The watchwords for timely applications of post-em herbicides in oilseed rape this spring are "be prepared", according to Dow AgroSciences.

So far crop, weed and weather conditions have all conspired together to challenge oilseed rape growers this spring, but with sound agronomic foresight and good preparation and planning, the window of herbicide spray opportunity can be grasped and damaging weeds controlled to good effect.

David Roberts of Dow AgroSciences warns that several species of difficult and competitive broad-leaved weeds in winter oilseed rape such as cleavers, sow-thistle, and mayweeds are already present in some crops and, as soon as the snow goes and weather warms up, they will be ready and waiting to grow away, causing yield and harvesting problems.  "These weeds need checking before they become too big a management issue. I would advise agronomists to get out there now and clearly identify those rape fields that will need a herbicide treatment once the weather warms up and then make sure that there is sufficient herbicide in farmers’ stores to tackle the problem as soon as conditions are appropriate."

David points out that there is still a very limited choice of spring-applied herbicides for rape.  "Galera, based on two active ingredients clopyralid and picloram, is the main spring applied herbicide for winter oilseed rape due to its high level of performance and its weed spectrum."


"The challenges that we face this season are that Galera has a reasonably short spray window and that it works best when weeds are starting to grow and when temperatures are starting to rise. Cleavers need to be actively growing for good results, more so than for sow-thistles. Currently we are seeing many lush oilseed rape crops with large canopies, which if they aren’t cut back by the frost, could shield herbicide applications and the recent weather has been cold – not ideal yet. However, it is important that farmers are well prepared to take advantage of the spray window when it does present itself and so hold off until conditions allow. Farmers plagued with difficult weeds that will impact yield and interfere with harvest must have sufficient Galera in readiness for optimum application timings, probably from end of February onwards this year," he says.

Galera can be applied from the 4 leaf stage of the crop up to the point just before flower buds are visible above the crop canopy – this cut-off is usually at the end of March or beginning of April.  "Most farmers have already made the decision to delay their first nitrogen because of advanced crop growth, but when it is applied it will promote rapid growth. Once the weather starts to warm up, both weeds and crop will start to grow and that is when Galera needs to be applied."

"Applied at 0.35 l/ha, Galera gives excellent control of mayweeds, creeping thistles, sow-thistle and very good suppression of cleavers. Groundsel is also well controlled up to the 6 leaf stage and whilst it is not a label weed good effects on cranes-bill have been reported," David says.

For further information, please contact David Roberts, Dow AgroSciences on 07976452475 (mobile) or via the Dow Technical Hotline on 0800 689 8899.