Californian Thistle Control

We combine our world class global research pipeline with our local understanding of pasture production to develop, launch and deliver to market our innovative portfolio of products meeting the needs of the New Zealand farmer.

Cali thistle, costing New Zealand’s pastoral farming sector an estimated $700 million annually, has long been a challenge for farmers. To address this, Corteva Agriscience and PGG Wrightson have joined forces, establishing demonstration sites on six dairy and red meat farms nationwide. These sites showcase a strategic, multi-phase approach to tackle this invasive weed effectively.

The first phase begins this summer, targeting the plant's hard-ball stage when sugars are actively moving to its deep rhizomatous root system. Corteva’s Tordon™ PastureBoss™, containing aminopyralid, is applied to disrupt the plant’s metabolic pathways, focusing on dense infestations. In autumn, PGG Wrightson’s Grassmaster™ MCPA herbicide is applied to deliver a final blow, targeting the roots to ensure the plant’s death.

By summer 2025, only spot-spraying Tordon PastureBoss will be necessary to manage any new shoots. Observers will document progress, demonstrating the effectiveness of combining herbicide applications with mowing or hard grazing.

This 18-month project aims to restore farmer confidence by providing practical, lasting solutions for Cali thistle control. It highlights how strategic partnerships and tailored chemical programs can help farmers reclaim their land and profitability.

Follow the progress of our Pilot farms below.