Dissipation of the Herbicide Benzobicyclon Hydrolysate in a Model California Rice Field Soil

Williams, Katryn L.; Gladfelder, Joshua J.; Quigley, Lindsay L; Ball, David B.; Tjeerdema, Ronald S.

doi:10.1021/acs.jafc.7b03679

Cited by 15 publications

(22 citation statements)

References 42 publications

(92 reference statements)

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“…Williams and Tjeerdema (2016) reported that water pH, temperature, and the presence of dissolved organic carbon affects conversion of benzobicyclon to benzobicyclon hydrolysate. Williams et al (2017) observed a decrease in benzobicyclon hydrolysate loss under flooded rice field conditions compared with nonflooded conditions, and higher temperatures increased benzobicyclon hydrolysate dissipation. However, control of Schoenoplectus juncoides (Roxb.)…”

Section: Introductionmentioning

confidence: 99%

Benzobicyclon Activity on Common Louisiana Rice Weeds

2018

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A study was conducted at three locations in Louisiana to evaluate the response of common Louisiana rice weed species to different rates of application of benzobicyclon herbicide. Benzobicyclon was applied at 31, 62, 123, 185, 246, 493, 739, 986, and 1,232 g ai ha–1into flooded field conditions when ducksalad was at the first elongated-leaf stage. Barnyardgrass, false pimpernel, and yellow nutsedge control never exceeded 50% from any rate of benzobicyclon applied, averaged across evaluation timing. Ducksalad control, averaged across evaluation timing, was 83% when treated with 493 g ha−1and did not increase when treated with higher rates of benzobicyclon. At 42 d after treatment (DAT), purple ammannia and Indian toothcup treated with 185 and 246 g ha–1of benzobicyclon were controlled 58% and 81%, respectively, and did not differ in control compared with higher rates of benzobicyclon. All weeds were hand-harvested from each plot and separated by species at the conclusion of the study. No differences in fresh-weight biomass were observed for barnyardgrass, false pimpernel, purple ammannia, or yellow nutsedge. Treatment with benzobicyclon at ≥62 g ha–1resulted in reduced ducksalad fresh weight 42 DAT compared with the nontreated sample. Indian toothcup fresh weight was reduced 77% to 96% compared with the nontreated sample when treated with benzobicyclon at 246 to 1,232 g ha–1.

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Section: Introductionmentioning

confidence: 99%

Benzobicyclon Activity on Common Louisiana Rice Weeds

2018

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“…In contrast, benzobicyclon hydrolysate is expected to have excellent phloem mobility (ion trapping) (Hsu and Kleier 1996) and has a predicted distribution coefficient (log D; i.e., log K ow plus pK a ) value of −1.5 at pH 7.4, which is similar to that of other triketone and pyrazole HPPD-inhibiting herbicides (0.58 > log D > −1.45 at pH 7.4) (Gandy et al 2015). However, benzobicyclon hydrolysate is ionizable (pK a 2.89) (Williams et al 2017) and will be negatively charged in spray solution and flood water; thus, it will have difficulty crossing the cuticle. In this study, benzobicyclon with or without adjuvants had little activity when spray droplets came in direct contact with leaf foliage, but the addition of an oil-based adjuvant, especially MSO, was necessary to optimize the activity of benzobicyclon when spray droplets came in contact with foliage and flood water.…”

Section: Amazon Sprangletopmentioning

confidence: 89%

Spray deposition, adjuvants, and physiochemical properties affect benzobicyclon efficacy

Brabham

Norsworthy²,

Sandoski³

et al. 2019

Weed Technol

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Benzobicyclon is a new pro-herbicide being evaluated in the Midsouth United States as a post-flood weed control option in rice. Applications of benzobicyclon to flooded rice are necessary for efficacious herbicide activity, but why this is so remains unknown. Two greenhouse experiments were conducted to explore how herbicide placement (foliage only, flood water only, foliage and flood water simultaneously) and adjuvants (nonionic surfactant, crop oil concentrate, and methylated seed oil [MSO]) affect herbicide activity. The first experiment focused on importance of herbicide placement. Little to no herbicidal activity (<18% visual control) was observed on two- to four-leaf barnyardgrass, Amazon sprangletop, and benzobicyclon-susceptible weedy rice with benzobicyclon treatments applied to weed foliage only. In contrast, applications made only to the flood water accounted for >82% of the weed control and biomass reduction achieved when benzobicyclon was applied to flood water and foliage simultaneously. The second experiment concentrated on adjuvant type and benzobicyclon efficacy when applied to foliage and flood water simultaneously. At 28 days after treatment, benzobicyclon alone at 371 g ai ha−1 provided 29% and 67% control of three- to five-leaf barnyardgrass and Amazon sprangletop, respectively. The inclusion of any adjuvant significantly increased control, with MSO providing near-complete control of barnyardgrass and Amazon sprangletop. Furthermore, we used the physiochemical properties of benzobicyclon and benzobicyclon hydrolysate to derive theories to explain the complex activity of benzobicyclon observed in our study and in field trials. Benzobicyclon applications should contain an oil-based adjuvant and must be applied to flooded rice fields for optimal activity.

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“…Similar observations for other pesticides have also been reported. 6,13,33 Additionally, degradation under sterilized conditions may be attributed to the recovery of soil microbes and enzymes aer autoclaving, 34,35 as well as abiotic degradation. Overall, biological degradation is a major mechanism for BIT dissipation in the soil, which is mediated by soil microbes capable of degrading BIT and assisted by abiotic processes.…”

Section: Degradation Of Bit In Soilsmentioning

confidence: 99%