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Japanese stiltgrass is regarded as one of the most troublesome invasive species in the United States. It is commonly found invading forested areas; however, more recently it has been noted to be invading golf course roughs and out-of-play areas. The purpose of this study was to evaluate POST herbicide control of Japanese stiltgrass in golf course and highly maintained turfgrass facilities. None of the treatments provided >80% Japanese stiltgrass control 2 wk after treatment (WAT). At 4 WAT >80% Japanese stiltgrass control was observed with MSMA, MSMA + metribuzin, amicarbazone, and sethoxydim, whereas metsulfuron, pinoxaden, and imazapic provided minimum control. By 8 WAT, MSMA, MSMA + metribuzin, amicarbazone, and sethoxydim provided >98% control, whereas quinclorac, metsulfuron, pinoxaden, and imazapic provided no visible control. Thiencarbazone-methyl + foramsulfuron + halosulfuron-methyl, and sulfentrazone provided limited (≤60%) control. This study indicates that POST control of Japanese stiltgrass can be achieved with MSMA, MSMA + metribuzin, amicarbazone, and sethoxydim. Future research should include long-term control over multiple growing seasons, repeat applications of herbicides, and evaluation of herbicides in combination for increased and longer-term Japanese stiltgrass control.

Two species, torpedograss and Southern watergrass, are very difficult to selectively control when they invade desirable turfgrass stands. The purpose of this study was to evaluate selective control of torpedograss and Southern watergrass in ‘Tifway’ bermudagrass turf. Greater than 86% control of torpedograss was observed 4 wk after sequential treatment (WAST) with quinclorac, trifloxysulfuron-sodium, quinclorac and trifloxysulfuron-sodium, sulfentrazone + imazethapyr and quinclorac and trifloxysulfuron-sodium, and quinclorac and trifloxysulfuron-sodium followed by (fb) glyphosate. However, by 8 WAST, control was reduced to

Goosegrass is a weedy C4species throughout the world and a major pest in turfgrass systems. Further research is needed to characterize morphological events of goosegrass germinating in late summer to enhance long-term management programs. The objective of this study was to determine whether goosegrass germinating on August 15 will complete a life cycle before the first killing frost, typically November 15 in Clemson, SC. A biotype from Clemson, SC, was collected and a growth-chamber experiment was conducted to simulate autumn maximum and minimum temperatures. Culm, leaf, root, and raceme biomass measurements were recorded weekly, and growth curves were modeled. The inflection point (i.e., point of maximum growth) occurred for the following growth parameters: culm dry weight at 26.5 d after emergence (DAE), leaf dry weight at 26.6 DAE, number of racemes per plant at 50.7 DAE, raceme dry weight (including germinable seed) at 56.0 DAE, and root dry weight at 42.1 DAE. The completion of the life cycle occurred on October 22 (68 DAE), approximately 3 wk before the typical first killing frost in Clemson, SC. In summary, turf managers need to address goosegrass that germinates through approximately the first week of September at this location to avoid production of viable seed.

Doveweed is a problematic weed of lawns and sod production, as well as golf course roughs, fairways, and tees. End-user reports of selective POST control options are inconsistent and control is often short-lived. In addition, inconsistent control with non-selective herbicides such as glyphosate is common. The goals of this research were: (1) evaluate selective POST doveweed control options in ‘Tifway’ hybrid bermudagrass turf; (2) compare efficacy of single vs. sequential applications of selective POST herbicides; (3) quantify doveweed tolerance to glyphosate; and (4) quantify recovery of foliar applied glyphosate following treatment with a C14-glyphosate solution. A single application of sulfentrazone metsulfuron; thiencarbazone iodosulfuron dicamba or 2,4-D MCPP dicamba carfentrazone; or thiencarbazone foramsulfuron halosulfuron provided >60% control 2 weeks after initial treatment (WAIT). A second application of these treatments 3 WAIT improved control 6 WAIT. Two applications of 2,4-D MCPP dicamba carfentrazone or thiencarbazone foramsulfuron halosulfuron provided ~80% control 6 WAIT. Doveweed was tolerant to glyphosate application up to 5.68 kg ae ha-1. Absorption of 14C-glyphosate was compared between doveweed with cuticle intact, doveweed with a disturbed cuticle, and smooth crabgrass. 14C-glyphosate recovery from the leaf surface of doveweed plants with an intact cuticle was 93.6%. In comparison, 14C-glyphosate recovery from the leaf surface of doveweed plants with a disrupted cuticle and the leaf surface of crabgrass plants was 79.1 and 70.5%, respectively.Nomenclature: Bromoxynil; carfentrazone; dicamba; foramsulfuron; glyphosate; halosulfuron; iodosulfuron; mecoprop; metsulfuron; MSMA; quinclorac; sulfentrazone; thiencarbazone; 2,4-D; doveweed, Murdannia nudiflora (L.) Brenan; smooth crabgrass, Digitaria ischaemum (Schreb.) Schreb. ex Muhl.; ‘Tifway’ bermudagrass, Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy.

Annual bluegrass is one of the most diverse plant species in the world and is the most problematic winter annual weed in commercial turfgrass. Continuous application of the same herbicide mechanism of action for annual bluegrass control on golf courses has increased herbicide-resistant populations. The purpose of this research was to simulate six herbicide-use strategies to evaluate the risk of annual bluegrass resistance evolution to glyphosate. In a worst-case scenario of yearly glyphosate applications at dormancy, resistance evolved within 10 yr and was predicted to evolve in > 90% of populations by yr 20. When glyphosate was rotated on alternate years with a unique mechanism of action, resistance was delayed for 12 to 15 yr. Season-long control of annual bluegrass often requires multiple herbicide applications. Therefore, additional strategies were simulated in which glyphosate was applied at dormancy with combinations of PRE and/or POST herbicides at various timings. Resistance was most effectively delayed with a PRE application in late summer, a POST application in fall, and alternating glyphosate with a different POST option at dormancy. This delayed resistance by 25 yr and a 35% risk was predicted after 50 yr. Strategies utilizing three annual herbicide applications with unique mechanisms of action were more effective for controlling population growth compared to other strategies. Resistance was predicted to evolve within 35 yr for each of the strategies simulated. However, these results indicate annual bluegrass herbicide resistance can be managed by using an integrated herbicide program, rotating unique mechanisms of action as frequently as possible.

American burnweed is an early successional summer annual species in the Asteraceae. This weed is a poor competitor; however, it rapidly colonizes disturbed and low-maintenance areas, especially following an environmental disturbance. Recently, turfgrass managers have made adjustments to maintenance practices to satisfy budget requirements and address environmental concerns. This has resulted in reduced mowing frequency in some golf course rough and out-of-play turf areas, and has allowed establishment of broadleaf weed species such as American burnweed which would otherwise be controlled by frequent mowing. The purpose of this study was to evaluate PRE and POST herbicide treatments for American burnweed control in an unmown bermudagrass golf course rough. Single PRE applications of simazine at 2.24 kg ai ha−1and indaziflam at 0.06 kg ai ha−1provided > 80% American burnweed control 24 wk after treatment (WAT) in 2012 and 2013. Sequential combination applications of liquid formulations of dimethenamid-p + pendimethalin (2.24 + 1.68 kg ai ha−1) provided 95% American burnweed control 24 wk after initial treatment in 2012 and 2013. Other PRE treatments did not provide consistent control of American burnweed across rating dates and years. Regardless of year, four POST treatments provided ≥ 87% control at 8 and 16 WAT. These included thiencarbazone + foramsulfuron + halosulfuron (0.02 + 0.044 + 0.07 kg ai ha−1), thiencarbazone + iodosulfuron + dicamba (0.02 + 0.15 + 0.005 kg ai ha−1), triclopyr + clopyralid (0.88 + 0.32 kg ai ha−1), and sulfentrazone + metsulfuron (0.4 + 0.04 kg ai ha−1). Several PRE and POST American burnweed control solutions exist for low maintenance bermudagrass areas. Future research should continue to screen other herbicides for control efficacy and focus on application timing to balance season-long control with minimal chemical inputs.

Studies were conducted for 12 wk from June 16 to September 8, 2003 and July 10 to October 4, 2004 with the objective of evaluating growth regulation, lateral regrowth, and injury of Tifway bermudagrass [Cynodon dactylon (L.) × C. transvaalensis Burtt-Davy Tifway] in response to two GA-inhibiting plant growth regulators, trinexapac-ethyl and flurprimidol. Trinexapac-ethyl was applied alone at 0, 0.052, and 0.104 kg ai/ha and flurprimidol alone at 0, 0.14, and 0.28 kg ai/ ha, plus all combinations. Applications were made every 3 wk for the duration of the study. Tifway bermudagrass clipping yield was reduced 33% and 54% by trinexapac-ethyl at 0.104 kg/ha at 4 and 8 wk after initial treatment (WAIT), respectively. Flurprimidol at 0.28 kg/ha reduced clipping yield 49% 8 WAIT. Lateral regrowth was reduced 20% 2 WAIT by trinexapac-ethyl at 0.104 kg/ha, and 26% 2 WAIT by flurprimidol at 0.28 kg/ha. Lateral regrowth was reduced 13% 4 WAIT by trinexapac-ethyl at 0.104 kg/ha, and 15% 4 WAIT by flurprimidol at 0.28 kg/ha. Overall, acceptable injury (

Fall applications of fenarimol on hybrid Bermudagrass (Cynodon dactylon×C. transvaalensis) provide effective preemergencePoa annua(L.) control and suppressOphiosphaerellaspp. pathogens; however, concerns exist for turf injury and root growth restrictions. Two 60-d greenhouse studies were conducted to evaluate the effects of fenarimol at 0, 1.6, and 3.2 kg ai/ha per 30 d with and without trinexapac-ethyl (TE) at 0.017 kg ai ha/15 d on ‘TifEagle’ Bermudagrass. Turf color was enhanced by TE 14 d after initial treatment (DAIT) and was continually superior throughout the experiment. Fenarimol at 3.2 kg/ha per 30 d decreased turf color 14 DAIT, but was similar to nontreated turf on all other observation dates. Increased fenarimol rates applied twice caused approximately 10% injury at 42, 49, and 56 d after treatment; however, injury was acceptable after initial and repeat applications. TE reduced clipping yield an average 39% from six sampling dates. Initial fenarimol applications (without TE) reduced clippings by 37% 20 DAIT and repeated applications reduced clippings 40, 50, and 60 DAIT. Increased fenarimol rate linearly decreased root mass for turf treated with and without TE; however, Bermudagrass receiving TE averaged 23% enhanced root mass 60 DAIT over all fenarimol rates. Bermudagrass receiving fenarimol at 0, 1.6, and 3.2 kg/ ha per 30 d with TE averaged 27, 24, and 16% higher root mass, respectively, compared to turf receiving fenarimol without TE. Treatments had no influence on root length. Results indicate that two consecutive fenarimol applications at 1.6 and 3.2 kg/ha per 30 d may cause minor injury to TifEagle Bermudagrass and restrict root growth. Repeated TE applications, however, could decrease injury from fenarimol and enhance rooting relative to fenarimol applied exclusively.

Turf managers combine ethephon with trinexapac-ethyl (TE) on bentgrass greens to suppress annual bluegrass, inhibit turf growth, and enhance turf quality; however, effects of this growth regulator combination have not been reported on bermudagrass greens. Two experiments were conducted at the Clemson University Greenhouse Complex to investigate the response of ‘TifEagle’ bermudagrass to ethephon and TE. TifEagle bermudagrass plugs were placed in pots with 23-cm depths, 324-cm2 total surface areas, and a soil medium of an 85:15 (v/v) sand and peat moss mix. Ethephon was applied at 0, 3.8 (EP1), and 7.6 (EP2) kg ai/ha/3 wk with TE at 0 and 0.04 kg ai/ha/ 3 wk over a 9-wk period. Initial responses of bermudagrass to ethephon included chlorotic leaves and severe thinning. Bermudagrass treated with ethephon had quality reduced as much as 33% from nontreated turf. TE enhanced turf quality 4 to 22% from 4 to 9 wk after initial treatment. TE helped mask ethephon-induced quality decline after the third application. In the presence of TE, bermudagrass clipping yield was reduced from nontreated turf by 57, 70, and 72% when ethephon was applied at 0, 3.8, and 7.6 kg/ha/3 wk. Ethephon linearly reduced root mass after 9 wk from nontreated turf by 20 and 33% at 3.8 and 7.6 kg/ha/3 wk, respectively. Compared with respective ethephon rates alone, bermudagrass treated with TE and ethephon at 0, 3.8, and 7.6 kg/ha/3 wk, averaged 28, 8, and 15% more root mass. Ethephon at 3.8 and 7.6 kg/ha/3 wk without TE reduced TifEagle bermudagrass root length 14 and 16%, respectively, compared with untreated turf. Bermudagrass treated with ethephon at 0, 3.8, and 7.6 kg/ha/3 wk with TE averaged 3, 11, and 17% higher root length compared with respective ethephon rates after 9 wk. Overall, ethephon may have negative effects on TifEagle root mass, root length, and turf quality. However, combining ethephon with TE may help reduce these deleterious effects.

Bahiagrass is used for roadsides, pastures, and lawns in the southeastern United States mainly because of drought and nematode tolerance. Metsulfuron is a sulfonylurea herbicide, which selectively controls bahiagrass in bermudagrass. Certain cultivars of bahiagrass were observed to be tolerant to recommended rates of metsulfuron. Therefore, research was conducted to investigate the susceptibility of five major bahiagrass cultivars to metsulfuron applied at increasing rates to 42 g ai/ha. Five bahiagrass cultivars were evaluated: ‘Pensacola’, ‘Tifton-9’, ‘Argentine’, ‘Common’, and ‘Paraguayan’. Argentine, Common, and Paraguayan cultivars showed a four- to fivefold increased tolerance to metsulfuron compared with Pensacola. Because of yearly inconsistencies, results for Tifton-9 were inconclusive. Nomenclature: Metsulfuron; Argentine bahiagrass, Paspalum notatum Fluegge var. notatum ‘Argentine’; bermudagrass, Cynodon dactylon (L.) Pers; Common bahiagrass, Paspalum notatum Fluegge var. notatum ‘Common’; Para...

Kyllinga squamulata has become problematic in bermudagrass turf in recent years, probably related to shifts in herbicide use strategies. Preemergence and postemergence greenhouse and field herbicide studies evaluated K. squamulata control in bermudagrass turf. Excellent (≥90%) postemergence control at 6 wk after initial treatment (WAIT) followed single and sequential applications of imazaquin at 0.42 kg ai/ha, MSMA plus imazaquin at 1.12 + 0.42 kg ai/ha, and sulfentrazone at 0.56 kg ai/ha. In one of two experiments, unacceptable (>30%) bermudagrass injury occurred with imazaquin at 0.42 and 0.56 kg ai/ha and MSMA plus imazaquin at 1.12 + 0.42 kg ai/ha 1 wk after application; however, plots recovered fully by 2 wk. In the field at 18 WAIT, preemergence control of greater than 70% was obtained with a single application of oxadiazon at 1.12 or 2.24 kg ai/ha and sequential applications of 1.12 kg ai/ha each 8 wk apart. Sequential applications 8 wk apart of sulfentrazone at 0.28 followed by 0.28 kg/h...

A field study evaluated the effects of green kyllinga establishment method (seed vs. stolon), two mowing heights (2.5 and 5.0 cm), and three nitrogen (N) rates (0, 24, and 49 kg/ha/mo) on green kyllinga infestation in ‘Tifway’ bermudagrass turf. The study was initiated in vigorous and newly established or “weak” bermudagrass turf in May 1997 and continued until December 1998. The green kyllinga area was measured periodically each year and plant dry weight (g/500 cm2) was calculated in December 1997 and 1998. In 1997, stolon established green kyllinga plots were twice as large as seeded plots in vigorous turf and four times larger in weak turf. Method of establishment, however, was less important in 1998 as seedling populations became more established. In weak turf, increasing N rate to 49 kg/ha/mo decreased green kyllinga spread by 50% in 1997 and by 40% in 1998 compared to no N. In vigorous turf, mowing height influenced green kyllinga infestation more than N. Low mowing height (2.5 cm) increas...

A 4-yr field study was conducted to evaluate yellow nutsedge suppression in ‘Tifway’ bermudagrass. Herbicide programs included preemergence (PRE) applications of metolachlor (3.4 kg ai/ha) and postemergence (POST) applications of imazaquin (0.28 kg ai/ha) plus MSMA (2.2 kg ai/ha) or halosulfuron (0.07 kg ai/ha) plus MSMA (2.2 kg/ha). Herbicides were applied to the same plots each year. Yellow nutsedge shoot suppression and tuber numbers were determined each year. Suppression of yellow nutsedge shoots increased over the 4-yr period from 83% by 1996 with two annual applications of imazaquin plus MSMA or halosulfuron plus MSMA. PRE metolachlor applications did not suppress shoot production in any year; nor did they enhance suppression from POST treatments. Sequential applications of halosulfuron plus MSMA and imazaquin plus MSMA increased shoot suppression by 17 to 24% at 3 mo after initial treatment (MAIT) compared to single applications. All treatments reduced tuber numbers (>60%...

Field trials evaluated sequential applications of plant growth retardants (PGRs) to bahiagrass for a 3-yr period at two Florida locations: Newberry (north Florida) and Okeechobee (south Florida). Seven PGRs from various chemical families were used: glyphosate, fluazifop, sethoxydim, maleic hydrazide, trinexapac-ethyl, imazapic, and imazaquin. In 1991 and 1992, PGRs reduced turf color for 2 to 4 wk after treatment (WAT) at the Newberry location but remained above acceptable levels (> 5.0) and recovered by 6 WAT. In 1993, glyphosate, fluazifop, and maleic hydrazide reduced turf color below acceptable levels (< 5.0) 4 WAT, but turf color was acceptable by 6 WAT. Turf color was slightly reduced following single and sequential imazapic applications in Okeechobee; however, turf recovered by 8 WAT. Cumulative seedhead suppression at both locations increased during the 3 yr resulting in at least a 60% reduction in seedhead numbers. Seedhead production each year was 10 to 50% less at 12 WAT in treated plots than in the previous year. Single applications of imazapic and imazapic + imazaquin provided 85 to 100% seedhead suppression for 12 WAT and 100% suppression for up to 16 wk following sequential applications made 8 wk after the initial application (WAI). Single applications of glyphosate, fluazifop, and maleic hydrazide provided ≥ 70% seedhead suppression for 4 to 8 WAT. Sequential applications of fluazifop made 8 WAI provided > 70% control of seedheads through 8 to 16 WAI for 3 yr.

The sedge genus Kyllinga consists of 40 to 45 species distributed in tropical, subtropical, and warm temperate regions around the world (KUkenthal 1936; Tucker 1987). This genus of low rhizomatous perennials or cespitose annuals is classified in the large cosmopolitan family Cyperaceae. Many Kyllinga species are considered weedy (Holm et al. 1979; Tucker 1987), while Kyllinga nervosa Steudel is considered an important forage plant in Africa (McNaughton 1985).

Field experiments were conducted near Marianna, Trenton, and Archer, FL in 1990 and 1991 to investigate the effect of nicosulfuron mixtures and time of application on five peanut cultivars. Nicosulfuron at 54 g ai/ha was applied alone or in mixture with 2,4-DB at 280 g ai/ha 5 weeks after planting (WAP), 9 WAP, or 5 plus 9 WAP. Injury was greater from early and sequential nicosulfuron applications while a single application 9 WAP typically did not cause significant injury or reduce peanut yield. The 5 WAP and 5 plus 9 WAP applications often caused early visible injury and sometimes reduced peanut yield. When peanut yields were compared, ‘Florigiant’ was the most sensitive cultivar while ‘Southern Runner’ and ‘Valencia’ were more tolerant to nicosulfuron. ‘Sunrunner’ and ‘NC-7’ were intermediate in tolerance to nicosulfuron. In several instances, the addition of 2,4-DB to nicosulfuron reduced initial crop injury and ameliorated yield losses resulting from nicosulfuron applied alone.

A 3-yr study investigated highbush blackberry control in bahiagrass turf using selective herbicides. Triclopyr applied alone at ≥ 0.56 kg/ha and in combination with other herbicides provided best (75 to 95%) control for up to 52 wk after treatment with minimal damage to bahiagrass turf. Triclopyr formulations (3A vs 4EC) provided similar highbush blackberry control and bahiagrass tolerance. The addition of either 2,4-D, dicamba, hexazinone, or sulfometuron to triclopyr provided slightly better blackberry control, but increased bahiagrass turf damage. Fluroxypyr applied at 0.14 to 0.28 kg/ha provided 60 to 80% control of highbush blackberry 12 WAT. Glyphosate and glufosinate treatments provided unacceptable highbush blackberry control and/or unacceptable bahiagrass turf injury. The addition of oxadiazon for residual control of subsequent highbush blackberry emergence was ineffective. Nomenclature: Dicamba, 3,6-dichloro-2-methoxybenzoic acid; fluroxypyr, [(4-amino-3,5-dichloro-6- fluoro-2-pyridinyl)oxy]acetic acid; glufosinate, 2-amino-4-(hydroxymethylphosphinyl)butanoic acid); glyphosate, N-(phosphonomethyl)glycine; hexazinone, 3-cyclohexyl-6-(dimethylamino)-l-methyl- 1,3,5-triazine-2,4( 1H,3H)-dione; oxadiazon, 3-[2,4-dichloro-5-( 1-methylethoxy)phenyl]-5-( 1,1 -dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one; sulfometuron, 2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]- carbonyl]amino]sulfonyl]benzoic acid; triclopyr, [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid; 2,4-D, (2,4-dichlorophenoxy)acetic acid; highbush blackberry, Rubus argutus Link # 3 RUBAG; bahiagrass, Paspalum notatum Fluegge var. saurae Parodi 'Pensacola' # PASNO.

Field experiments conducted in Marianna, Trenton, and Archer, FL in 1990 and 1991 investigated the effect of time of application of nicosulfuron and nicosulfuron mixtures on ‘Sunrunner’ peanut. Nicosulfuron was applied alone at 36 g ai/ha and in mixture with acifluorfen, bentazon, chlorimuron, chlorothalonil, fluazifop-P, imazethapyr, lactofen, or pyridate at 5, 7, or 9 weeks after planting (WAP). Applying nicosulfuron with chlorimuron, pyridate, or imazethapyr increased visible peanut injury and reduced yields more than nicosulfuron alone. Conversely, nicosulfuron applied with acifluorfen or lactofen was less injurious than nicosulfuron applied alone. Bentazon, chlorothalonil, and fluazifop-P generally did not influence phytotoxicity from nicosulfuron. Peanut tolerance to nicosulfuron increased with age.

Field and greenhouse studies were conducted to evaluate selected PRE-applied herbicides for sprangletop control. In greenhouse studies, oxadiazon and dithiopyr provided excellent (> 89%) red sprangletop (L. filiformis) control. Pendimethalin and metolachlor + atrazine provided good (80–89%) to excellent control for 6 mo and 2 mo during studies 1 and 2, respectively. Isoxaben and atrazine provided poor (< 70%) control during both greenhouse studies. In field studies, good to excellent bearded sprangletop (L. fascicularis) control followed dithiopyr, pendimethalin, metolachlor, and metolachlor + atrazine treatments. Dithiopyr at 0.8 kg ai/ha provided best (> 95%) sprangletop control throughout the 6-mo testing period. Under field conditions, control was inconsistent following oxadiazon with good to excellent control during one study and poor control in another study. Better or equal control than metolachlor + atrazine followed dithiopyr, pendimethalin, and metolachlor alone treatments. Oxadiazon also provided similar or better control than metolachlor+atrazine in three of four studies. Over all studies, dithiopyr provided best sprangletop control, followed by metolachlor, metolachlor + atrazine, pendimethalin, and oxadiazon. Isoxaben and atrazine treatments provided poorest or inconsistent sprangletop control.

Torpedograss has invaded fine turfgrasses in the Southern U.S. due to its tolerance to most commonly used turfgrass herbicides. Research was conducted to determine torpedograss and 'Tifway' bermudagrass tolerance to quinclorac and tank-mix combinations with other turf herbicides. Quinclorac rates in excess of 2.2 kg ai/ha were required for control (2 80%) of torpedograss. Sequential applications were more effective than single applications. Generally, sequential applications made 3 wk after the initial were more effective than delaying sequential applications until 4 wk after the initial application. Tifway bermudagrass injury from quinclorac applied at 4.5 kg/ha, or at 2.2 kg/ha followed by a sequential application of 1.1 or 2.2 kg/ha, was observed at 4 to 10 wk; however, turf recovered thereafter. Sequential applications of quinclorac plus imazaquin (1.1 + 0.6 kg/ha) increased torpedograss control (approximate 35%) as compared to quinclorac plus MSMA (1.1 + 1.1 kg/ha) but also decreased turf quality versus quinclorac applied alone or in combination with MSMA. Quinclorac applied at 2.2 kg/ha followed by 1.1 kg/ha applied 3 or 6 wk after the initial controlled torpedograss best with least reduction in bermudagrass quality. Quinclorac is the first herbicide reported to selectively control torpedograss in bermudagrass turf. Nomenclature: Imazaquin, 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-lH-imidazol-2-yl]-3-quinolinecarboxylic acid: MSMA, monosodium salt of methylarsonic acid; quinclorac, 3,7-dichloro-8-quinolinecarboxylic acid; torpedograss, Panicum repens L. #3 PANRE; 'Tifway' bermudagrass, Cynodon dactylon (L.) Pers. x C. transvaalensis Burt-Davy. Additional index words: Golf course, BAS 514, imazaquin, MSMA, quinclorac, PANRE.

Postemergence grass weed control in turf-type bermudagrass is currently available only with repeated applications of organic arsenicals and/or with combinations of metribuzin which decrease turf quality. Research was conducted to determine tolerance of the turf-type bermudagrass cultivars, Tifway, Ormond, and common, to diclofop rates ranging from 0.54 to 4.48 kg ai ha-1with and without MSMA (2.2 kg ai ha-1) and metribuzin (0.2 kg ai ha-1). Bermudagrass cultivars tolerated diclofop well. When injury was evident, a rate response was noted, with higher rates (3.4 and 4.5 kg ha-1) resulting in increased phytotoxicity. However, this level of phytotoxicity was acceptable and the turf soon recovered (3 to 14 d). The addition of crop oil concentrate (1.25% v/v) did not affect turf quality. Addition of MSMA resulted in slightly lower turf quality than diclofop alone. However, these responses were acceptable and usually the turf recovered by 14 d after treatment. Metribuzin applied alone or in combination with diclofop damaged turf to unacceptable levels and up to 21 d were required for turf recovery.

In field experiments conducted near Marianna, Trenton, and Archer, FL in 1990 and 1991, nicosulfuron applied 55 weeks after planting (WAP) at 18, 27, 36, or 54 g ai/ha injured peanut initially. When applied 7 WAP, only the two higher nicosulfuron rates injured peanut more than 10%. By 6 wk after application, crop injury was less than 8% for all treatments, except the highest (54 g/ha) rate. Nicosulfuron applied 5 or 7 WAP at 54 g/ha reduced peanut yield and sound mature kernels.

Carpetgrass is a warm season grass used in the south as low maintenance turf, especially in wet areas where other turf species do not persist. The response of carpetgrass to postemergence (POST) herbicides currently available for turf producers has not been thoroughly investigated and was the objective of four experiments conducted over a 2-yr period. Slight reduction in turf quality followed application of atrazine (2.2 kg ai ha-1), bentazon (2.2 kg ai ha-1), imazaquin (0.4 and 0.6 kg ai ha-1), mecoprop (1.1 kg ai ha-1), triclopyr (0.6 kg ai ha-1), metsulfuron (0.2 kg ai ha-1), 2,4-D (1.1 kg ai ha-1), 2,4-D plus dicamba (0.8 + 0.3 kg ai ha-1), and 2,4-D plus dicamba plus mecoprop (0.9 + 0.1 + 0.5 kg ai ha-1). Marginally acceptable turf quality followed sulfometuron (0.2 kg ai ha-1), sethoxydim (0.3 and 0.6 kg ai ha-1), and diclofop (2.2 kg ai ha-1) treatments. Unacceptable turf quality resulted from asulam (2.2 kg ai ha-1) and MSMA (1.1 and 2.2 kg ai ha-1) treatments. Carpetgrass tolerated most POST broadleaf and sedge herbicides but was sensitive to most POST grass herbicides used in other turf species, with the exception of sethoxydim.