Yellow bristle grass: Be vigilant

SUE O'DOWD
Last updated 11:27 15/08/2014
A seedhead of yellow bristle grass in flower.
Fairfax NZ
IN FLOWER: A seedhead of yellow bristle grass in flower.

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After fighting yellow bristle grass (YBG) for the past three years, an award-winning Taranaki sharemilker wants the focus to turn to eradicating the weed.

Taranaki Regional Council (TRC), the New Plymouth, Stratford and South Taranaki district councils, NZ Transport Agency, Federated Farmers, DairyNZ and roading and rural contractors are making a concerted effort to minimise YBG's impact.

Although Tony Penwarden is delighted with the campaign, he wants its focus to be on getting rid of YBG. "But that's a tall order," he said.

While he acknowledges eradicating YBG might take 10 years, he said it could be achieved if district councils managed roadside spraying in a way that didn't create conditions for the weed to thrive and if farmers backed up control programmes.

He and wife Loie are 50/50 sharemilkers on Faull Farms' Trewithen Farm, which won the inaugural Taranaki Ballance Farm Environment Award this year.

He said they and their staff had spent quite a bit of time controlling YBG since it appeared in 2011 and they'd developed a farm map to identify sites where it grew.

Spraying with Roundup and PumaS provided good control and picking seedheads for bagging in seed bags carried on their four- wheeler vehicles was time- consuming but effective at minimising seed drop.

He said the time and money he'd spent on controlling YBG had minimised its effect on their farming operation.

He hopes farmers will alert others to the weed when they see it on the roadside. "We can't put our heads in the sand, ignore it and hope it goes away."

New Zealand Sharemilker of the Year and Taranaki Federated Farmers sharemilkers' vice- chairman Charlie McCaig is also pleased about Taranaki's combined approach to tackle YBG, which, he said, was widespread in Taranaki. Last summer he saw it around Okato, Rahotu, Opunake and Manaia, and it was also in North Taranaki and in the Manutahi area.

Like Penwarden, he'd like to see a focus on eradicating the weed from Taranaki. "We need to be proactive. It's not as established in Taranaki as in the Waikato, so we have an opportunity for much tighter control. This campaign is really positive - it's exactly what we need and it's an opportunity to nip yellow bristle grass in the bud."

Once locations had been identified, a co-ordinated approach to stop it taking hold could be adopted. While it was expensive to control, farmers would generate huge savings by getting on top of it, he said.

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Three years ago retired Tikorangi farmer Ian Vickers began raising farmers' awareness of YBG so he's delighted Taranaki organisations are getting together to confront it.

"It's rewarding for those farmers who have recognised the danger of the weed and have already put measures in place in attempts to eradicate it. The rural sector has enough problems without letting this weed dominate."

Federated Farmers Taranaki president Bronwyn Muir said eradication was probably an unrealistic goal, but the weed's effect would be minimised if everyone worked together. YBG could cost farmers more than $1100 per hectare in lost production, and also caused mouth lesions and poor stock health.

The organisation would work to ensure farmers, contractors, council representatives and the general public knew how to identify it and how to reduce its effect.

Federated Farmers would assist with the development of a location map marking where YBG had been spotted and would be involved in discussions on dealing with it. It might be possible to alter the timing and methods of spray application and of roadside mowing. Covering maize crops at harvest and during transport might reduce YBG'S spread.

She said all farmers should be vigilant and learn about the weed. "There is plenty of very good information that can show you what to look for and give management tips."

DairyNZ regional leader Katrina Knowles said the campaign was the result of a lot of work by a lot of people over the last three years.

She said nowhere in Taranaki was exempt from the weed, which had even been found growing close to the mountain.

"The experts didn't think it would grow at altitude."

Farmers using Roundup to control YBG needed to follow instructions on the label to prevent resistance. "You won't get a better kill by adding extra."

She said farmers often didn't recognise the weed until the seedhead appeared but she advised them to start looking for it in October because germination depended on warmth and damp.

TRC environment services manager Steve Ellis said the weed was a prolific seeder that produced seeds within four weeks of germination. "It can quickly infest areas of bare ground, especially during and following drought conditions, and become dominant in a paddock.

"While it is palatable to livestock during the vegetative stage, it has poor nutritive values and stock avoid it after seed heads emerge - usually from mid- January to May."

He said the first step in the campaign was identifying the location of infestations. "We already know about many of them, but we need more information. We're urging people to call the council on 0800 736 222, or email biosecurity@trc.org.nz."

The next stage will be a targeted awareness campaign offering advice and information on controlling YBG. "The grass is not new to Taranaki. It was first recorded here back in the 1930s."

The best way to counter its impact was to be vigilant.

He said poor weed hygiene practices were a factor in spreading it. Wrapped baleage and sufficiently fermented silage appear to destroy the viability of yellow bristle grass seeds.

Seeds were dispersed by water, soil movement, animals, machinery, and as contaminants of crop seed and hay. YBG survived passage through the rumen so grazing stock on roadsides moved the seed around in dung.

A guide covering identification and control of YBG can be downloaded by clicking here or requested from Dairy NZ.

UNDER CONTROL

Strategies to manage yellow bristle grass (YBG):

Roadsides

-Spray with glyphosate when the seedheads emerge in December or January.

-Create a thatch of dead plants to stop germination.

-Mowing doesn't kill YBG but lessens the risk of it spreading.

-Roadsides shouldn't be grazed between December and May.

Small infestations

-Manual removal is a good option.

-Avoid seed being spread further afield by fencing off, mowing, spraying, and collecting seed.

-Don't graze when the seedhead is visible.

Large infestations

-Spray YBG with PumaS from mid-December.

-Top it to reduce the quantity of seed set.

-Lengthen grazing rounds in early summer so there is more grass cover and post-grazing residue.

-Shorten grazing rounds in summer and autumn to minimise flowering.

-Avoid grazing clean paddocks by stock exposed to YBG seed.

- Taranaki Daily News

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