Managing your GRT infestations

GRTAre you tackling giant rat’s tail grass (GRT)?

GRT is one of the toughest weed challenges facing Queensland right now. And regardless of whether you’re managing a property, pipe line, power line or production line, GRT doesn’t discriminate.

More than 30% of Australia (and 60% of Queensland) is believed to be at risk from GRT. Seed is readily spread by livestock, vehicles, machinery and other materials and can remain viable for up to 10 years.

According to the Department of Agriculture and Fisheries, GRT can have a number of significant impacts:
• GRT quickly dominates an area and can reduce carrying capacity and production by up to 80%.
• GRT is a Class 2 declared pest plant under Queensland legislation. This means that landholders are required to control GRT on their properties, requiring a significant long term investment.
• Weed infestations, such as GRT, can also be a considerable source of community angst for major landholders and efforts need to be taken to protect your interests by preventing any potential for spread.
• As a Class 2 declared pest plant, you are prohibited from supplying any material that may contain GRT (without a permit). This has significant implications for those who operate in GRT affected areas or who supply or transport materials such as livestock, seed, hay, gravel and other supplies.

So what can we do about GRT?

A landholder in Central Queensland has been wondering just that… Like many others across the region, they’ve tried spot spraying, aerial spraying, grazing, burning, buffers and hygiene. But to date, their efforts appear to have been met with mixed results.

So, to improve their management of the property, we’ve been working with them to review their weed management operations. Here are some of the key lessons learned from these experiences.

1. Have a holistic and practical plan
Controlling GRT requires a long term commitment by the landholder and everyone who accesses the land. To make the best use of scarce resources, you need to consider:

  • What are your long term management objectives?
  • What’s the current situation?
  • How will you benchmark your current infestations and then monitor the progress of your actions to ensure they’re effective?
  • How can you use hygiene measures and buffer zones to prevent further spread?
  • Can you increase your weed resilience by minimising disturbance and promoting good competitive ground cover?
  • Do you have any sensitive or high priority areas that need to be considered?
  • What are your control priorities?
  • What resources have you got to work with?
  • What additional support will you need?
  • How will you communicate your plans and actions with your stakeholders?
  • Are neighbours having similar issues and is there any way to coordinate your activities to reduce costs (for example, collaborating on aerial spraying efforts to reduce travel/ferry costs or could you buy chemical in bulk)?

2. Implement your plan and ensure regular follow up
Consistent implementation, review and follow up are critical to the long-term success of your GRT program. Once established, GRT is extremely difficult to eradicate and unfortunately there is no silver bullet. Management can be further complicated where the predominate land use is grazing and stock exclusion is not an option or where there are multiple groups accessing the land.

When completing the review for the major CQ landholder, we found that they needed a clear management approach at the paddock scale. By considering their overall property objectives and then breaking the property into smaller more manageable blocks, the required actions become far more practical and achievable. It also becomes easier to identify and monitor the current weed liability. Where appropriate, this can be as simple as identifying weed infestations, plotting some GPS points on a map and determining the extent and density of each infestation at each regular check. This also makes it easier to identify new and emerging weed threats to your property as part of your regular monitoring and maintenance activities.

Once you’ve got your plan, it’s important to implement it and ensure regular monitoring and follow up. One of the issues the landholder faced was that after treating an area with Fluproponate in the first year, the initial results appeared fairly promising, so no treatment occurred in the second year. In the third year, the GRT returned with similar densities to those prior to initial treatment.

In our experience, we have seen a number of CQ control activities deliver good results after the initial treatment. But established infestations generally have an extensive seed bank in the soil (upwards of 85000 seeds per plant annually), so it’s important to commit to an integrated long term management approach. This will generally involve maintaining residual fluproponate in the soil for both a second and third year (pending seasonal conditions).

Continuous followup is the key to getting on top GRT and reducing the seedbank.

3. Regularly review your control options and their effectiveness
As the collective knowledge and experience with GRT grows, it’s important to continue to review your management approach and to take into account new research and control options. Overall, you’ll be more likely to achieve your objectives and make the best use of your time and resources if you consider the following:

  • Are your prevention and containment practices working? If not, why not? And what else can you do?
  • Are you creating a resilient landscape that can assist in competing with GRT? By giving your land adequate rest and recovery you’ll be promoting healthy pastures and other native grasses and ground cover.
  • Are your control activities reducing the density of your current infestations, if not consider trialling a new method?
  • Have you recently explored what other control options might be available for your specific situation? For example, Fluproponate is now available in both liquid and granular form, simplifying aerial applications and also selected ground applications. You might also like to consider other control techniques such as spray topping, wick wiping, burning to reduce biomass and seed bank prior to a chemical control program and fertilising GRT infested areas to improve palatability and digestibility of the GRT plants by cattle. The biocontrol crown rot fungus Nigrospora oryzae might also provide some hope in southern areas however to date CQ trials have proved unsuccessful.
  • Have you considered getting a second opinion? You might like to seek further advice or even a property inspection by a specialist to see if there are any new control practices that could be more effectively utilised for your specific situation.

Other handy references

How are you tackling GRT? What’s working for you and what’s not?