Rice Grass

Rice Grass projects in the Cradle Coast Region

There are two Rice Grass removal projects to protect Coastal Saltmarsh currently underway in the region.

Circular Head Coastal Saltmarsh Project

Rice Grass (Spartina anglica) was purposely planted in the Duck River in the 1950’s to stabilise the banks and improve the visual amenity of mudflats. Rice Grass is an aggressive aquatic weed that clogs up waterways and displaces native Coastal Saltmarsh. It prevents resident and migratory shorebirds from feeding and reduces access to boat ramps and oyster leases.

Spraying is scheduled during low tide events and is dependent on favourable weather conditions, and this summer was wet and windy.

With access to Rice Grass across mudflats also an issue, spraying certainly presents a challenge. A one-week harvest closure needs to be negotiated with Oyster farmers before spraying takes place. This year, March was the big spray week with weed contractors using 4WD trucks with long hoses, quad bikes and knapsacks.

The dedicated Circular Head Landcare Group found early morning low tides often had low winds. They walked 77 kms of coastline, totalling 364 hours of volunteer time, looking for and spraying small Rice Grass outliers.

In total, 123 kms of coast, covering 833 hectares was treated between December to March during the 2020/2021 Rice Grass spraying season, an incredible effort.

This project is supported by Cradle Coast Authority, through funding from the Australian Government’s National Landcare Program.

Rubicon Rice Grass Project

Rice Grass has invaded more than 660 ha of intertidal mudflats in the Rubicon – Port Sorell Estuary. This is now the second largest infestation in Australia. Rice Grass control has been underway since 1996. The objective of the Rice Grass Management Plan is to reduce and contain the Rice Grass infestation and create a Rice Grass free zone (north of Squeaking Point to Eagle Point).

Even though wet and windy weather hampered the Rice Grass program this season from February to April, the total area treated was more than 424 ha, exceeding our annual target of 405 ha.

Weed contractors completed follow-up treatment at Narawntapu National Park and reported a high kill rate of 90% plus from last season spraying. Initial weed treatment commenced at North East Arm, Brown’s Creek, Squeaking Point, Thompsons Creek and Panatana Rivulet (Muddy Creek). Rice Grass control was slow and difficult due to large infestations in creeks and access required through private property.

A trial weed treatment of 0.8 ha of a Rice Grass meadow has commenced at Finger Point in the Rubicon Estuary to monitor sediment movement.

Rice Grass interpretation signs have now been installed at Bakers Beach, Squeaking Point and Port Sorell boat ramps to explain why Rice Grass is a threat to the estuary and the values of saltmarsh, mudflats and seagrass.

This project received funding from the Australian Government.

Iona Flett measuring Rice Grass meadow, Rubicon Estuary, for weed treatment.