When establishing a new pasture, your end game is to have a high performing feed for your livestock. With perennial pasture, you want persistence of good quality and weed-free feed.

Weeds compete with your newly establishing pasture for space, light, moisture and nutrients, reducing its performance and longevity. Good weed control is essential to give your new seedling plants the best start.

There are two types of weeds: perennial and annual. They can be either grass or broadleaf plants. It is essential to aim to control all perennial weeds before planting new pasture. This can be done with the use of crop rotation and selective herbicides in other crop species other than those in pasture. Spray with an appropriate dose of glyphosate during spray-out before and after each crop is grown. As perennial weeds are already established and are large, they get a head start over new pasture, making it nearly impossible to kill perennial weeds using clover safe chemicals.

Annual weeds, however, grow from seed at the same time as pasture and usually grow at the same rate. As both weeds and pasture are at the same growth stage, timing herbicide sprays is easier. Spraying when both weeds and pasture species are small allows greater spray coverage, and as weeds are small, the use of clover safe chemicals is more effective at controlling them than perennial weeds, leaving a clean weed free pasture.

Sprays containing MCPB+MCPA, MCPB, Bentazone or Flumetsulam are commonly used to control a broad spectrum of broadleaf weeds in new pasture. As long as the seedling pasture grasses and other species, such as clover, are at the right growth stage, they are safe from the sprays.

Weeds in general should be sprayed before they reach the four to six leaf stage to ensure good control, but in many cases the broadleaf constituent of your pasture mix (clover or herbs) must be big enough for the spray to be used.

All too often I get calls from people who haven’t got onto the weeds early enough and then need to salvage the situation. This poses a number of problems. If weeds get too big, the damage is already done as far as affecting the establishment of your pasture, competing with the establishing grass and clover, and sometimes reducing their numbers and slowing their development. To spray big weeds, a more robust chemistry is required that won’t be as clover safe, reducing the performance of the establishing pasture.

For further advice on controlling weeds in new pasture, contact your local PGG Wrightson Technical Field Representative.

Top Tips

• Control all perennial weeds before planting your new pasture.
• Make the most of spray-out glyphosate products and crop rotation using other non-pasture safe chemicals.
• Walk the new pasture, monitor and identify weed species and size.
• Select a herbicide appropriate to the weeds and pasture mix and size.
• Aim to spray the weeds before they get six true leaves so they don’t get too big to easily control.