Making Every Glyphosate Spray Count

Clean Water.
Clean Kill.
Every Time.

Get More Out of Your Glyphosate

In theory, every glyphosate application starts with maximum performance.

In practice, that performance is steadily influenced – and often reduced – by a series of decisions and conditions between filling the sprayer and hitting the target weed.

Here we explore how those influences interact across the full spray journey – from tank chemistry through to application practice and field conditions to help you get more out of your glyphosate applications.

Roger Bradbury

Herbicide Technical Lead, Bayer

Rob Suckling

Commercial Technical Manager, De Sangosse

David Felce

Midloe Grange Farm

John Cussans

Principal Weed Scientist, ADAS

Introducing Our Technical Panel

Building on our Clean Water. Clean Kill. glyphosate stewardship campaign, this page brings together practical farming experience, independent research and technical expertise from across the industry to deliver the best advice from tank-to-target.

Weed target

Canopy architecture

Plant stress

Conditions

Mix partners

Product choice

Dose rate

Surfactant choice / loading

Rainfastness

Timing

Water hardness

Water volume

Nozzle choice

Boom height

Performance is Eroded, Not Lost

A key message from our panel is that disappointing glyphosate results are rarely caused by a single failure. Instead, performance is shaped by multiple interacting factors, including:

Environmental factors such as weed growth stage, plant stress, canopy architecture, and prevailing weather
Chemical factors including product choice, dose rate, surfactant loading, mix partners and rainfastness
Application practice, from timing and water volume to nozzle choice, boom height – and critically water quality

Examples of glyphosate under-performing, courtesy of Bayer.

Cumulative Performance Factors

Each factor on its own may only reduce performance slightly. But together, these small losses can accumulate, leaving applications underperforming despite appearing “correct” on paper.

This is something many growers will likely recognise in the field.

Most poor control isn’t down to one obvious mistake. It’s usually a series of small compromises. When they stack up, you don’t get the result you expected.

Water Quality: The Foundation of Performance

Among all the factors, water quality – and specifically water hardness is one of the most consistently overlooked risks to glyphosate performance .

So what is water hardness? It is not pH.
pH is a measure of acidity. Hardness is a measure of the concentration of calcium and magnesium ions in the water, which carry a positive charge, and we refer to them as cations. When glyphosate is mixed with hard water, these cations form less soluble complexes, reducing glyphosate uptake through the leaf.

A key showing colours on the water hardness map

A map showing colours on the uk representing water hardness

Key: In the UK water hardness is usually expressed
as ppm (parts per million) CaCO3

The Hard Water Problem is Widespread

This is a map of England and Wales, where the blue and very blue areas represent the hard and very hard water areas of the country. There is a very strong correlation between the hard water areas and the major combinable crop production areas of the UK where agrochemicals are mostly used, including glyphosate, to control weeds in arable crops.

As the water gets harder, the greater the impact on herbicide performance can be. If calcium ions are present and unmanaged, glyphosate efficacy can be significantly reduced.

With many arable regions routinely using moderately hard to very hard water, this means a large proportion of glyphosate applications may be unknowingly compromised before the sprayer even leaves the yard.

Test Your Different Spray Water Sources

Water hardness varies, depending on water source and how it is stored, so testing is important and conditioning needs to be correct – and consistent – every tank where it is needed.

Using a conditioner occasionally, or at a guessed rate, is one of the biggest risks we see. Water hardness varies, depending on water source and how it is stored, so testing is important and conditioning needs to be correct – and consistent – every tank.
– Rob Suckling, Commercial Technical Manager at De Sangosse

How to Test Your Spray Water

To prevent hard water cations causing sub-optimal glyphosate performance, you should establish how hard the water is that you use for spraying. This will enable you to correct the water if you need to.
You cannot reliably judge water hardness without testing.

Testing for water hardness is straightforward, with the TDS meter being the quickest and easiest for farmers to use. Available through De Sangosse free of charge, these meters provide a digital reading of water hardness that mean the required dose of water conditioner can be easily determined.

Lab test

Most accurate. Takes a few days. Only accurate for the sample sent

TDS Meter

For ongoing and fast testing. Quick and easy reading for daily use

Paper Test Strips

Can be inaccurate. The strips only offer a ranged result.

Reading Water Hardness (mg/l CaCO₃)	Level	Glyphosate Risk
<100 ppm	Soft water	Ideal
100-150 ppm	Slightly hard	Reduction possible
150-200 ppm	Moderately hard	Reduction very likely
200-300 ppm	Hard	Major efficacy loss
>300 ppm	Very hard	Risk of glyphosate failure

Correct Tank-Mix Order

Once you have your water hardness test result (in ppm calcium carbonate equivalent), you can determine your water hardness level and risk to glyphosate performance – as shown in the table here.

If your water is moderately hard or worse, performance reduction is very likely and adding a true water conditioner (dosed to the hardness of your spray water) is recommended.

Correct tank-mix order is critical. It is vital to add the water conditioner to the spray tank before glyphosate to neutralise calcium and other polyvalent cations contributing to water hardness

Filling a spray hopper conditioning water for herbicide performance

Conditioning Properly – Every Tank

If you do have hard water conditioning needs to be correct – and consistent – every tank. Using a conditioner only occasionally, or at a guessed rate, should be avoided.

True water conditioners - products containing chelating or sequestering agents - such as X-Change, are the most effective solutions for dealing with hard water. By dosing the correct rate to water hardness, you can deal with 100% of the problematic cations in the water, thereby preventing them from interfering with glyphosate.

Other approaches such as straight ammonium sulphate offer only partial mitigation but do not fully eliminate the issue. This behaves more like a water softener to compete with the calcium ions; sometimes it wins, sometimes it doesn’t. So rather than mitigate water hardness, you only reduce its impact.

The use of high rates of pure citric acid are strongly advised against. Citric acid is very acid. When you add it to the solution, you acidify to about pH 3 which is too acidic for glyphosate to work properly. It can result in worse performance than if you actually did nothing to deal with water hardness alone.

Beyond the Tank: Matching Application to the Target

Even with well-conditioned water, application decisions remain central to success.

Target growth stage and spray delivery must align. Small, actively growing weeds are far more susceptible than stressed or stem-extending plants.

Glyphosate must be translocated to the roots to be effective, but this does not happen in these scenarios

Always apply glyphosate at the correct rate for the weed size.

Small, actively growing weeds are far more susceptible than stressed or stem-extending plants. Glyphosate must be translocated to the roots to be effective, but this does not happen in these scenarios. Always apply glyphosate at the correct rate for the weed size.
– David Felce, Farmer and Spray Application Expert from Midloe Grange Farm

Think About the Target

Spray volume, droplet size and nozzle choice all need to reflect where the weed is and how well it’s protected by the canopy.

In reduced tillage and cover crop systems, weeds are often shielded, increasing the importance of getting droplets to the target and maintaining coverage – this is where choosing the right water volume and nozzle for the operation is an important consideration – particularly where glyphosate is relied upon as a crucial control tool.

Why Stewardship Protects Profitability

Insights from John Cussans highlight that glyphosate resistant Italian ryegrass is already present in several locations in the UK – but its development is not inevitable. It’s not just about time or exposure. It’s about how glyphosate is being used on individual farms.

Repeated sub-optimal glyphosate performance doesn’t just risk poor control in the short term – it increases resistance pressure and long-term costs.

Common Risk Factors - Populations Identified to Date

The map adjacent shows populations identified in different regions that all share a similar background in terms of agronomy:

Low levels of cultivation
Low disturbance (no-til drill system)
Lots of long duration undisturbed stubble
(indicated by lots of spring cropping)

KEY FOR MAP ADJACENT

Suspected cases of glyphosate resistant ryegrass

Confirmed cases of glyphosate resistant ryegrass

Easier to Act Before Resistance Occurs Than to React

Even small numbers of surviving weeds have a disproportionate impact. They are more likely to tolerate glyphosate, more likely to reproduce, and more likely to shape future resistance.

For growers affected, the consequences of glyphosate resistance occurring can be significant, requiring increased cultivation, higher input costs and changes to system design:

Re-introduction of mechanical weeding
Maximise in-crop herbicide effectiveness
Prevent individual plants from getting too large between crops
Best practice glyphosate use still provided 90%+ control on ryegrass
No straw movement off farm
Harvest equipment needs to be ring-fenced to the individual farm
Transparency with immediate neighbours is important

Clean Water. Clean. Kill. Tank‑to‑Target

Optimising glyphosate performance is not about a single change, but about improving every stage of the process – from water quality and mixing, to timing and application technique. The Clean Water. Clean Kill. campaign reflects this approach, encouraging growers to think more carefully about how glyphosate is used and how its performance can be protected. Because ultimately, success is not just applying glyphosate. It’s about ensuring it works – every time, from tank-to-target.

Download Stewardship Guide

Plant GS:	Seedling	Tillering	Stem Extension	Flowering
Spray timing	Ideal	OK	DO NOT spray	OK
Dose rate (g/ha)	540 – 720	720 – 1440	-	1080 – 1440

Clean Water. Clean Kill. Every Time.

Clean Water.
Clean Kill.
Every Time.