Have you spotted any yellow bristle grass?
Its distinctive spiky seed heads begin to appear in late December, but are most obvious in January and February.
It may look harmless growing on our country roadsides, where it has notably increased over recent years. But when this invasive annual seeding weed jumps the fence, it poses a serious threat to pasture.
What’s the problem?
Yellow bristle grass is unpalatable to farm stock after the seed heads emerge, from about mid-January until the first frost. So animals avoid it, meaning pasture is under-utilised. Meanwhile the seeds are rapidly further dispersed by animals, water, soil movement, machinery, and through contaminated hay or maize brought into paddocks.
Once established, yellow bristle grass is notoriously hard to remove, and is becoming a significant agricultural issue in the Waikato.
What are we doing about it?
The Council is collaborating with the Waikato Regional Council, AgResearch and roading contractors to improve control of yellow bristle grass on our District road network.
Traditionally we carry out two complete rounds of chemical spraying each year, generally in October and March, planned for when it will best combat spring germination and autumn growth and keep road signs and marker posts clear and visible.
In a key change this year, we’ve launched a January/February network-wide spray campaign. In the future, to minimise seed spread during this period when the seed heads are mature, there will be no roadside mowing during this time.
When we do mow, our contractors will stop short of the fenceline – leaving a barrier of tall growing grasses to inhibit the spread of yellow bristle grass into roadside paddocks – and avoid having runoff that could wash seed into the paddocks.
We’ll follow up with autumn spraying as usual. Then the need for spraying in spring will be monitored – the objective being to allow winter weeds and broadleaf to remain and become established around roadside traffic service structures so yellow bristle grass can’t re-establish.
What can farmers do?
Some AgResearch guidelines
For roadside spraying to be effective, farmers need to implement their own parallel controls.
To minimise the chances of importing yellow bristle grass onto the farm:
- Have agricultural contractors clean their vehicles and equipment before accessing your property.
- Inspect incoming hay; and if you have any infested hay, feed it out only to areas where yellow
- bristle grass can be readily controlled by means such as glyphosate spray.
- Ensure that all incoming maize chopped for silage gets into the pit (seed in the silage will be killed).
To minimise the spread of yellow bristle grass within the farm:
- Reduce seed production by spraying before seedheads emerge, or by topping pre or post-grazing.
- Avoid moving stock from infested paddocks or roadside to clean paddocks.
- Clean agricultural equipment after use in any infested paddocks.
- Make silage rather than hay if yellow bristle grass is present.