Winter Weeds in Established Pasture

Weeds cost New Zealand farmers over $1.6b annually (based on 2014 costs).
Whilst that figure might seem high, it only allows for 10 of the known 187 weeds that affect pastures here in New Zealand.**

Not only do weeds compete for; moisture, light, nutrients, or space, they can also compete with desired species. This leads to a more open pasture and can become a pasture persistence issue further down the track.

Weeds can also greatly affect animals’ ability to graze and utilise feed grown in farmers’ paddocks. There are statistics for several weeds and their impact on animals’ ability to utilise this feed, and these can equate to significant amounts of feed value per hectare.

There are a few key practices that help provide the best results, such as;

• Correctly identify the weeds present.
• Select the appropriate product(s).
• Use the correct rate based on the weed size.
• Spraying smaller weeds generally delivers the best results as they’re easier to control when small.

Spraying weeds while they are small can give higher levels of control, reduce pasture competition, reduce the potential of lost feed for animals, improve pasture quality and even sometimes, means less chemicals will be required…

Weeds can affect animals’ grazing potential, often reducing feed availability during key times of year when farmers are tight for feed.

Spraying weeds while they are small generally offers the best results.

Assessing thistles with a spade – While some thistles may look like small rosettes, when root crowns are larger than a 50c piece they may need; higher product use rates or even the help of a spike herbicide (such as Conquest or Archer 750).

A well timed application can provide great weed control and allow animals to eat more more of what is grown, reducing feed losses.

When thick weed patches are left unchecked or controlled, they can totally out compete grasses and clovers. As the weeds reach the end of their growing season it can result in bare ground once they die off. This creates the perfect environment for other weed seeds already in the soil to germinate and another wave of weeds to take hold.

** J. T. Saunders, G. Greer, G. Bourdôt, C. Saunders, T. James, C. Rolando, J. Monge & M. S. Watt (2017) The economic costs of weeds on productive land in New Zealand, International Journal of  Agricultural Sustainability. https://doi.org/10.1080/14735903.2017.1334179