As the main autumn drilling window approaches alongside a period of wet weather, farmers are advised to think strategically about how to maximise the longevity of pre-emergence herbicide efficacy in the weed germination zone, to ensure a robust start to the growing season.
The pre-emergence herbicide programme is often the most crucial part of the chemical weed control strategy to avoid reliance on less effective contact chemistry post-emergence. It’s vital pre-ems remain active in the weed zone for as long as possible to avoid putting effective weed control, crop establishment and a successful harvest at risk.
Excess rainfall can compromise the efficacy of these herbicides, leading to increased weed pressure in the subsequent growing season. However, with caution and integrating residual herbicide adjuvants into their weed management strategies, farmers can enhance the performance of pre-emergence herbicides and safeguard their crops.
Key Areas:
- Understanding pre-emergence herbicides
- Challenges of a wet autumn
- The role of residual herbicide adjuvants
- Best practice for utilising residual herbicide adjuvants
- Why choose adjuvant Backrow Max to secure your fields
- Experience the Backrow Max difference
Understanding pre-emergence herbicides
Pre-emergence herbicides are designed to control weeds before they emerge from the soil. They provide a crucial layer of protection to crops to prevent weeds competing for space, moisture, nutrients and sunlight.
However, the effectiveness of residual herbicides can be significantly reduced in wet conditions due to runoff, poor retention and dilution.
Wet soils and heavy rainfall increases the risks of herbicides moving out of the weed zone, reducing their effectiveness.
Challenges of a wet autumn
Runoff: Heavy rainfall can cause surface runoff in poorly structured soils, which can wash away herbicides before they have the chance to work on germinating weed seeds.
Poor retention: Excessive rainfall can lead to the leaching of pre-emergence herbicides from the weed germination zone, reducing their longevity in the soil and ultimately lowering their effectiveness.
Dilution: Prolonged wet conditions can dilute herbicide concentrations in the weed germination zone, diminishing their ability to effectively control weeds.
The role of residual herbicide adjuvants to enhance pre-emergence herbicides
Residual herbicide adjuvants are products that can be co-applied with residual herbicides to improve their performance. In suboptimal weather and application conditions adjuvants can be a crucial addition to enhance their effectiveness. Here’s how they can help:
Improved retention: Adjuvants can increase the adhesion of herbicides to soil particles, helping to ensure that the herbicide is retained and remains effective in the weed germination zone, even after heavy rain. This improved retention can reduce the likelihood of leaching and runoff.
Improved soil interaction: Certain adjuvants improve the ability of herbicides to bind to soil, enhancing their residual activity. This is particularly beneficial in wet conditions where soil moisture can otherwise hinder herbicide performance.
Compatibility with diverse formulations: Many adjuvants are designed to be compatible with a wide range of herbicide formulations, allowing farmers to tailor their weed management strategies to their specific needs.
Best practice for utilising adjuvants
To maximise the benefits of using an adjuvant to enhance pre-emergence herbicide efficacy, farmers are advised to consider the following best practices:
Assess soils and fix poor structure: The properties of your soil will determine how fast herbicides will move out of the weed germination zone. In lighter soils with less organic matter for herbicides to bind to, the risk will be greater. Know your soils.
Poor soil conditions can dramatically hinder residual herbicide effectiveness. The foundation of good herbicide efficacy is to get soils in good condition to ensure good tilth, no compaction and good porosity. For more information on the effects of soil structure on herbicide performance, click here.
Choose the right adjuvant: Select adjuvants specifically for use with residual herbicides and proven benefits to ensure compatibility and effectiveness.
Time applications carefully: Apply herbicides at the recommended timing after drilling for maximum efficacy. Apply pre-emergence herbicides when rain is forecast but avoid periods of heavy rain to ensure herbicides have sufficient time to bind to soil particles. While an effective adjuvant will aid herbicide binding to soil particles, you should still try to avoid periods of intense rainfall after application to optimise its retention in the weed zone for as long as possible.
Monitor weather patterns: Stay informed about local weather patterns and be prepared to change application strategies where needed. This proactive approach can help mitigate the risks of unexpected heavy rainfall.
Follow manufacturer guidelines: Always adhere to the manufacturer’s recommendations for the application rates of both the herbicide and the adjuvant. Proper dosing is crucial for optimal performance. Also pay attention to mixing order advice as this is likely to affect performance and compatibility.
Why choose Backrow Max to enhance pre-emergence herbicide efficacy
Backrow Max is a trusted and proven residual herbicide adjuvant demonstrating significant improvements in various studies and field trials under wet conditions. Farmers who integrate Backrow Max into their pre- and peri-emergence herbicide applications can expect the following benefits:
Top-performing herbicide retention: Studies show enhanced retention in the top 5cm of soil compared to competitor adjuvants tested, with improved performance across various herbicides: +6% Luximo; +7% clomazone; +8% pendimethalin.
Enhanced residual activity: Up to a 17% improvement in weed control for black-grass, ryegrass, and brome.
Reduced crop phytotoxicity: A 20% reduction in chlorosis and increased wheat emergence by up to 29 plants per sqm.
Reduced risk of herbicides and nitrates leaching to groundwater.
Experience the Backrow Max difference
Join the many farmers who have already experienced the benefits of Backrow Max.
Backrow Max can be purchased through Agrii in the UK.
For more information, download our latest guide here – for independent trials results with the latest herbicides, farmer case studies and more. You’ll also find an extensive list of approved crops.
Please get in touch with Stuart below if you require any technical assistance or further information.