Weeds management update - 17 December 2024

17 December 2024

Murray Irrigation is currently managing a large increase in pond weed (Potamogeton) within some of the network.

The weed growth has been discovered in areas that have been desilted and reformed as little as six months ago, as well as channels that were last drained and desilted two years ago as per our annual maintenance strategy and Murray Irrigation Weed Manual.

The Murray Irrigation Weed Manual forms an important part of the annual maintenance strategy. The manual identifies the weeds impacting the Murray Irrigation footprint, any legal requirements relating to biosecurity and the steps taken to control the weeds.

View Murray Irrigation's Weed Manual

Please note, Murray Irrigation it is permitted to use off label rates of certain chemicals for controlling particular weeds, for this to happen an application to the APVMA must be made and a fee paid. The permit will allow the holder to apply chemical rates at higher than recommended rate. Weeds that exist on MIL channels that this permit is used on are Cumbungi, Sagitaria, Milfoils and Pin rush. The rates allowed for these weeds is up to 6% higher than the standard rate. 60mls per 1litres.

Impacts:

Like most other submergent weeds, excess growth will impact the volume of water that can be delivered through the channels which is causing capacity reduction issues within isolated sections across the footprint, a small number of which have impacted some customers.

What are we doing:

The current weed management strategy is working effectively to balance the costs of weed mitigation against known customer demand with the Elodea and Sagittaria weeds. The increase in pond weed this season has been unexpected and has happened quickly.

To ensure customer impacts are minimised, Murray Irrigation currently has 15 excavators operating across the footprint to clear weeds from channels in the areas that are predicted to have high customer demand based on the irrigation intentions survey carried out in October 2024 and current demand.

As an additional measure, we have also procured the services of an Amphibious Harvester, which harvests floating, submerged and emergent aquatic weeds, to assist us to manage this weed growth quickly and efficiently in the short term.

Murray Irrigation will continue to monitor demand to prioritise these works in areas of high demand and keep affected customers updated.

Customers are urged to provide as much order notice as possible to assist with this planning.