% and suppressed bermudagrass until mid-July in 1988 and mid-June in 1989. Application of 0.8 + 1.7 kg ha–1 flurprimidol plus ethofumesate on April 15 and 0.4 + 0.8 kg ha–1 on June 1 injured creeping bentgrass 25 to 28% and effectively suppressed bermudagrass until late August in 1988 and late June in 1989. Application of 0.8 + 54 kg ha–1 flurprimidol plus siduron or 0.8 + 1.7 kg ha–1 flurprimidol plus ethofumesate applied in June or June and July to plots treated in April did not improve bermudagrass suppression. In most instances there was an inverse relationship between bermudagrass suppression and number of bermudagrass stolons. There were interactions between flurprimidol-herbicide treatments on bermudagrass cultivars on number of stolons but not on suppression.

Preplant control of mannagrass was greater than 90% with clethodim, glyphosate, sethoxydim, and sulfosate. Glyphosate at 0.5 to 1.0 kg ai/ha controlled mannagrass greater than 97%, and was not increased with any adjuvant. Fenoxaprop applied POST controlled mannagrass 97% but injured rice 33%. Except for fenoxaprop-ethyl, all POST treatments increased rice yields at least 1560 kg/ha more than the non-treated check. Southern watergrass was controlled 79 and 89% with 1.0 kg ai/ha glyphosate and 4.5 kg ai/ha sulfosate, respectively, while control was less than 55% with other herbicides.

Green kyllinga is a relatively new weed species in well-irrigated turfs in the southwest US. To understand the germination requirements of green kyllinga, the effects of planting depth, temperature, pH, and osmotic potential were determined. Green kyllinga emergence was sensitive to planting depth. At 21 days after planting (DAP), emergence of green kyllinga was 60% when planted at the soil surface but only 20% at 0.5 cm and less than 5% at 1 cm. Germination occurred at temperatures between 17 and 30 C but was notably better between 20 and 24 C. Germination was uniform from pH 5.5 to 9.5. Germination decreased between the water potentials −0.1 to −0.6 MPa, although germination was high at water potentials found in irrigated turf. The environmental conditions found in nonstressed turf areas in Arizona will likely support the establishment of green kyllinga. The efficacy of herbicides for the control of green kyllinga was also determined. Control of kyllinga (95% or greater) was obtained with preemergence applications of oxadiazon, dithiopyr, and metolachlor, and with postemergence applications of DSMA, halosulfuron-methyl, and imazaquin.

Velvetleaf control and sugarbeet response to POST triflusulfuron applied alone and in combination with desmedipham plus phenmedipham, nonionic surfactant, and urea ammonium nitrate (50:50) were evaluated in the greenhouse (velvetleaf only) and field. In a second field study, the effect of POST applications of triflusulfuron, desmedipham plus phenmedipham, ethofumesate, endothall, or combinations of these herbicides on sugarbeet root yield and quality was determined in the absence of weeds. Triflusulfuron controlled velvetleaf only when nonionic surfactant (NIS) was added to the spray solution. Desmedipham plus phenmedipham plus triflusulfuron gave greater velvetleaf control than triflusulfuron in the absence of NIS in the field. However, adding desmedipham plus phenmedipham to triflusulfuron plus NIS decreased velvetleaf control in the greenhouse. Adding desmedipham plus phenmedipham to triflusulfuron plus NIS increased visible sugarbeet response compared to triflusulfuron plus nonionic surfactant or desmedipham plus phenmedipham 14 d after the last POST application in 1994. In the absence of weeds, POST herbicide applications that included triflusulfuron did not reduce sugarbeet root yield more than other POST herbicides.

Ethofumesate, [(+)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] applied preemergence provided selective control of annual bluegrass (Poa annua L.) in perennial ryegrass (Lolium perenne L.) overseeded on dormant bermudagrass [Cynodon dactylon (L.) Pers. X C. transvaalensis Burtt Davy ‘Tifdwarf’] golf greens. Control in excess of 95% was obtained with single applications at the 2.2 kg/ha rate in 2 of 3 yr, but multiple applications were required when ethofumesate was applied at 1.1 kg/ha or less. Ethofumesate caused temporary cessation of bermudagrass growth when applied in the fall. February applications slowed the spring transition to bermudagrass.

Economical combinations of herbicides and hand labor for weeding sugarbeets (Beta vulgaris L.) in high and low weed densities were determined for irrigated production in the southern Great Plains. Ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] preplant incorporated, a 50:50 mixture of phenmedipham (methyl m-hydroxycarbanilate m-methylcarbanilate) and desmedipham (ethyl m-hydroxycarbanilate carbanilate (ester)] sprayed postemergence on small weeds, and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) incorporated at layby controlled pigweed (Amaranthus spp.) and kochia [Kochia scoparia (L.) Schrad.] with acceptable selectivity in sugarbeets. Sucrose yield was identical for all methods of weed control. Using herbicides did not lower, and in some cases doubled, the total cost of weed control in an area with a low weed density. On the other hand, effective herbicide combinations saved $298 to $966/ha compared to total reliance on hand labor in an area with a high weed density. Elaborate combinations of herbicides were not justified even with heavy weed density. The last few weeds remaining in a field can be most economically removed by hand labor.

Field experiments were conducted near Scottsbluff, NE, to evaluate the selectivity of sequential POST applications of ethofumesate and triflusulfuron for weed control in sugarbeet. When applied alone ethofumesate and triflusulfuron reduced common lambsquarters, hairy nightshade, and redroot pigweed density while triflusulfuron also reduced kochia density compared with an untreated control. Combining ethofumesate with desmedipham plus phenmedipham increased sugarbeet injury compared with desmedipham plus phenmedipham. Combining triflusulfuron with desmedipham plus phenmedipham increased kochia control but did not increase sugarbeet injury over that obtained with desmedipham plus phenmedipham. Weed control and sugarbeet injury from herbicides generally were unaffected by application in 97 or 182 L/ha of water carrier. However, herbicide control of hairy nightshade in 1993 was greater with 97 than 182 L/ha of water carrier.

Velvetleaf control in sugarbeet by clomazone and commercially available sugarbeet herbicides was investigated in greenhouse and field studies. In greenhouse studies, clomazone at 0.07 and 0.04 kg ai ha-1 controlled 97 and 69% of velvetleaf, respectively, with little visible sugarbeet injury. Adding clomazone to pyrazon, TCA, ethofumesate, pyrazon plus TCA, or TCA plus ethofumesate increased velvetleaf control but increased visible sugarbeet injury. In field studies, clomazone at 0.07 kg ha-1 did not enhance sugarbeet injury. However, velvetleaf was not controlled by clomazone alone or clomazone plus pyrazon, ethofumesate, combinations of pyrazon plus TCA, pyrazon plus ethofumesate, or pyrazon plus TCA plus ethofumesate. Cycloate preplant incorporated plus pyrazon preemergence followed by postemergence herbicides controlled velvetleaf in all 3 yr of research. Postemergence herbicides increased velvetleaf control from soil-applied herbicides in 1987 and 1988.

Ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] applied postemergence in November at rates from 1.4 to 4.5 kg/ha eliminated all annual bluegrass (Poa annua L.) that had survived application of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in fall carbon-planted perennial ryegrass (Lolium perenne L.) seed fields. Ethofumesate also eliminated all annual bluegrass in established perennial ryegrass seed fields when applied in late October at rates from 1.1 to 3.4 kg/ha or when applied as sequential treatments with atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 1.4 kg/ha or with simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 2.2 kg/ha. In most experiments, perennial ryegrass seed yields were not adversely affected by applications of ethofumesate alone or by sequential treatments with diuron, atrazine, or simazine.

The postemergence herbicide ethofumesate and the plant growth regulator paclobutrazol were evaluated for annual bluegrass control in creeping bentgrass turf managed as golf fairways. Both products were applied under several different timing regimes relative to the time of the year. Paclobutrazol treatments provided significantly greater annual bluegrass control than ethofumesate. There were no differences between rates of paclobutrazol (0.28 and 0.14 kg ai/ha) when applied from spring through summer. Annual bluegrass control after spring and summer applications of paclobutrazol was 85% or more. Clipping weight data indicated that paclobutrazol suppressed growth in annual bluegrass longer than in creeping bentgrass. It was concluded that prolonged suppression of annual bluegrass by paclobutrazol resulted in creeping bentgrass dominance and subsequent annual bluegrass control. Additionally, applications of ethofumesate in autumn–winter, followed by paclobutrazol applied in spring–summer, provided significant control of annual bluegrass in 1 yr of the study.

Volunteer potatoes are difficult to control in onions and can greatly reduce onion growth and yield. Herbicides and cultivation were evaluated for control of simulated volunteer potatoes in onions in 1996 and 2000. Three interrow cultivations did not control potatoes in the onion row and the remaining plants reduced onion yield 50 and 73% compared with the hand-weeded checks. Three applications of oxyfluorfen (0.2 + 0.17 + 0.17 kg ai/ha) or bromoxynil plus oxyfluorfen (0.2 + 0.17 kg ai/ha) at the two-, three-, and four- to five-leaf stages of onions followed by a cultivation after each application reduced potato tuber weight 69 to 96% and tuber number 32 to 86% compared with cultivation alone and prevented onion yield loss associated with potatoes. Ethofumesate applied preemergence at 0.6 kg/ha followed by postemergence ethofumesate plus bromoxynil and cultivation reduced potato tuber weight 90% and tuber number 68% compared with cultivation alone, and onions yielded equal to hand-weeded checks. Two applications of fluroxypyr (0.3 kg ai/ha) plus bromoxynil (0.2 kg ai/ha) at the two- and three-leaf stages of onions followed by a cultivation after each application reduced potato tuber weight by greater than 90%, but onion yields were reduced 38 to 66%.