Cultural control methods cannot fully compensate for the loss of cereal grass weed herbicides, weed scientists said at the 46th British Crop Production Council annual weed review in Peterborough.
But there were methods that could support the performance of the products that were still available, they suggested.
A number of key products are likely to be removed as new EU legislation works through in the coming years, while very few new products are being developed.
In a review of research from the past 40 years Peter Lutman and Stephen Moss of Rothamsted Research showed, in general, cultural control was less effective, more variable and more expensive that using herbicides.
The most effective agronomic practices could only achieve 70 to 80% control of blackgrass, for example, while the best herbicides could give over 90%.
However, appropriate cultural controls could take the pressure off herbicides, said Dr Lutman. “The current techniques of non-inversion tillage, early planting, low crop seed rates and continuous winter cropping, all put huge pressure on herbicides. This approach will not succeed in the future when fewer products are available and if grass weed resistance becomes more of a problem.”
Major adjustments would be needed to farming practices, including rotational ploughing and spring crops in the rotation, he said. “If we do not change the way we grow our crops, we run the risk that they will be overwhelmed by unmanageable grass weeds in the future.”