ChileanJAR

Both the toxic and formulation properties ofsome herbicides have produced environmental changes. Controlled-release herbicide formulations allow for a deliberate release of active ingredients, therefore avoiding excess of herbicide in the environment. This study reports the effect ofa commercial and a controlled-release formulation based on bark as supporting material ofhexazinone upon the weed control of Monterey pine (Pinus radiata) nurseries. Experimental plots had naturallevels ofweed infestation and three-month oldPinus radiata plants. Results are expressed as percentage of weed control and a Productivity Index for Pinus radiata plants. After 6 months, the bark-based formulation displayed a better weed control than commercial formulations, with weed controllevels of27% and 13%, respectively, whereas Productivity Index values indicated a negative effect on the growth of Pinus radiata plants when the conventional formulation was applied, with a reduction of productivity of 27%. The bark-based formulation achieved a better weed control than the commercial one, with no apparent damage on Pinus radiata plants.