Evaluation of dicamba volatilization when mixed with glyphosate using imazethapyr as a tracer. (1st September 2022)

• Record Type: Journal Article
• Authors: Zaccaro-Gruener, Maria Leticia; Norsworthy, Jason K.; Brabham, Chad B.; Barber, L. Tom; Butts, Thomas R.; Roberts, Trenton L.; Mauromoustakos, Andy
• Is Part Of: Journal of environmental management. Volume 317(2022)
• Publication Date: 2022-09-01
• Subjects: Volatilization -- Drift -- Environmental conditions -- Vegetation cover -- Microclimates; ae acid equivalent -- BAPMA N, N-Bis-(3-aminopropyl) methylamine salt -- DGA diglycolamine salt -- DMA dimethylamine salt -- DR dicamba-resistant -- HAA hours after application -- Kow coefficient of partition in n-octanol/water -- PUF polyurethane foam -- TTI Turbo TeeJet Induction -- VP vapor pressure; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115303
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Expansion of dicamba-resistant crops increased the frequency of off-target movement issues, especially in the midsouthern United States. Six field trials were conducted over two growing seasons with the purpose to determine the contribution of volatilization and physical suspension of particles to the off-target movement of dicamba when applied with glyphosate and imazethapyr - a non-volatile herbicide used as a tracer for physical off-target movement. Applications included dicamba at 560 g ha −1, glyphosate at 1260 g ha −1, and imazethapyr at 105 g ha −1 . Applicators include glyphosate with dicamba to increase the spectrum of weed control from these applications; however, this addition increases potential for dicamba volatilization. Following application of the mixture, air samplers were placed in the field to collect dicamba and imazethapyr. Results showed there was at least 50 times more dicamba than imazethapyr detected even though the dicamba:imazethapyr ratio applied was 5.3:1. Dicamba was detected in the treated area and the off-site locations and all intervals of air sampling, ranging from 126 to 5990 ng. No more than 37.5 ng of imazethapyr was detected during the first 24-h after application (HAA) inside the treated area. Imazethapyr was only detected in 9 of the 20 sampling combinations during these experiments, and most of these detections (6) occurred during the first 24 HAA and inside the treated area. While some movement from the suspension of particles occurred based on the detection of imazethapyr in air samples, results show that most dicamba detection was due to the volatilization of the herbicide. Graphical abstract: Image 1 Highlights: Imazethapyr was used as a tracer to determine the sources of off-target movement of dicamba. Low imazethapyr detections during trials indicated the presence of suspended spray particles. Suspension of spray particles in air had a minor impact on the overall dicamba detection. The detection of dicamba was at least 50 times greater than imazethapyr in air samples. Volatility was the main source for the detection of dicamba in air samples.