Article taken from the Anglia Farmer
Wheat growers could soon be growing autumn-established cover crops to help ward off the menace of resistant black-grass that threatens to engulf their crops.
The finding is one of the first to come out of Project Lamport, an innovative five-year rotational trial set up in Northamptonshire last autumn by Agrovista and supported by Bayer CropScience to develop new practical recommendations to control the weed.
The heavy land site at Lamport contains a background infestation of over 500 heads/sq m of highly resistant black-grass. But spring-sown wheat drilled after an autumn-sown cover crop containing black oats and purple vetch was almost free of the weed, despite a limited herbicide programme.
The cover crop was sprayed twice with glyphosate in March before the wheat was drilled. But the wheat received only low doses of pendimethalin, flufenacet and DFF as per label recommendations.
A similarly managed spring wheat plot sown after a traditional overwintered stale seed-bed that had been sprayed four times with glyphosate still contained a moderate black-grass infestation, says Agrovista technical manager Mark Hemmant.
The cover crop residue retained more moisture on the soil surface than the overwintered stale seed-bed. He believes this is a key reason for the “massive difference” in blackgrass control seen in the two spring wheat plots.
“Even though the crop was direct drilled the fallowed soil was dry enough to shatter between the rows. That was enough for stimulate blackgrass to germinate. The cover crop residue and roots helped minimise soil disturbance and there was much less blackgrass to be seen.”
The particular cover crop used in this trial also allowed blackgrass to establish and be controlled within the cover crop – unlike ‘traditional’ cover crops, he adds. Called Chlorofiltre 26, it is a blend of black oats (65%) and purple vetch (35%) bred from French breeder Jouffray-Drillaud and available through Agrovista at about £50/ha. It was combi-drilled at 25kg/ha on 3 September.
“The combination allowed blackgrass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March. Its more vigorous, later growth produced lots of biomass to benefit the soil,” says Mr Hemmant.
The main reason for including cover crops is to make spring cropping more reliable by helping heavy soils to dry out at depth. “We know spring cropping offers the most potential when it comes to non-chemical methods. However, it is challenging on heavy soils,” he explains.
“Cover crops also provide soil structure benefits to allow direct drilling of spring wheat. The last thing we want is to create a seed-bed for blackgrass in the spring – it’s where a lot of people go wrong.”
The aim of Project Lamport is to develop new practical recommendations that go beyond current techniques such as stale seed-beds, delayed drilling and increasing seed rates that are often impractical and have a limited effect.
This is vital to prolong the activity of Atlantis and contribute to other herbicide stewardship while maintaining profitable crop production, including winter wheat, says Mr Hemmant.
In all, there are seven rotational systems in the project which include fallow, hybrid rye whole-cropped for anaerobic digestion and cover crops left to grow through the season as well as autumn sown ones followed by spring wheat.
After five years these will be compared with a rotation of September- and October-sown winter wheat plus OSR, which, as on many arable farms, is becoming unsustainable at Lamport, despite being treated with glyphosate twice pre-drilling and very comprehensive pre- and post-emergence herbicide applications, says Mr Hemmant.
“Growers are asking if we are going to see £150/ha blackgrass programmes in winter wheat. The answer is yes. But can we guarantee they will work? No, we can’t, so we have to do something different in the rotation.
“Currently, cover cropping ahead of spring wheat looks to be particularly promising.”
Wheat growers could soon be growing autumn-established cover crops to help ward off the menace of resistant black-grass that threatens to engulf their crops.
The finding is one of the first to come out of Project Lamport, an innovative five-year rotational trial set up in Northamptonshire last autumn by Agrovista and supported by Bayer CropScience to develop new practical recommendations to control the weed.
The heavy land site at Lamport contains a background infestation of over 500 heads/sq m of highly resistant black-grass. But spring-sown wheat drilled after an autumn-sown cover crop containing black oats and purple vetch was almost free of the weed, despite a limited herbicide programme.
The cover crop was sprayed twice with glyphosate in March before the wheat was drilled. But the wheat received only low doses of pendimethalin, flufenacet and DFF as per label recommendations.
A similarly managed spring wheat plot sown after a traditional overwintered stale seed-bed that had been sprayed four times with glyphosate still contained a moderate black-grass infestation, says Agrovista technical manager Mark Hemmant.
The cover crop residue retained more moisture on the soil surface than the overwintered stale seed-bed. He believes this is a key reason for the “massive difference” in blackgrass control seen in the two spring wheat plots.
“Even though the crop was direct drilled the fallowed soil was dry enough to shatter between the rows. That was enough for stimulate blackgrass to germinate. The cover crop residue and roots helped minimise soil disturbance and there was much less blackgrass to be seen.”
The particular cover crop used in this trial also allowed blackgrass to establish and be controlled within the cover crop – unlike ‘traditional’ cover crops, he adds. Called Chlorofiltre 26, it is a blend of black oats (65%) and purple vetch (35%) bred from French breeder Jouffray-Drillaud and available through Agrovista at about £50/ha. It was combi-drilled at 25kg/ha on 3 September.
“The combination allowed blackgrass to germinate through the autumn and to be controlled effectively by glyphosate when it was sprayed off in March. Its more vigorous, later growth produced lots of biomass to benefit the soil,” says Mr Hemmant.
The main reason for including cover crops is to make spring cropping more reliable by helping heavy soils to dry out at depth. “We know spring cropping offers the most potential when it comes to non-chemical methods. However, it is challenging on heavy soils,” he explains.
“Cover crops also provide soil structure benefits to allow direct drilling of spring wheat. The last thing we want is to create a seed-bed for blackgrass in the spring – it’s where a lot of people go wrong.”
The aim of Project Lamport is to develop new practical recommendations that go beyond current techniques such as stale seed-beds, delayed drilling and increasing seed rates that are often impractical and have a limited effect.
This is vital to prolong the activity of Atlantis and contribute to other herbicide stewardship while maintaining profitable crop production, including winter wheat, says Mr Hemmant.
In all, there are seven rotational systems in the project which include fallow, hybrid rye whole-cropped for anaerobic digestion and cover crops left to grow through the season as well as autumn sown ones followed by spring wheat.
After five years these will be compared with a rotation of September- and October-sown winter wheat plus OSR, which, as on many arable farms, is becoming unsustainable at Lamport, despite being treated with glyphosate twice pre-drilling and very comprehensive pre- and post-emergence herbicide applications, says Mr Hemmant.
“Growers are asking if we are going to see £150/ha blackgrass programmes in winter wheat. The answer is yes. But can we guarantee they will work? No, we can’t, so we have to do something different in the rotation.
“Currently, cover cropping ahead of spring wheat looks to be particularly promising.”