4 6 1 Review

• Main Authors: L Jason Krutz, A Dale L Shaner, B Mark Aweaver, C Richardmtwebb, Robert M Zablotowicz, A Krishna N Reddy, A Yanbo Huanga, Steven J Thomsona
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: enhanced biodegradation; modeling; leaching; weed control; pesticide; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.603.729; http://www.ars.usda.gov/sp2UserFiles/Place/64025500/Publications/Krutz/Krutzetal2010PMS66-461-481.pdf

Novel catabolic pathways enabling rapid detoxificationof s-triazine herbicides havebeen elucidated anddetected at a growing number of locations. The genes responsible for s-triazine mineralization, i.e. atzABCDEF and trzNDF, occur in at least four bacterial phyla and are implicated in the development of enhanced degradation in agricultural soils from all continents except Antarctica. Enhanced degradation occurs in at least nine crops and six crop rotation systems that rely on s-triazine herbicides for weed control, and, with the exception of acidic soil conditions and s-triazine application frequency, adaptation of the microbial population is independent of soil physiochemical properties and cultural management practices. Froman agronomic perspective, residual weed control could be reduced tenfold in s-triazine-adapted relative to non-adapted soils. From an environmental standpoint, the off-site loss of total s-triazine residues could be overestimated 13-fold in adapted soils if altered persistence estimates and metabolic pathways are not reflected in fate and transport models. Empirical models requiring soil pHand s-triazineusehistoryas inputparameterspredict atrazinepersistencemoreaccurately thanhistorical estimates, thereby allowing practitioners to adjust weed control strategies andmodel input values whenwarranted.