Response of direct-seeded dry bulb onion to simulated glyphosate drift with variable rates and application timings

Journal or Publishing Institution: Weed Technology

Study: https://www.jstor.org/stable/pdf/23358280.pdf

Author(s): Felix, J., Boydston, R. and Burke, I.C.

Article Type: Peer Reviewed Study

Record ID: 675

Abstract: Field studies were conducted in 2011 at the Malheur Experiment Station, Ontario, OR and Prosser, WA to evaluate the effect of simulated glyphosate drift on direct-seeded dry bulb onion. Glyphosate was applied at 8.6, 25.8, 86, 290, 434, and 860 g ae ha−1 when onion plants were at the flag-, two-, four-, and six-leaf stages. Onion foliar injury was directly related to the glyphosate dose and varied with application timing. Foliar injury at 7 d after treatment (DAT) ranged from 0 to 12% for glyphosate ≤ 25.8 g ha−1. Foliar injury increased at 21 DAT when glyphosate was applied ≥ 25.8 g ha−1 to plants at the flag- and four-leaf stage, and ranged from 24 to 99%. The 50%-injury glyphosate dose at 21 DAT was lowest when onion was treated at the four-leaf and flag stages and was estimated to be 76.8 and 81 g ha−1, respectively. Onion injury severity increased when glyphosate was applied at ≥ 86 g ha−1 and eventually resulted in plant death at 860 g ha−1. Foliar injury was inversely correlated to U.S. no. 1 onion yield. Onions displayed sensitivity to very low glyphosate doses especially at the four-leaf stage. Shikimic acid accumulation increased with the increase in glyphosate dose and was positively correlated with foliar injury and negatively correlated with plant height and onion yield.

Keywords: Onions, Plants, Herbicides, Fertilizer application timing, Plant growth, Vegetable crops, Dose response relationship, Vegetable production, Plant bulbs, Glyphosate

Citation: Felix, J., Boydston, R. and Burke, I.C., 2012. Response of direct-seeded dry bulb onion to simulated glyphosate drift with variable rates and application timings. Weed Technology, 26(4), pp.747-756.