A summary of research into the use of low rates of glyphosate as a pasture management tool

Abstract

Investigations into the use of low rates of glyphosate as a pasture management tool in New Zealand are summarised. Rates of 250 ml/ha Roundup (360 g/l a.i. glyphosate) increased white clover and decreased dead material contents on sites throughout New Zealand. Results were variable depending on site, weather and application conditions. Variable responses in perennial ryegrass content were noted, with repeated annual applications helping to improve ryegrass content. Lamb growth rates increased by an average of 30 g/d or 20%. Californian thistle numbers were reduced by annual application of low rates of glyphosate. Thistles that were not killed remained vegetative and small. The use of low rates of glyphosate to control late-spring growth improved pasture nutritional characteristics. Pastures must have enough time to recover before the onset of drought to avoid grass death and weed invasion. Careful use of this technique can aid in the management of pastures in late spring to increase pasture quality in summer. More research is needed to define rate-by-environment interactions, effects on pasture growth and feed quality through small well-designed experiments. Keywords: botanical composition, Californian thistles, dead material, drought, glyphosate, lamb growth, pasture management, ryegrass, white clover