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United States Department of Agriculture

Agricultural Research Service

Title: Influences of Soil Ph-Sorption Interactions on Imazamox Carryover

Authors
item Bresnahan, G - NORTH DAKOTA STATE UNIV
item Koskinen, William
item Dexter, A - NORTH DAKOTA STATE UNIV

Submitted to: Crop Protection Council British Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1999
Publication Date: N/A

Technical Abstract: Soil pH affects imazamox sorption-desorption, which in turn can affect persistence and bioavailability. Long-term carryover of some imidizolinones has been observed in soil that is below pH 6.5, resulting in significant sugarbeet damage. We found 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, there were differences in bioavailability, 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 and 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.

Last Modified: 8/2/2014