Putting the brakes on black-grass Black-grass is spreading out of its heartlands into the North and West but farmers in those regions can take heart from success stories – particularly when the response was quick and decisive. Farmers Guide speaks to two farmers who are keeping blackgrass in check. Leicestershire farmer Chris Tolley.
Chris Tolley grows winter cereals, oilseed rape and spring barley on a heavy land farm in Leicestershire that is susceptible to black-grass. “There has always been black-grass on the farm so attention to detail is essential for dealing with it,” he points out. He starts by drawing up maps
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of weed patches before harvest – these maps are the basis for all further planning of cultural and chemical controls. As importantly, Chris constantly checks results of the control throughout the season so he is better able to understand what went well and what didn’t. “Black-grass is variable across fields, often linked to soil texture. We can target a stronger pre-emergence herbicide programme on particular parts of the field. We may also come back and overspray the worst areas depending on how they are oriented in relation to the tramline. This obviously takes more time and planning but helps keep costs in check and ensures we’re not using more pesticides than necessary.”
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Mr Tolley starts by drawing up maps of weed patches before harvest and these are the basis for all further planning of cultural and chemical controls.
Delayed drilling Mr Tolley uses delayed drilling to keep control of black-grass in winter wheat but cautions against simply trying to drill as late as possible. “Crop competition and establishment cannot be underestimated. We aim to produce a good seedbed that is rolled to boost pre-em efficacy. If drilling is delayed too long, the opportunity for an autumn post-em becomes limited. “The foundation to any herbicide black-grass programme is a product containing flufenacet such as Liberator (flufenacet + diflufenican). If black-grass populations are low and other cultural control methods are practised, then this alone may suffice. Once there is an increasing level of black-grass in the field then stacking with other residual herbicides is probably needed.” Due to the challenge on his farm, Mr Tolley follows up with Atlantis (mesosulfuron + iodosulfuron) in autumn when plants are still small and actively growing. He has monitored closely and is confident it is still delivering control in the right conditions, and has the sprayer ready to go seven days a week to take advantage of any opportunity to spray.
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Farm manager Matthew Copley oversees 880ha (2,170 acres) of combinable crops at two sites in West Yorkshire and North Yorkshire. There is some black-grass at both sites and having seen the problems black-grass can cause further south, he uses robust cultural and chemical control methods. Rotation and cultivation are a vital part of Mr Copley’s approach. Typically, he ploughs prior to
winter barley to bury seed and start with clean land. In his opinion, it is difficult to deal with a large population of black-grass in barley because of the early sowing date and the lack of chemical options. He then aims for shallow cultivation in the rest of the rotation – usually two wheats and oilseed rape ideally cultivating to 3in to produce a good tilth for the crop but not moving black-grass seed around the soil profile. Rotational ploughing isn’t the complete answer though, so in some particularly troublesome areas he is moving to spring barley. “Winter barley wasn’t too bad last time but there was some black-grass afterwards,” he notes. In wheat, as well as preemergence sprays he uses Atlantis post-emergence. “I think Atlantis is like a cat with nine lives; you can only use it so many times, so we only spray when it’s essential to. To back this up, if we use Atlantis any survivors are rogued or get glyphosate as this should reduce resistance build-up. Even with 90 per cent control there will be survivors that shouldn’t be allowed to shed seed.” Second wheats are also a highrisk crop for black-grass so they are all late drilled. He focuses the late drilling effort on second wheats so he is flexible enough to respond to conditions to drill crops at the right time. Treating drilling then the pre-em spray as one operation is essential. “If you can’t spray don’t drill; conditions need to be right for spraying and for herbicides. That’s the problem with pre-ems – too wet and they can wash away, too dry and they are not effective. Last autumn, things were just right.” ■
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