Dogged determination saw them rid their farm of their first target – ragwort – but until recently, Californian thistles have proved impossible to eliminate despite annual spraying.

Justin Downing and his wife Liesl are equity partners, managing a farm near Morrinsville in conjunction with Justin’s parents Lloyd and Olwyn, as well as owning another farm which employs a contract milker.

Lloyd Downing is a well-known, outspoken Waikato dairy farmer who has held prominent roles in the farming community including Federated Farmers’ Waikato president. He is also stepping down after more than 30 years’ involvement with the National Fieldays Society, including terms as both chairman and president.

Milking 500 cows on 200 ha, Justin Downing says ragwort and Scotch thistles were the first priority. Once these were controlled, attention turned to Californian thistles.

“Apart from cosmetically it looks terrible, the patches get bigger and thicker every year if you don’t do anything. Cows end up grazing amongst the thistles, reducing the area of productive pasture.”

Frustrated with chemical spraying annually for about 10 years, only for Californian thistles to regrow, Downing was persuaded by RD1 (Farm Source) representatives to try Tordon PastureBoss.

A more expensive option, it includes a new generation herbicide particularly effective at controlling weeds with large root systems such as Californian thistle.

“We found in the past, using another chemical, 24-D, we were spraying the same patches of Callies year after year. The thistles would die, but because of their huge root system would just grow back again the next year.

“With Tordon PastureBoss, we sprayed it once and 90 per cent of Callies are gone.”

About 10 ha was sprayed last summer with Tordon Pasture- Boss, boom spraying the big patches and spot spraying areas that can’t be accessed by tractor.

While Tordon PastureBoss is more expensive at $100/ha, applied at 2 litres/ha, it is worth it as it works, says Downing. This compared with the previous chemical, which after annual applications at a cost of $40/ha still failed to provide control.

“We now spray all weeds with PastureBoss. We go around with knapsacks, so if we see ragwort or a Scotch thistle, it gets spot sprayed,” he says.

PastureBoss also controlled oxeye daisy, a problem weed on his other farm.

“Like Californian thistles, it is now at the stage we can just spot spray.”