Latest agronomy advice for northern growers

Crop Progress

While winter barley harvest was a little stop-start in the north, most growers flew through the winter wheat, finishing well before any rain in mid-late August. As we approach the August bank holiday only some spring beans are left to do, in a mostly positive harvest, apart from the omnipresent fire risk.

Yields of winter wheat were generally good – above average on many farms. Winter barley was a bit disappointing for a few people, while oilseed rape was better than expected.

Tom’s agronomy tips for September

1. Quick developing oilseed rape varieties key in September

Unlike further south, there was some rain in early August in parts of the north, which allowed some growers to drill some oilseed rape. That’s emerged so time will tell if it avoided cabbage stem flea beetle attack.

Some areas then caught thunderstorms in the middle of August potentially allowing more to be drilled, and with some more rain forecast in the lead up to the bank holiday, again there might have been an opportunity.

For those who haven’t been lucky with the rain, or still have more to drill, there is still an opportunity to establish oilseed rape in September. The decent price and lack of options for break crops will almost certainly encourage some to keep going until mid-September once there is moisture in the soil.

In September, other than moisture availability, a key requirement is picking a quick developing variety to get it up and away to avoid cabbage stem flea beetle attacks and to get a decent sized canopy by winter.

Hybrid varieties such as DK Exstar fit that bill as a good all-round variety, with which you can be fairly flexible with drilling date.

Conserving available moisture will also be important obviously, so disturbing the soil as little as possible when drilling is key, while using starter fertilisers or organic manures, like chicken muck, can also act as rocket fuel to get crops away quickly.

2. Take advantage of stale seedbeds for weed control ahead of cereals

Grassweed dormancy, at least black-grass dormancy is forecast by ADAS to be low this season following dry, warm weather during seed maturation. That should mean with moisture they germinate quickly.

That could mean you don’t need to do much, if any, cultivation to get a decent flush to spray off ahead of drilling. Avoiding cultivation will obviously help retain any moisture in seedbeds.

The exception is perhaps with bromes, which took a lot of people by surprise last season, where a little bit of cultivation to bury sterile and great brome seeds will encourage them to break dormancy and germinate. Meadow, soft and rye bromes should be left on the surface for a month following harvest before again lightly cultivating to get them to chit.

The early harvest should allow for more time to create stale seedbeds this season. That might allow for time for two applications of Roundup (glyphosate) pre-drilling – the maximum number you should use to follow the Weed Resistance Action Group guidelines to minimise the risk of resistance developing to glyphosate. But only use two where grassweed pressure warrants it.

It's also important to use the correct dose of glyphosate. For grassweeds at the 2-3 leaf stage, use a minimum of 540g a.i./ha, while once they start to tiller a minimum of 720g a.i/ha should be applied. If two applications are used, ensure you use some mechanical cultivation to take out any survivors between the applications, as necessary.

Concentrate on spray application technique. Glyphosate is the best weed killer we have, so maximise its efficacy by not going too quickly – 10-12 km/h is plenty fast enough – which will help give a steady boom at 50cm above the target, and using the correct nozzles to hit the target with the spray, while being wary of drift.

3. Look out for new option for weed control in winter barley

With winter barley drilling likely to start in September, look out for a new option for pre-emergence weed control in winter barley in Proclus (aclonifen).

Used in conjunction with 0.6 L/ha Liberator, the mix will give a good uplift in control of black-grass and Italian ryegrass over what you would expect from Liberator alone.

In winter barley the maximum dose is 1.0 L/ha compared with the 1.4 L/ha you can use in winter wheat, and there is no support for any additional tank mix partners. Make sure crops are drilled to a depth of at least 32mm.

4. Delay winter wheat drilling until October where grassweed pressure is high

While the temptation might be to drill winter wheat in September, if you have significant grassweed pressure then delaying as long as possible, not only gives time for stale seedbeds, but also likely reduces the amount that will come up in the crop.

If you are drilling in September, choose fields with a lower grassweed burden.

Where there are grassweeds to control, Liberator + Proclus is a good option, while for annual meadowgrass or much lower grassweed threats, Alternator Met or Octavian Met (flufenacet + diflufenican + metribuzin) could also be considered. Up until the end of September these metribuzin products can be used at 1.0 L/ha.

5. Monitor for Cercospora in sugar beet

Sugar beet crops have struggled with the dry, hot summer weather, although disease levels have been mostly low. However, BBRO’s Cercospora alerts signalled a high risk from the disease for the northern parts of the sugar beet region coming into the August bank holiday so keep monitoring.

Helpfully, Caligula (fluopyram + prothioconazole) has recently been given approval for the control of Cercospora and other sugar beet diseases. In trials it has given unrivalled protection against Cercospora.

The approval is for one spray from 1 September, and we recommend using at 1.0 L/ha.

6. Tuber blight could pose threat

Like sugar beet, potato crops have not had the easiest growing season, and initial yield digs have shown that tubers are quite small, perhaps not surprisingly in some crops.

Blight pressure has been low, but in warm temperatures and with more moisture that could change. At the end of the season, tuber blight becomes an equal concern to foliar blight, which is where the dual activity from Infinito (fluopicolide + propamocarb) fits well.