Damian Harrison owns and operates a 323-hectare (800-acre) farm in Cheviot, where he also works as a contractor specialising in spraying for weed control. Over the past three years, he has installed an irrigation system covering 110 hectares of his property.
Since introducing irrigation, Damian has faced a significant increase in Californian thistles, with some paddocks experiencing up to 40–50% coverage. Aware of the impact on grazing quality, he has been proactive in tackling the issue. Photos show fat lambs avoiding Cali-infested patches, highlighting the challenge.
Farm Conditions & Challenges
Soil & Climate: The farm has typical regional loamy soils with varying depths of clay over shingle. The land is productive, with an annual rainfall of around 33 inches, which helps sustain growth during dry spells. However, the last four years of severe drought have been particularly challenging.
Stocking & Performance: Damian runs 3,000 stock units of sheep, though drought conditions have temporarily reduced numbers to 1,500. His latest lambing percentage was lower than usual at 110%, but the lambs have thrived thanks to post-Christmas rainfall and irrigation-driven feed growth.
Contracting Work
In addition to running his farm, Damian stays busy spraying paddocks for local clients, helping manage weed and pest control across the region.
Goals & Approach to Thistle Control
Damian recognises that Cali thistles have significantly reduced available grazing since irrigation began. He has trialed various treatments, including Versatill (100ml/ha) plus Batten (2L/ha), but results have not matched the effectiveness of Tordon PastureBoss.
By successfully controlling Cali thistles, Damian aims to:
✅ Reclaim lost grazing land
✅ Increase stock numbers
✅ Maximize returns on his irrigation investment
His goal is to eliminate the thistles and restore high-quality pasture, ensuring better productivity and profitability in the long run.
Having trialed various methods for controlling Californian Thistles including Versatill PowerFlo and Baton, Damian is satisfied that nothing else matches the effectiveness of Tordon PastureBoss.
His data and photos show a vast difference in the regrowth of thistles treated with other methods compared to those treated with Tordon PastureBoss.
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.
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