Article taken from Farm Contractor Magazine
Despite all the talk and advice surrounding blackgrass control over the years, the problem refuses to go away. As a consequence, Agrovista and Bayer CropScience joined forces to set up Project Lamport, a 5 year project to develop new ways of controlling blackgrass on heavy land.
Agrovista technical manager, Mark Hemmant explains the thinking behind these trials: ""Blackgrass control is getting worse and despite trials showing a 90% control from our herbicide programme we unfortunately need 98% control just to maintain the seed bank in the soil and so stand still.
Agrovista, despite being perceived as an agrochemical supply company realised that if we carry on like this many of our customers will be putting their land down to grass and grazing sheep. We have to find a way to keep our customers farming. Like most we have played around with things like increasing wheat seed rates and delayed sowing, but in many places with heavy land if you told farmers to delay sowing until the middle of October, they would tell you to go away. ""Ploughing can be very beneficial but on the other hand it can be very negative, if we plough every year we plough down the problem only to plough it back the very next year. Besides that, ploughing heavy land presents its own special problems.
Spring Sown Crops & Cover Crops
""Realistically, if you want to control blackgrass on this type of land you have to use spring sown crops. There is so much blackgrass in the weed seed bank here that we also have to consider direct drilling. Because with blackgrass you have a big germination peak in the autumn and then a small peak in the spring, if you delay sowing till the spring and control the blackgrass with glyphosate and cultivations or both, then you will get much less blackgrass in the spring. When you have a lot of blackgrass in the seed bank and you crack the seedbed then you will encourage more seed to germinate," he says.
Mark adds that he sees it as their job to help farmers to create a spring crop with a direct drill. With a blank piece of paper we set about designing a cover crop to help dry out the soil and improve the soil structure. It is also important that the cover crop is fairly open early on to allow the blackgrass to germinate and grow. Once this has happened the cover crop can then fill in the space, bulk out and keep growing to help dry out and condition the soil. ""The mixes we have come up with are a variety of black oats (Avena strigosa) mixed with either vetch or berseem clover. They are renowned for growing in cold conditions and possess deep roots, which is important. With regards to spraying off the cover crop, we tend to do a split dose of glyphosate, the first half dose a few weeks ahead of planting just to take the cover crop down and expose the blackgrass, which will be treated just before sowing.
Mr Hemmant points out that he achieved a good crop of spring wheat with hardly any blackgrass in the first two years of the trial, producing a clean crop of Willow spring wheat despite using very little chemistry Herold (diflufenican + flufenacet) at one quarter rate as well as 30g/ha of diflufenican and 1,000j/ha of pendimethalin. ""The winter wheat in the trials treated with a herbicide programme is giving 90% control which is clearly not enough to reduce the seed bank. If you add in stale seed beds and spring wheat you can bring this up to 96% with the cover crop this has given us an extra 3.6% which very nearly brings it up to 100% control.
This is all from a starting point of 2000 blackgrass plants per square metre. This year despite the fact that the spring was wet and got even wetter it has been very challenging to establish spring sown crops. However, with this system it has worked again which should give farmers the confidence to adopt this policy. ""We are now expanding the trial to look at cover crop destruction timings and nitrogen application. In one of the trials this year we destroyed the cover crop before the end of November and then gave it another dose of glyphosate immediately before sowing at the end of March. This trial is also looking to show a good overall blackgrass control," he reports.