With autumn herbicide programmes working well in most oilseed rape crops, growers now have a short window to control any spring-emerging weeds. 

After a warmer than average winter, spray programmes were generally well timed and will have kept weeds such as cleavers, cranesbill and fumitory at bay. 
 
But even if pressure appears to be low, a spring flush is likely as temperatures rise so Corteva Agriscience is advising growers to keep an eye on crops and take appropriate action. 
 
John Sellars, Oilseed Rape Herbicide Category Manager, said: “Your oilseed rape may look great now but we all know how quickly crops and weeds can grow away in the spring. 
 
“The main objective at this time of year is to take out red-faced weeds – those that appear above the crop and can cause embarrassment as well as issues with harvesting and quality if left unchecked. Growers should be on the lookout for poppies, mayweeds, cleavers and thistles in particular.” 
 
From today (1 March), the application window for Korvetto opens – a product which has excellent activity on those key target weeds. It contains Arylex Active – the same active ingredient used in autumn herbicide Belkar – in formulation with clopyralid. 
 
With many crops well advanced, growers are advised to make applications as soon as conditions allow. 
 
John said: “There are two reasons why acting sooner rather than later is appropriate this year. First, hitting weeds when they are small increases the level of control from the product. Second, you must apply Korvetto before growth stage BBCH 50, which won’t be too far away for crops which were drilled early and have grown away well.” 
 
There are no following crop restrictions in conventional rotations, and farmers can still use 1l/ha of Korvetto if they have applied a post-emergence herbicide in the autumn such as Belkar or AstroKerb.
 
Treatments should be made prior to crop canopy closure and before flower buds are visible from above the crop canopy (BBCH 50).
 
Farmers in Ireland can now also benefit from Korvetto’s superior control of a wide range of annual broad-leaf weeds after the herbicide was approved for use in the country for the first time.