Abstract
Sequential applications of three pre-emergence herbicides were made to four species of newly planted proteas. Herbicides were applied at three-month intervals over a two-year period. Protea trunk diameter growth in response to herbicide treatments and two types of synthetic mulch were recorded after a one-year establishment period. Protea neriilolia R. Br. growth was significantly reduced by oryzalin at 6.7 kg a.i. ha-1. Banksia menziesii R. Br. growth was reduced in untreated plots where weeds were removed by hoeing: growth of all other proteas was improved with weed removal. Growth of all other Protea species was unaffected by herbicide applications. Synthetic mulches of woven black polypropylene and a polyester spunbound fabric did not adversely affect protea growth. However, the polyester mulch collected soil, providing a surface for weed-seed germination and growth through the fabric. All herbicides tested provided adequate weed control, but oryzalin provided only marginal control of a leguminous weed, Medicago truncatula Gaertn.
