Is now the time for a radical re-think on black-grass?

With crops rapidly ripening (or dying with the dry weather) by the day, harvest is now not far away for many.   With this, thoughts turn to the next crop in the rotation – which one might have the best gross margin, work for the rotation, fit the markets that you have….and might work best to manage black-grass levels.

This year has certainly been a challenge with black-grass – pressure that hasn’t been seen for the last couple of years has shown many fields that now have a very challenging level of control, especially after the wet spring.

Some fields have been able to be rogued over the last few weeks and many now have the worse patches sprayed off.  However, there are some fields that I have driven past, where neither option has been taken up so far and black-grass certainly looks to be the most dominant crop in the field.

Black-grass

Where next for these fields?   Is a radical re-think required?

When thinking about the next steps for a particular field, there are 5 key things to remember about black-grass:

  1. 97% control is needed to prevent weed populations increasing
  2. 80% of plants emerge in early autumn
  3. Plants emerge from seeds within 5cm of the soil surface
  4. Average seed decline is 74% per year
  5. Aim for fewer than 5 plants per square metre to minimise yield losses

The chemical options for black-grass control are proving less and less effective, cultural options can be successful if done effectively, for example spring cropping (88% control), ploughing (69% control) or delayed autumn drilling (>31% control).

But, is this the year to take a step further – is there another solution to look at?

With more interest in incorporating livestock into the arable rotation, could a grass ley be the best solution to the problem this year?  A two-year grass ley can mean that less than 10% of seeds are likely to remain at the end of the period.  However, it is very important that this ley is managed when it is down to minimise the seed return and after it comes back into the rotation, to ensure that the seeds don’t germinate again.  Ideally, the following crop would be direct drilled into a sprayed off ley, which works well with a bean crop for example and then a winter wheat the following year.

Do you have a market for the hay/haylage from this field?  Could you work with a local sheep, beef or dairy farmer to provide extra grazing?   Have you got a local AD plant that needs an additional source?   If these are an option, there is a lot of advice and guidance available in our new guide, Livestock and the Arable Rotation – click here for the information.

Alternatively, is there new technology that you could employ on the farm? The first year of the chaff deck trial at EW Davies in north Essex, showed that black-grass seeds could be effectively consolidated in the tramlines, with a 6 fold increase in the tramlines compared to the rest of the field with less than £1/ha cost.

It could also be that the BEN approach needs to be taken, looking at blocked rotations to enhance black-grass selection, drainage needs to be planned for the wettest fields or cropping changed to lengthen rotations.

Whichever route is taken, it is important that a plan of action is put into place and the advantages and disadvantages of the options discussed with your team, agronomist or advisor, with cost implications in mind.

Best wishes for a successful harvest,

Teresa

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Teresa Meadows

Teresa Meadows

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