Yellow Bristle Grass Spreading

An aggressive pest plant which is a concern for farmers has been found in northern Hawke’s Bay.

Yellow bristle grass (YBG) has been discovered by Hawke’s Bay Regional Council Pest Plant Advisors in the Wairoa area, mostly on roadsides and in cropping paddocks.  

The pest plant spreads rapidly and reduces pasture quality, because it is unpalatable to stock after the seed heads emerge from January into autumn.  Animals avoid it which means pasture is under-utilised.

Once established, yellow bristle grass is difficult to control.  It is spread by mowers and other machinery, stock, contaminated hay, maize, silage, effluent or by moving soil.

“It’s essential that all landowners keep up their biosecurity hygiene practices to clean equipment and vehicles moving off their properties.  This will help slow the spread of this sort of plant,” says HBRC Pest Plant Advisor Alice McNatty.

Yellow bristle grass (Setaria pumila) is an upright plant with yellow-green leaves about 25-45 cm high.  It can be difficult to identify until it produces seed heads which turn golden brown.  Until then it can be confused with other bristle and sticky headed grasses.   HBRC recommends farmers check DairyNZ’s useful guide about yellow bristle grass on their website, www.dairynz.co.nz, which includes comparisons with other grasses.  

Farmers should contact Hawke’s Bay Regional Council Pest Advisors in the first instance, for assistance with identifying any suspect plant and to get advice about control options.   HBRC Pest Plant Advisors have put in place biosecurity protocols on known affected sites in the Wairoa district. 

Yellow bristle grass, photo courtesy DairyNZ

23 April 2018

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