Flupropanate and its use in Australian agriculture

Flupropanate is a selective, systemic herbicide widely used in Australian agriculture to control perennial grass weeds. Its residual action makes it a valuable tool for land managers, graziers, and farmers dealing with invasive species that compete with desirable pastures and native vegetation.

Discover the key aspects of flupropanate, including how it works, its formulations, the pros and cons of using it, and best practice tips for application and timing.

What is flupropanate?

Flupropanate is a slow-acting herbicide that targets perennial grass species by inhibiting essential enzyme functions. When applied, it’s absorbed through the plant roots and foliage, where it is translocated through the plant, eventually leading to plant death.

Unlike contact herbicides that provide instant results, flupropanate has a prolonged control period, which makes it effective against hard-to-eradicate weeds.

Which species is flupropanate used to control?

In the Australian context, flupropanate is predominantly used to control the following perennial weeds:

Serrated tussock (Nassella trichotoma): A highly invasive grass that reduces pasture productivity and is unappetising to livestock.
Giant rats tail grass (Sporobolus spp.): A tough, fibrous weed that competes aggressively with pasture species.
African lovegrass (Eragrostis curvula): A robust species of grass that invades degraded pastures and outcompetes native species.
Parramatta grass (Sporobolus fertilis): A weed that spreads quickly in grazing areas, reducing feed quality.
Chilean needle grass (Nassella neesiana): An invasive perennial tussock grass that is problematic due to its sharp, needle-like seeds.

Flupropanate is also used in pasture rehabilitation, rangeland management, and roadside vegetation control settings to ensure long-term control of problem weeds.

When should flupropanate be used?

When considering whether to use flupropanate for your particular circumstances, there are a handful of things to consider. Its effectiveness is very dependent on application timing and environmental conditions, including:

- Soil moisture: Because flupropanate is residual (i.e., continues to act in the soil for a long time after it is first applied), it relies on soil moisture for optimal activation and uptake. By applying flupropanate during adequate periods of rainfall, you’ll ensure the herbicide reaches the target root zones.

Growth stage: The best results occur when weeds are actively growing, as this permits effective translocation of the chemical throughout the plant.

Seasons: Flupropanate should be applied when there’s adequate rainfall, which, depending on your location, may be in late autumn to early winter or late spring to early summer.

How is flupropanate applied?

Flupropanate has two primary formulation methods: granular and liquid. Each of these are suited to different applications and contexts – let’s break them down in more detail.

Granular flupropanate application

Granular flupropanate is a popular choice because of its long-lasting residual control (up to several years in some conditions), its reduced risk of spray drift, and its efficacy in hard-to-reach areas where spraying is impractical. However, it requires rainfall to activate, which may delay weed control in dry areas.

Granular flupropanate is applied directly to the soil and activated by rainfall. It’s typically broadcast using:

Aerial spreading for large-scale application and in rough terrain
Ground-based fertiliser spreaders for targeted paddock applications
Hand-operated spreaders for small-scale spot treatments

It’s critical to note that because granular flupropanate needs rainfall to activate, it’s not ideal in extremely dry areas, as this may delay weed control. When applying granular flupropanate, always carefully calibrate your application rates to manufacturer recommendations to avoid overuse and residual soil impacts.

Liquid flupropanate application

Liquid flupropanate is quickly absorbed into the plant compared to granular formulations, which makes it an excellent choice for time-sensitive scenarios. It’s generally applied via foliar spraying or soil drenching, which allows for more precise weed targeting in smaller or more sensitive areas.

Standard application methods include:

Boom spraying for treating large paddocks and roadside infestations

Spot spraying via backpack or ATV-mounted sprayers for targeted control

Soil drenching around the base of problem weeds for optimal root absorption

In terms of application, liquid flupropanate can be mixed with other herbicides or adjuvants to improve efficacy, which will be a plus for many landowners.

However, due to its application method, liquid flupropanate carries a greater risk of spray drift, so it shouldn’t be applied under windy weather conditions. Unlike granular formulas, liquid flupropanate may require repeat applications for complete control in heavily infested areas.

Pros and cons of using flupropanate

Like any herbicide, flupropanate has its advantages and limitations – here’s what you need to consider before adding this control solution to your weed management strategy.

Pros of flupropanate

Long-term control: Flupropanate’s residual activity in the soil suppresses weed regrowth over an extended period which reduces the need for frequent reapplication.

Efficacy against tough weeds: This herbicide controls hard-to-manage grasses that may be resistant to other active ingredients.

Selective action: Flupropanate targets specific grass species while leaving broadleaf pastures and native plants largely unaffected.

Flexible formulations: Because flupropanate is available in both granular and liquid forms, it’s suited to a wide variety of application needs.

Cons of flupropanate

Slow activity: It can take weeks to months for the full effects of flupropanate to be felt, which mightn’t be ideal if you have immediate control needs.

Residue persistence: Flupropanate’s long-lasting residual activity has the potential to become a negative, as it may impact desirable pasture regeneration if not appropriately managed.

Weather dependency: This herbicide requires sufficient rainfall for activation, which limits its effectiveness in drought-prone regions where rain is irregular and uncertain.

Restricted use: Regulatory restrictions that prohibit the use of flupropanate may apply in certain sensitive environments.

Best practices for effective flupropanate use

To maximise the effectiveness of flupropanate whilst minimising environmental impacts, we recommend adhering to these best practice principles:

Correct identification: Ensure target weeds are correctly identified before application to avoid unnecessary herbicide use.

Optimal timing: Always apply flupropanate when soil moisture levels are conducive to absorption and plant translocation.

Application calibration: Use appropriate equipment and follow application rates to a tee to prevent excessive or insufficient dosage.

Integrated weed management: Combine flupropanate with other weed control strategies such as strategic grazing, pasture improvement, and mechanical weed removal for better long-term outcomes.

Withholding periods: Avoid grazing treated areas too soon to prevent herbicide residue from affecting livestock health.

Flupropanate is an essential tool in combating invasive perennial grasses in the Australian agricultural context. Its selective, residual action makes it particularly effective against problem weeds including serrated tussock and giant rats tail grass. As is the case with most herbicides, it’s best used as part of a comprehensive weed management strategy alongside best practices for optimal weed control results.

Not sure whether flupropanate is the right herbicide for your unique needs? We’re always available to chat through your needs and circumstances – get in touch with our team now.