Published on 31/07/2025
That’s the message from Nufarm national product manager Matt Strahan, who says the company’s unique Grassmanship.nz digital calculator makes short work of quantifying a farmers’ return on investment from appropriate seasonal weed control.
At this time of the year, the focus is on winter weeds, and he has some compelling figures around the financial benefits of well-timed winter herbicide applications.
Using Grassmanship.nz, and a hypothetical example of a bull beef grazing system in the Waikato, he’s run a scenario on expected costs and payback of controlling medium density thistles.
With Agritone 750 at 2 litres per hectare, an application cost of $40 per ha, and a bull beef carcase value of $6.50 per kg, spraying 50 ha to remove thistles could provide a return of about $14 - $15,000 after the cost of herbicide and application is taken into account.
“That’s just one example of the type of return that is possible over six to eight months.
“In this case we know thistles cause grazing avoidance, and depending on thistle species, act antagonistically to suppress the growth of surrounding pasture plants for up to 75 cm.
“So that adds up to a lot of potential grazing lost, and with it, lost animal liveweight gain.”
Farmers and growers can run their own scenarios through Grassmanhip.nz, thanks to different calculators for different times of the year, and the ability to specify both stock type and location for regional pasture and animal production rates, sourced from leading industry organisations.
“All the data for the bull beef example is based on Beef + Lamb NZ resources on growing bulls and dressing out rates. We have done the same for dairy production using statistics from Dairy NZ.”
Strahan says in addition to the calculators, Grassmanship.nz also provides useful information to help farmers and their advisors get the optimal results from a pasture protection programme, including a range of Nufarm’s resources that support best practice.
It’s free, and designed to help all New Zealand farmers get the best out of their pastures year-round.