Walk through any agricultural region where spring barley grows, and you'll see a sea of golden grain swaying in the breeze—a picturesque scene that belies an ongoing battle happening beneath the surface.
For generations, farmers have waged war against weeds, those stubborn plants that compete with crops for sunlight, nutrients, and water, potentially reducing yields and threatening our food supply. Since the 1940s, when the first modern herbicides like 2,4-D were introduced, the approach has often been "more is better"—apply the strongest chemicals at the highest doses to ensure complete weed control 1 .
Years for weed resistance to develop with repeated herbicide use 1
Has withdrawn numerous active substances, limiting farmers' options 1
Approach uses herbicides strategically like a surgeon's scalpel
The concept of reducing herbicide doses might seem counterintuitive at first. If a little herbicide works well, shouldn't more work better? The reality of weed control is far more nuanced. Researchers have discovered that precision application and strategic timing often matter more than sheer chemical quantity.
Reduced herbicide applications align with the principles of Integrated Pest Management (IPM), an approach that emphasizes using all available plant protection methods in a way that minimizes risks to human health, animal health, and the environment 1 .
Integrated Pest Management combines multiple approaches for sustainable weed control while minimizing environmental impact.
Fewer chemicals enter the soil and water systems, preserving ecosystems and biodiversity.
Reduced selection pressure on weed populations delays herbicide resistance development.
Farmers spend less on inputs without sacrificing yield, improving profitability.
Preservation of beneficial microbial communities in the soil supports long-term fertility.
One key insight driving this movement is that we don't necessarily need to eradicate every weed in a field—we just need to reduce weed pressure enough that crops can grow without significant yield loss.
To understand the real-world potential of reduced herbicide strategies, let's examine a comprehensive study conducted from 1997-2000 in northeastern Croatia 2 .
The researchers established experimental plots on lessive pseudogley soil and implemented four distinct tillage systems:
The conventional intensive tillage approach
A reduced tillage system alternating every second year
Another form of reduced tillage
The most intensive of the reduced tillage approaches
Within these tillage systems, they tested a mixture of two herbicides (triasulfuron and chlortoluron) at three different dose levels: the full recommended rate, a half rate, and a quarter rate 2 .
Data from the Croatian study showing weed pressure under different tillage systems 2
The findings from this multi-year study provided compelling evidence for the potential of reduced herbicide strategies:
The data revealed that tillage systems dramatically influenced weed pressure. Continuous disk harrowing, a reduced tillage approach, produced over four times more weed biomass than continuous mouldboard ploughing 2 .
| Herbicide Dose | Reduction in Control Efficacy | Overall Control of Main Annual Weeds |
|---|---|---|
| Full recommended rate | Baseline | 99% |
| Half recommended rate | 6% less | 94% |
| Quarter recommended rate | 15% less | 84% |
"One half and one quarter of the recommended rate decreased the control efficacy of total weed biomass by 12 and 19%, respectively in wheat and by 6 and 15%, respectively in barley compared to the highest dose but they still provided a very good biomass control of main annual weeds (94-96 percentage units)" 2 .
While the Croatian study demonstrated the potential of reduced doses, subsequent research has revealed another critical factor: application timing. A 2022 study investigated the effectiveness of different application times for modern herbicides in spring barley crops 3 .
This research compared the efficacy of two herbicides—Kvelex (containing halauxifen-methyl and florasulam) and Lancelot 450 WG—applied at various development phases of both the crop and weeds.
Herbicide application in the cotyledon to first true leaf phase of weeds (corresponding to the BBCH 18 phase of spring barley) achieved 95.5% effectiveness with Kvelex and 94.4% with Lancelot 450 WG against annual weeds 3 .
Comparison of herbicide efficacy based on application timing 3
This early application timing proved significantly more effective than later applications during the BBCH 25-30 phases of the crop. The early-treated plots also produced higher barley yields—4.5 tons per hectare for Kvelex and 4.42 tons per hectare for Lancelot 450 WG—compared to later application timings 3 .
This principle represents a fundamental shift from calendar-based spraying to condition-responsive management.
For farmers interested in implementing reduced herbicide strategies, understanding the available tools is essential.
Application: Up to pre-boot stage
Rotation: 90-day to soybeans or vegetables
Popular ChoiceApplication: Before flag leaf emergence
Rotation: Short 7-day to soybeans
Fast RotationApplication: Up to flag leaf emergence
Rotation: 120 days to soybeans, 9 months to vegetables
Long RotationApplication: Effective against chickweed
Note: Use at least 5 fl oz for best control
Caution on Rates"Starane Ultra is an herbicide I often hear folks using at rates less than 5 fl oz as a way of cutting costs. I have found that we really need to use at least 5 fl oz to get best control" .
This highlights that not all herbicides are equally suitable for dose reduction—the approach must be product-specific and knowledge-based.
The research clearly demonstrates that reduced herbicide doses can play a valuable role in sustainable spring barley production, but success requires more than simply using less chemical.
Effective implementation involves an integrated approach that combines multiple strategies:
Farmers using reduced tillage systems should anticipate higher weed pressure and plan accordingly 2 .
Apply herbicides during the most vulnerable weed stages (cotyledon to first true leaf) to enhance efficacy 3 .
Use herbicides with different modes of action to prevent resistant weed populations 1 .
Support barley's natural advantage through proper nutrition and optimal planting density 1 .
Combine chemical control with cultural, mechanical, and biological methods 1 .
"In integrated cereal protection, particular emphasis is placed on non-chemical methods, such as appropriate crop rotation, mechanical weed control, optimal fertilization levels, and cultivar selection" 1 .
The research on reduced herbicide dosages in spring barley offers a promising path toward more sustainable agriculture. Evidence from multiple studies indicates that we can significantly reduce chemical inputs while maintaining effective weed control and protecting yields.
The keys to success lie in understanding the interaction between tillage systems, herbicide timing, and crop competitiveness. As we move forward, the challenge will be to translate these research findings into practical field-level strategies that account for local conditions, weed spectrums, and economic realities.
In the end, the story of reduced herbicide use in spring barley is part of a larger narrative about working smarter, not harder, and learning to harness ecological principles rather than fighting against them. It's an approach that promises to benefit farmers, consumers, and the planet alike—a rare trifecta in modern agriculture.