SUGARCANE SOILS EXHIBIT ENHANCED ATRAZINE DEGRADATION AND CROSS ADAPTATION TO OTHER s-TRIAZINES

Reports of reduced residual weed control with atrazine in Florida and Hawaii soils indicate that enhanced triazine degradation may be occurring across the entire United States sugarcane production region. A previously developed triazine degradation assay was used to determine if Florida and Hawaii soils were positive for enhanced atrazine degradation and if confirmed adapted soils were also cross-adapted with ametryn, and metribuzin. The objectives of this study were to 1) determine if soils collected from the United States sugarcane regions (i.e., Florida and Hawaii) exhibit enhanced atrazine degradation; and 2) determine if atrazine adapted soils also degrade other triazine herbicides used use in sugarcane production. Florida and Hawaii soils with a previous atrazine use history did exhibit enhanced atrazine degradation. Atrazine adapted soils were cross-adapted with ametryn, another s-triazine; however, the atrazine adapted soils were not cross-adapted with the non-symmetrical triazine herbicide, metribuzin. Results indicate that 1) enhanced atrazine degradation occurs across the full range of the United States sugarcane production region; and that 2) atrazine adapted sugarcane production soils will likely be cross-adapted with ametryn but not metribuzin. Consequently, metribuzin may be a viable alternative to for sugarcane productio n soils with reduced residual weed control arising from enhanced s-triazine degradation.