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Did the weather stop your pre-em herbicide applications?

Last autumn saw a large proportion of winter cereal crops drilled later than the previous season, due to wet weather delaying operations. Subsequently, the window for pre-emergence herbicide applications may have been missed because ground conditions prevented sprayers travelling.

There was a delay in planting some cereal crops, particularly in the west, due to unfavourable weather, and by the time autumn drilling was completed, some crops were past the pre-em stage for herbicide applications.

For growers who were able to drill on time, wet weather in November may have meant ground conditions were unsuitable for spraying, also resulting in missed applications.

Alternative options

However, for growers who were unable to deliver pre-em herbicide applications, all is not lost and with careful planning, it is still possible to get on top of potential weed problems.

Some of the pre-em herbicides, alone or in a mixture, can still be effective when sprayed early post-em of cereal crops. However, while they can be applied after emergence of the crop, they must be applied before weeds begin to emerge.

For example, if the original plan was to use diflufenican (DFF) pre-em but this wasn’t possible, the chemical could still be applied post-em to control annual meadowgrass (AMG) provided that the weed hadn’t yet emerged.

Unfortunately, by this stage in the winter, we are already too late for this option as once AMG has emerged, DFF alone will not give acceptable levels of control.

However, there are still chemicals available that can be used to control AMG.

Products containing the active ingredients iodosulfuron and mesosulfuron, are effective for AMG control at this stage of the season, so it’s worth discussing the options with your Wynnstay agronomist. They can take into account crop safety and incorporate the new plans into an existing weed control programme.


My top tips for weed control:
- Know the field history and the weed spectrum

- Plan timings for sprayings according to weed growth stages and weather conditions

- Liaise with your Wynnstay agronomist to create a bespoke herbicide plan

- Be prepared to revert to plan B


For more advice, click here to find your local Arable & Forage Specialist.
This article can also be read in more detail in the Feb edition of Farmers Guardian!

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