THE EFFECTS OF TRICLOPYR ON 2,4-D MINERALIZATION IN 2 SOILS

The effects of the herbicide triclopyr (3,5,6 -trichloro-2-pyridinylox yacetic acid) on the mineralization of 2,4-D (2,4-dichlorophenoyxaceti c acid) in two soils which differed in their histories of prior exposu re to the two herbicides were investigated. The relative effects of tr iclopyr on 2,4-D mineralization and most probable numbers of 2,4-D deg raders were dependent upon the soil. Triclopyr was shown to increase 2 ,4-D mineralization rates in a soil which had been exposed to both 2,4 -D and triclopyr, but decreased the mineralization rate of 2,4-D and i nhibited the increase of most probable numbers of 2,4-D degraders in a soil that had not been directly exposed to either herbicide.