Adsorption and bioactivity of di‐allate, tri‐allate and trifluralin*

Summary: Studies were conducled to cstmiate the adsorption parameter k and the bioactivity (in terms of G R50) of di‐allate [S‐2,3‐dichloroallyl N, N‐di‐isopropyl (thiocar bamate)], iri‐allate [S‐2,3,3‐trichloroallyl N, N ‐di‐isopropyl (thiocar bamate], and [trifiuralin (2,6‐dinitro N, N‐dlpropyl‐4‐trifluoromelhylaniline) in a number of Saskatchewan soil. The k values ratiged from 5 for di‐allate adsorption m Asquilh loamy sand to 315 for trifluralin adsorption on Melfort loam and were closely related to the soil organic matter content. The relative degree of adsorption was irifluralin > tri‐allate >di‐allaie. For each herbicide, the G R50 values were positively correlated wich organic matter conienl atid wilh k. It was suggested that these nonionic herbicides may be amenable to a predictive approach for field application rates in different soils. Among herbicides for any one soil, however, there was not the same relationship between G R50andk. since the G R50 was least for trifluralin and there was no significant difference between di‐allate and tri‐allate.