Make it stick - second Cali spray is the missing link.
In the battle against one of New Zealand’s most unwanted pasture weeds, Californian thistle is winning more than it should be at the moment.
And one of the reasons for that is coming up very soon – a specific spray window in late summer or early autumn that routinely gets missed, thereby setting the stage for continued infestation in the year ahead.
Ian Kirkland, upper North Island territory sales manager for Corteva Agriscience, says it’s no wonder farmers get disheartened when their efforts to control Calis don’t seem to work.
If they don’t adopt a two-spray programme over 12 months from the get go, with a good understanding of how this persistent species grows and spreads, they usually end up back where they started.
One herbicide application over 12 months is simply not enough.
Thistles sprayed at hardball stage late last year, for example, will have died on top of the soil but the massive underground root system supporting each plant will have already retaliated by sending up fresh new shoots nearby.
And it’s these that need to be hit hard in coming weeks, ideally at about knee high, with plenty of green leafy growth to absorb the herbicide and allow it to be carried down to the roots.
After 16 years in the field, Ian Kirkland has seen enough paddocks to notice the impact of more and more farmers skipping that second spray, which he describes as the missing link in most control programmes.
“The problem certainly seems to be getting worse. People are effectively dedicating huge areas to cropping Calis. I’ve seen that through my own territory, in the Waikato and Bay of Plenty, as well as down south.
“They’re even encroaching north of Auckland where traditionally they weren’t seen. It’s widespread and very noticeable.”
He puts this proliferation of Calis down to a lack of understanding about the plant in general, as well as a plethora of information (and misinformation), opinion and theory about how to control it.
“It’s easy for farmers to get confused, and then discouraged.”
But it’s also easy for reps to start setting them straight with sound advice and the right herbicide, as of now.
“If your clients did spray at hardball stage back in November or December, great. Now it’s time to execute the second half of the plan. Get them organised to follow up and use Tordon™ Pasture Boss™ to kill the new shoots which have emerged following that first spray.
“If they didn’t spray late last year, this is when their two-spray programme starts – one Tordon Pasture Boss application in late summer, with another in spring.”
Bad infestations may need two years of this programmed approach, but the first year will go a long way towards breaking the back of the problem, he says.
“Tordon Pasture Boss is the best of the bunch, but it’s still not a one-shot application. They can’t just spray and walk away, wave goodbye from the gate.”
The withholding periods are relatively short (three days for milk; seven days for meat) and although it will damage clover, pasture production and grazing is already much reduced where thistle populations are high, and that ground will be re-gained the following season, he says.
What’s more important than any herbicide is often a change in mindset.
“Farmers get overloaded with information, the message is diluted, and in some cases they end up not even starting a control programme.
“They need confidence in the fact that they can get things turned around, with the right advice and the right approach. And reps are the people best placed to help them achieve this.”
For more detail contact your Corteva AgriScience territory sales manager.
