Four broadleaf herbicides and combinations were compared for two years with mefluidide, a growth regulator, for effects on ‘Ky 31’ and ‘Fawn’ tall fescue. Seedhead densities averaged 33% of the check with 8.4 g ai/ha of metsulfuron, 17% with 70 g ai/ha of imazethapyr, and 9% with 280 g ai/ha of mefluidide, while forage yields were reduced to about 40% of the check. Forage crude protein (CP) concentrations were increased by mefluidide, imazethapyr, and 8.4 g/ha of metsulfuron. Neutral-detergent fiber (NDF) of Ky 31 but not Fawn forage was reduced by mefluidide, imazethapyr, and metsulfuron at 6.3 and 8.4 g/ha, but Fawn NDF was increased by dicamba plus 2,4-D. In vitro dry matter digestibility was increased by metsulfuron at 6.3 and 8.4 g/ha, mefluidide, and imazethapyr in one of two years. Adding 2,4-D to metsulfuron reduced some effects of metsulfuron. Total CP/ha was no more adversely affected by imazethapyr and metsulfuron than mefluidide. Imazethapyr and metsulfuron can thus be used to control weeds without reducing fescue forage value.

Preplant incorporation of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] at 3.6 kg ai/ha, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 2.2 kg ai/ha, and tank mixtures of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} with either alachlor at 0.14 + 2.2 kg ai/ha or metolachlor at 0.14 + 1.1 kg ai/ha controlled >90% red rice (Oryza sativa L. # ORYSA) in soybeans [Glycine max (L.) Merr.]. Also, FMC-57020 [2-(2-chlorophenyl)methyl-4,4-dimethyl-3-isoxazolidinone] at 1.7 kg ai/ha applied preplant incorporated controlled > 80% of the red rice. DPX-Y6202 {2-[4-[(6-chloro-2-quinoxalinyl)oxy]-phenoxy]-propionic acid, ethyl ester} was the best and most consistent postemergence herbicide treatment for red rice control when applied once at 0.28 kg ai/ha or sequentially at 0.14 kg ai/ha each time. Haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanoic acid} applied at 0.16 kg ai/ha followed by another application at 0.14 kg ai/ha gave excellent red rice control in 2 of 3 years. Soybeans were uninjured by the herbicide treatments and yield was higher from treated than untreated soybeans.

The addition of chlorflurenol (methyl 2-chloro-9-hydroxyfluorene-9-carboxylate) at 0.6 kg ai/ha or mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl] acetamide} at 0.3 kg ai/ha to picloram (4-amino-3,5,6-tricloropicolinic acid) at 0.3 kg ae/ha increased leafy spurge (Euphorbia esula L. # EPHES) control compared to picloram alone. Application of 84 kg/ha nitrogen in the fall prior to a spring treatment of 0.3 kg/ha picloram decreased the original stand (75%) compared to no nitrogen (18%). In greenhouse experiments, chlorflurenol and mefluidide increased the amount of 14C-picloram absorbed approximately twofold when applied in combination but not when applied independently. Based on 14C-picloram absorbed, chlorflurenol and mefluidide each increased the amount of 14C translocated to the root system, whether applied independently or in combination with picloram. An increase in root bud numbers was observed following an application of 0.6 kg/ha chlorflurenol or nitrogen.

Sequential applications of MSMA plus metribuzin with selected plant growth regulators interacted synergistically and increased injury of ‘Tifway’ bermudagrass 1 and 2 wk after treatment. However, the higher injury at 3 wk after treatment, from sequential MSMA plus metribuzin with flurprimidol plus mefluidide or paclobutrazol with mefluidide, was additive. The vegetative growth suppression of bermudagrass at 2 wk after treatment with 2,4-D plus mecoprop plus dicamba with flurprimidol was antagonistic. The higher growth suppression 2 wk after treatment for MSMA plus metribuzin and flurprimidol plus mefluidide was additive compared to flurprimidol with mefluidide alone.

Plant growth regulators were evaluated on common and African ‘Tifway’ bermudagrass. Flurprimidol plus mefluidide applied at 1.1 plus 0.14 kg ha-1 and followed by 0.56 plus 0.14 kg ha-1 at 2- to 3-week interval suppressed vegetative growth of mowed common bermudagrass for 5 wk (17 to 23%) and unmowed turf for 6 wk (40%), but severely injured the turf. The injury ranged from 25 to 32% from 2 to 6 wk after treatment. The plant growth regulators that injured common bermudagrass less than flurprimidol plus mefluidide did not suppress the mowed turf for as long a period. Vegetative growth of common bermudagrass not mowed was suppressed for 6 wk when treated once with flurprimidol plus mefluidide and twice with flurprimidol, mefluidide, imazethapyr, paclobutrazol (1.1 plus 1.1 kg ha-1), and paclobutrazol plus mefluidide. Of the plant growth regulators evaluated, only imazethapyr suppressed common bermudagrass seedheads. The suppression was 70% for 4 wk, but reduced to <70% by 5 wk. Paclobutrazol applied initially at 1.1 kg ha-1 and followed at 0.56 kg ha-1 suppressed vegetative growth of mowed Tifway bermudagrass for 5 wk and unmowed turf for 8 wk without causing severe injury. The suppression of mowed Tifway bermudagrass with two applications of paclobutrazol was as good or better than with any other plant growth regulator. All plant growth regulators suppressed vegetative growth of unmowed Tifway bermudagrass for 8 wk.

Field studies were conducted at Charleston, SC to evaluate the effects of six chemical treatments on bahiagrass and the potential of these treatments to reduce mowing operations. Sulfometuron, maleic hydrazide, and imazethapyr plus imazapyr, in decreasing order of effectiveness, were the most consistent treatments evaluated during the 2-yr study. Sulfometuron reduced bahiagrass vegetative height (23%) for 6 to 8 WAT and suppressed 87 to 92% of seedheads without adversely affecting turf quality. All treatments temporarily discolored turf; however, effects were not objectionable for medium- to low-quality turf settings. Sulfometuron, maleic hydrazide, and imazethapyr plus imazapyr controlled growth and maintained acceptable turf quality for an average of 9, 9, and 8 wk, respectively; thereby reducing mowing operations by an average 29%. Mefluidide plus fluazifop-P, mefluidide plus sulfometuron, and chlorosulfuron were the least effective and/or consistent treatments evaluated.

Both alachlor at 3.6 kg ai/ha and metolachlor at 2.8 kg ai/ha applied preplant incorporated consistently controlled red rice 82% and 90%, respectively, over a 3-yr period. Averaged across years, only mefluidide at 0.14 kg ai/ha plus bentazon at 0.84 kg ai/ha, haloxyfop at 0.28 kg ai/ha, and quizalofop at 0.14 kg ai/ha applied postemergence controlled red rice comparable to the preplant herbicide treatments. High rates of sethoxydim and fluazifop (0.56 kg ai/ha), haloxyfop (0.28 kg ai/ha), and quizalofop (0.14 kg ai/ha) were needed to obtain soybean yields equivalent to alachlor and metolachlor.

Mon 4620 at 2.8 kg ai/ha, paclobutrazol plus mefluidide at 1.1 plus 0.4 kg ai/ha, and flurprimidol plus mefluidide at 1.1 plus 0.4 kg ai/ha were applied on four dates to determine their influence on highly maintained tall fescue turf. Seedhead suppression was good to excellent by Mon 4620 applied March 1 or 18 and by paclobutrazol plus mefluidide and flurprimidol plus mefluidide applied anytime from March 1 until April 1. None of the plant growth regulators (PGRs) suppressed seedheads effectively when applied April 15 when the grass was near the end of the rapid growth cycle and just before seedhead emergence. Vegetative growth of mowed tall fescue was suppressed for 8 weeks in 1987 when PGRs were applied March 1 immediately after full green-up. Application dates were not as important in 1988 as in 1987. Tall fescue was injured the least by Mon 4620 applied in March and by flurprimidol plus mefluidide applied on March 18. Paclobutrazol plus mefluidide injured the turf severely regardless of application date.

A red fescue (Festuca rubra L.)- Kentucky bluegrass (Poa pratensis L.) turf was treated annually with amidochlor {N-[(acetylamino)methyl]-2-chloro-N-(2,6-diethylphenyl)acetamide} at 2.2, 2.8, and 3.4 kg ai/ha, mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} at 0.4 kg ai/ha, and ethephon [(2-chloroethyl) phosphonic acid] at 5.6 kg ai/ha for three consecutive years. Recuperative potential of treated turfgrass was determined in the field and in a greenhouse study. Amidochlor and mefluidide treatments injured turfgrass (11 to 64%) four weeks after application. However, turfgrass recovered after eight weeks. Amidochlor at 2.8 to 3.4 kg/ha and mefluidide at 0.4 kg/ha suppressed (75 to 100%) seedhead development. Ethephon at 5.6 kg/ha was ineffective. Turfgrass recovered normally each spring after amidochlor treatments, with no delay in spring green-up. Root length, root weight, and root:shoot weight ratio of the plugs from the greenhouse study were unaffected by three consecutive annual applications of amidochlor, mefluidide, and ethephon. One annual spring application of amidochlor, mefluidide, and ethephon for three consecutive years caused no adverse effects that would limit their use on red fescue-Kentucky bluegrass turf.

CGA 163935, paclobutrazol, and paclobutrazol plus mefluidide were evaluated for their growth regulating effect on centipedegrass over 3 yr. Paclobutrazol did not effectively suppress seedhead production or vegetative growth. Paclobutrazol plus mefluidide at 1.1 + 0.3 kg ai ha–1 in each of two applications at a 2-wk interval suppressed seedhead development 77% (average of 3 yr) at 10 wk after the initial treatment without severe injury or loss of stand, but duration of vegetative growth suppression was variable (0 to 6 wk). CGA 163935 applied at 0.4 kg ai ha–1 and followed by 0.2 kg ai ha–1 2 wk later suppressed vegetative growth of mowed and nonmowed centipedegrass for 10 wk, while suppressing seedhead production for 3 to 5 wk. CGA 163935 caused severe injury and stand loss of centipedegrass.

Two yr of field research were conducted to evaluate the efficacy of BAS-9021 {2-[1-(N-allyloxyamino)butylidene]-5,5-dimethyl-4-methoxycarbonylcyclohexane-1,3-dione, Na salt}, HOE 29152 {methyl 2-[4-(4-trifluoromethylphenoxy)phenoxy]propanoate}, and mefluidide N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide as selective herbicides applied postemergence to johnsongrass [Sorghum halepense (L.) Pers.]. All three herbicides afforded 85% or greater control of rhizome johnsongrass in one experiment in 1977, where repeat applications were made and ideal growing conditions prevailed. HOE 29152 also afforded excellent control with a single application made at the boot stage of johnsongrass. In a second experiment in 1977, when drought conditions prevailed, HOE 29152 was the only herbicide that afforded 70% or greater control of the johnsongrass. Both BAS-9021 and mefluidide afforded less than 60% control of johnsongrass in the single 1978 experiment, when evaluated at the end of the season. This study also was subject to drought conditions throughout the growing season.

When centipedegrass was unmowed, seedhead suppression generally was better with imazethapyr than with mefluidide either alone or with flurprimidol, but these treatments were not effective for 8 weeks. In several instances, imazethapyr at 0.30 kg ai/ha and MH at 2.2 and 4.5 kg ai/ha severely injured (>30%) centipedegrass. Mowing weekly did not control seedhead development effectively, and none of the plant growth regulator plus mowing treatments effectively suppressed seedheads for 12 weeks. To effectively suppress seedhead production for 8 weeks, centipedegrass treated with mefluidide required mowing 3 weeks after treatment, while centipedegrass treated with imazethapyr or flurprimidol plus mefluidide required mowing at 3 and 6 weeks.

Plant growth regulators were evaluated on African ‘Tifway’ and common bermudagrass. The vegetative growth of mowed Tifway bermudagrass was suppressed 15 to 22% for 3 weeks by flurprimidol at 0.84 kg ai/ha while mowed common bermudagrass was suppressed 30 to 34% during the same period by flurprimidol at 1.1 kg/ha. When nonmowed bermudagrass was treated with flurprimidol, the growth of Tifway treated at 0.84 kg/ha was suppressed 42% at 8 weeks while growth of common bermudagrass treated at 1.1 kg/ha was suppressed 26% at 6 weeks. Excessive injury by flurprimidol occurred when common and Tifway bermudagrass were treated at rates above 1.1 and 0.84 kg/ha, respectively. Imazethapyr excessively injured both bermudagrass cultivars. Mefluidide and Mon 4620 injured both bermudagrass cultivars slightly, but neither suppressed vegetative growth as effectively as flurprimidol.

This study describes separate methods for injecting growth retardants into herbaceous and woody plants. Bean plants (Phaseolus vulgaris L. ‘Black Valentine’) were treated by injecting growth retardant solutions into the hypocotyl cavity with a syringe. The chemical was subsequently absorbed into the vascular system. Woody California privet (Ligustrum ovalifolium Hassk.) was injected by forcing chemical solution into the vascular system via a predrilled hole. Results with NAA (1-napthalene-acetic acid) and MH (1,2-dihydro-3,6-pyridazinedione) validated the methods by inhibiting growth, respectively. New growth regulators, mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl) sulfonyl]amino]phenyl]acetamide} and dikegulac (sodium salt of 2,3: 4,6-bis-O-(1-methylethylidene-α-L-xylo-2-hexulofuranosonic acid], inhibited the growth of bean with concentrations of 60 mg/L and 480 mg/L, respectively. Sprout growth of privet was inhibited by 30 mg/L of mefluidide and by 188 mg/L dikegulac.

Red rice (Oryza sativa L. # ORYSA) control in soybeans [Glycine max (L.) Merr.] was 93% or more with shallow-incorporated alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] at 3.9 kg ai/ha, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 2.8 kg ai/ha, and trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] at 1.7 kg ai/ha. Junglerice [Echinochloa colonum (L.) Link. # ECHCO] control was 80% with alachlor but 90% or more with metolachlor and trifluralin when applied at the same rates. Sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} at 560, fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy]phenoxy]propanoic acid} at 280, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} at 140, and mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} plus bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4 (3H)-one 2,2-dioxide] at 140 plus 840 g ai/ha applied postemergence on two- to four-leaf red rice provided at least 87% control. Junglerice control with these treatments was 85% or more with the exception of fluazifop and mefluidide plus bentazon.

Experiments were conducted in 1985 and 1986 at three locations in eastern Arkansas to evaluate red rice control in soybeans with postemergence grass herbicides and plant growth regulators applied singly or sequentially at early to late-tillering growth stages of red rice. Haloxyfop at 0.21 kg ai/ha and quizalofop at 0.14 kg ai/ha applied singly or sequentially and fluazifop at 0.21 kg ai/ha applied sequentially consistently controlled red rice and suppressed seedhead production in soybeans. Mid-season treatments were not beneficial when high soil moisture stress conditions existed. Mefluidide or sethoxydim applied singly or sequentially or amidochlor applied singly provided erratic control and seedhead suppression of red rice in soybeans.

Mefluidide, Mon 4620, paclobutrazol plus mefluidide, and flurprimidol plus mefluidide temporarily injured and discolored tall fescue without reducing shoot density. Mefluidide at 0.43 kg ai/ha and Mon 4620 at 2.8 kg ai/ha suppressed vegetative growth of mowed grass 4 weeks while unmowed grass was suppressed for 8 weeks. Mefluidide at 0.14 kg/ha with either flurprimidol at 1.1 kg ai/ha or paclobutrazol at 1.1 kg ai/ha suppressed vegetative growth of mowed tall fescue for 5 and 6 weeks, respectively. Combination treatments also suppressed the growth of nonmowed tall fescue 8 to 10 weeks. Mowing effectively suppressed seedheads for 12 weeks when the grass was mowed at 3 and 6 weeks, while mowing only once at 4 weeks did not. Seedhead suppression was not improved with weekly mowing compared with two mowings. Mowing influenced the performance of plant growth regulators on vegetative growth and seedhead control but not plant injury, quality, or shoot density.

Options for suppressing bermudagrass seedheads in managed turfgrass systems are limited. Experiments were conducted in 2009 and 2010 evaluating the use of fenoxaprop (25, 50, 75, and 100 g ha−1) for ‘Riviera’ bermudagrass seedhead suppression and growth regulation compared to imazapic (52 g ha−1), trinexapac-ethyl (91 g ha−1) and mefluidide (561 g ha−1). In field experiments, seedhead suppression ranged from 77 to 100% for fenoxaprop and imazapic at 35 d after treatment (DAT). Comparatively, seedhead suppression was < 25% for either trinexapac-ethyl or mefluidide at 35 DAT. Seedhead suppression was > 90% from 7 to 35 DAT for fenoxaprop applied at ≥ 50 g ha−1. Injury, determined visually, from fenoxaprop and imazapic in both the field and greenhouse measured < 25% on all rating dates, with no significant injury present after 21 DAT. In greenhouse experiments, fenoxaprop and trinexapac-ethyl showed similar reductions of bermudagrass growth; no differences in aboveground biomass were detected between these treatments at 42 DAT. Results of the current study illustrate that fenoxaprop and imazapic can be applied for bermudagrass seedhead suppression and growth regulation if moderate (< 25%) injury can be tolerated up to 21 DAT. Additional research is needed to evaluate the use of fenoxaprop and imazapic for seedhead suppression on other common and hybrid bermudagrasses.

Field research was conducted to evaluate plant growth-regulator efficacy for tall fescue growth and seedhead suppression applied using application placement equipment. Specially designed equipment outfitted with fluid application systems applies low-volume plant growth regulator directly on plant foliage, reducing opportunity for drift and visible application. Wet-blade mowers are equipped to apply plant growth regulators and mow in a single pass, whereas rotary-wick applicators simply wipe chemicals directly on uncut vegetation. Therefore, a wet-blade, rotary-wick, and broadcast sprayer system were chosen to apply imazapic at three rates (9, 35, and 53 g ai/ha), and a mefluidide + chlorsulfuron tank mix at 7 + 140 g ai/ha to tall fescue roadsides for vegetative growth and seedhead suppression. Experiments were conducted during the spring and summer of 2004 in central and western North Carolina. Tall fescue was slightly injured and discolored by all treatments but fully recovered by 2 mo after treatment. Imazapic suppressed new vegetative growth 3 mo after treatment compared with the nonmowed–nontreated control (16.1 cm of growth) and the mowed–nontreated control (21.1 cm) when applied with the rotary-wick applicator (8.5 cm) and broadcast sprayer (6.2 cm). However, differences in vegetative height primarily occurred when application placement equipment treatments were compared with nontreated vegetation as opposed to mowed–nontreated plants. Although mowed–nontreated and wet-blade–treated plots had more new vegetative growth, nonmowed–nontreated plots still consistently had the greatest vegetative height. Seedhead suppression ranged from 87 to 100% when compared with the nonmowed–nontreated control, with wet-blade treatments consistently providing the least-effective seedhead suppression. Overall, application placement equipment did not improve plant growth-regulator efficacy when compared with the foliar broadcast spray.

Experiments were conducted to evaluate safety and effectiveness of herbicides during establishment of seeded centipedegrass. Centipedegrass tolerance to herbicides was evaluated at seeding and early postemergence. Imazapic at 105 g ai/ha, sulfometuron at 53 g ai/ha, or metsulfuron at 21 or 42 g ai/ha applied at seeding reduced centipedegrass ground cover compared with the nontreated. Imazapic at 18 or 35 g/ha or applications of atrazine or simazine at seeding did not reduce centipedegrass ground cover compared with the nontreated. Applications of chlorsulfuron plus mefluidide (7 + 140 g ai/ha) or metsulfuron at 21 or 42 g/ha applied 6 wk after seeding (WAS) centipedegrass (one-leaf to one-tiller growth stage) caused 20, 16, and 83% phytotoxicity, respectively, 56 d after treatment (DAT). Imazapic, sulfometuron, atrazine, or simazine applied 6 WAS caused <15% phytotoxicity 56 DAT. When large crabgrass and centipedegrass were seeded together, large crabgrass emergence was reduced 41% when atrazine (1,100 g ai/ha) was applied at seeding. Centipedegrass tiller production was reduced with increasing amounts of crabgrass. However, centipedegrass tiller production and ground cover were higher when atrazine was applied because of reduced interspecific interference from large crabgrass. These data indicate that centipedegrass can be established more quickly if appropriate herbicides are used at seeding or shortly after seeding.