In addition to rotational ploughing, stale seedbeds, delayed drilling and spring cropping, a large number of cultural practices are now being widely used to control grassweeds, according to the 2016 National Grassweed Study.
These include increased seed rates, more competitive varieties and longer rotations as well as spraying-off infested crop areas and hand-rogueing (Figure 5).
On average, growers are using 6.25 of these techniques, with 45% employing seven or more and 12% nine or more. Those with the most widespread black-grass and the most serious resistance problems are, not surprisingly, making the greatest use of cultural controls – particularly stale seedbeds, delayed autumn drilling, spring cropping, increased seed rates and more competitive varieties.
Unsurprisingly too, growing more spring crops, improving stubble weed control, drilling more winter wheat later and improving weed control in winter OSR are the most popular management changes being considered to address grassweed problems.
Using higher wheat seed rates, increasing break cropping, reducing second wheat growing and greater use of rotational ploughing are also on the agenda for a quarter or more of managers, underlining the extent to which problem grassweeds are now becoming the key management driver for so many farms.