THISTLES lead to many problems for landowners and the Arawata/Mt Eccles Landcare Group has urged people to act now to control their spread.
Four species of concern in South Gippsland are Slender/Shore Thistle (Carduus pycnocephalus), Spear Thistle (Cirsium vulgare), Variegated Thistle (Silybum marianum) and Californian Thistle (Cirsium arvense).
A Landcare spokesman said thistles were spikey, and contaminated wool and hay silage.
Thistle spines can also injure the mouths, paws and feet of livestock.
Thistles are high in nitrates which are poisonous to stock and grow in areas of high rainfall and high nutrient levels.
Each plant can produce hundreds of seeds and rapidly replace desirable pasture species, as well as harbour vermin such as foxes and rabbits.
The four species are classified as regionally-controlled weeds which means it is the landowner’s responsibility to control them.
The environmental weeds can threaten the value of natural ecosystems.
The Landcare spokesman said small infestations could be tackled by grubbing or weeding by hand, but it was important to remove most of the taproot.
Plants should be removed because flowering thistles could go on to ripen and spread seed.
If spraying with herbicides, use a boom spray with a selective registered herbicide while plants are still seedlings.
Spot spray from spring to summer. Stronger herbicides may be required for mature thistles.
Now is the best time to control thistles with herbicide as seedlings are emerging.
Californian Thistles are later to emerge, typically around December.
Time to tackle thistles