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Tom Sowerby

How to handle weed control and late OSR drilling in the north

Article overview

Current situation (19 August)

Harvest is progressing well in Yorkshire with many growers well into wheat now. With decent weather this week some growers might well finish wheat around the August bank holiday.

Yields are just OK – it’s certainly not a record-breaking year, but equally I've not heard anybody say they've had a disaster, although this season that is possible unfortunately given the conditions through winter.

On our home farm our Palladium wheat did quite well while the Dawsum was OK but nothing special. Oilseed rape which looked pretty terrible all year eventually yielded around 4t/ha, which we were pretty happy with. Winter barley was the real star at home, yielding 9.5t/ha.

Quite a bit of oilseed rape was drilled at the beginning of August. It's quite difficult to say where the area will end up this year. There are some growers who all the way up to harvest were saying they would not drill it again and then found a decent yield and decided to jump back in. But overall I expect the area will be down slightly again - growers have started to lose the will with it although what has been drilled is coming slowly through.

1) Stale seedbeds will be crucial ahead of drilling

Stubble management had taken a back seat to combining, but recently I have seen a few ploughs, Sumos and more shallow cultivators around so people are starting to move soil and create stale seed beds.

Given what happened last autumn and over winter there are a lot of growers who are considering drilling earlier this autumn. I am sure there will also be some people who will hold off until October.

Even if you are considering starting to drill in mid-September there should be time to get at least one flush of grass-weeds ahead of drilling. It will be crucial this season to maximise any weed control possible outside of the crop, especially when early drilling.

Where you are concerned about a possible green bridge increasing risk of barley yellow dwarf virus, the best time to spray Roundup (glyphosate) is 10 days before drilling. This gives time for any volunteers or green material to be destroyed before the new crop emerges, preventing aphids from jumping from residue to crop.

This is a bit of a balancing act as weeds could emerge in the 10 days before drilling. In that case it is possible to do a second application in with the pre-emergence herbicide if necessary.

When using glyphosate don't forget the sprayer basics. It's easy to rush this application but it is the one which will likely give the best weed control of the entire season. Check stubbles for weed type and size, and use an appropriate dose, water volume, nozzle and forward speed.

2) Drill early, prepare to spend more

Early drilling will, unfortunately, almost certainly lock growers into higher input spend. That's the case with autumn residual herbicides where two sprays will likely be required this side of Christmas.

Persistency is a key attribute to look for because likely warmer soil temperatures in September will contribute to active substances breaking down faster than when applied in October or November.

Aclonifen in Proclus has a longer half-life than most other residuals and is also less affected by drier conditions. When used in mix with Liberator (flufenacet + diflufenican), it is a good option to begin programmes. Proclus must be used pre-emergence, so ideally apply within 48 hours of drilling.

It also allows the use of cinmethlyin as a top up spray around three weeks later, which could be a safer from a crop perspective.

3) Check cabbage stem flea beetle migration patterns with Magic Trap

Most growers have chosen to plant oilseed rape, if they have chosen to continue with the crop, in the early August window. Companion cropping with buckwheat and vetch has been popular this season while many have also used organic manures to try and get the crop up and running.

A second strategy is to delay drilling until after cabbage stem flea beetle peak migration has occurred. It is possible to monitor this with one of Bayer’s Magic Traps. These are water traps with a camera attached and give almost real time insights into flea beetle migration patterns.

Once peak migration has occurred, it is safe to consider drilling oilseed rape in September. If you are taking this option, make sure you pick a variety that has a flexible drilling date and decent autumn vigour.

4) Watch out for Cercospora in sugar beet

Most sugar beet growers will have applied at least one fungicide by the end of August, if not two. Disease levels have been relatively normal so far, but BBRO started to warn about Cercospora in August, and this, along with rust, will be a key disease to keep track of in September.

Where Cercospora is a threat, then Caligula (fluopyram + prothioconazole), which can only be applied from 1 September, is a viable option. With this disease keeping intervals tight – no longer than 28 days – is crucial.

Liberator® contains flufenacet and diflufenican. Proclus® contains aclonifen. Roundup® contains glyphosate. Caligula® contains flluopyram and prothioconazole. Liberator, Proclus, Roundup and Caligula are registered trademarks of Bayer. 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 2024

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