Response of Dry Bulb Onion, Sugar Beet, and Pinto Beans to Imazosulfuron Soil Residues

Abstract

Field studies were conducted in 2010 in Ontario, OR, to evaluate the response of direct-seeded dry bulb onion, sugar beet, and pinto beans to imazosulfuron soil residues 12 mo after application to control weeds in potato. The studies were organized as randomized complete block designs with three replications each. Imazosulfuron was applied alone PRE at 224 and 450 g ai ha−1, sequentially at 224 g ha−1PRE and POST, or in tank mixture withS-metolachlor 1,060 g ha−1. Very few onion plants emerged in plots previously treated with imazosulfuron at 224 g ha−1, regardless of timing. Emerged onion plants were severely injured and never matured. No onions emerged from residues of imazosulfuron applied at 450 g ha−1. A few sugar beet plants emerged from 224 g ha−1but were severely stunted and never grew beyond the first set of leaves. There was no sugar beet emergence from imazosulfuron sequential applications, regardless of the rate and application timing. However, imazosulfuron residues did not affect pinto beans, which emerged and produced marketable yield, similar to grower standard and nontreated plots. The results suggest sensitivity of direct-seeded dry bulb onion and sugar beet, but not pinto beans, to imazosulfuron residues 12 mo after application.