Submitted to: American Society of Sugar Cane Technologists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2010
Publication Date: 1/5/2010
Citation: Shaner, D.L., Krutz, L.J., Henry, W.B., Hanson, B.D., Poteet, M.D., Rainbolt, C.R. 2010. Sugarcane Soils Exhibit Enhanced Atrazine Degradation And Cross Adaptation To Other Triazines. American Society of Sugar Cane Technologists. 30:1-11. Interpretive Summary: Triazine herbicides are vital for weed management in sugarcane production. Recently growers have complained that atrazine is not controlling weeds as long as it used to. To determine if this lack of weed control was due to the herbicide being rapidly degraded in the soil, we tested a number of soils from sugarcane fields in Hawaii and Florida. We found that atrazine was being very rapidly degraded in soils where the growers were having problems. We also found that these same soils would rapidly degrade ametryn, another triazine used in sugarcane, but the soils did not degrade metribuzin, an asymmetrical triazine that is also used in sugarcane. Our results show that enhanced atrazine and ametryn degradation are occurring in sugarcane field soils. However, since metribuzin is not rapidly metabolized in these soils, growers could switch to this herbicide to control their weeds.
Technical Abstract: 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, propazine 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 production soils with reduced residual weed control arising from enhanced triazine degradation.