Fenoxaprop effectively controls crabgrass in tall fescue turf, but antagonism with growth-regulating herbicides reduces potential to apply fenoxaprop in combination with many herbicides registered for broadleaf weed control. Aminocyclopyrachlor is a new broadleaf weed control herbicide that has not been evaluated in combination with fenoxaprop. Field experiments were conducted in Georgia, New Jersey, and Tennessee to investigate tank mixtures of fenoxaprop with aminocyclopyrachlor for smooth crabgrass and white clover control. Fenoxaprop alone exhibited substantial activity on smooth crabgrass but control was greater with fenoxaprop + aminocyclopyrachlor treatments. By 4 and 6 wk after treatment (WAT), approximately 22 and 44% less fenoxaprop was required to achieve 80% smooth crabgrass control when the herbicide was tank-mixed with aminocyclopyrachlor at 52.5 and 79 g ai ha −1 , respectively. Fenoxaprop did not reduce white clover control with aminocyclopyrachlor because 97% control was achieved by 4 WAT for all aminocyclopyrachlor + fenoxaprop treatments. Tall fescue was not injured by any treatment. Results suggest aminocyclopyrachlor enhances fenoxaprop efficacy for smooth crabgrass control in tall fescue.

Bispyribac-sodium and sulfosulfuron are labeled for roughstalk bluegrass control in creeping bentgrass but comprehensive investigations are limited for long-term control. The objective of these field experiments was to investigate roughstalk bluegrass control with these herbicides on a creeping bentgrass fairway over three years. Bispyribac-sodium was applied twice at 37, 74, or 111 g a.i./ha or thrice at 37 or 74 g/ha. Sulfosulfuron was applied twice or thrice at 6.5 or 13 g a.i./ha or once at 26 g/ha. Creeping bentgrass chlorosis from herbicides was less than 20% by two to three weeks after applications while all treatments generally provided substantial reductions in roughstalk bluegrass cover by late July. However, roughstalk bluegrass regrowth was detected by October in all three years suggesting herbicide applications visually eliminated foliage but did not control the entire plant. Overall, bispyribac-sodium and sulfosulfuron effectively suppressed roughstalk bluegrass ground cover in summer months but regrowth during fall months prevented long-term successful control.

Amicarbazone has potential for selective annual bluegrass control in cool-season turfgrasses, but seasonal application timings may influence efficacy. To test this hypothesis, field experiments in New Jersey and Indiana investigated amicarbazone efficacy from fall or spring applications and growth chamber experiments investigated the influence of temperature on efficacy. Fall treatments were more injurious to creeping bentgrass and Kentucky bluegrass than spring applications, but fall applications were also more efficacious for annual bluegrass control. In growth chamber experiments, injury and clipping weight reductions were exacerbated by increased temperatures from 10 to 30 C on annual bluegrass, creeping bentgrass, Kentucky bluegrass, and perennial ryegrass. Results suggest that amicarbazone use for annual bluegrass control in cool-season turf may be limited to spring applications, but increased temperature enhances activity on all grasses.

Bispyribac-sodium selectively controls annual bluegrass in cool-season turf but efficacy may be influenced by management practices, such as plant growth regulator use. Experiments were conducted in New Jersey to investigate efficacy and absorption of bispyribac-sodium applied with trinexapac-ethyl for annual bluegrass control and turfgrass tolerance. In laboratory experiments with annual bluegrass, creeping bentgrass, and perennial ryegrass, tank-mixing trinexapac-ethyl with 14 C-bispyribac-sodium increased presumed foliar absorption of 14 C-bispyribac-sodium compared with nontrinexapac-ethyl treated; absorption increased with trinexapac-ethyl rate. Differences in 14 C-bispyribac-sodium absorption were not detected among emulsifiable concentration, microencapsulated concentration, and wettable powder trinexapac-ethyl formulations. In field experiments, sequential bispyribac-sodium applications controlled annual bluegrass 93%, but trinexapac-ethyl did not affect efficacy. Tank-mixing all trinexapac-ethyl formulations with bispyribac-sodium provided similar annual bluegrass control and creeping bentgrass quality compared with bispyribac-sodium alone. Applications of bispyribac-sodium reduced dollar spot cover in both years, whereas trinexapac-ethyl reduced dollar spot cover only in 2005.

Bispyribac-sodium is an efficacious herbicide for annual bluegrass (Poa annua L.) control with potential for use in perennial ryegrass (Lolium perenne L.) and tall fescue [Festuca arundinaceae (L.) Shreb.]. Field experiments investigated bispyribac-sodium efficacy applied sequentially for annual bluegrass control in perennial ryegrass and tall fescue under home lawn maintenance. Bispyribac-sodium from 37 to 296 g a.i./ha injured perennial ryegrass and tall fescue no greater than 15% and 23%, respectively, while both grasses completely recovered from injury after two months. Bispyribac-sodium from 37 to 148 g a.i./ha provided inconsistent levels of annual bluegrass control over years but treatments at 222 and 296 g/ha provided ≥ 90% control in both years. Overall, sequential bispyribac-sodium applications appear to safely control annual bluegrass in perennial ryegrass and tall fescue.

ABSTRACTTransgenic herbicide‐resistant cultivars of creeping bentgrass (Agrostis stolonifera L.) have been developed and are being considered for commercial release. Concerns regarding transgenic species include potential for outcrossing of the crop, which may produce novel genotypes with increased weediness. Persistence and multiyear growth of interspecific hybrids between creeping bentgrass and velvet bentgrass (A. canina L.), colonial bentgrass (A. capillaris L.), dryland bentgrass (A. castellana Boiss. and Reut.), and redtop bentgrass (A. gigantea Roth) and the backcross progeny of the hybrids were compared with the parental species in field experiments. The plants were evaluated over 2 yr in residential Kentucky bluegrass (Poa pratensis L.) and a low maintenance roadside turf of mixed species. With the exception of redtop bentgrass by creeping bentgrass interspecific hybrids, all interspecific hybrids between creeping bentgrass and colonial, dryland, and velvet bentgrasses were equally or less competitive relative to their parental species. Backcross progeny of interspecific hybrids, including those of redtop bentgrass by creeping bentgrass hybrids, were equally or less competitive than parental species. Bentgrasses that were highly competitive in residential turf were also competitive under roadside maintenance, suggesting bentgrasses have weediness potential regardless of management intensity.

Spray adjuvants may enhance bispyribac–sodium efficacy for annual bluegrass control but chelated iron may be needed to reduce potential turf discoloration. Field and laboratory experiments were conducted to investigate the influence of iron and adjuvants on bispyribac–sodium efficacy for annual bluegrass control in cool-season turf. In laboratory experiments,14C–bispyribac–sodium foliar absorption increased in four grasses by approximately 50 and 100% when applied with a nonionic surfactant and methylated seed oil, respectively, compared to the herbicide alone. Chelated iron did not reduce14C–bispyribac–sodium absorption. In field experiments, spray adjuvants enhanced annual bluegrass control from bispyribac–sodium at 37 g ai/ha but not at 74 g ai/ha. Iron did not reduce annual bluegrass control from bispyribac–sodium, with or without adjuvants, but mitigated creeping bentgrass discoloration for all treatments.

Bispyribac-sodium is an efficacious herbicide for annual bluegrass control in creeping bentgrass fairways, but turf tolerance and growth inhibition may be exacerbated by low mowing heights on putting greens. We conducted field and greenhouse experiments to investigate creeping bentgrass putting green tolerance to bispyribac-sodium. In greenhouse experiments, creeping bentgrass discoloration from bispyribac-sodium was exacerbated by reductions in mowing height from 24 to 3 mm, but mowing height did not influence clipping yields or root weight. In field experiments, discoloration of creeping bentgrass putting greens was greatest from applications of 37 g/ha every 10 d, compared to 74, 111, or 222 g/ha applied less frequently. Chelated iron effectively reduced discoloration of creeping bentgrass putting greens from bispyribac-sodium while trinexapac-ethyl inconsistently reduced these effects. Overall, creeping bentgrass putting greens appear more sensitive to bispyribac-sodium than higher mowed turf, but chelated iron and trinexapac-ethyl could reduce discoloration.

Bispyribac-sodium selectively controls annual bluegrass in creeping bentgrass and perennial ryegrass, which might be attributed to differential metabolism among species. To test this hypothesis, we investigated metabolism of 14 C-bispyribac-sodium in annual bluegrass, creeping bentgrass, and perennial ryegrass. Creeping bentgrass and perennial ryegrass metabolized approximately 50% of the 14 C-bispyribac-sodium after 1 d, while annual bluegrass metabolized less than 20%. Parent herbicide recovered 7 d after treatment in annual bluegrass, creeping bentgrass, and perennial ryegrass was 73, 32, and 39% of total radioactivity per species, respectively. Polar metabolites recovered after 7 d in annual bluegrass, creeping bentgrass, and perennial ryegrass were 24, 59, and 55% of total radioactivity per species, respectively. Half-life of 14 C-bispyribac-sodium in annual bluegrass, creeping bentgrass, and perennial ryegrass was estimated at greater than 7 d, 1 d, and 2 d, respectively. Results support the hypothesis that differential tolerances of these grasses are attributed to herbicide metabolism.

Roughstalk bluegrass (Poa trivialis L.) and tall fescue [Festuca arundinaceae (L.) Shreb.] are problematic weeds in Kentucky bluegrass (Poa pratensis L.) with limited herbicides for selective control. Field experiments in 2006 and 2007 investigated sulfosulfuron efficacy on these weeds in Kentucky bluegrass. Sulfosulfuron controlled tall fescue ≥ 97% and was similar to sequential chlorsulfuron applications. However, sulfosulfuron was not as injurious to Kentucky bluegrass as sequential chlorsulfuron treatments. Sulfosulfuron controlled roughstalk bluegrass up to 95% with acceptable turf injury (< 20%). Overall, sulfosulfuron appears to have potential for tall fescue and roughstalk bluegrass control in Kentucky bluegrass.

Sulfosulfuron was recently registered for grassy weed control in creeping bentgrass, but turf sensitivity is a concern for intensively managed golf courses. Field and growth chamber experiments in New Jersey investigated creeping bentgrass growth responses and tolerance to sulfosulfuron. Creeping bentgrass chlorosis increased with sulfosulfuron rate but turf had less chlorosis from sequential sulfosulfuron applications compared to bispyribac–sodium. Herbicide-treated turf had similar root weight compared to untreated turf on six sampling dates. In growth-chamber experiments, creeping bentgrass treated with sulfosulfuron had chlorosis and clipping weight reductions exacerbated by reductions in temperature from 25 to 15 C. Overall, creeping bentgrass appears to tolerate sequential sulfosulfuron applications better than or comparable to bispyribac-sodium in early summer, whereas creeping bentgrass sensitivity to sulfosulfuron increases at cooler temperatures.

Field and laboratory experiments were conducted in New Jersey to investigate the influence of spray adjuvants on foliar absorption and efficacy of bispyribac–sodium on annual bluegrass, creeping bentgrass, and perennial ryegrass. In laboratory experiments on annual bluegrass, 14C–bispyribac–sodium without an adjuvant had 25% foliar absorption by 8 h after treatment, whereas absorption increased to 45, 46, and 75% when applied with crop oil concentrate, nonionic surfactant, and methylated seed oil, respectively. In creeping bentgrass fairways, sequential bispyribac–sodium applications at 37 g ai/ha with spray adjuvants controlled annual bluegrass similarly to 74 g ai/ha applied sequentially without adjuvants. In perennial ryegrass, treatments with methylated seed oil and nonionic surfactant required 25 and 41% lower bispyribac–sodium rates, respectively, to obtain annual bluegrass control levels comparable to bispyribac–sodium rates without adjuvants. Spray adjuvants did not exacerbate turf-grass discoloration from bispyribac–sodium. Overall, spray-adjuvant use with bispyribac–sodium may allow practitioners to reduce application rates and enhance efficacy for annual bluegrass control. Nomenclature: Bispyribac–sodium, annual bluegrass, Poa annua L., creeping bentgrass, Agrostis stolonifera L., ‘L-93’, ‘Penncross’, perennial ryegrass, Lolium perenne L., ‘Manhattan 4’

Annual bluegrass ( Poa annua L.) is a problematic weed in Kentucky bluegrass ( Poa pratensis L.). Bispyribac-sodium herbicide can effectively control established annual bluegrass in other cool-season turfgrasses, but unacceptable injury to Kentucky bluegrass has been reported. However, only a few Kentucky bluegrass cultivars have been evaluated. The objective of this study was to determine the extent of intraspecific variability among Kentucky bluegrass cultivars and selections to sequential applications of bispyribac-sodium herbicide. Field experiments were conducted in 2004 and 2005 in New Jersey to determine the response of 55 Kentucky bluegrass cultivars and selections to bispyribac-sodium. The herbicide was applied at 188 g·ha −1 followed 3 weeks later by a second application of 281 g·ha −1 . Kentucky bluegrass injury ranged from 8% to 93% 8 weeks after initial treatment (WAIT). ‘Blackstone’, ‘Serene’, and A98-962 were the most tolerant to bispyribac-sodium, exhibiting less than 20% injury 8 WAIT. Conversely, ‘Washington’, 95AN-10, and ‘Avalanche’ were the most susceptible with up to 93% injury 8 WAIT. The range in tolerance to bispyribac-sodium within Kentucky bluegrass indicates the potential for the identification and development of cultivars with improved tolerance to bispyribac-sodium herbicide.

Annual bluegrass is a troublesome weed of Kentucky bluegrass because of a lack of selective POST herbicides for control. Field experiments were conducted in New Jersey to investigate the potential of bispyribac-sodium, primisulfuron, and sulfosulfuron for selective annual bluegrass control in Kentucky bluegrass. Primisulfuron provided the best combination of Kentucky bluegrass safety and annual bluegrass control with greater efficacy in summer than fall. Bispyribac-sodium also provided substantial annual bluegrass control, especially in the summer, but caused unacceptable (> 20%) Kentucky bluegrass injury, whereas annual bluegrass control with sulfosulfuron was inconsistent. Growth chamber experiments confirmed that greater primisulfuron efficacy in summer than fall may be attributed to higher temperatures. Overall, primisulfuron has promising implications for future use in Kentucky bluegrass for annual bluegrass control whereas bispyribac-sodium will likely be more applicable in other cool-season turfgrasses.

Previous research has demonstrated that bispyribac-sodium can selectively control established annual bluegrass ( Poa annua L.) in creeping bentgrass ( Agrostis stolonifera L.). Annual bluegrass is also a problematic weed in other cool-season turfgrass species. However, the relative tolerance of other cool-season turfgrass species to bispyribac is not known. Field experiments were conducted at Adelphia, N.J., in 2002 and 2003 to gain understanding of the phytotoxic effects that bispyribac may have on kentucky bluegrass ( Poa pratensis L.), perennial ryegrass ( Lolium perenne L.), tall fescue ( Festuca arundinacea (L.) Schreb.), and chewings fine fescue ( Festuca rubra L. subsp. commutata Gaud.). Single applications of bispyribac at 37 to 296 g·ha –1 were applied to mature stands of each species on 11 June, 2002 and 10 June, 2003. Visual injury was evaluated and clippings were collected 35 and 70 days after treatment (DAT). Visual injury at 35 DAT increased as bispyribac rate increased. Kentucky bluegrass was least tolerant to bispyribac with up to 28% injury when applied at 296 g·ha –1 . Injury on other species did not exceed 20%. Initial injury on perennial ryegrass, tall fescue, and chewings fine fescue was primarily in the form of chlorosis, while kentucky bluegrass exhibited more severe stunting and thinning symptoms. Bispyribac at rates from 74 to 296 g·ha –1 reduced kentucky bluegrass clipping weights by 19% to 35%, respectively, as compared to the untreated control at 35 DAT in 2002. Initial visual injury on perennial ryegrass, tall fescue, and chewings fine fescue dissipated to ≤5% by 70 DAT. However, recovery of kentucky bluegrass was less complete. These studies suggest that bispyribac-sodium has potential to severely injure kentucky bluegrass. Injury on perennial ryegrass, tall fescue, and chewings fine fescue appears to be less severe and persistent; therefore, bispyribac can be used for weed control in these species. Chemical names used: 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoic acid (bispyribac-sodium).

Studies were conducted in 2002 and 2003 on a golf course fairway in New Jersey to compare spring, summer, and fall treatments of bispyribac-sodium for annual bluegrass control and creeping bentgrass tolerance. Single applications at 74, 111, or 148 g ai/ha were applied in May, August, or October. Split applications of 37 followed by (fb) 37 or 74 fb 74 g/ha applied 3 wk apart were also evaluated. Summer-applied bispyribac-sodium did not reduce bentgrass quality, whereas spring and fall treatments reduced turf quality at 3 wk after treatment and fall treatments in 2002 substantially reduced bentgrass quality. Summer treatments were more effective than spring or fall treatments in reducing annual bluegrass cover. Final evaluations revealed 36, 31, 21, and 26% annual bluegrass cover averaged across nontreated, spring-treated, summer-treated, and fall-treated plots, respectively. This study demonstrates that two split applications of bi spyribac- sodium at 74 g/ha in summer can effectively reduce annual bluegrass cover while minimizing creeping bentgrass injury.

Bispyribac-sodium is a POST herbicide that selectively controls annual bluegrass in creeping bentgrass, but inconsistent results with seasonal applications are believed to occur from temperature influences on bispyribac-sodium efficacy. Growth chamber experiments at the New Jersey Experimental Greenhouse Research Complex, New Brunswick, NJ, investigated three temperature regimes on 'L-93' creeping bentgrass and annual bluegrass responses to bispyribac-sodium. Annual bluegrass and creeping bentgrass exhibited contrasting responses to bispyribac-sodium as temperature increased from 10 to 30 C. Regressions of 4 week after treatment (WAT) data revealed as temperature increased from 10 to 30 C, required bispyribac-sodium rates for 50% clipping reduction (CR50) of annual bluegrass decreased from 85 to 31 g ai/ha and required rates for 50% leaf chlorosis decreased from greater than 296 to 98, indicating increased herbicidal efficacy at higher temperatures. In contrast, required bispyribac-sodium rates for creeping bentgrass CR50 increased from 200 to greater than 296 as temperature increased from 10 to 30 C. Bispyribac-sodium discolored creeping bentgrass 0 to 20% at 20 and 30 C and discoloration increased 10 to 50% at 10 C. Thus, warmer temperatures (20 and 30 C) increase bispyribac-sodium efficacy for annual bluegrass control with minimal bentgrass discoloration; however, cooler temperatures (10 C) have minimal efficacy on annual bluegrass and increase bentgrass chlorosis.

Turf managers may wish to reseed turfgrass species into areas where weeds have been eliminated by sulfosulfuron treatments. Field studies were conducted in 2002 and 2003 in New Jersey to determine when creeping bentgrass ( Agrostis stolonifera L.), Kentucky bluegrass ( Poa pratensis L.), and perennial ryegrass ( Lolium perenne L.) can be safely reseeded after a sulfosulfuron application. Sulfosulfuron at 34 or 67 g ai/ha was applied 6, 4, 2, or 1 week before seeding (WBS). Data pooled across sulfosulfuron rates revealed ground cover of creeping bentgrass, Kentucky bluegrass, and perennial ryegrass at 3 weeks after seeding (WAS) was reduced to 41, 30, and 70% of the untreated by applications 1 WBS, respectively. Our study suggests that perennial ryegrass can be safely reseeded two weeks after a sulfosulfuron application, whereas creeping bentgrass and Kentucky bluegrass may require two to four weeks before reseeding can occur.

Plant growth regulators (PGRs) are commonly applied for annual bluegrass (Poa annua L.) suppression but various PGR regimens may be more applicable in creeping bentgrass (Agrostis palustris Huds.) management than exclusive applications. Two field experiments in Riverton, NJ investigated various regimens of paclobutrazol ((⁺/-)-(R*,R*)-b-[(4-chlorophenyl) methyl]-a-(1, 1-dimethyl)-1H-1,2,4,-triazole-1-ethanol) (PB) and trinexapac-ethyl ([4-(cyclopropyl-[a]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester]) (TE) for Poa annua control in creeping bentgrass golf course fairways. Over four years, Poa annua coverage was greater in the spring compared to summer and fall. In the first experiment, Poa annua reductions from initial populations were 22 and 30% in untreated turf and turf treated only with TE, respectively. Reductions in Poa annua were ≈ 55% for turf receiving PB with and without TE applications. In the second experiment, PB reduced Poa annua populations to approximately half those of the untreated plots but combinations with TE did not enhance turf quality or Poa annua suppression. Routinely applying PB at 0.14 kg/ha every 3 weeks provided similar Poa annua control to single applications of 0.56 kg/ha while both regimens gave better control than PB at 0.28 kg/ha applied in the spring and fall. Overall, PB will be an effective tool for suppressing Poa annua in creeping bentgrass fairways for northeastern golf courses; however, tank mixing TE with PB will likely not enhance these effects.