Corteva Agriscience is warning growers that the unseasonably mild temperatures mean that weeds will continue to emerge in oilseed rape crops.
While the picture varies from region to region, late-sown crops are still small and weeds are just starting to come through. This is in contrast to earlier drilled crops which are forward, with large canopies.
However, a benefit of the mild weather is that growers will have the conditions to apply herbicides to control key problem weeds.
Joe Martin, oilseed rape herbicides field technical manager, said: “After last autumn when many farms either struggled to drill or failed to get on with the sprayer, the chance to apply a contact herbicide in late October and early November will be welcome.
“Growers are usually preparing for propyzamide applications to control grassweeds now, but soil temperatures need to be 10 degrees and falling and most parts of the country are some way from that at the moment.
“Where the weather is favourable, there is a chance to take out key problem weeds.”
He adds that the company’s Belkar broad-leaved weed herbicide can play a part in strategies. It is applied post-emergence and is effective on a wide range of weeds, including poppy, cleavers, shepherd’s purse, fumitory and cranesbill.
Joe said: “Where certain key weeds are a problem at this point in autumn, the actives in both Belkar and Astrokerb will give good control of the majority of these weeds.
“One example is mayweeds which can germinate in numerous flushes and are controlled best with a programmed or robust approach. Arylex active and aminopyralid are both key active ingredients and can be used together or in a sequence.”
Around 0.25 litres/ha of Belkar should give good control at present, although as weeds continue to grow, in crops beyond the six-leaf stage, the rate should be increased to 0.5 litres.
It can be applied now, or in a tank mix later with propyzamide. Tank mixes with either Astrokerb or Kerb Flo 500 can be used until the end of December, and Belkar can now be mixed with boron as the previous label-restriction has been removed.
For more information go to www.corteva.co.uk