The Hidden Infrastructure Risk
Find out why proactive herbicide resistance management is critical to protecting infrastructure assets, reducing risk and maintaining effective vegetation control.
Vegetation managers responsible for maintaining roadsides, rail corridors, utility networks, substations, airports, industrial sites and other critical infrastructure face an increasing range of challenges. While issues such as fire risk, access restrictions and compliance requirements are often front of mind, one long-term threat is frequently overlooked: herbicide resistance.
Herbicides remain one of the most effective and economical tools available for controlling unwanted vegetation. However, their long-term effectiveness cannot be taken for granted. Across the globe, weeds are continuing to evolve resistance to herbicides, making control more difficult, increasing management costs and reducing the effectiveness of existing weed management programs.
According to the International Herbicide-Resistant Weed Database, there are 548 unique cases of herbicide-resistant weeds globally, spanning 275 species (156 dicots and 119 monocots). Weeds have evolved resistance to 21 of the 31 known herbicide sites of action and to 168 different herbicides. Herbicide-resistant weeds have been reported in 102 crops in 76 countries.
The rate at which resistance develops depends on several factors, including the weed species, the herbicide used, and the overall herbicide program. Repeated reliance on the same herbicide or herbicide mode of action places significant selection pressure on weed populations, accelerating the development of resistant individuals. Over time, these resistant weeds survive treatment, reproduce and become increasingly dominant within a site.
Importantly, herbicide-resistant weeds do not recognise property boundaries. The movement of resistant weed seed or plant material from neighbouring agricultural, horticultural or industrial areas can introduce resistance into previously unaffected sites. This means resistance management is not only an individual site responsibility but also a broader industry-wide concern. Maintaining the effectiveness of current herbicides requires proactive stewardship and the adoption of sound weed management practices across all sectors.
Strategies for managing herbicide resistance
1. Mix and rotate herbicides
Understanding the mode of action of herbicides is fundamental to resistance management. Herbicide labels identify their mode of action through a group number, indicating how the product affects the target weed.
Repeated applications from the same mode of action group increase the likelihood of resistance developing. Rotating between different herbicide groups from one application to the next can help reduce this selection pressure and delay resistance development.
An even more effective strategy is the use of tank mixes containing two or more herbicides with different modes of action. By exposing weeds to multiple control mechanisms simultaneously, the likelihood of resistant individuals surviving treatment is significantly reduced.
2. Optimise spray efficacy
Even the most effective herbicide can underperform if it is not applied correctly. Maximising spray efficacy is essential to achieving consistent weed control and minimising the risk of survivors that may contribute to resistance development.
Key considerations include using properly calibrated application equipment, selecting the correct spray nozzles, applying the appropriate water volume, and incorporating suitable adjuvants where recommended. Environmental conditions such as temperature, humidity and wind speed should also be considered to ensure optimum herbicide performance.
Achieving high levels of weed control with every application reduces the number of plants that survive treatment and helps maintain the long-term effectiveness of herbicide programs.
3. Prevent weed seed set
Any weeds that survive a herbicide application should be controlled before they have the opportunity to flower and produce seed.
At the heart of every successful weed management program is management of the soil seed bank. The soil seed bank represents the reserve of viable weed seeds present in the soil, often accumulated over many years. Left unmanaged, this seed bank can continually replenish weed populations and undermine control efforts.
The long-term objective should be to progressively reduce the size of the soil seed bank while preventing the addition of new seed. By stopping weed seed set, vegetation managers can significantly reduce future weed pressure and improve overall control outcomes.
4. Use non-herbicide weed control techniques
Effective resistance management requires an Integrated Weed Management (IWM) approach. No single control method should be relied upon in isolation.
Combining chemical, mechanical and, where appropriate, biological control techniques can help reduce weed populations while minimising dependence on herbicides alone. Techniques such as slashing, mowing, cultivation and strategic vegetation management can all contribute to a more resilient weed control program.
Good site hygiene is equally important. Cleaning machinery, equipment and vehicles before moving between sites can help prevent the spread of weed seed and vegetative material, reducing the risk of introducing resistant populations into new areas.
Supporting long-term resistance management
Long-term residual herbicides can also play an important role in reducing weed pressure and supporting resistance management strategies.
Esplanade® Herbicide is a broad-spectrum residual herbicide designed to help reduce the soil seed bank by controlling emerging weeds before they can establish. By preventing successful establishment, it reduces the number of weeds that reach maturity and contribute new seed to the soil.
Esplanade inhibits root development in emerging seedlings, providing long-lasting residual control across more than 30 key weed species commonly found in utility and industrial vegetation management environments.
Importantly, Esplanade offers a different mode of action to many traditional vegetation management programs. Incorporating alternative modes of action into weed control programs is a key principle of resistance management, helping reduce reliance on existing chemistry and supporting the long-term sustainability of herbicide tools.
As resistance continues to emerge globally, vegetation managers cannot afford to take a reactive approach.
Phil Logan, Key Account Manager – IVM, said the cost of doing nothing is not simply reduced weed control.
“Over time, it can result in higher maintenance costs, greater operational disruption, increased safety risks and fewer effective control options available to vegetation managers,” he said.
“By implementing integrated resistance management strategies today, infrastructure managers can help protect the long-term performance of herbicides and maintain safe, compliant and operational assets into the future.”
Drawing on expertise in herbicide technologies, vegetation management solutions and integrated vegetation management strategies, Envu works closely with customers to address evolving operational challenges, regulatory requirements and asset management objectives.
Whether assessing current vegetation management practices, identifying opportunities to optimise maintenance programs, or evaluating the long-term economic impacts of vegetation control decisions, Envu works with organisations to support more sustainable vegetation management outcomes.
For more information, visit the Envu Esplanade Resource Centre.
To learn how Esplanade can be integrated into a vegetation management program, or to arrange an on-site discussion, contact Phil Logan on +61 402 777 664 or philip.logan@envu.com.
Herbicides remain one of the most effective and economical tools available for controlling unwanted vegetation. However, their long-term effectiveness cannot be taken for granted. Across the globe, weeds are continuing to evolve resistance to herbicides, making control more difficult, increasing management costs and reducing the effectiveness of existing weed management programs.
According to the International Herbicide-Resistant Weed Database, there are 548 unique cases of herbicide-resistant weeds globally, spanning 275 species (156 dicots and 119 monocots). Weeds have evolved resistance to 21 of the 31 known herbicide sites of action and to 168 different herbicides. Herbicide-resistant weeds have been reported in 102 crops in 76 countries.
The rate at which resistance develops depends on several factors, including the weed species, the herbicide used, and the overall herbicide program. Repeated reliance on the same herbicide or herbicide mode of action places significant selection pressure on weed populations, accelerating the development of resistant individuals. Over time, these resistant weeds survive treatment, reproduce and become increasingly dominant within a site.
Importantly, herbicide-resistant weeds do not recognise property boundaries. The movement of resistant weed seed or plant material from neighbouring agricultural, horticultural or industrial areas can introduce resistance into previously unaffected sites. This means resistance management is not only an individual site responsibility but also a broader industry-wide concern. Maintaining the effectiveness of current herbicides requires proactive stewardship and the adoption of sound weed management practices across all sectors.
Strategies for managing herbicide resistance
1. Mix and rotate herbicides
Understanding the mode of action of herbicides is fundamental to resistance management. Herbicide labels identify their mode of action through a group number, indicating how the product affects the target weed.
Repeated applications from the same mode of action group increase the likelihood of resistance developing. Rotating between different herbicide groups from one application to the next can help reduce this selection pressure and delay resistance development.
An even more effective strategy is the use of tank mixes containing two or more herbicides with different modes of action. By exposing weeds to multiple control mechanisms simultaneously, the likelihood of resistant individuals surviving treatment is significantly reduced.
2. Optimise spray efficacy
Even the most effective herbicide can underperform if it is not applied correctly. Maximising spray efficacy is essential to achieving consistent weed control and minimising the risk of survivors that may contribute to resistance development.
Key considerations include using properly calibrated application equipment, selecting the correct spray nozzles, applying the appropriate water volume, and incorporating suitable adjuvants where recommended. Environmental conditions such as temperature, humidity and wind speed should also be considered to ensure optimum herbicide performance.
Achieving high levels of weed control with every application reduces the number of plants that survive treatment and helps maintain the long-term effectiveness of herbicide programs.
3. Prevent weed seed set
Any weeds that survive a herbicide application should be controlled before they have the opportunity to flower and produce seed.
At the heart of every successful weed management program is management of the soil seed bank. The soil seed bank represents the reserve of viable weed seeds present in the soil, often accumulated over many years. Left unmanaged, this seed bank can continually replenish weed populations and undermine control efforts.
The long-term objective should be to progressively reduce the size of the soil seed bank while preventing the addition of new seed. By stopping weed seed set, vegetation managers can significantly reduce future weed pressure and improve overall control outcomes.
4. Use non-herbicide weed control techniques
Effective resistance management requires an Integrated Weed Management (IWM) approach. No single control method should be relied upon in isolation.
Combining chemical, mechanical and, where appropriate, biological control techniques can help reduce weed populations while minimising dependence on herbicides alone. Techniques such as slashing, mowing, cultivation and strategic vegetation management can all contribute to a more resilient weed control program.
Good site hygiene is equally important. Cleaning machinery, equipment and vehicles before moving between sites can help prevent the spread of weed seed and vegetative material, reducing the risk of introducing resistant populations into new areas.
Supporting long-term resistance management
Long-term residual herbicides can also play an important role in reducing weed pressure and supporting resistance management strategies.
Esplanade® Herbicide is a broad-spectrum residual herbicide designed to help reduce the soil seed bank by controlling emerging weeds before they can establish. By preventing successful establishment, it reduces the number of weeds that reach maturity and contribute new seed to the soil.
Esplanade inhibits root development in emerging seedlings, providing long-lasting residual control across more than 30 key weed species commonly found in utility and industrial vegetation management environments.
Importantly, Esplanade offers a different mode of action to many traditional vegetation management programs. Incorporating alternative modes of action into weed control programs is a key principle of resistance management, helping reduce reliance on existing chemistry and supporting the long-term sustainability of herbicide tools.
As resistance continues to emerge globally, vegetation managers cannot afford to take a reactive approach.
Phil Logan, Key Account Manager – IVM, said the cost of doing nothing is not simply reduced weed control.
“Over time, it can result in higher maintenance costs, greater operational disruption, increased safety risks and fewer effective control options available to vegetation managers,” he said.
“By implementing integrated resistance management strategies today, infrastructure managers can help protect the long-term performance of herbicides and maintain safe, compliant and operational assets into the future.”
Drawing on expertise in herbicide technologies, vegetation management solutions and integrated vegetation management strategies, Envu works closely with customers to address evolving operational challenges, regulatory requirements and asset management objectives.
Whether assessing current vegetation management practices, identifying opportunities to optimise maintenance programs, or evaluating the long-term economic impacts of vegetation control decisions, Envu works with organisations to support more sustainable vegetation management outcomes.
For more information, visit the Envu Esplanade Resource Centre.
To learn how Esplanade can be integrated into a vegetation management program, or to arrange an on-site discussion, contact Phil Logan on +61 402 777 664 or philip.logan@envu.com.
Read the original article and other stories published by Utility Magazine on their website here.
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