Spray strips at least 1.5 m wide with a boom spray, or spray spots at least 1.5 m diameter where trees will be planted. When to spray Pasture topping - in spring, the year before tree planting. Perennial weeds - in summer or autumn, before soil preparation. Annual weeds - in the late autumn or early winter, after soil preparation, shortly before planting. Second year weed control - in May or June.
Later applications are less effective.
Application tips Knockdown herbicides work best on healthy weeds, especially after rain has stimulated their growth. They are less effective on unhealthy weeds, especially if nitrogen deficient. Dense weeds must be removed by heavy grazing, cultivation or knockdown herbicide before applying residual herbicides. Residual herbicides work best if applied to moist soil. Only a residual herbicide is needed if the pre-planting application is done after soil preparation, but before weed emergence.