Thomas V. Reed

Flucarbazone-Sodium Absorption, Translocation, and Metabolism in Bermudagrass, Kentucky Bluegrass, and Perennial Ryegrass

Abstract Perennial ryegrass is overseeded in bermudagrass and Kentucky bluegrass to improve turf quality, but selective control may be warranted for transition back to monostand turfgrass. Flucarbazone–sodium controls perennial ryegrass in bermudagrass and Kentucky bluegrass, but the physiological basis of selectivity has received limited investigation. Greenhouse and laboratory experiments were conducted to evaluate efficacy, absorption, translocation, and metabolism of flucarbazone–sodium in these grasses. Flucarbazone–sodium reduced perennial ryegrass shoot mass from the nontreated an average ≈ 22 times and 3 times more than bermudagrass and Kentucky bluegrass at 4 wk after treatment, respectively. In laboratory experiments, foliar and root absorption of 14C–flucarbazone–sodium were similar among species. Bermudagrass distributed ≈ 25% more foliar-absorbed 14C to nontreated shoots than Kentucky bluegrass and perennial ryegrass. From root applications, all grasses averaged 84% distribution of 14C to shoots. Bermudagrass and Kentucky bluegrass metabolized 100% and 74% of 14C–flucarbazone–sodium at 1 d after treatment (DAT), whereas perennial ryegrass metabolism measured 44, 58, and 65% at 1, 3, and 7 DAT, respectively. Bermudagrass, Kentucky bluegrass, and perennial ryegrass had 4, 4, and 2 metabolites after 7 d, respectively. Results suggest differential metabolism of flucarbazone–sodium is attributed to selectivity for controlling perennial ryegrass in bermudagrass and Kentucky bluegrass. Nomenclature: Flucarbazone–sodium; bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-Davy] ‘Princess-77’; Kentucky bluegrass (Poa pratensis L.) ‘Midnight’; perennial ryegrass (Lolium perenne L.) ‘Manhattan V’.

Indaziflam Enhances Buckhorn Plantain (Plantago lanceolata) Control from Postemergence Herbicides

Abstract 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 of 14C-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−1 controlled 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. Nomenclature: Buckhorn plantain, Plantago lanceolata L.; bermudagrass, Cynodon dactylon L. Resumen Plantago lanceolata es una maleza perenne en céspedes y la eficacia de herbicidas POST es comúnmente inconsistente para su control en la primavera. Indaziflam es un inhibidor de la biosíntesis de cellulose usado para el control PRE de malezas anuales en césped y su aplicación ha demostrado ser dañina para plantas establecidas de P. lanceolata. Los objetivos de esta investigación fueron evaluar (1) los efectos de la dosis y lugar de aplicación de indaziflam sobre el daño de P. lanceolata; (2) los efectos de mezclar en tanque indaziflam con herbicidas POST para el control de P. lanceolata; y (3) los efectos fisiológicos de indaziflam en la absorción y translocación de 14C-2,4-D en P. lanceolata. En experimentos de invernadero, indaziflam redujo la masa de tejido aéreo de P. lanceolata 61 a 75% en comparación al testigo no-tratado a 4 semanas después del tratamiento (WAT) y el ranking jerárquico del lugar de aplicación fue: foliar + suelo ≥ suelo ≥ foliar. No se detectaron diferencias en la reducción de biomasa según la dosis de aplicación (27.5 y 44 g ai ha−1). En los experimentos de campo, indaziflam a 55 g ha−1 controló P. lanceolata 34% a 9 WAT, pero mejoró la velocidad de control de todos los herbicidas evaluados en mezclas en tanque. Aplicaciones exclusivas de 2,4-D o 2,4-D + dicamba + MCPP brindaron un control pobre (<70%) de P. lanceolata a 9 WAT, pero las mezclas en tanque con indaziflam brindaron 81 a 98% de control, respectivamente. Fluroxypyr y simazine solos controlaron P. lanceolata <38%, pero las mezclas en tanque con indaziflam mejoraron el control en más del doble en comparación con las aplicaciones solas. El mezclar en tanque indaziflam con metsulfuron no mejoró el control en comparación con metsulfuron solo a 9 WAT. No se detectó daño en Cynodon dactylon con ninguno de los tratamientos. En los experimentos de laboratorio, la absorción y translocación de 14C-2,4-D en P. lanceolata fue similar con o sin mezclas en tanque con indaziflam a 72 y 168 h después del tratamiento. En general, indaziflam mejoró el control de P. lanceolata con herbicidas POST al brindar una fitotoxicidad aditiva en las mezclas en tanque en la primavera.

Effect of Fumigation with 1,3-Dichloropropene and Chloropicrin on Fomesafen Dissipation in Eggplant Plasticulture Production

Fomesafen is a protoporphyrinogen oxidase (PROTOX) inhibitor that has the potential to be used as an alternative mechanism of action for PRE nutsedge and broadleaf weed control in Florida production of small fruit and vegetables. Fumigation in the raised-bed plasticulture system may increase herbicide persistence. Fomesafen persistence could dissuade Florida growers from using the herbicide for fear of injury to subsequent susceptible crops. Field experiments were conducted in Balm, FL, in 2015 and 2016 to investigate the effect of fumigation on fomesafen dissipation, eggplant tolerance, and purple nutsedge control. Treatments included fomesafen at 0.42 kg ai ha-1, S-metolachlor at 1.06 kg ai ha-1, and a nontreated control in either a fumigated bed injected with a combination of 39% 1,3-dichloropropene and 59.6% chloropicrin at 336 kg ha-1 or no fumigant. Fomesafen concentration in the soil decreased by 83% and 96% from application to harvest in 2015 and 2016, respectively. Fumigation did not affect fomesafen dissipation in either year. At 2 wk after transplant (WATr), fomesafen caused 14% eggplant injury. Injury decreased to less than 5% at 6 WATr. Fomesafen and S-metolachlor treatments did not reduce eggplant height or yields compared with the nontreated control. Fumigation and fomesafen did not decrease purple nutsedge density; however, S-metolachlor applications resulted in a 48% reduction. Further research is needed to assess efficacy on broadleaf and grass weeds. Nomenclature: 1,3-dichloropropene; chloropicrin; fomesafen; S-metolachlor; purple nutsedge, Cyperus rotundus L.; eggplant, Solanum melongena L.

Persistence and Movement of Fomesafen in Florida Strawberry Production

Abstract Fomesafen is a protoporphyrinogen oxidase–inhibitor herbicide with an alternative mode of action that provides PRE weed control in strawberry [Fragaria × ananassa (Weston) Duchesne ex Rozier (pro sp.) [chiloensis × virginiana]] produced in a plasticulture setting in Florida. Plasticulture mulch could decrease fomesafen dissipation and increase crop injury in rotational crops. Field experiments were conducted in Balm, FL, to investigate fomesafen persistence and movement in soil in Florida strawberry systems for the 2014/2015 and 2015/2016 production cycles. Treatments included fomesafen preplant at 0, 0.42, and 0.84 kg ai ha− 1. Soil samples were taken under the plastic from plots treated with fomesafen at 0.42 kg ha-1 throughout the production cycle. Fomesafen did not injure strawberry or decrease yield. Fomesafen concentration data for the 0.0- to 0.1-m soil depth were described using a three-parameter logistic function. The fomesafen 50% dissipation times were 37 and 47 d for the 2014/2015 and 2015/2016 production cycles, respectively. At the end of the study, fomesafen was last detected in the 0.0- to 0.1-m depth soil at 167 and 194 d after treatment in the 2014/2015 and 2015/2016 production cycles, respectively. Fomesafen concentration was less than 25 ppb on any sampling date for 0.1- to 0.2-m and 0.2- to 0.3-m depths. Fomesafen concentration decreased significantly after strawberry was transplanted and likely leached during overhead and drip irrigation used during the crop establishment.