How to… Create the best stale seed bed for black-grass control

Pre drilling it’s vital to kill as much black-grass as possible so it doesn’t germinate in the crop. This ensures the crop gets away well with minimum competition and chemicals will work more effectively.

The most important step is to understand where the black-grass seed is in the soil profile. This will depend on previous drilling and cultivation strategies. Your choice of cultivation should depend on where your black-grass seed is now and where you want it to be.

If seed is in the top few centimetres, encourage flushes by light cultivation, no more than 2cm deep, and by rolling to get a good seedbed. Black-grass is a tiny seed so likes a fine, well consolidated soil to get maximum germination.

If black-grass seed is mixed at different depths through the soil profile from more aggressive cultivation techniques eg. discing, then ploughing may be the best option for control if the soil has not been ploughed for the previous 3 years. It is vital that the plough is set up correctly. Speeds must be slow enough to get complete soil inversion, too fast and soil will be thrown rather than placed back into the furrow and this leaves cracks where black-grass seed can germinate from.

When spraying off black-grass with glyphosate pre crop drilling, chose the correct dose. Skimping and poor spray application may lead to resistance problems or poor control. Choose a flat fan nozzle with a fine droplet for maximum coverage over the tiny target. Sprayer speeds should be low, around 12kph and boom height should be 50cm off the ground to reduce drift and ensure the spray is where it needs to be rather than being blown off course.

A fine consolidated seed bed not only encourages maximum germination from black-grass, it removes clods which black-grass seed can be encased in and it allows the herbicides to work more effectively as roots are more likely to be in contact with the soil, this is the same for all root uptake herbicides, not just glyphosate.

Reduced water volumes are just as effective when spraying stale seed beds and an extra flush and subsequent spray off will make all the difference to the control in the crop.



These winter wheat crops were drilled in the same field with the same drill and cultivation method. The crop on the right has had three applications of glyphosate pre drilling, the crop on the left has had 2.

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