Weed Watch – Gazania
Posted on 8 June, 2012 by Connecting Country
The following information was originally published by Geraldine Harris in the Castlemaine Naturalist newsletter, and has been kindly re-written by her for the Connecting Country website.
Some plants become environmental weeds when they escape from our gardens into the surrounding countryside and start competing with local native indigenous species. I want to look at how some of these infestations can be controlled and which native plants can be used in their place.
Our native plants cannot be expected to perform as vigorously as pest plants that have been selectively bred for survival over hundreds of years. However, getting rid of pest plants and replacing them with native species will help preserve the integrity of our local habitats, attracting and providing resources for more native birds and other animals.
Gazanias are the large daisy-type yellow flowers that are escaping from private gardens and appearing more and more abundantly along our local roadsides and in bushland throughout Victoria, South Australia, Western Australia and New South Wales.
These very showy plants originated in South Africa and are being promoted in many plant nurseries as a tough drought resistant species. Many hybrids have been developed in cultivation between Gazania linearis and a closely related environmental weed species Gazania rigens. These plants produce abundant wind-blown seeds that can be dispersed many kilometres from the source, producing ever-increasing patches of gazania that compete with locally indigenous species. Gazanias also have the ability to re-grow from their bare roots, which enables them to spread into our bushland by the dumping of garden waste containing the tuberous root systems of these plants. Native animals tend not to eat them as they are low in nutritional value.
Control methods include pulling out by hand if the infestation is small (making sure the roots are removed so it doesn’t re-grow) or spraying with a registered systemic herbicide into the heart of the rosette. If you have a large outbreak amongst grasses or in a lawn, a broadleaf-selective herbicide maybe a much better option. At very least, remove and then bag the flower heads. The ‘bagging’ prior to disposal is important because even when the gazania flower heads are detached, most still have the ability to develop as mature flower heads with masses of viable seed.
As substitutes you could plant native daisies such as Sticky Everlasting (Xerochrysum viscosum), Common Everlasting (Chrysocephalum apiculatum) and Clustered Everlasting (Chrysocephalum semipapposum). Pigface (Carpobrotus modestus) would also be a useful substitute requiring no water and producing large pink-mauve flowers all summer.
Rayner C. 2012, ‘Weed of the Month’, Angair Newsletter. No 1, p6.
Marriot N.2011, ‘Plant ‘Aussies’ – not weeds’, Growing Australian, Vol 54.3, No 216, p12-13.
OK, so clearly I’m researching this on the run – maybe the moderator might like to condense this into one post?
This is useful too, from New Zealand. http://ecan.govt.nz/publications/General/wom-gazania-may2015.pdf
Might be possible to get an off-label permit. check out what these guys suggest – http://www.platypus.org.au/not-so-common-weeds.html
According to the Public Chemical Registration Information System Search on the Australian Pesticides and Veterinary Medicines Authority website (http://apvma.gov.au/ ) there are no herbicides registered for use on Gazania.
I’ve heard that a surfactant is required for any herbicide to have an effect, and also that glyphosate and dicamba/mcpa based products are not very effective.
Could somebody please be able to help. On Mt Wycheproof we are trying to kill the gazanias and could we please get advice on the spray to use and when to spray. They are getting to be a problem and if we don’t start soon they will be out of control, please help. Allan Milburn