Watch out for Coolatai grass

By Merilyn House, of Helensburgh Landcare

It was only relatively recently that I first became aware of Coolatai grass, Hyparrhenia hirta. My daughter asked me if the grass growing below the netball courts on the bike track was Coolatai grass. I took photos and asked the Illawarra District Weeds Authority (IDWA). Unfortunately, it was. I later found out that it was already growing in the old rubbish tip area and the IDWA had been spraying it with herbicide once a year.

Unfortunately, once a year spraying is not going to remove it. The Helensburgh Off Road Cycle Club has had a few working bees to try to tackle the problem.

Coolatai grass is a long-lived perennial that produces short rhizomes that form dense grass tussocks and grow to 1.5m. Being drought tolerant, it can rapidly respond to rain, producing new culms from the tussock base and flowering in a matter of weeks. It is well adapted to fire, with tussocks surviving hot burns.

I believe it has been spread into Helensburgh by trucks and machinery. I have noticed it growing along the roadside in Walker Street, opposite Cemetery Road. Unfortunately, it was disturbed during the 2021 re-surfacing of the top part of Walker Street.

If you see Coolatai grass on your property, remove it before it flowers and sets seed. You could also report it to Dave Pomery at dpomery@isjo.org.au and find more information on the DPI's website.

Visit the Helensburgh Landcare website for more Weed Wise advice