Feature Story •  14/03/2025

Waimara - Masterton

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Simon Campbell runs a 520-hectare sheep and beef farm in Mount Bruce, Wairarapa. The farm is a family-owned and operated business, with Simon’s father still residing on the property. 

The operation primarily focuses on fattening beef, running a couple of thousand ewes alongside Speckle Park cattle, utilizing the Halter collar system for improved livestock management. The property incorporates winter cropping, though the majority of the system is pasture-based.

The Challenge: Californian Thistle Infestation

For generations, the farm has battled Californian thistles, which have significantly impacted pasture quality. The property’s sedimentary soils become extremely wet in winter, making it susceptible to pugging. This creates additional challenges in managing thistle growth, as past attempts to control the weed—such as mowing—have been largely ineffective.

Simon recalls that his father spent thousands of dollars trying to control Californian thistles, even using a weed wiper attached to the front of his tractor. However, despite these efforts, the thistles kept coming back. The farm previously wintered cattle, which would clean up thistle patches after flowering, but this approach only addressed the visual nuisance rather than eradicating the problem.

Thick patches of Californian thistles have also led to health concerns for their sheep, with some developing scabby mouth, which significantly limits their feed intake. Additionally, land cultivation is only carried out after winter cropping to avoid disturbing the extensive root system of the thistles, which would otherwise encourage further spread.

Cows in Paddock
Wintered cattle would clean up thistle patches after flowering, but this approach only addressed the visual nuisance.
Cows in Paddock
Wintered cattle would clean up thistle patches after flowering, but this approach only addressed the visual nuisance.

A New Approach: Tordon® PastureBoss®

Determined to improve pasture quality and overall productivity, Simon has implemented Corteva’s Tordon PastureBoss as part of a structured three-step control program. He has treated an initial 30 hectares of his property and is eager to see the results. If the program proves successful, he plans to extend the treatment across the farm in stages.

This strategy presents an exciting opportunity to get ahead of Californian thistles before establishing winter crops, ultimately setting up the land for high-quality, permanent pasture. Simon is hopeful that with the right approach, he can finally gain control over this persistent weed and achieve better pasture quality to support his livestock operation long-term.

Follow Simon’s journey as he takes on Californian thistles with Corteva’s proven solutions.

Progress Photos

Follow Simon's journey in photos below.

Untreated thistles If the programme proves successful, Simon plans to extend the treatment across the farm in stages.
Untreated thistles If the programme proves successful, Simon plans to extend the treatment across the farm in stages.
Californian thistles can cause animal health issues and reduce productive pasture.
Californian thistles can cause animal health issues and reduce productive pasture.
Cali thistles have been treated with Tordon PastureBoss as part of a 3 step control programme
Cali thistles have been treated with Tordon PastureBoss as part of a 3 step control programme
Dense Cali thistles An average of 17 thistle plants per square metre.
Dense Cali thistles An average of 17 thistle plants per square metre.
6 Weeks After Application The thistles have browned off and more pasture is exposed.
6 Weeks After Application The thistles have browned off and more pasture is exposed.
6 Weeks After Application The Cali thistles have died off. An Autumn spray of MCPA GrassMaster will tidy up any stubborn shoots.
6 Weeks After Application The Cali thistles have died off. An Autumn spray of MCPA GrassMaster will tidy up any stubborn shoots.

Want to know more?

For expert advice on Californian Thistle control or help tailoring this programme to your farm talk to your Corteva Agriscience Territory Manager or your local PGG Wrightson Technical Representative.

Find your Territory Manager