Farmers urged to protect OSR crops against spring-emerging weeds
21st February 2023
Following reports of weeds such as cranesbill, scentless mayweed and cleavers emerging in oilseed rape (OSR) crops, farmers are being advised to monitor fields closely and take prompt action if necessary.
Despite autumn herbicide programmes working well in most crops, spring-emerging weeds are already being spotted by growers. While dense canopies have offered good suppression of weeds and competition so far, recent frosts have begun to open these up, leaving crops exposed.
With a spring flush looming as the mild weather continues to prevail, Corteva Agriscience warned early action may be necessary to keep weeds at bay. OSR category manager Clare Stapley said: “Although crops may be looking great now, spring-emerging weeds are not hard to find.
“Later flushes of cleavers are being seen following autumn herbicides. It is key to control these as they can cause issues at harvest.”
Ms Stapley also reminded farmers to keep an eye out for weed flushes where cabbage stem flea beetle larvae are present, as these can cause crops to open up further.
With this year’s OSR crop already well advanced, growers are advised to begin herbicide treatment as soon as the application window opens and conditions allow. The window for Korvetto, a product recommended by Corteva Agriscience due to its excellent activity on target weeds, opens on 1st March.
According to the company, Korvetto contains the same active ingredient used in the autumn herbicide Belkar – Arylex Actve – in formulation with clopyralid.
“Korvetto is essential for those growers starting to see evidence of cleavers as it controls them up to 10cm,” Ms Stapley said.
Moreover, she reminded farmers of the importance of taking a proactive approach to weed control this year.
“Acting sooner rather than later is key. Targeting weeds when they are small increases the level of control from the product. And 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.”
As there are no following crop restrictions in conventional rotations, farmers can still use a 1l/ha dose of Korvetto even if they applied a post-emergence herbicide such as Belkar or AstroKerb in the autumn. The herbicide can now also be used in Ireland followings its approval in the country for the first time in 2022.
For best results, Corteva Agriscience recommends farmers apply Korvetto prior to crop canopy closure and before flower buds are visible from above the crop canopy (BBCH 50).
