Broad spectrum control of seedling weeds in new pasture

1 April 2017

Removing broadleaf weeds soon after planting new grass and clover helps prepare autumn-sown pastures to produce high dry matter (DM) yields by spring, when feed is needed to get the next season off to a strong start.

If not well controlled, weeds like fathen and chickweed can permanently and significantly damage new pasture before your livestock have a chance to graze it. Complete pasture loss is uncommon, but it’s easy to underestimate the immediate and ongoing effect of early weed competition on the quality, composition, yield and persistence of your newly re-grassed paddocks.

Fortunately, several post-emergence herbicides are now available to kill weeds at different stages of pasture establishment – you just work out which best suits your needs and your timing.

Spraying early, about six weeks after sowing and before the first full grazing, is widely recommended as the best option. If this does not work for you, other herbicides are suitable for spraying after the first grazing.

Spraying before the first full grazing has several advantages. Weeds are small, more susceptible to herbicides and cheaper to control. They are also removed before stealing sunlight, water and nutrients from new grass seedlings. Tribal® Gold is the premium treatment at this time and is perfect for farmers wanting to control a broader weed spectrum and hard-to-kill weeds like chickweed, shepherds purse and buttercup. Thistrol® Plus has a narrower weed spectrum and is also very effective before the first full grazing. Valdo® 800WG can be added, if required, to extend the range of weeds controlled. Both herbicides work best under warm active growth conditions. It’s recommended to use Bonza® spraying oil with Tribal Gold and spray when approximately 70 percent of the ground is covered and when clovers have two identifiable trifoliate leaves.

If spraying after the first full grazing is your only option, be aware that different chemistry is required to kill broadleaf weeds at this stage of pasture establishment. It’s important not to confuse the first full grazing with the light nip-off recommended at about six weeks after sowing. Baton® is the preferred herbicide for this timing and is formulated to kill larger, more advanced weeds and has a very broad spectrum. Although it is more clover-friendly than other 2,4-D formulations, young clover leaves must be properly grazed before application to minimise the risk of clover damage. For weeds that don’t respond to phenoxy herbicide, like perennial buttercup and chickweed, Valdo can be mixed with Baton to extend the spectrum of weeds controlled.

No matter when you spray, be vigilant about checking all newly sown pasture for weeds from day one. That way, you’ll have a head start on identifying which weed species are present, and can plan the right programme to stop them over-running new grass and clover.

® Bonza, Valdo, and Tribal are registered trademarks of Nufarm Limited. ® Baton and Thistrol are registered trademarks of Nufarm Australia Ltd.

Contact your local Fonterra Farm Source TSR for further information and advice to help get new pastures off to a clean, strong start.

Article supplied by Nufarm