Article taken from the Farmers Guide
An autumn –sown cover crop ahead of a spring cereal could provide a significant key to the control of black-grass.
This is the early finding from Project Lamport, a five-year rotational study by Agrovista, supported by Bayer CropScience.
Set up only last autumn with the aim of producing practical recommendations for the control of highly resistant black-grass in combinable crop rotations, the project is already pointing to the promise that cover crops might hold.
On the heavy land site in Northamptonshire infested with more than 500 heads per square metre of highly resistant black-grass, spring wheat drilled after an over-wintered cover crop is almost free of the weed, despite only a restricted herbicide programme comprising low rates of pendimethalin, flufenacet and diflufenican.
That compares with a “moderate” infestation in a similarly managed plot sown after a traditional overwintered stale seedbed.
Agrovista technical manager Mark Hemmant points out that the cover crop residue retained more moisture on the soil surface than the overwintered stubble. This, he believes, is a key reason for the “massive” difference in black-grass control seen between the two plots.
He says: “Even though the crop was direct-drilled, the fallow soil was dry enough to shatter between the rows – that was enough for black-grass to germinate.
“The cover crop residue and roots also helped minimise soil disturbance, and there was much less black-grass to be seen.”
Unlike ‘traditional’ cover crops, the particular mixture used in this trial allowed black-grass to establish and be controlled within it, he adds. Called Chlorofiltre 26, it is a blend of 65 per cent black oats and 35 per cent purple vetch, bred by French breeder Joufray-Drillaud and available from Agrovista at about £50/ha.
Mark says: “The combination allowed black-grass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March.
“We know that spring cropping offers the most potential when it comes to non-chemical control,” says Mark. “Rothamsted Research’s publications show it offers a mean of 88 per cent control in a range from 78 to 96 per cent.
“However, while it is effective, establishment can be challenging on heavy soils.”
Cover crops also benefit soil structure, allowing direct drilling of spring wheat. “The last thing we want to do is to create a seedbed for black-grass in the spring – this is where a lot of growers go wrong,” Mark states.
Project Lamport aims to look beyond current techniques such as stale seedbeds, delayed drilling and increased seed rates, which are often impractical and have a limited effect. This, says Mark, is “vital” to prolong the activity of Atlantis and to contribute to the stewardship of other herbicides while maintaining profitable crop production – including winter wheat.
Other systems within the project include September – versus October-sown winter wheat/oilseed rape rotation, fallow, hybrid rye whole-cropped for anaerobic digestion (AD) 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 establish how successful the different systems have been.
Hybrid rye would appear to be a strong contender, says Mark. “However, relatively few growers have access to AD plants, although ensiling rye on mixed farms might be an attractive alternative.”
Apart from autumn cover cropping, other options are likely to be less profitable and may not offer sustainable levels of control. These include the winter wheat/ oilseed rape rotation which forms the bedrock of many arable systems, Mark states.
Over the past three years in Agrovista trials at Lamport, control in winter wheat has ranged from 45 per cent in 2012 to 95 per cent 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 per cent needed to reduce the seed bank, Mark points out.
“These spray programmes are almost completely dependent on the weather.
“We can’t rely on chemicals to control black-grass in winter wheat any longer. We have to do something different in the rotation. And, currently, cover cropping ahead of spring wheat looks to be particularly promising,” he ends.
An autumn –sown cover crop ahead of a spring cereal could provide a significant key to the control of black-grass.
This is the early finding from Project Lamport, a five-year rotational study by Agrovista, supported by Bayer CropScience.
Set up only last autumn with the aim of producing practical recommendations for the control of highly resistant black-grass in combinable crop rotations, the project is already pointing to the promise that cover crops might hold.
On the heavy land site in Northamptonshire infested with more than 500 heads per square metre of highly resistant black-grass, spring wheat drilled after an over-wintered cover crop is almost free of the weed, despite only a restricted herbicide programme comprising low rates of pendimethalin, flufenacet and diflufenican.
That compares with a “moderate” infestation in a similarly managed plot sown after a traditional overwintered stale seedbed.
Agrovista technical manager Mark Hemmant points out that the cover crop residue retained more moisture on the soil surface than the overwintered stubble. This, he believes, is a key reason for the “massive” difference in black-grass control seen between the two plots.
He says: “Even though the crop was direct-drilled, the fallow soil was dry enough to shatter between the rows – that was enough for black-grass to germinate.
“The cover crop residue and roots also helped minimise soil disturbance, and there was much less black-grass to be seen.”
Unlike ‘traditional’ cover crops, the particular mixture used in this trial allowed black-grass to establish and be controlled within it, he adds. Called Chlorofiltre 26, it is a blend of 65 per cent black oats and 35 per cent purple vetch, bred by French breeder Joufray-Drillaud and available from Agrovista at about £50/ha.
Mark says: “The combination allowed black-grass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March.
“We know that spring cropping offers the most potential when it comes to non-chemical control,” says Mark. “Rothamsted Research’s publications show it offers a mean of 88 per cent control in a range from 78 to 96 per cent.
“However, while it is effective, establishment can be challenging on heavy soils.”
Cover crops also benefit soil structure, allowing direct drilling of spring wheat. “The last thing we want to do is to create a seedbed for black-grass in the spring – this is where a lot of growers go wrong,” Mark states.
Project Lamport aims to look beyond current techniques such as stale seedbeds, delayed drilling and increased seed rates, which are often impractical and have a limited effect. This, says Mark, is “vital” to prolong the activity of Atlantis and to contribute to the stewardship of other herbicides while maintaining profitable crop production – including winter wheat.
Other systems within the project include September – versus October-sown winter wheat/oilseed rape rotation, fallow, hybrid rye whole-cropped for anaerobic digestion (AD) 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 establish how successful the different systems have been.
Hybrid rye would appear to be a strong contender, says Mark. “However, relatively few growers have access to AD plants, although ensiling rye on mixed farms might be an attractive alternative.”
Apart from autumn cover cropping, other options are likely to be less profitable and may not offer sustainable levels of control. These include the winter wheat/ oilseed rape rotation which forms the bedrock of many arable systems, Mark states.
Over the past three years in Agrovista trials at Lamport, control in winter wheat has ranged from 45 per cent in 2012 to 95 per cent 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 per cent needed to reduce the seed bank, Mark points out.
“These spray programmes are almost completely dependent on the weather.
“We can’t rely on chemicals to control black-grass in winter wheat any longer. We have to do something different in the rotation. And, currently, cover cropping ahead of spring wheat looks to be particularly promising,” he ends.