Keep up to date with the latest advice for growers in the west

Use MagicTrap to understand flea beetle migration

It’s been a difficult season for oilseed rape, but it still has a lot of value in the rotation, if you can get past the cabbage stem flea beetle challenge.

To help our fully autonomous MagicTraps are now available. These are digitalised yellow water traps with a camera attached that provide continuously updated information on pest pressures to your phone or computer.

In oilseed rape they can be used to give an indication of when peak cabbage stem flea beetle migration is happening, which means you might be able to adapt your drilling date or management.

If you use it to wait until after peak migration, which will probably mean a later drilling date, then choosing a hybrid variety with lots of autumn vigour will help the crop get away quickly.

Earlier drilling remains an option, although later drilled crops have looked better this year than earlier drilled ones. In that case light leaf spot and standing power are probably key attributes to look for in a variety. Ultimately pick the variety to suit your drilling date.

The critical factor around establishment remains soil moisture, but, while there are no silver bullets, there are a number of other tools that can be used to help crops get away and avoid pest damage, such as the use of starter fertiliser, manures and companion cropping.

Weed control starts at harvest

If, as it is beginning to look, harvest is delayed or catching, while drilling next season’s crops moves a week or two earlier because of the risk of not getting crops established before winter weather closes in, then weed management post-harvest is likely to need to be spot on.

That could start with a harvest management desiccation spray in the previous crop if there’s an opportunity to stop grass weed seed being viable, or seedling germination at the base of the crop is starting to occur.

Other reasons for a glyphosate application pre-harvest including evening up ripening but remember not to use it on crops intended for seed or malting barley. Timing is also important – don’t go too early. You can check timing with the thumbnail test in grain – if the imprint of your nail remains in more than 75% of grains, it’s under 30% moisture and can be sprayed.

Once harvested, in an ideal world, cultivate to destroy any seedling survivors from a pre-harvest Roundup (glyphosate) application and / or encourage another flush of black-grass or Italian ryegrass. While it could be a high dormancy year for black-grass, hopefully there is another moisture to encourage a chit, and remember not all seed that comes up will be freshly shed from this season.

When spraying glyphosate in stubbles it’s key to make sure you have a big enough leaf to get the Roundup into the plant, and don’t leave too big a gap between spraying off and drilling, preferably with a low disturbance drill.

Maintain blight programmes in difficult season

Blight pressure in the west has been high, which is creating challenges both for efficacy and product availability. In southwest Wales, for example, I’m hearing reports of blight in crops.

While there haven’t been any reports, so far, of the new fungicide resistant strain 43_A1 in the country, growers have been keeping intervals tight and alternating actives and modes of action as much as possible.

That will need to continue to be the strategy, although product availability and label restrictions on the number of applications are also factors to keep an eye on.

Infinito (fluopicolide + propamocarb) has been used earlier in programmes than perhaps usual this season – a reflection on the pressures above. It can be used a maximum of four times in the programme – a total dose of 6.4 L/ha – so it may be worth considering keeping an application back for towards the end of the programme when its tuber blight activity becomes important. Equally if pressure remains high, then you need to use the best products available.

Understand your objective for cover crops

My first question to any grower about cover crops is always why? That’s not to say don’t grow one, but to make sure everyone is clear about what they are wanting to achieve.

Once you know what you’re trying to achieve, how long the crop will be in the ground, then you can tailor the species choice, seed rates, etc., to your needs.

One thing that doesn’t really change with objective, is that the earlier you can get them established the better they will be. With moisture, at least as I write, currently looking plentiful, it looks like it should be a decent year for establishing cover crops.

Another factor to be aware of, and also applies to oilseed rape, is what herbicides were applied, and when to any previous crop. The risk factors for herbicide carry over affecting cover crop species are threefold – what and when was the herbicide applied, what cultivations have been done and how much rainfall.

The shorter the interval, the less intensive the cultivations and the drier it has been, the more risk of damage. Fortunately, in this instance anyway, the rainfall has been high which should reduce risk this autumn from sulfonylurea residual effects, but do consider whether you need to do any cultivation before drilling cover crops.

Do you do your own on-farm trials?

On-farm trials can be highly insightful in understanding how different systems, varieties, products compare in your own situation.

Measuring the results of such tramline style trials is one of the things Climate FieldView excels at, making it a really useful tool for inquisitive farmers, who like testing out different things.

If you’re interested in having a free demo, please contact us via this webpage: https://cropscience.bayer.co.uk/fieldview