Pyridate, a contact postemergence herbicide that inhibits photosystem II, was recently reintroduced by Belchim USA (Wilmington, DE) after its discontinuation by Syngenta Crop Protection (Greensboro, NC) in 2007. Since pyridate has previously been demonstrated to control yellow nutsedge in production crops, this study evaluated the herbicide’s potential to control false green kyllinga (FGK) and yellow nutsedge (YNS) in cool-season turfgrass. The hypothesis posited that pyridate would control these weeds in similar ways to those of standard, commercially available herbicides. Two objectives were set: to determine the effective dose of pyridate to control FGK and YNS in turf and to compare its performance alone or in combination with sulfentrazone against standard herbicides. Field trials at multiple sites with varying FGK and YNS infestations were carried out in a randomized complete block design. Pyridate was applied at different rates, alone or combined with sulfentrazone. Weed control and turfgrass injury were visually assessed at 7, 14, 28, and 42 d after treatment (DAT). Pyridate at 0.2 to 0.7 kg ae ha−1 provided57% to 83% control of FGK at 42 DAT, with 0.7 kg ha−1 performing equivalently to standard treatments. At higher rates (0.7 to 2.8 kg ha−1), control of both FGK and YNS reached 79% to 95% by 42 DAT, matching the efficacy of sulfentrazone and imazosulfuron and surpassing that of halosulfuron. Applications of pyridate + sulfentrazone provided 90% to 98% control of both sedges across all trials. Only pyridate applied at 2,800 g ha−1 caused unacceptable injury (>30%) to tall fescue and to Kentucky bluegrass + perennial ryegrass turf at 7 DAT; no other treatment caused more than 16% injury to turf. At 14 DAT and beyond, turf injury was not evident from any treatment. This study concludes that pyridate, especially when applied at rates ≥0.7 kg ha−1, effectively controls FGK and YNS in turfgrass, offering a viable alternative or complement to existing herbicides.

Managing yellow nutsedge and southern root-knot nematode (SRKN) is particularly challenging in organic sweetpotato production. Anaerobic soil disinfestation (ASD) has emerged as a promising nonchemical pest management strategy that entails incorporating labile carbon amendments into the soil, covering the soil with impermeable plastic mulch, and irrigating the amended soil to saturation. Field studies were conducted at Clemson University in Charleston, South Carolina, in the 2023 and 2024 growing seasons, to evaluate the effect of ASD on yellow nutsedge and SRKN. Treatments were structured as a factorial arrangement of three carbon amendments (Brassica residue [BR], chicken manure + molasses [CM+M], and cotton seed meal [CSM]) and an unamended control (UC) by four sweetpotato clones (Bayou Belle, Monaco, Murasaki-29, and USDA-18-040) with four replications using a randomized complete block design. ASD was terminated 3 wk after initiation, and sweetpotato slips were planted 1 wk after ASD termination. Greater cumulative anaerobicity was observed in the CM+M and CSM treatments with increments exceeding 220% relative to UC at ASD termination. Six weeks after planting, yellow nutsedge densities across all sweetpotato clones were significantly lower with CM+M (4 to 10 plants m−2) and CSM (6 to 8 plants m−2) treatments than the UC (21 to 27 plants m−2). Both bunch cultivars (Monaco and USDA-18-040) and spreading cultivars (Bayou Belle and Murasaki-29) sweetpotato clones resulted in similar yellow nutsedge densities. Soil population densities of SRKN at 16 wk after planting were reduced by 23% to 44% in CM+M treatments and by 29% to 46% in CSM treatments, relative to the UC. Marketable sweetpotato yield rose from 47% to 131% with the CMM and CSM treatments compared with UC yield. The findings of this study demonstrate that CM+M and CSM-induced ASD have the potential to suppress yellow nutsedge and SRKN in organic sweetpotato production systems while increasing the marketable sweetpotato yield.

Florpyrauxifen-benzyl has generated complaints and concerns around rice injury and off-target movement to soybean since its commercial launch in 2018. Developing a precise method for applying florpyrauxifen-benzyl was imperative for its continued use. Experiments were conducted in 2020 and 2021 to evaluate rice weed control as influenced by preflood application interval and flood loss following florpyrauxifen-benzyl at 30 g ai ha−1 applied as a spray or coated on urea. In a preflood application experiment, coating florpyrauxifen-benzyl on urea and applying it the day of flood establishment and 5 and 10 d prior to flooding (DPTF) resulted in lower yellow nutsedge, broadleaf signalgrass, and barnyardgrass control than when the herbicide was spray at 3 and 5 wk after final treatment (WAFT). Coating florpyrauxifen-benzyl onto urea provided only 61% to 63% yellow nutsedge control at 3 and 5 WAFT, which was 35 to 37 percentage points lower than when the spray was applied at 5 or 10 DPTF. Likewise, rice yields following applications of florpyrauxifen-benzyl coated onto urea were 1,200 kg ha−1 less than yields following spray applications. Florpyrauxifen-benzyl coated onto urea and clomazone provided lower levels of weed control than spraying the herbicide alone, suggesting an explanation for the yield losses. The timing of flood loss experiment suggested that when florpyrauxifen-benzyl coated onto urea at 30 g ai ha−1 was applied preflood and flood was relinquished at 2 h, 24 h, and 7 d after flood establishment, hemp sesbania and yellow nutsedge control were not affected. However, loss of floodwater 2 h after flood establishment resulted in lower barnyardgrass control than when the flood was lost 24 h and 7 d after flooding. Generally, the period between a herbicide application and flooding completion should be minimized to aid in weed control. These results indicate the importance of maintaining a flood for weed control and nutrient management.

In 2021 and 2022, research was initiated at two locations to evaluate the efficacy and safety of sulfentrazone in transplanted cabbage and broccoli. Treatments included oxyfluorfen at 560 g ha−1 applied pretransplant (PRE-T), sulfentrazone applied at 116 or 233 g ha−1 PRE-T, and S-metolachlor applied at 715 g ha−1 immediately after transplanting (POST-T) followed by (fb) oxyfluorfen applied at 210 g ha−1 postemergence (POST) 14 d after planting (DAP). The weedy cover of nontreated plots averaged between 6% (14 DAP) and 72% (42 DAP); all herbicide-treated plots averaged less than 30% cover at 42 DAP. At 14 and 28 DAP, oxyfluorfen, S–metolachlor fb oxyfluorfen, and the high rate of sulfentrazone reduced total monocotyledonous and dicotyledonous weed densities by 62% and 100%, respectively, relative to the nontreated control. The density of hairy galinsoga (in New Jersey) and combined ladysthumb and prostrate knotweed (in New York) were reduced by 71% to 99%. Except for the low rate of sulfentrazone, all herbicide treatments reduced weed biomass at harvest by ≥88%. Crop injury varied in response to herbicide treatments or weed competition but was also affected by crop and location. Between 14 and 28 DAP, the greatest amount of stunting (22%) was noted in the S-metolachlor fb oxyfluorfen treatments at both locations. Averaged over treatments, greater stunting was observed in broccoli than in cabbage in New York, whereas stunting estimates were higher for cabbage in New Jersey. All treatments in New Jersey resulted in significantly increased cabbage yield and broccoli and cabbage head sizes relative to the nontreated controls. No yield difference was noted between herbicide treatments and the nontreated check in New York. Data derived from these studies will be used to enhance crop safety recommendations in northeastern U.S. production environments for sulfentrazone used PRE in transplanted cabbage and support a potential label for broccoli.

Methyl bromide (MBr) was widely used as a soil fumigant to manage pests in the planting bed prior to transplanting fresh market tomato; however, it has been banned by the United Nations Environment Programme. Alternatives to MBr must be implemented to sustain productivity in fresh market tomato. Dimethyl disulfide plus chloropicrin (DMDS : Pic) is a fumigant alternative to methyl bromide for the management of yellow nutsedge and other soil-borne pests in tomato. Fumigant costs, environmental concerns, and risk mitigation measures encourage reduced fumigant application rates. Virtually impermeable film (VIF) and totally impermeable film (TIF) provide greater fumigant retention than low density and high density polyethylene film, VIF and TIF can allow for reduced fumigant application rates while maintaining fumigant efficacy. The objectives of this research were to evaluate TIF with reduced rates of shank-applied DMDS : Pic (79 : 21 w/w) for the control of yellow nutsedge in tomato. Treatments included a standard rate of DMDS : Pic (468 L ha−1) under VIF and TIF, a high rate (561 L ha−1) under VIF, three reduced rates (187 L ha−1, 281 L ha−1, and 374 L ha−1) under TIF, and a nontreated control under TIF and VIF. Results indicated rates may be reduced from a standard 468 L ha−1 under VIF to 187 L ha−1 (67% reduction) under TIF while maintaining yellow nutsedge control and tomato yields. In addition, the results indicated that nontreated TIF managed yellow nutsedge better than nontreated VIF because of decreased penetration of the mulch by yellow nutsedge.