One shot at volunteer control
Cereal volunteers in oilseed rape crops have emerged quickly and, together with grass-weeds, are already competing with the crop. This season growers are being advised to time their volunteer and grass-weed control measures carefully as the most commonly used graminicides, fops and dims, are restricted to one application per crop, according to Interfarm UK Ltd.
“PSD has introduced restrictions in the use of ACCase inhibitor herbicides to one application of any one specific fop or dim graminicide per crop. This means that low-dose split applications of any particular product are no longer permitted. However the new regulations allow some degree of flexibility in that a second application of a different ACCase inhibitor product is permitted ‘to control different weeds at different timings,’ explains Dr. David Stormonth, Technical Manager for Interfarm UK Ltd.
“In other words a different graminicide can be used at a later timing providing the target is not the same weed. This may appear to be difficult in oilseed rape but, depending on the autumn and winter, such opportunities could occur. A graminicide such as Co-Pilot (quizalofop-p-ethyl) could be used early on to control cereal volunteers in oilseed rape, providing the black-grass has not yet emerged, and another ACCase product could then be used later, perhaps in mix with propyzamide, for control of black-grass,” says David.
“But it will be even more important to use a high and effective dose, as a repeat spray or split dose application of a specific graminicide cannot be used any more.”
“Whatever the season brings, the choice of graminicide is important and, with only one shot being likely, it is important to make sure that a really effective dose is used. Co-Pilot has been shown to be much more effective on wheat volunteers than other graminicides and with the current crop rotations, wheat volunteers are far more common. It contains its own specific adjuvant within the formulation, negating the need to tank mix an adjuvant at its standard rate of 375 ml/ha.”
“Development work shows that the higher the volunteer population, the more yield will be eroded, particularly during the early establishment stage of oilseed rape. In independent trials, 80 cereal volunteers per square metre caused up to 20% yield loss. Dealing with this problem in a cost-effective manner will mean the use of a suitably priced graminicide, such as Co-Pilot, when the volunteers have 2 to 3 leaves,” says Dr. Stormonth.
“After efficacy and cost, graminicide choice should also take into account practical considerations such as rainfastness and tank mixability. Co-Pilot has excellent rainfastness of less than one hour. It has no LERAP. It can also be tank mixed with many insecticides, fungicides and other herbicides including propyzamide products such as Propose and Flomide. This makes Co-Pilot an excellent choice for growers looking for effective weed control at an affordable price,” reminds David.
