Hexazinone weed control in re-established Pinus radiata plantations
The effect of two formulations of hexazinone at two rates with two application methods (1.5 m wide strip and total area) on fynbos were tested in a one-year-old Pinus radiata stand. Total manual weeding and mechanical ring weeding of one metre radius were added as experiment treatments to obtain 10 treatments. Tree height and diameter growth were monitored to determine the effect of weed control. After 13 months the liquid formulation of hexazinone was significantly better than the powder formulation. There were no significant differences between the two application methods. The higher herbicide rates showed better weed suppression than the lower rates although non-significantly so. Floristic surveys conducted over a three-year period indicated satisfactory weed suppression. Plant moisture stress measurements in the first three summers (dry season) after application indicated that the trees were not under water stress.