Herbicide mixes that outperform single products

When farmers start spraying in a paddock or down a fenceline, they don’t usually reach for a single jug and call it a day. Smart tank mixes and the right adjuvants regularly outperform single-product applications, making them critical tools in not just lessening, but eradicating, problem broadleaf and woody weeds.

We’ve rounded up the why, what, and how of using herbicide mixes, including the most popular mixes contractors rely upon, how they boost performance, and the benefits of including a penetrant for best results.

Why do herbicide mixes perform better?

The practice of mixing multiple herbicides offers four key benefits to farmers when treating broadleaf and woody weeds, compared to a single product:

1. Broader spectrum of control at once: Different herbicides target different species and life stages. Mixing a knockdown (fast-acting) product with a systemic product can provide both immediate results and long-term control, reducing the need for continual applications. This permits contractors to clean up fencelines, headlands, or small paddocks in just one spray.
2. Resistance management: In many Australian regions, glyphosate and other herbicides are now facing resistance when used to treat weeds like annual ryegrass, fleabane, and sowthistle. By using compatible herbicides with varied modes of action at once, you can reduce the likelihood of individual plants surviving, since few are resistant to two unrelated herbicides. According to the Grains Research and Development Corporation (GRDC), this ‘mix-and-rotate’ tactic will be critical in future broadleaf eradication.
3. Dual or multi-action results: Multiple modes of action often means multiple points of failure for the target weed. If a plant has a resistance mechanism, such as reduced uptake or a target-site mutation, a second chemical active that works differently can still kill it. According to the GRDC, some active ingredients act rapidly at the surface and weaken plants, so systemics (glyphosate, triclopyr) can move through the plant and complete the job. Other mixes either widen leaf coverage or reduce wash-off risk, thereby increasing the amount of active ingredient that actually enters the plant.
4. Complementary speed and persistence: In the broadacre context, fast-acting contact herbicides (butafenacil, carfentrazone, oxyfluorfen, saflufenacil) cause rapid wilting and desiccation, whereas systemic herbicides (triclopyr, aminopyralid) move into the plant’s roots for longer-lasting control. A mix helps users achieve both immediate visual results and eventual death of broadleaf weeds. For woody weeds, mixing triclopyr, picloram, and aminopyralid with metsulfuron-methyl and a penetrant will yield faster, longer-lasting results than a single herbicide like glyphosate.
5. Operational efficiency and cost efficacy: A single, well-chosen herbicide mix reduces repeat applications, cutting labour costs and machinery hours – a major driver behind best practices in Australia, and an easier way to yield fast results. The time saved from combining products is a leading reason why contractors choose labelled, compatible mixes with historically demonstrated, reliable performance.

Common broadleaf herbicide mixes used in Australia

There are a number of practical, widely-used herbicide mixes that have shown to garner great results in the Australian context. Let’s explore the most common options and their usages for treating a variety of broadacre weeds. 

Glyphosate and 2,4-D Amine

Mixing glyphosate with 2,4-D Amine is ideal for broadleaf weed knockdown, particularly when aiming to target a broad spectrum of weed species in a single pass. Glyphosate maximises the knockdown of target biomass, and 2,4-D Amine ensures broadleaf species are controlled once the glyphosate has translocated into plants. For best results, always use a good surfactant or wetter.

Glyphosate and glufosinate 

Over the last decade, the combination of glyphosate and glufosinate has become one of the most talked-about knockdown options in Australian broadacre farming. Farmers increasingly view this mix as a premium knockdown solution, especially when glyphosate resistance is present or suspected, or where large, stressed weeds need to be controlled immediately.

This combination is widely used in broadacre farming because the two active ingredients have very different modes of action. Glyphosate is systemic and slow-acting, moving through the plant to critical growth points, whereas glufosinate is a fast-acting contact herbicide that causes rapid leaf desiccation. Because they attack weeds in fundamentally different ways, very few species in Australia currently show resistance to both – making this mix extremely valuable for resistance management.

Glyphosate and haloxyfop or clethodim

The mixture of glyphosate and haloxyfop or clethodim offers broadleaf and grass control (via glyphosate) along with robust control of other grasses and management of glyphosate-resistant ryegrass. Trials and regional surveys have shown that glyphosate and clethodim specifically reduced the occurrence of resistance in these populations.

Glyphosate and saflufenacil

Contact chemistry between glyphosate and saflufenacil can speed up visual knockdown and help to eradicate tough broadleaf species. However, caution should be exercised when mixing these chemicals – not all label combinations are inherently compatible.

Pasture-selective mixes

2,4-D or MCPA (2-methyl-4-chlorophenoxyacetic acid) can be blended with selective grass herbicides, when labelled, to target broadleaf weeds in pastures. Contractors working on properties often mix these chemicals for pasture clean-up, in line with grazing withholding periods and label constraints.

For information on rapid knockdown and zero-till fenceline herbicide application, check out our blog post about the herbicide halo method and its many benefits.

Treating woody weeds with herbicide mixes

Woody weeds are fundamentally different to annual broadleaf weeds. They are typified by:

• Thick, waxy, or hairy leaves
• Lignified (rigid or woody) stems
• Large carbohydrate reserves in roots and crowns
• Multi-stemmed regrowth capacity in many cases

As a result, they require a different approach to mixing herbicides to yield long-term results. In Australian conditions – especially in semi-arid and variable-rainfall areas – single herbicide applications can cause cosmetic damage without offering ongoing control. Farmers quickly learn that woody weed eradication almost always requires a well-designed herbicide mixture, combined with the appropriate application method.

Why mix herbicides for woody weed control?

A herbicide mixture is an effective tool in woody weed control for two primary reasons:

• Efficient leaf kill and root death: Fast contact damage alone is rarely enough when treating woody weed species. Farmers and land managers want rapid defoliation (to stop photosynthesis) and deep systemic movement into roots and lignotubers. Mixing herbicides allows these two effects to occur simultaneously for faster, longer-term control.

• Broader control in mixed infestations: Australian fencelines, creek lines, and paddocks rarely contain a single woody weed species. One job might need to control lantana, sweet briar, blackberry, prickly acacia, African boxthorn, and young eucalypt or acacia regrowth, all simultaneously. A single active rarely performs equally well across all target species, so contractors use mixes to cover a wider botanical range. 

Popular woody weed herbicides used in Australia

There are a few active ingredients used in herbicides relied upon by Australian farmers seeking woody weed control: 

• Triclopyr, picloram, and aminopyralid: These ingredients are highly effective on woody weed species thanks to their translocation through the plant. Most commercial woody weed products in Australia are reliant on these actives, either alone or in combination.
• Non-selective systemics (glyphosate): Glyphosate is a useful tool for smaller woody weeds and regrowth, but is often reliable on established plants by itself.
• Contact herbicides (glufosinate): Glufosinate provides rapid leaf burn but limited translocation through the plant, serving a supporting role only in woody weed control.

Triclopyr, picloram, and aminopyralid mixes

Triclopyr, picloram, and aminopyralid is the gold-standard mix for many Australian woody weeds. Each ingredient has a role to play – triclopyr targets stems and leaves, picloram adds persistence and deep root activity, and aminopyralid broadens activity on certain legumes and composite species. Together, these actives provide strong foliar uptake, reliable translocation, and excellent regrowth suppression.

By adding metsulfuron-methyl to this mix as a spike, contractors and farmers can achieve more effective woody weed control with minimal additional cost.

Though other herbicides can be used to target woody weeds, this is by far the most effective and thus, the most popular.

Using penetrants and oils in woody weed mixes

Woody weed species have thick cuticles, waxy or hairy leaves, and reduced spray retention – so without a penetrant, you’re severely limiting the amount of herbicide that can enter the plant.

Organosilicone surfactants (often called silicone penetrants or ‘super-spreading’ surfactants) are extremely powerful and widely used by contractors in woody weed work. They: 

• Dramatically reduce surface tension so droplets spread thinly and wet more of the leaf’s surface
• Improve spreading across rough and waxy leaves
• Increase cuticular penetration and uptake into the weed, allowing the herbicide to move into the plant faster and in greater quantities

Oils vs silicones for woody weed support

Oils and silicones serve different purposes when treating woody weeds: 

• Oils (vegetable or mineral) are preferred for bark penetration and basal work. 

• Silicones are ideal for foliar uptake on tough leaves. 

Choosing the wrong adjuvant is a common cause of poor woody weed results, so select wisely, and always seek expert advice if unsure.

Why woody weed mixes outperform single products?

In summary, herbicide mixes outperform single products because they: 

• Attack multiple plant systems at once
• Reduce reliance on perfect seasonal conditions
• Improve reliability across variable species and plant sizes
• Reduce costly re-treatments, a major consideration for contractors

A single herbicide may appear cheaper by hectare, but failed woody weed control is one of the most expensive mistakes made on Australian farms – making a fantastic case for mixing products.

Practical tips for mixing and administering herbicides

Before you mix herbicides, consider these top tips for getting the most out of your product:

• Match mix to method and weed: When selecting a herbicide mix, consider the application method (foliar, basal, or cut-stump) and the target weed species to inform your decision. Selecting products that are compatible with each other and your chosen method, and effective against the target weeds, is essential to avoid reapplication.

• Adhere to label instructions: In Australia, labels are the law. Some herbicides are explicitly not to be tank-mixed with other products, whereas others have specific adjuvant guidance. Read each label carefully, and never use a product off-label without a permit to avoid breaching APVMA regulations.

• Jar test first: Before committing to a full tank, perform a simple jar test to check physical compatibility (i.e., no precipitates, oils, or separation). These are highly recommended by bodies like the GRDC, especially for complex mixes.

• Use penetrants deliberately: Responsible and considered use of penetrants is critical when mixing herbicides. Always refer to the guidelines found on your chosen mixture’s labels when adding a penetrant to the mix.

• Follow recommended rates: Never cut application when applying a herbicide mixture to woody weeds, as underdosing selects for survival. Similarly, a huge cocktail doesn’t substitute for a good technique.

• Consider mixing order and agitation: The GRDC mixing order guide and many manufacturers’ tank-mix instructions are designed to minimise incompatibility and field failures. Add products in the correct sequence (water-solubles, suspension concentrates, emulsifiable concentrates, then adjuvants) and allow dispersion time.

• Monitor water quality and volume: Hard water can affect some herbicides, and many mixes require higher carrier volumes to ensure coverage. Others will underperform if water quality is ignored.

• Consider timing and weather: Temperature, humidity, and rain can affect performance and increase risk. Weather condition information can generally be found on the relevant Product Label.

• Apply herbicide mixes safely: Always consider off-target movement (volatilisation, drift), grazing and withholding periods, and sensitive neighbours like vineyards or horticulture. Adding potent adjuvants or changing spray volumes can alter drift potential and increase phytotoxic risk. APVMA guidance, label instructions, and state weed handbooks are the practical and legal backbone of safe herbicide application in Australia.

• Understand chemical resistance: If resistance risk exists, use appropriate mixes and non-chemical tactics to get weeds under control.

• Keep detailed records: Maintain a log of mixes, rates, weather conditions, and results to ensure good stewardship, resistance monitoring, and client reporting.

• Expect slower visual results for woody weeds: True woody weed eradication will likely take weeks, not days – so be patient when waiting for results.

Tank-mix herbicides and organosilicone penetrants are powerful tools in a farmer’s toolbox. Used correctly – with label compliance, the right adjuvant, and attention to resistance management – a carefully chosen mix will outperform single products for many on-farm situations.

As with all herbicide applications, certainty and adhering to best practices is key for efficacy and safety. If you need support selecting the right mix for your operations, contact the Specialist Sales team for expert advice.