There has been a new weed found recently in WA. If infestations are reported and dealt with promptly it will be possible to prevent it establishing and becoming the problem here that it is in South Australia where it infests more than 35,000 hectares in the Flinders Ranges. Wheel Cactus (Opuntia robusta) has recently been discovered for the first time in WA in two locations, one in Dowerin and the other in Yarloop. It is usually a dull blue-green colour and similar in appearance to Prickly Pear but the segments are round (hence the common name) rather than oval or teardrop shaped as in Prickly Pear. Birds eat its fruit and spread the seeds widely. It belongs to the opuntioid group of cacti which have been declared Weeds of National Significance. If you see a plant you suspect is Wheel Cactus report it to the Department of Agriculture and Food’s Pest and Disease Information Service on freecall 1800 084 881. For more information go to www.agric.wa.gov.au.
Search for ‘cacti’. If you have a large infestation of Narrow Leaf Cottonbush slashing and burning during winter can assist in its control by destroying some of the soil seed bank and make it easier to carry out follow up spraying when the plants reshoot and new seedlings emerge as the weather warms up in spring. Slashed plants usually reshoot or send up suckers so follow up is important.
Arum Lily (Zantedeschia aethiopica) is also appearing now and spraying can be carried out from June through to November. If you do not wish to use herbicides and instead manually remove plants it is very important to ensure all pieces of the roots are removed and the infested area regularly monitored for further growth. Arum Lily is a declared plant and is poisonous to humans and livestock. It is a particular problem in wetlands and along watercourses. More information on local weeds and weed control can be obtained by contacting Chittering Landcare Centre on firstname.lastname@example.org or 9571 0400.