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Crop Advice & Expertise

Five agronomy tips for the west as the new seasons begins

Gareth Bubb outlines five tips for cereals and oilseed rape crops as cereal drilling progresses this October.

Crop Progress

Growers have been cracking on with winter cereals drilling in the west, with 40% already drilled by the third week in September – a far cry from last year. Oilseed rape establishment is perhaps 10% down on average in the region, with a larger proportion drilled earlier than previously.  Potato crops are being harvested with variable yields.

 

Gareth’s agronomy tips for October

1. Watch out for Phoma and light leaf spot in oilseed rape

Early sown oilseed rape was established into generally good conditions and is up and away. Cabbage stem flea beetle damage has been less than last season because of both earlier drilling to avoid the main migration, and more favourable conditions. Any damage seems to have been localised.

Surviving early drilled crops should have now avoided the worst of the adult damage and will have just the larvae to contend with later in the season.

Later drilled crops suffered more partly because of the dry weather in September, but rain came towards the end of the month, which should have helped it get away.

Phoma is already being seen in some of the very early drilled crops, and with the weather outlook generally being more unsettled for October, it could become an issue for some crops. The smaller later drilled crops, in particular, will be at more risk so don’t wait too long before treating these.

Phoma in the bigger, earlier drilled crops is less significant, but these crops are likely to be more at risk from light leaf spot. You can check risk from both diseases by using the free Bayer SpotCheck service.

The likelihood is that growers will only apply one fungicide in the autumn, if any at all. If that’s the case make sure it has activity against both diseases, such as with Proline (prothioconazole), rather than something with just activity against Phoma.

With one spray the recommendation is to apply 0.46 L/ha of Proline, while if you are planning two sprays the rate for the first spray is 0.32 L/ha.

 

2. Check sprayer capacity and consider contractors for weed control in cereals

Many growers started drilling wheat from mid-September. They know they shouldn’t be drilling early if they have grassweed pressures, but because of the last season they are understandably keen to get on with it.

For those that are delaying into October, it’s worth looking at your system, your planned area and how much you can drill in a day and base when to start on that. Ideally target fields with the fewest grassweed issues first, and consider getting contractors in to help with drilling, if necessary.

The same applies for pre-emergence herbicides. Don’t miss the timing because you’re busy drilling. Pre-emergence is the key herbicide timing for grassweed control once the crop is drilled.

But if you have drilled early in fields with significant grassweeds, monitor them closely as, and you won’t want to read this, you might need to consider pressing the reset button if you can’t control them adequately.

 

3. Make use of a range of active ingredients for grassweed control

Generally seedbeds have been good, and while it was dry through a lot of September which could have compromised efficacy from early applications, the rain at the end of the month should mean control is pretty good. It’s just the numbers they are dealing with will be the issue.

It makes sense to use all the actives available for black-grass and rye-grass control, but be mindful that the more actives in the tank the more risk of damage. Risk factors for damage include light, stony soils, crops just emerging at application and heavy rainfall just after application.

Bayer has two new actives available this autumn. Aclonifen as in Proclus is available for wheat and metribuzin in Alternator MET and Octavian MET are now options in wheat and barley. Depending on grassweeds, our trials have shown a 10-20% lift in control over Liberator (flufenacet + diflufenican).

 

4. Make the most of pre-emergence weed control in winter barley

In winter barley, it’s even more important to focus on pre-emergence applications as there are very few post-emergence options for grassweed control. Most of the pre-emergence options for wheat are also available in barley, apart from Proclus, but we advise avoiding mixing Liberator with Defy (prosulfocarb) as it can be a little bit warm on the crop.

 

5. Use available alerts to help understand BYDV risk

Growers are understandably feeling reluctant to use pyrethroids to control aphids transmitting barley yellow dwarf virus. But having seen so much virus yellows in beet crops, I fear with earlier sowings this year we could be in for the same with BYDV.

There are some good services available to help judge risk – whether it is Rothamsted Research’s aphid alert, which can send you suction trap alerts from Hereford, Wellesbourne or Starcross in the west or AHDB’s T-Sum calculator, so these will be worth keeping an eye on to help growers make rational decisions.