Controlling Weeds Over Winter

Winter is the perfect time to tackle problem weeds in your established pasture. By applying our phenoxy herbicides like WHACK – 2,4-D 800 and Rainbow & Brown MCPA750, you can target invasive weeds such as thistles, ragwort, and buttercup when they’re small yet actively growing. These weeds germinate in autumn, and winter provides the ideal opportunity to eliminate them before they take hold. This strategic approach maximises pasture utilisation and increases available dry matter during the critical winter months when grazing options are limited.

Rainbow & Brown Herbicide Solutions:

• Rainbow & Brown MCPA750 -  a 750g/L MCPA water-soluble concentrate similar or equivalent to Agritone ® 750 ⁽¹⁾, Maestro,⁽²⁾  Synergy MCPA 750 ⁽³⁾
  Controls: annual buttercup, scotch thistle, hedge mustard, nodding thistle, variegated thistle, winged thistle, catsear, dandelion, nettle, plantains, twin cress, wild turnip, willow weed, hoary cress, creeping mallow, Californian thistles and perennial buttercup.
• WHACK - 2,4-D 800 – a non-volatile, soluble 2,4-D micro granule similar or equivalent to the well-known Baton® 800WSG ⁽¹⁾
  Primary target: Similar to Rainbow & Brown MCPA, but also good on Ragwort.
• Pasture Star – a dual-action product containing 375g/L MCPB and 25g/L MCPA. The big advantage of this is that it’s gentle on clover, while still tough on weeds. The MCPB ingredient is safe for clover, and once inside the weed, it converts into MCPA to kill the weed effectively. This means you can target thistles and other problem weeds without damaging your valuable clover or pasture grasses.

When to Spray

WHACK - 2,4-D 800 is more clover friendly than Rainbow & Brown MCPA750, so generally apply Rainbow & Brown MCPA750 when clover is dormant.  WHACK - 2,4-D 800 is an amine, not an ester formulation, so the high spray drift risk and volatility of 2,4-D esters are not an issue with WHACK - 2,4-D 800.  To be effective, you need to be spraying when the weeds are actively growing, so don’t spray when the weather is frosty or too cold.

For larger, established weeds, consider adding GrassMate or Ralid. These products can increase clover damage though so spot spraying might be preferred.

Grazing and Withholding

Other than the mandatory 1-day required by MPI for good agricultural practice, there isn’t a specific withholding period for grazing stock, however, our recommendation is to keep stock from grazing for 10–14 days to allow the herbicides to do their job.  Also remember that many poisonous weeds, such as Ragwort, which stock normally won’t eat when alive, become more palatable but no less poisonous when dying, so keep stock away until these are completely dead.