Response of Alfalfa, Green Onion, Dry Bulb Onion, Sugar Beet, Head Lettuce, and Carrot to Imazosulfuron Soil Residues 2 Years after Application

Abstract

Field studies were conducted from 2009 to 2011 in Oregon and from 2006 to 2008 in California to evaluate the response of various crops to imazosulfuron soil residues 91 to 731 d after application (DAA). Imazosulfuron rates applied in Oregon were 224 or 450 g ai ha−1PRE, sequential 224 g ha−1PRE and POST, or 450 g ha−1as a tank mixture with PRE appliedS-metolachlor at 1,060 g ai ha−1followed by 224 g ha−1POST to potato. Imazosulfuron was applied on bare ground PRE at 224, 336, and 450 g ha−1and applied sequentially at 450 g ha−1in California. Sugar beet planted 91 to 364 and 458 to 731 DAA were injured 83 to 94% and 54 to 78% among imazosulfuron rates and application timing in 2007 and 2008, respectively. Alfalfa planted 701 DAA at rates greater than 224 g ha−1was injured, and the forage yield was reduced. Onion, spinach, carrot, and broccoli were also injured by imazosulfuron residues when planted 91 to 731 DAA, regardless of the rate or interval before planting. Imazosulfuron applied at 224 to 450 g ha−1458 to 731 d before planting head lettuce resulted in moderate injury that did not reduce fresh-weight yield. The results indicated that imazosulfuron residues in the soil have the potential to injure many rotational specialty crops for 2 yr or more in soils with pH > 6.9.