Article taken from the Agronomist & Arable Farmer
Autumn-sown cover cropping ahead of a spring cereal can play a key role in controlling black-grass.
Project Lamport, a five-year rotational study set up by Agrovista (supported by Bayer CropScience), aims to produce practical recommendations to control highly resistant black-grass in combinable crop rotations and is already revealing the early promise that cover crops hold.
Spring Wheat
Spring wheat drilled after an over-wintered cover crop, on the heavy land site infested with over 500 heads/m² of highly resistant black-grass, is now almost weed-free, despite a restricted herbicide programme consisting of low rates of pendimethalin, flufenacet and DFF.
That compares with a moderate infestation of black-grass in a similarly managed plot sown after a traditional overwintered stale seedbed.
The cover crop residue retained more moisture on the soil surface than overwintered stubble and is believed to be a key reason for the massive difference in black-grass control seen in the two plots.
Even though the crop was direct drilled, the fallowed soil was dry enough to shatter between the rows and that was enough to germinate black-grass. The cover crop residue and roots helped minimise soil disturbance so there was much less black-grass to be seen.
The cover crop solution used in this trial (Chlorofiltre 26) allowed black-grass to establish and be controlled within the cover crop – unlike ‘traditional’ cover crops. Chlorofiltre 26 is a blend of black oats and purple vetch, bred by French breeder Jouffray-Drillaud and available through Agrovista. It was combi-drilled at 25kg/ha on 3rd September.
The combination allowed black-grass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March. It is a vigorous mix with later growth producing lots of biomass to benefit structure and helping heavy soils to dry out a depth.
Spring cropping offers most potential when it comes to non-chemical control. Rothamsted Research shows it offers a mean of 88% control and a range from 78% to 96%. However, while it is effective establishment can be challenging on heavy soils.
Project Lamport aims to look beyond current techniques such as stale seed-beds, delayed drilling and increasing seed rates that are often impractical and have a limited effect.
Other systems in the project include September versus October-sown winter wheat/OSR rotation, fallow, hybrid rye whole-cropped for anaerobic digestion plants and cover crops left to grow through the season.
In the final year of the project all rotations will end up in winter wheat to compare the success of each system.
Hybrid rye looks to be a strong contender. However, relatively few growers have access to AD plants, though ensiling rye on mixed farms might be an attractive alternative.
Less profitable options
Autumn cover cropping aside, other options are likely to be less profitable and may not offer sustainable levels of control. That includes the winter wheat/OSR rotation, the bedrock of many arable systems.
In the past three seasons of Agrovista trials at Lamport, control in winter wheat has ranged from 45% in 2012 to 95% this season, despite two glyphosate sprays applied pre-drilling and very robust stacked pre- and post-emergence herbicide applications. Control still fell short of the 98% needed to reduce the seed bank.
Spray programmes are almost completely dependent on the weather, therefore something different must be done in the rotation to control black-grass in winter wheat. Currently, cover cropping ahead of spring wheat looks to be particularly promising.
Project Lamport
Cover Crop / Spring Wheat – Establishment and Early Management
Autumn-sown cover cropping ahead of a spring cereal can play a key role in controlling black-grass.
Project Lamport, a five-year rotational study set up by Agrovista (supported by Bayer CropScience), aims to produce practical recommendations to control highly resistant black-grass in combinable crop rotations and is already revealing the early promise that cover crops hold.
Spring Wheat
Spring wheat drilled after an over-wintered cover crop, on the heavy land site infested with over 500 heads/m² of highly resistant black-grass, is now almost weed-free, despite a restricted herbicide programme consisting of low rates of pendimethalin, flufenacet and DFF.
That compares with a moderate infestation of black-grass in a similarly managed plot sown after a traditional overwintered stale seedbed.
The cover crop residue retained more moisture on the soil surface than overwintered stubble and is believed to be a key reason for the massive difference in black-grass control seen in the two plots.
Even though the crop was direct drilled, the fallowed soil was dry enough to shatter between the rows and that was enough to germinate black-grass. The cover crop residue and roots helped minimise soil disturbance so there was much less black-grass to be seen.
The cover crop solution used in this trial (Chlorofiltre 26) allowed black-grass to establish and be controlled within the cover crop – unlike ‘traditional’ cover crops. Chlorofiltre 26 is a blend of black oats and purple vetch, bred by French breeder Jouffray-Drillaud and available through Agrovista. It was combi-drilled at 25kg/ha on 3rd September.
The combination allowed black-grass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March. It is a vigorous mix with later growth producing lots of biomass to benefit structure and helping heavy soils to dry out a depth.
Spring cropping offers most potential when it comes to non-chemical control. Rothamsted Research shows it offers a mean of 88% control and a range from 78% to 96%. However, while it is effective establishment can be challenging on heavy soils.
Project Lamport aims to look beyond current techniques such as stale seed-beds, delayed drilling and increasing seed rates that are often impractical and have a limited effect.
Other systems in the project include September versus October-sown winter wheat/OSR rotation, fallow, hybrid rye whole-cropped for anaerobic digestion plants and cover crops left to grow through the season.
In the final year of the project all rotations will end up in winter wheat to compare the success of each system.
Hybrid rye looks to be a strong contender. However, relatively few growers have access to AD plants, though ensiling rye on mixed farms might be an attractive alternative.
Less profitable options
Autumn cover cropping aside, other options are likely to be less profitable and may not offer sustainable levels of control. That includes the winter wheat/OSR rotation, the bedrock of many arable systems.
In the past three seasons of Agrovista trials at Lamport, control in winter wheat has ranged from 45% in 2012 to 95% this season, despite two glyphosate sprays applied pre-drilling and very robust stacked pre- and post-emergence herbicide applications. Control still fell short of the 98% needed to reduce the seed bank.
Spray programmes are almost completely dependent on the weather, therefore something different must be done in the rotation to control black-grass in winter wheat. Currently, cover cropping ahead of spring wheat looks to be particularly promising.
Project Lamport
14 different rotational systems set within a high indigenous black-grass population.
Incorporates winter and spring cropping, autumn cover crops / spring wheat rotations, traditionl fallows, hybrid rye for AD plants, winter wheat / OSR rotation and later drilling of winter wheat.
All rotations will end up in winter wheat in final year.
Success will be based both on final black-grass control and economic return.
Cover Crop / Spring Wheat – Establishment and Early Management
June 2013 ploughed
July pressed
August rolled
3rd September Chlorofiltre 26 cover crop combi-drilled 25kg/ha
4th September – Cambridge rolled
1st March 2014 – glyphosate (2 litres/ha Clinic Ace) + adjuvant
13th March – glyphosate (as above)
17th March – direct drilled wheat (KWS Willow) at 500 seed/m²
18th March – rolled
18th March – Stomp Aqua (pendimethalin) 1.75 litres/ha + Herold (DFF + flufenacet) 0.15litres/ha + Grounded (adjvant) 0.2 litres/ha