Submitted to: Crop Protection Council British Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/15/1999
Publication Date: N/A
Technical Abstract: Long-term carryover of some imidizolinone herbicides has been observed in soil that is below pH 6.5, resulting in significant sugarbeet damage. In a field study in Southwest Minnesota, imazamox concentration decreased rapidly in field soil, regardless of pH. In spite of similar amounts of imazamox remaining in aged soils at different pH levels, bioavailability differed with pH, which can be explained by sorption-desorption. At low pH more imazamox was sorbed than at high pH, but it readily desorbed. At high pH less imazamox was sorbed initially, but it did not readily desorb. Thus, after three months, the remaining imazamox in low pH soil was desorbable and bioavailable, resulting in injury to canola and sugarbeet. Liming aged low pH soil, released bound imazamox residues, which would then be degraded and result in less carryover.