Broadleaf weeds and nutsedge are persistent problems with limited management options for strawberry growers in Florida. Experiments were conducted in 2012 to 2013 (year 1) and 2013 to 2014 (year 2) at the Gulf Coast Research and Education Center in Wimauma, FL, to evaluate tolerance of two strawberry cultivars (‘Strawberry Festival' and ‘WinterStar'™) to PRE herbicides applied on the bed top or injected through the drip tape. The bed-top herbicides were applied to formed beds following fumigation but prior to laying the plastic mulch. Herbicides evaluated included two rates of EPTC, fomesafen, halosulfuron, and S-metolachlor as well as tank mixes of EPTC + S-metolachlor, fomesafen + S-metolachlor, and napropamide + oxyfluorfen. Drip-applied herbicides were applied through a single drip tape and strawberries were transplanted 1, 7, 15 and 30 d following application. Drip-applied herbicides included two rates of EPTC and fomesafen as well as two rates of a tank mix of napropamide + oxyfluorfen. None of herbicides applied on the bed top except S-metolachlor 214 g ai ha−1 consistently injured either strawberry cultivar or impacted yields. None of the drip-applied herbicides damaged the strawberry plants or reduced yields at all planting dates. In year 1, EPTC at 229 g ai ha−1 and EPTC at 229 g ha−1 + S-metolachlor at 107 g ha−1 resulted in a 70 to 86% reduction in purple nutsedge density compared to the nontreated control. No differences in nutsedge density among treatments were observed in year 2. The herbicides evaluated are safe for use on strawberry and would provide growers with alternative herbicide options, application timings, and application techniques. Further research is needed to evaluate efficacy.

Virginia buttonweed and smooth crabgrass are problematic weeds in tall fescue and may warrant control with herbicides at similar timings. The objectives of these field experiments were to evaluate (1) aminocyclopyrachlor rate and application regimens for controlling Virginia buttonweed and (2) the influence of growth stage on aminocyclopyrachlor efficacy for controlling smooth crabgrass. Single applications of aminocyclopyrachlor at 0.05 and 0.08 kg ai ha−1 provided poor (< 70%) and fair (70 to 79%) control of Virginia buttonweed, respectively, but sequential applications improved control to 83 to 99%. Single and sequential applications of aminocyclopyrachlor at 0.11 kg ai ha−1 provided good (80 to 89%) and excellent (> 90%) control of Virginia buttonweed, respectively. Aminocyclopyrachlor at 0.11 kg ha−1 provided fair control of smooth crabgrass at the multileaf growth stage prior to tillering but control was poor when applied at the multitiller stage. Aminocyclopyrachlor at 0.05 and 0.08 kg ha−1 provided poor control of crabgrass at both timings and were less effective than fenoxaprop at 0.10 kg ai ha−1.

Buckhorn plantain is a perennial weed in turfgrass and efficacy of POST herbicides is often inconsistent for control in spring. Indaziflam is a cellulose biosynthesis inhibitor used for PRE control of annual weeds in turf and applications have shown to be injurious to established buckhorn plantain. The objectives of this research were to evaluate (1) effects of indaziflam application rate and placement on buckhorn plantain injury; (2) effects of tank-mixing indaziflam with POST herbicides for buckhorn plantain control; and (3) physiological effects of indaziflam on absorption and translocation of14C-2,4-D in buckhorn plantain. In greenhouse experiments, indaziflam reduced buckhorn plantain shoot mass 61 to 75% from the nontreated at 4 wk after treatment (WAT) and hierarchical rank of application placements were: foliar + soil ≥ soil ≥ foliar. Differences in biomass reduction from application rates (27.5 and 55 g ai ha−1) were not detected. In field experiments, indaziflam at 55 g ha−1controlled buckhorn plantain 34% at 9 WAT but enhanced the speed of control from all herbicides tested in tank mixtures. Exclusive applications of 2,4-D or 2,4-D + dicamba + MCPP provided poor control (< 70%) of buckhorn plantain at 9 WAT, but tank mixtures with indaziflam provided 81 and 98% control, respectively. Fluroxypyr and simazine alone controlled buckhorn plantain < 38% but tank mixtures with indaziflam enhanced control more than twice as much from exclusive applications. Tank-mixing indaziflam with metsulfuron did not improve control from metsulfuron alone after 9 wk. Bermudagrass injury was not detected from any treatment. In laboratory experiments,14C-2,4-D absorption and translocation in buckhorn plantain was similar with or without indaziflam tank mixtures at 72 and 168 h after treatment. Overall, indaziflam may improve buckhorn plantain control from POST herbicides by providing additive phytotoxicity in tank mixtures in spring.

Swinecress [Coronopus didymus (L.) Sm.] is a problematic weed in newly seeded tall fescue (Festuca arundinacea Schreb.) and often warrants control with herbicides. The objective of this research was to investigate the influence of application timing on efficacy of aminocyclopyrachlor, fluroxypyr, and triclopyr for swinecress control compared with dichlorophenoxyacetic acid (2,4-D) + 3,6-dichloro-o-anisic acid (dicamba) + methylchlorophenoxypropionic acid (MCPP). Aminocyclopyrachlor at 0.05 and 0.10 kg a.i./ha provided less than 35% control from February applications, but both rates averaged greater than 90% control with April applications. Fluroxypyr at 0.26 and 0.52 kg a.i./ha provided poor (less than 70%) control from February applications but control increased to 71% and 90% from April treatments, respectively. Triclopyr at 0.56 and 1.12 kg a.i./ha provided greater than 90% swinecress control at both application timings and was comparable to 2,4-D + dicamba + MCPP. Overall, aminocyclopyrachlor and fluroxypyr were only effective for controlling swinecress in April, whereas triclopyr provided excellent control with February and April applications.

Flumioxazin is a protoporphyrinogen oxidase inhibitor with potential for POST annual bluegrass control and PRE smooth crabgrass control in bermudagrass. However, flumioxazin applications are often less effective in winter, compared with fall, because of reduced efficacy on mature annual bluegrass. The objective of this research was to evaluate tank-mixtures of flumioxazin with six other herbicide mechanisms of action for POST annual bluegrass control in late winter and residual smooth crabgrass control. Flumioxazin at 0 or 0.42 kg ai ha−1was evaluated in combination with flazasulfuron at 0.05 kg ai ha−1, glufosinate at 1.26 kg ai ha−1, glyphosate at 0.42 kg ae ha−1, mesotrione at 0.28 kg ai ha−1, pronamide at 1.68 kg ai ha−1, or simazine at 1.12 kg ai ha−1. Flumioxazin alone controlled annual bluegrass 61 to 70% at 8 wk after treatment (WAT) in three experiments from 2012 to 2014 in central Georgia. Flumioxazin tank-mixed with flazasulfuron, glyphosate, glufosinate, pronamide, and simazine provided good (80 to 89%) to excellent (> 90%) control of annual bluegrass at 8 WAT in 2 of 3 yr. These tank-mixtures were also more effective than flumioxazin alone in 2 of 3 yr, and control was greater or equal to the tank-mix partners applied alone. Treatments that included flumioxazin provided excellent (≥ 90%) control of smooth crabgrass at 6 mo after treatment in all 3 yr. Overall, tank-mixing flumioxazin with other herbicide chemistries may improve POST annual bluegrass control, compared with exclusive treatments, and effectively control smooth crabgrass in bermudagrass.