A field comparison of strategies for the control of Chilean needle grass in Hawke's Bay

Abstract

Management strategies to control Chilean needle grass comprised two re-grassing regimes using the competitive pasture species cocksfoot, combined with lax grazing using sheep or young cattle, no attempted management, and forestry. The presence of Chilean needle grass and cocksfoot densities were assessed by examining 50 mm turf cores taken annually from 1994, and from the forestry site since 1997. There was a strong inverse relationship between Chilean needle grass frequency of occurrence and the sown cocksfoot density. The establishment of cocksfoot and its promotion by lax grazing reduced the frequency of occurrence of Chilean needle grass from 60% in October 1994 to 9% in 1998. Although cocksfoot suppressed Chilean needle grass, eradication appears unlikely or at least a long-time process. In the young pine plantation, Chilean needle grass grew unchecked with 24 and 27% of the cores containing Chilean needle grass in 1997 and 1998 respectively. Under forestry the Chilean needle grass seed bank is likely to develop until canopy closure. Keywords: Chilean needle grass, cocksfoot, Dactylis glomerata, forestry, grazing, Pinus radiata, Stipa neesiana, weed control