Enhanced degradation cross-adaptation

The phenomenon of cross-enhancement, or the ability of soils pretreated with specific herbicides to degrade other structurally related herbicides more rapidly than in untreated control soils, has been known for nearly 40 years. Both enhanced degradation and cross-adaptation have been observed under field conditions for phenoxyalkanoic acid herbicides (3-5). ... 

There is evidence from a relatively few studies to show that repeated treatments of 2,4-D and MCPA result in enhanced degradation rates under field conditions as a result of adaptation of soil microorganisms. Even less is known about the phenomenon of cross-enhancement under field conditions, where previous applications of either 2,4-D and MCPA may result in enhanced breakdown of both phenoxyalkanoic herbicides. 

Cross-Adaptation. To determine if other carbamothioate herbicides would degrade more rapidly in soils exhibiting enhanced EPTC degradation, the degradation of EPTC, and two similar carbamothioates, butylate and vernolate (S-propyl dipropylcarbamothioate), were monitored for 44 days following applications to non-history and EPTC-history Kennebec soil (13). 

Degradation Studies. Some laboratory studies on enhanced biodegradation have involved use of gas chromatographic analyses while lather studies have included measurement of CO2 resulting from C-labeled pesticide degradation to assess the severity of the problem, delineate the impact of environmental factors, or determine cross-adaptation Qi)- In our soil... 

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