Controlling St John’s wort
For control of St John’s wort, apply high-volume hand spraying of Grazon Extra at a rate of 500 mL/100 L of water applying 3000 L/ha to thoroughly wet the foliage of a dense infestation; lower spray volumes (2000 L/ha) will be effective on moderate to sparse infestations. Boom spraying with Starane Advanced at 1.8 L/ha and 200–250 L of water/ha is also effective and aerial application via helicopter using Grazon Extra at 4 L/ha is effective for hillside spraying.
Ensure the plant is actively growing (15–50 cm tall), and both the upper-flower canopy and sub-canopy lying prostrate are wet. Focus on spraying open areas where pasture productivity can be improved by the removal of St John’s wort without damaging remnant vegetation.
Herbicides for control of St John’s wort
Product# | Method of application | Rate* | State |
Grazon® Extra Herbicide |
Foliar spray |
500 mL/100 L of water |
All |
Starane® Advanced Herbicide |
Foliar spray |
300 mL/100 L of water |
All |
Trezac® Arylex® active Herbicide |
Foliar spray |
200 mL + 300 mL Starane® Advanced/100 L of water |
All |
Grazon® Extra Herbicide |
Boom application |
2 to 4 L/ha |
ACT, NSW |
Starane® Advanced Herbicide |
Boom application |
1.8 L/ha (200 L water/ha) |
All |
Grazon® Extra Herbicide |
Controlled droplet application |
Apply undiluted |
All |
Grazon® Extra Herbicide |
Gas gun application |
500 mL/10 L of water |
ACT, NSW, Tas, Vic |
Grazon® Extra Herbicide |
Aerial (helicopter only) |
4 L/ha |
ACT, NSW |
# Note: Preferred product option in bold. * Consult label for details of growth stage and use, especially where range of rates is given.