Herbicide Planning For Busy Spring Season

01 April 2026, UK: Effective spring herbicide strategies hinge on timing spray windows with periods of active weed growth.

Early drilling followed by wet weather conditions mean many winter crops have large populations of both grass weeds and broad-leaved weeds, reports Syngenta Technical Manager and grass weed specialist, Georgina Young.

Planning herbicide sequences and the potential for tank mixes now, will make the best use of every opportunity that arises. This season the need for early fungicides in many crops presents an opportunity to reduce application time and costs as AXIAL^® Pro can be tank mixed with a wide range of other plant protection products.

AXIAL® Pro Top Tips

• Plan for AXIAL® Pro tank mix opportunities
• Understand the field population and if winter or spring germinators are your biggest problem
• Be aware of sequence limitations with some herbicides
• Adjust rates according to weed size
• Focus on application to achieve the best deposition on weed targets

It is always recommended to use AXIAL^® Pro at the full rate for the target weed when mixing with some herbicides including ALS inhibitors, halauxifen, fluroxypyr and clopyralid. These mixes would be best avoided if growing conditions are suboptimal at the time of application. Recent fluctuations between day and night temperatures mean that careful consideration should be given to ensure the optimal spray window.

With multiple spring herbicide applications a high possibility, after poor autumn control, it’s important to note that where AXIAL^® Pro is used first, for example to target overwintered grass weeds, SU/ALS inhibitor or hormone herbicides can be applied just seven days later. 

However, if the SU/ALS inhibitor or hormone herbicide is applied first in the sequence, growers should wait 21 days before applying AXIAL^® Pro – by which time grass weeds will have grown progressively larger and may require higher rates for optimum control.

Active growth

Active weed growth at the time of application is essential to achieve high levels of control from all herbicides, as well as to minimise the risk of temporary crop effects. 

Trials have shown that it is better to wait until conditions are favourable for weed growth before a herbicide application, even if higher rates are then required to tackle larger weeds.

Syngenta research with NIAB has demonstrated that larger, overwintered grass weeds are more competitive and produce far higher seed returns compared to later spring-germinating weeds. Knowledge of the field situation and the likely germination pattern is crucial to ensure maximum control of the entire population. Waiting to see all spring germinators come through can result in poor control of large, overwintered weeds which then contribute a high seed return, perpetuating the problem for future years.

Achieving good levels of grass weed control in the relatively uncompetitive spring barley crop is essential to prevent wild oat and ryegrass populations multiplying and negating the value of spring cropping.

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