Serious Pasture Weed Incursion on the West Coast

21/05/2015 12:00 a.m.

Yellow Bristle Grass has been located on the West Coast for the first time. Yellow Bristle Grass is a serious pest throughout the central North Island where it is proving very hard to control.  Yellow Bristle Grass is an extremely aggressive annual plant which once established in a pasture, spreads rapidly and reduces pasture quality. When Yellow Bristle Grass sets seed (around Christmas-January depending on the season,) cows will avoid grazing it unless no other feed is available. Seed heads will persist until the first frosts in autumn, leading to lower pasture utilisation during this period, and a cost for supplementary feed required to maintain milk production.

These costs are estimated to be between $350-$1100/ha depending on the level of infestation.

On the West Coast, Yellow Bristle Grass was first noticed by a farmer who had recently been visiting a friend in Waikato. His friend, whose farm is affected by Yellow Bristle Grass, had pointed out the plant and described its impacts on his property. Upon returning to the Coast the farmer was dismayed to find Yellow Bristle Grass growing on the roadside adjacent to his property. A sample was collected by West Coast Regional Council Biosecurity staff, and Landcare Research confirmed it as Yellow Bristle Grass. Further searching by Biosecurity Staff found numerous small patches on the roadside most of the way through the Buller Gorge. Infestations to date have only been found around marker pegs on the roadside which provides an early opportunity to try and prevent further spread into pasture.

In order to know the full extent of Yellow Bristle Grass spread on the Coast, it is important that farmers ensure they are familiar with the plant, and are actively look for it on their property and the adjoining roadside. Roadside mowing contractors have been shown the plant and will be looking while they complete their work programme throughout the districts, as well as local Weedbusters staff and other contractors who are working throughout the region.

Anyone who thinks they may have seen Yellow Bristle Grass on their property or the roadside please contact Cam Doake at the West Coast Regional Council on (03) 768 0466 or

Page reviewed: 21 May 2015 11:39am