Weed control in new pasture

Have you just planted new grass? Have you got a programme in place to ensure you grow strong and healthy pasture?

Here's where we can help you out.

Why spray?

Short term: Seedling weeds affect pasture composition as they vigorously compete for nutrients, moisture, light and most importantly, space. Early removal of these weeds allows for more rapid and even establishment of new pasture resulting in an increased amount of feed for stock.

Long term: Poor establishment of newly sown pasture results in decreased pasture productivity and an increase in chemical costs from the extra weed control requirements down the track.


Thistrol® Plus

The best time to spray weeds in new pasture is 4 - 8 weeks after sowing, prior to the first full grazing. At this time weeds are still small and there is about 70% or more ground cover. Ideally, you need a herbicide that will not damage the newly established clover while providing effective weed control.

Thistrol Plus is a clover friendly herbicide that will control a wide range of seedling broadleaf weeds in newly sown pastures. It can be applied to new pasture once the clovers have reached the first trifoliate leaf stage, which is approximately four to six weeks after the initial sowing of the seed. At this time, susceptible weeds are usually small and will be easily controlled.

For the best results with Thistrol Plus:

  • Identify the main weeds presnet in the paddock and check the label to confirm they are effectively controlled by Thistrol Plus.
  • Spray weeds when they are small - between the cotyledon and three to four leaf stage. This is especially important for nodding, winged and variegated thistles. Larger weeds will not be adequately controlled.
  • Apply Thistrol Plus when weeds are actively growing (when soil tempartures are around 10C or higher). Do not apply if the weeds are under stress from heavy frosts, or in wet or drought conditions.
  • Ensure the weeds are well exposed at spraying. If necessary lightly graze the paddock, leave for three to seven days for the weeds to freshen, then spray.

Post Grazing


After the first full grazing, weeds tend to be larger and more difficult to control. Baton is a selective phenoxy herbicide that provides excellent weed control in new pastures. Baton's water soluable granule formulation is low odour, non-volatile and is less damaging to valuable clovers than other 2,4-D formulations.

Weeds controlled by Baton in new pasture

Weeds controlled include: fathen, hedge mustard, nettles, shepherd's purse, black nightshade, wild turnip, cresses, red root, thistles, storksbill.

If red clover has been sown use a maximum of 1kg/ha of Baton to minimise damage. Higher rates reduce red clover plant numbers. Add Valdo 800WG to Baton for chickweed control.

For nodding thistles, Baton applied at 1.5kg/ha will only control seedlings and very small rosettes (up to 7cm diameter). Typically, nodding thistles will reach this size within six to eight weeks after germination. Larger thistles may be controlled with higher rates of Baton (2-3kg/ha), but clover mortality will occur.

For best results with Baton:

  • Apply Baton at 1-1.5kg/ha 3 - 7 days after the first full grazing. Grazing both exposes the weeds and removes much of the clover leaf, thus reducing the herbicide uptake by the clover and minimising damage.
  • Ensure complete coverage of the foliage. Phenoxy herbicides are absorbed through the foliage and translocated to the growing points. Within reason, higher water rates give better results.
  • There is no prescribed withholding period after spraying, but it is recommended that grazing be delayed for about 14 days as early grazing may reduce the level of weed control.

Increasing your weed spectrum

The addition of Valdo 800WG to Thistrol Plus or Baton will broaden the spectrum of weeds controlled. This includes two key damaging weeds in new pastures: field chickweed and stinking mayweed. These weeds can completely smother seedlings and can prevent clover from establishing effectively.

Clover should have a minimum of two trifoliate leaves prior to using Valdo 800WG so it is important to check clover growth stage prior to tank mixing. Valdo 800WG should be applied with Bonza oil to ensure good coverage and uptake. Thistrol Plus, Valdo 800WG and Bonza tank mixes are considered clover-safe.

However, the addition of adjuvants and oils to Baton can increase the level of clover damage. On-farm experience indicates that in general, Baton, Valdo 800WG and Bonza tank mixes have had little long-term effect on clovers and that leaving chickweed uncontrolled will potentially have a greater effect on pasture establishment and production.

For best results with Valdo® 800WG:

  • Ensure clovers have a minimum of two trifoliate leaves.
  • Add Bonza oil at 500ml/100L water to enhance weed control.
  • Select appropriate rate according to weed species and size at the time of spraying.
  • Do not graze pasture for 14 days after Valdo 800WG application.

Click here to view

Optimum weed size for spraying with Thistrol Plus.