Whether it is short-term ryegrass between crops, or high-value grazing for the next few years, take action to ensure rhizomatous grass weeds like couch, mercer grass or paspalum are not present in autumn-sown pastures.

If they are present when new grass seed goes in the ground, they stay there for the life of the pasture.

Nufarm Territory Manager Paul Greenbank says rhizomatous grass weeds are common in both crop-to-grass and grass-to-grass pasture renewal situations.

“Once new grass seed goes in the ground, it is too late to get rid of them. The key is to remove them before re-sowing.”

Fortunately, he says, plant biology is on your side at this time of year, improving the chance of eliminating them before they devalue newly sown pasture. That is because late summer is when these grass weeds start to move energy reserves down to their roots in preparation for winter.

Paul recommends spraying rhizomatous grass weeds now with a herbicide before sowing and the plant’s internal transport system will carry the chemical where it needs to be for an effective kill.

Another tip from Paul is to make sure target weed species are green and growing, with enough leaf area for the herbicide to land on and penetrate.

Spraying out paddocks that are moisture-stressed and/or newly grazed, with minimal re-growth, does not give as good a result, so it is important to build this into your pre-plant plan this autumn.

Nufarm’s Lion® 490DST is a patented formulation of glyphosate utilising Dual Salt Technology for fast-acting, reliable control.

“Lion 490DST can be included in a pre-plant herbicide programme as it is good at killing grass weeds. For some broadleaf weeds, like docks and buttercup though, you need to add different chemistry,” advises Paul.

Some herbicides added to Lion 490DST to broaden the weed spectrum have longer plantbacks so be sure to confirm these periods.

For advice on preparing paddocks for sowing short-term or perennial pasture in autumn, contact your local PGG Wrightson Technical Field Representative.