title: Evaluating the effects of herbicide drift on nontarget terrestrial plants: A case study with mesotrione.
abstract: Nature of exposure is a fundamental driver in nontarget terrestrial plant risk assessment for pesticides; consequently a novel study was designed to generate field-based drift exposure and evaluate corresponding biological effects of the herbicide mesotrione. The approach used a combination of US guideline drift reduction technology and vegetative vigor approaches. In each of 3 independent replicate spray application trials, 10 pots each of lettuce and tomato were placed at distances of 10, 20, 30, 40, and 50 ft (∼3, 6, 9, 12, and 15 m) from the downwind edge of the spray boom. Each application was conducted using a commercial 60-ft (18-m) boom sprayer fitted with TeeJet®Technologies TTI110025 nozzles, with a nominal application rate of 0.2 lb a.i./A (224 g a.i./ha). The environmental conditions required by the protocol (air temperature 10-30 °C and wind perpendicular to the swath (±30°) blowing toward the plants at a mean wind speed of ≥10 mph [≥4.5 m/s] measured at 2.0 m above the ground) were met for each application. Following exposure, plants were transferred to a greenhouse for the 21-d vegetative vigor phase of the study. Symptoms of phytotoxicity and plant height were assessed at 7, 14, and 21 d after treatment. On completion of the 21-d after treatment assessment, all plants were harvested and dried in an oven to determine shoot dry weight. The biological data indicated that no statistically significant effects were observed at a distance of 30 ft (∼9 m) from mesotrione drift at wind speeds of ≥10 mph (10.9-12.4 mph); this endpoint (30 ft) is defined as the no observed effects distance (NOED). Environ Toxicol Chem 2017;36:2465-2475. © 2017 SETAC.
authors.affiliation: Syngenta Crop Protection, Greensboro, North Carolina, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Brain
authors.affiliation: Syngenta Crop Protection, Greensboro, North Carolina, USA.
authors.forename: Jeff
authors.initials: J
authors.lastname: Perine
authors.affiliation: Smithers Viscient, Harrogate, North Yorkshire, United Kingdom.
authors.forename: Catriona
authors.initials: C
authors.lastname: Cooke
authors.affiliation: Silsoe Spray Applications Unit, Silsoe, Bedford, United Kingdom.
authors.forename: Clare Butler
authors.initials: CB
authors.lastname: Ellis
authors.affiliation: Smithers Viscient, Harrogate, North Yorkshire, United Kingdom.|phife.uk, Nunthorpe, Middlesbrough, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Harrington
authors.affiliation: Silsoe Spray Applications Unit, Silsoe, Bedford, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lane
authors.affiliation: Silsoe Spray Applications Unit, Silsoe, Bedford, United Kingdom.
authors.forename: Christine
authors.initials: C
authors.lastname: O'Sullivan
authors.affiliation: Syngenta Crop Protection, Greensboro, North Carolina, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Ledson
mesh_terms: D003512:Cyclohexanones / Q000633:toxicity*; D004784:Environmental Monitoring; D006540:Herbicides / Q000633:toxicity*; D010944:Plants / Q000187:drug effects*; D018570:Risk Assessment; D014919:Wind
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; C432907:mesotrione
keywords: Drift; Ecological risk assessment; Herbicide; No observed effect distance; Nontarget terrestrial plants; Phytotoxicity