Independent agronomist Stewart Sinclair of Hampshire Arable Systems was faced with a lawn of black-grass in some of his oilseed rape last autumn, but by getting the application of Kerb Flo and Laser spot on, he controlled this weed successfully and produced a 5 plus tonne/ha crop with high oil content and high returns.
Stewart advised the use of the residual herbicide Kerb Flo with the contact herbicide Laser in winter oilseed rape crops in November last year and was very pleased with the outcome. "This mix was used in those fields where the black-grass problem was so intense that it looked like a lawn! Kerb Flo was really the only option, but I was aware of the need to get everything just right in order to get the good results I needed. And I would say that we got the Kerb Flo and Laser spot on last year."
He explains how to get the Kerb application right. "Starting with cultivation, it is important to establish the rape crop well but do not too cultivate too deeply. We don’t want any weed seed to come from deeper than 5cms, as the black-grass would then be germinating below the Kerb Flo barrier layer. Non-inversion tillage is best. If you do plough, the addition of a contact herbicide Laser helps. Last autumn Kerb Flo and Laser was applied in late November when the black-grass was still small, no more than 3 to 4 leaves, and the conditions cold and the soil moist. For best performance, soil temperatures need to be low - around 10ºC at 30cms and falling. Cold temperatures mean longer persistence. Good soil moisture is needed to help the herbicide distribute evenly in the top few cms of the soil and Dow AgroSciences report regularly on soil moisture and temperatures which is helpful."
"The Kerb Flo spray window was in the week just before the winter closed in. Any later and I would have missed my chance. If you are hoping for weed control consistency after the winter, you could struggle - the crop is usually stressed, the weeds are tillering and the conditions are warming up," he says.
Stewart intends to advise the use of Kerb Flo where necessary this year. "The weed control programme in rape usually starts with a metazachlor + quinmerac pre-emergence. This gives us a good start and brings some black-grass activity as well as good broad-leaved weed control. With some herbicide supply problems this autumn, we have used this in most of our fields, but have had to modify our usual approach and use metazachlor + clomazone instead in some fields."
Stewart Sinclair plans to use a range of herbicide choices across the crop rotation for black-grass. "Although we don’t have severe weed resistance, we don’t want to encourage it either. Black-grass is a problem that you can’t ignore and needs to be controlled across the rotation with different chemistries. You need to plan well in advance what you are going to use in different crops. However good it can be, you can’t rely on Atlantis in wheat alone, but need to integrate it and other herbicides into a medium term plan and indeed protect this and other chemistry for the future."
Stewart urges his growers to adopt good Stewardship practices. "Care must be taken to avoid any risk of contamination to water and to get application just right. Buffer strips are already in place and we always take care to avoid spraying crops that are water logged or saturated or if heavy rain is forecasted. Kerb Flo is such a vital ingredient and we all have a responsibility to make sure that its future is protected and that no water contamination occurs. I can’t imagine how we could grow oilseed rape without it."
