Agronomy tips for October and beyond in Scotland

Edward’s agronomy tips for October and beyond

1) Consider whether a follow up herbicide is needed for September-drilled wheats

One of my biggest concerns is where growers have used a cheap and cheerful pre-emergence on a September drilled wheat crop, but they’re in a field situation where there are some trickier grass weed issues. Those fields need monitoring for whether a follow up herbicide is required.

If it is, using a metribuzin co-formulation, such as Alternator® Met, Cadou® Met or Octavian® Met, at the full dose would be a good shout. The metribuzin helps provide an extra 10% grassweed control over Liberator® as a post-emergence, plus if you have broadleaf weeds like bur chervil and groundsel coming through it’s better to control them in the back end rather than waiting to use a single-site active in the spring and risk a resistance problem developing.

2) Advice for October-drilled crops

With that desire to grow more winter crops, a lot of potato land will be followed by winter wheat. Weed control decisions for these fields will depend on field history and what weeds are likely to be a problem.

If you have a particularly bad weed problem, use a robust pre-em., and, if needed and the weather remains kind, a post-em. herbicide too.

Where there are difficult grassweeds, such as bromes, the pre-em. could be based on Liberator® + Proclus®, not forgetting Avadex® Factor for extra control of brome, while prosulfocarb could be added for Italian rye-grass.

I’d also suggest applying a pre-em., such as a half rate of Liberator® in fields where annual meadow-grass and broadleaf weeds are the main weed challenges. Timing is key with annual meadow-grass, which seems to almost come out of the ground tillering – pre-em. is usually better than post-em., especially for winter barley.

And again, this could be followed up with a full dose of a metribuzin co-form if the broadleaf weeds need post-em. treatment.

3) Watch out for volunteer potatoes in overwintered stubbles

Volunteer potatoes in stubbles seem to be becoming more of an issue in Scotland, judging by how much I’m seeing when driving about and walking fields. A hangover from potato crops two or more seasons previously in some cases, these could be taken out in October in stubbles being overwintered, assuming frost hasn’t started to kill top growth.

Around 1440g a.s/ha of a good quality branded Roundup® would be ideal to apply, and then that could be left to translocate through the plant through the winter and kill the tubers.

4) Monitor for oilseed rape diseases

Light leaf spot is the main danger for oilseed rape crops once past establishment. Left untreated, it can be a real challenge in the spring. Make use of forecasting tools, and if you see some suspicious symptoms, take some leaf samples, place in a plastic bag, and leave the sealed bag in a warm room for two to three days. After incubation, look for the characteristic presence of white, sugar-like spores around the lesion.

Where present, treat with prothioconazole and / or tebuconazole to prevent infections getting out of control. Timing can coincide with applying nutrition or propyzamide for grass weed control. It’s also a good way to assess the success of establishment of the whole field and look for signs of slug or pigeon damage.

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Avadex® contains tri-allate. Alternator® Met, Cadou® Met and Octavian® Met contain diflufenican, flufenacet and metribuzin. Liberator® contains diflufenican and flufenacet. Proclus® contains aclonifen. Roundup® contains glyphosate. Alternator®, Cadou®, Liberator®, Octavian®, Proclus® are registered Trademarks of Bayer. Roundup® is a registered Trademark of the Bayer Group. All other brand names used are Trademarks of other manufacturers in which proprietary rights may exist. Use plant protection products safely. Always read the label and product information before use. Pay attention to the risk indications and follow the safety precautions on the label. For further information, including contact details, visit www.cropscience.bayer.co.uk or call 0808 1969522. © Bayer CropScience Limited 2025