DEKALB varieties top independent Clearfield variety trials

DEKALB varieties took the top three places in the first full set of independent trials assessing the UK performance of Clearfield oilseed rape, with DK Impression CL and DK Imperial CL standing out for their consistency as well as overall output rating.

NIAB-TAG testing of nine varieties of winter OSR tolerant to Cleranda and Cleravo herbicides across three sites in 2015/16 recorded a mean gross output of 3.54 t/ha. In a season of generally disappointing winter rape yields, the average variety performance at all three sites was very much in line with the organisation’s other OSR work at the same locations.

Topping the three-site average with gross outputs of 108% and 107% of the trial mean respectively were DK Impression CL and DK Imperial CL. In third place with a gross output of 106% was the only other DEKALB variety in the trial, DK Imaret CL.

All three varieties were clearly ahead of the six non-DEKALB varieties tested and among the only four to record above-average gross outputs.

What’s more, both DK Impression CL and DK Imperial CL demonstrated their consistency by out-performing all the other varieties at both the highest and lowest yielding sites.

Their average oil contents of 44.3% and 44.6% were noticeably ahead of the rest too, with the next best variety in this respect (DK Imaret CL) averaging 43.5% oil.


As well as its leading performance in independent Clearfield trials, DK Imperial CL stands out for the combination of other valuable characteristics it carries as part of the DEKALB package.

A medium to rapid autumn growth habit combined with its vigorous establishment ability makes DK Imperial CL suitable for drilling into early September and particularly well able to cope with less-than-ideal autumn conditions.
Double phoma resistance gives valuable extra autumn spraying flexibility, while an autumn PGR may be appropriate before winter under favourable growing conditions.
Pod shatter resistance will reduce the risk of seed losses in the run-up to and at harvest, protecting yields under difficult conditions or where combining is delayed and reducing subsequent volunteer control pressures.


The Clearfield trait makes DK Imperial CL tolerant to the sulfonylurea herbicide, imazamox.
As a result, DK Imperial CL is especially valuable wherever:

  • Cruciferous weeds are a problem;
  • Double low volunteer OSR populations are significant;
  • There is a risk of erucic acid contamination from HEAR volunteers;
  • Pre-emergence herbicides are either inappropriate or undesirable; or
  • SU herbicide residues from previous crops may restrict crop vigour.

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