Distribution, ecology and control of Cassinia arcuata (sifton bush) in New South Wales

Abstract

The area of New South Wales infested with Cassinia aiwuta (sifton bush) increased from 93 000 ha in 1975 to 616 000 ha in 1988, indicating a need to investigate its biology and control. Of 6 samples of seed collected over 3 years from 2 sites, 5 germinated readily, emerged from a soil depth of 15 mm or less, and grew 7-48 times slower than pasture species in 28 days. The remaining sample had an after-ripening period of more than 5 months before full germination was achieved. Lime depressed growth of C. arcuata seedlings whilst superphosphate promoted growth. Preemergence herbicides simazine and atrazine killed seedlings in the cotyledon stage, while post-emergence herbicides glyphosate, triclopyr + picloram and hexazinone killed 40-, 78- and 139-day-old seedlings. Control on arable land could be achieved by burying seeds below 15 mm, followed by cultivation or herbicide application to remove establishing seedlings and addition of lime and spelling to allow sown species to smother late-establishing seedlings. On non-arable land burning to remove mature plants, spraying to kill establishing seedlings and aerial application of seed of improved species and superphosphate will contribute to control on soils that can support sown species without the application of large quantities of lime.