Article taken from Arable Farming Magazine
Dedicated R&D sites are driving new thinking on controlling this most challenging of weeds. Heather Briggs and Teresa Rush report on some of the latest developments.
At Agrovista’a Project Lamport black grass site, in Northampton shire, the focus on achieving successful spring cropping on heavy land in order to achieve food control of black grass. Agrovista technical manager Mr Mark Hemmant says “We need to find a way to reliably grow profitable crops. Where there is black grass, the best way is going to be spring cropping and we are seeking ways to do this on heavy soils.” Work at the site is almost entirely focused on cultural control, taking in cover crops, direct drilling for minimal soil disturbance and spring cropping. With heavy soils one of the main challenges is to dry ground out sufficiently to enable spring drilling, says Mr Hemmant. “The traditional approach is to cover the ground early (after harvest) but that is when the black grass comes up. “What we are about is asking can we have a cover crop to sow at a low seed rate to allow the black grass to germinate but also to have a sufficient growth and low temperatures growth to dry out the ground.”
“We then also need to minimise soil disturbance when establishing the subsequent. The cover crop should allow you to direct drill and put in soil structure.” The work at Lamport is currently in its second year. The black grass population at the start of the project was in the region of 2000 heads/sq m, with levels of resistance to key grass weed herbicides. The best level of black grass control achieved at the site with a typical pre and post emergence herbicide programme was 75%. Ahead of the current project the site was ploughed (for the first time in 10 years) after a failed oilseed rape crop, which had been sprayed off with glyphosate. “Our intention is to leave nature to control whats in the soil and minimise black grass seed return to the soil surface” Says Mr Hemmant. Results from the site are already highlighting the potential for new thinking on black grass control.
Hybrid rye grown as a biomass crop for anaerobic digestion (AD) plants and removed in early July competes well with black grass. More suitable for a heavy land site than maize, yield last year was 48 tonnes/hectare at 35% dry matter, generating an income of £1500/ha.
Recently completed work by WRAP confirms black grass seed does not survive the AD process, as long as it remains in the digester for five days at 37.5degC. Why not wheat? Wheat would reach the 35% DM target for cutting much later, by which time black grass would have set seed. Two years of autumn sown chlorofiltre 26 (black oat +vetch) cover crops, then two applications of glyphosate followed by KWS Willow spring wheat planted in Mid – March at 500 seeds / sq m (to ensure a competitive crop), drilled with a Great Plains V300 drill (to minimise soil disturbance) and receiving a pre emergence application of Herold (flufenacet + pendimethalin) reduced black grass head numbers to just 2/sq m.
One year fallow with x6 stale seedbeds followed by winter wheat with a full herbicide programme – black grass head count this season is 40 heads/sq m. “This approach is less profitable than the spring wheat system. You are better off with two spring wheats if you do it right” says Mr Hemmant. Flexibility with cover crop timing? Planting a black oat + vetch cover crop in July and destroying it in November still had a positive effect in terms of reduced black grass numbers in a spring wheat crop drilled the following March. “It means we have got flexibility in terms of when we destroy the cover crop. You can destroy your cover crop earlier.”
Dedicated R&D sites are driving new thinking on controlling this most challenging of weeds. Heather Briggs and Teresa Rush report on some of the latest developments.
At Agrovista’a Project Lamport black grass site, in Northampton shire, the focus on achieving successful spring cropping on heavy land in order to achieve food control of black grass. Agrovista technical manager Mr Mark Hemmant says “We need to find a way to reliably grow profitable crops. Where there is black grass, the best way is going to be spring cropping and we are seeking ways to do this on heavy soils.” Work at the site is almost entirely focused on cultural control, taking in cover crops, direct drilling for minimal soil disturbance and spring cropping. With heavy soils one of the main challenges is to dry ground out sufficiently to enable spring drilling, says Mr Hemmant. “The traditional approach is to cover the ground early (after harvest) but that is when the black grass comes up. “What we are about is asking can we have a cover crop to sow at a low seed rate to allow the black grass to germinate but also to have a sufficient growth and low temperatures growth to dry out the ground.”
“We then also need to minimise soil disturbance when establishing the subsequent. The cover crop should allow you to direct drill and put in soil structure.” The work at Lamport is currently in its second year. The black grass population at the start of the project was in the region of 2000 heads/sq m, with levels of resistance to key grass weed herbicides. The best level of black grass control achieved at the site with a typical pre and post emergence herbicide programme was 75%. Ahead of the current project the site was ploughed (for the first time in 10 years) after a failed oilseed rape crop, which had been sprayed off with glyphosate. “Our intention is to leave nature to control whats in the soil and minimise black grass seed return to the soil surface” Says Mr Hemmant. Results from the site are already highlighting the potential for new thinking on black grass control.
Hybrid rye grown as a biomass crop for anaerobic digestion (AD) plants and removed in early July competes well with black grass. More suitable for a heavy land site than maize, yield last year was 48 tonnes/hectare at 35% dry matter, generating an income of £1500/ha.
Recently completed work by WRAP confirms black grass seed does not survive the AD process, as long as it remains in the digester for five days at 37.5degC. Why not wheat? Wheat would reach the 35% DM target for cutting much later, by which time black grass would have set seed. Two years of autumn sown chlorofiltre 26 (black oat +vetch) cover crops, then two applications of glyphosate followed by KWS Willow spring wheat planted in Mid – March at 500 seeds / sq m (to ensure a competitive crop), drilled with a Great Plains V300 drill (to minimise soil disturbance) and receiving a pre emergence application of Herold (flufenacet + pendimethalin) reduced black grass head numbers to just 2/sq m.
One year fallow with x6 stale seedbeds followed by winter wheat with a full herbicide programme – black grass head count this season is 40 heads/sq m. “This approach is less profitable than the spring wheat system. You are better off with two spring wheats if you do it right” says Mr Hemmant. Flexibility with cover crop timing? Planting a black oat + vetch cover crop in July and destroying it in November still had a positive effect in terms of reduced black grass numbers in a spring wheat crop drilled the following March. “It means we have got flexibility in terms of when we destroy the cover crop. You can destroy your cover crop earlier.”