Effect of some selective herbicide oversprays on newly emerged eucalypt and hopbush seedlings in Central Western New South Wales

Abstract

Unlike parts of Victoria and South Australia, direct seeding of woody plants has been unreliable in Central Western New South Wales where failures have been attributed to low rates of seedling emergence and competition from herbaceous weeds. We investigated the usefulness of overspraying newly emerged seedlings of eucalypt (Eucalyptus spp.) and Narrow-leaf Hopbush (Dodonaea viscosa ssp. angustissima) in an existing or potentially weedy seedbed using a grass-selective herbicide (Fusilade® or Sertin®) and/or a soil-residual herbicide (Simazine®). These treatments were investigated at two sites over three sowing seasons in Central Western NSW. In most cases, the herbicides failed to enhance seedling survival because grasses were not the main component of the weed species present or because the herbicide damaged the seedlings. Hopbush was relatively tolerant to Simazine but eucalypt seedlings were not, particularly at the site with sandy soils. Grass-selective herbicides did not appear to damage seedlings. Suggestions for increasing the reliability of direct seeding in this region are presented. © 2006 Ecological Society of Australia.