Don’t get caught out drilling your oilseed rape. The window between completing the wheat harvest and drilling oilseed rape is narrow at the best of times. In recent years poor weather conditions have made this operation even more challenging. Ploughing can be unnecessary and time consuming; seedbed preparation can be difficult to encourage crop germination and subsequent herbicide activity. Many oilseed rape crops are drilled with a single pass cultivation, for example, on heavier land a seeder box on a subsoiler, according to Dow AgroSciences.
“Last autumn many farmers were caught out by difficult weather conditions which meant that they drilled too late, often into poor seedbeds. The result has been lower yields and disappointing weed control in these later drilled crops. Additionally we are conscious of poorer weed control, particularly black-grass in cereals this year, in part due to fewer applications of residual herbicides and challenging weather conditions. So, more than ever, we need to be using oilseed rape as the key break crop in the rotation, where the grass-weed, in particular black-grass, cycle is at least broken,” says Andy Bailey of Dow AgroSciences.
“But to do this effectively in oilseed rape you need to adopt LifeCycle principles, (www.myfarmlifecycle.com) and consider other factors that contribute to weed control– in this case crop establishment and cultivations. The aim is to keep black-grass seed in the top 5cms of soil as well as establishing the crop into clod-free and firm soil. By achieving this it keeps as much black-grass weed seed in the Kerb Flo ‘lethal soil zone’ as you can. A range of establishment techniques do this, including one pass cultivations combined with direct drilling,” says Andy Bailey.
“Remember ploughing will bury seed but it will also bring some up from deeper levels. Weeds coming from variable depth of emergence and lower down are difficult to control. Fundamentally ploughing also reduces soil moisture levels and getting oilseed rape to germinate you must have sufficient moisture in the seedbeds. Moisture conservation is important,” he says
“Once the oilseed rape crop is established, residual herbicides such as Kerb Flo 500 and ASTROKerb can be used from October onwards. Optimal black-grass control in oilseed rape is important in the rotation, as levels of control are high with these products and there are no challenges of resistance to contend with. You really need to get the greatest proportion of black-grass controlled in this crop, if we are to get on top of this damaging weed,” says Andy.
As well as cultivation strategy, soil temperatures and moisture are key to getting good results with Kerb Flo 500 and ASTROKerb. Dow AgroSciences will be providing valuable information on these two variables to help growers and agronomists pin point the best timing.
Andy also points out that time and workloads are issues at this time of year. “Ploughing is a slower process than min cultivation and is a task which is heavy on time. This can only delay drilling further which you don’t really want with oilseed rape. Min cultivation is also a lower cost option which, with lower rape prices, may fit better when calculating returns on the crop.”
Andy reminds growers to look at the whole rotational approach – and that wheat fields treated with the herbicide UNITE in the spring do not need ploughing ahead of oilseed rape, not the case with many other post-emergence cereal graminicides.
