"On your marks for weed control" - Dow AgroSciences warning for oilseed rape growers

UK - January 19, 2007

Get spraying against sow-thistles, mayweeds and cleavers in winter oilseed rape crops just as soon as conditions allow, advises Dow AgroSciences. 

“Oilseed rape crop growth is varied across the UK with a lot of active weed growth,” says Dow’s agronomist Rene Pollak. “Our major concern at the moment is sow-thistle, mayweed and cleavers control using Galera (clopyralid + picloram) as extremely forward crops race through their growth stages.   

“Stem extension in winter oilseed rape is driven by temperature rather than day length.  If current high temperatures continue there is a real risk that the optimum crop growth stage for Galera will speed by.” 

Mr Pollak advises growers to have Galera ready on farm and snatch the opportunity to spray when it arises; usually as soon as fields have a chance to dry out, growers will be keen to spray.  The ideal scenario would be still conditions, dry leaves, high and stable ambient temps with no frosts forecast, trackable fields and actively growing weeds. 

Applications of Galera can be made until the crop green buds start to show above the crop, but cannot be applied after GS 3.5.  Once the crop reaches GS 3.5 - flower buds raised above the leaf canopy – it is too late.  

“Galera works most effectively in milder conditions, when there is no chance of a frost.  The only risk of an early start to pre-empt flowering is a sudden cold snap, during or after treatment which is likely to reduce activity against cleavers,” says Mr Pollak.