In August, Bayer’s team of Crop Doctor experts will visit two farms to discuss how to get next season’s crops off to the best start.
At Russell McKenzie’s farm in Bedfordshire, cultivations expert Philip Wright will be giving advice about how to best prepare seedbeds and drilling strategies to ensure good establishment without kicking black-grass into life, while Bayer’s Darren Adkins will cover handling and drilling treated seed, and the benefits of using seed treatments for early pest and disease control, and how it helps ease workload in a busy time.
At the second farm, David Felce and Colin Lloyd of Agrii will provide tips on setting up sprayers effectively for pre-emergence spraying, and will discuss control of black-grass through the rotation.
To get involved and ask questions of our Crop Doctor experts, tweet the @Bayer4CropsUK account with the hashtag #CropDoctor, or email email@example.com. Coverage of the day will be through the @Bayer4CropsUK and @DrBlackgrass twitter accounts, and via Farmers Weekly.
But before then, combines are already rolling across the country and growers will be making crucial decisions about stubble management that can have a big impact on weed numbers in the subsequent crop.
In the period between harvest and drilling, the aim is not only to produce a good quality seedbed but also reduce viable weed seed numbers in the germination zone down to low enough levels for selective herbicides to finish the job. It is also a chance to sort out any compaction or drainage issues in the soil. How to achieve this is more complicated – weather conditions, weed spectrum and available machinery all affect what happens on each farm. Here’s a list of some things to consider:
- The combine is the first cultivation: Make sure straw has a good consistent chop and spread behind the combine so that cultivation isn’t needed to deal with excessive crop residues.
- Does the soil need cultivating? If soil is well-structured and well-aggregated following harvest, deep cultivation is probably unnecessary. On the other hand, if there is compaction at depth it needs to be sorted out for the good of the next crop. Even on soils in good condition shallow cultivation may be needed to produce a seedbed and help with pre-drilling control of grass weeds. In this situation, keeping things shallow – 3 inches at most is very important otherwise too much weed seed is mixed in the soil profile.
- Can direct mortality destroy more black-grass seeds? Leaving fields untouched after harvest can be a very good strategy. John Cussans of NIAB-TAG has shown that in drier seasons not cultivating soil and promoting direct mortality gets better results than stimulating germination and spraying off after harvest. However, to make things complicated, in wetter years cultivating and burying seed is more effective at reducing black-grass numbers.
For more information please read 'weed control - Devil's in the detail'
Direct mortality depends on weather conditions so having flexibility is essential to use it as a management tool. A further complication is from other grass-weeds – particularly bromes. Sterile and Great Brome germinate in the dark and so cultivation soon after harvest will encourage germination. However Meadow, Rye & Soft brome require light to ripen on the soil surface before they will germinate and so cultivations need to be delayed for one month if trying to stimulate germination prior to crop establishment. Choosing the best approach has to be done field-by-field looking at weed spectrum and soil condition.
- Disturbance should be lower at drilling than previous operations: Black-grass thrives in disturbed soil – so the drill pass should be as gentle as possible to minimise further soil disturbance. Black-grass stimulated to emerge by earlier operations can always be followed up with glyphosate prior to driling.
- Be ready to compromise: There is always a balance to be struck between seedbed quality and weed control. And, there is always a risk that solving one problem may create another, for example subsoiling will deal with compaction but may result in newly-shed black-grass seed being mixed through the soil profile. As long as you are aware of the downsides, you can manage the risk.
The Crop Doctor tour takes place on 23 August but in the meantime, look out for videos
from soil and cultivation specialist Philip Wright about the pros and cons of different types of drills to establish winter cereals. And, for anyone with the time to get ahead of the game, check out videos from 2016 by spray application specialist David Felce – he gives a run-down of the how to set up the sprayer for autumn.
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1. Try to disturb less soil at drilling than during previous operations
1. Target drilling of winter wheat after the main flush of black-grass, which is typically from early September to the middle of October, depending on soil moisture.
1. As black-grass seed left on the surface suffers from predation and direct mortality, consider leaving fields alone after harvest, particularly if conditions are dry and sunny.