The onset of summer and associated warmer temperatures will see the emergence of caltrop, also known as bindii or cat’s head.
Agriculture Victoria is encouraging landowners in the Mansfield area and across Goulburn Broken region to begin their seasonal planning for treatment of this herbaceous annual weed.
Infestations of caltrop can have far-reaching consequences such as reduction in pasture productivity through competition, contamination of food and fibre products as well as significant impacts on livestock such as damage to feet, mouth and stomach, and in extreme cases death if grazed due to its toxicity.
Caltrop (Tribulus terrestris L.) germinates in summer when soil temperatures rise and throughout the warmer weather after rainfall events.
Leading Biosecurity Officer Kate Cunnew said the fruit of caltrop is the most well-known feature of the plant – a woody burr with sharp, hard spines that embed in footwear and vehicle tyres, and can easily attach to animals’ feet and in the fleece of sheep.
“The ability of the weed to disperse great distances as a contaminant on vehicles, people and animals can create new infestations in previously clean areas,” Ms Cunnew said.
Caltrop is a declared noxious weed in Victoria under the Catchment and Land Protection Act 1994 and is classified as Regionally Controlled in the Goulburn Broken Catchment. Landowners in this area have an obligation to control the growth and spread of the weed on their property.
Caltrop is more likely to occur where competition is minimal, such as overgrazed pastures, fallow areas, stock yards, roadsides and waste lands. Management of the weed can include the complete physical removal of small infestations or the appropriate application of a registered herbicide.
Ms Cunnew said landowners are advised to seek professional advice from their local agronomist or chemical retailer when undertaking chemical treatment of any weed to ensure they have the most up-to-date information on products and application methods.
“Cultivation as a method of control should only be used for juvenile plants before flowering and in combination with other methods of control, as burial of the seed can increase the longevity of the seedbank.
“Multiple treatments may need to occur throughout the growing season, as new plants can germinate with each rainfall event and quickly mature in the warmer weather. In suitable conditions germination to seed set can occur within a month.
“Timing of grazing and removal of stock to increase summer ground cover or germination of pasture species at key periods can also assist in increasing competition against the weed.”
