OSR PROGRESS (4) 02-Aug-2018

DEKALB trials manager, Anders Christensen uses his observations from the company’s 25 site trials network to assess crop progress in the immediate run-up to harvest.


Searing summer takes the shine off yield expectations

Well-rooted, fairly short crops with well-structured canopies, a short sharp flowering and great pod set across our trials left me pretty of confident going into June. Especially with  such good levels of May sunshine and sufficient soil moisture in most places.

Since then, though, the almost total lack of rain across much of the country – less than 10 mm in many southern and eastern counties – coupled with seriously high temperatures have taken the shine off my yield expectations.  I continue to be pleased with the way the OSR has been coping with a season of such extremes. However, pod fill is bound to have suffered from such unrelenting dryness and heat.

As I write at the start of the second week in July, some crops are already being combined – a good two weeks earlier than normal. And by the time you read this most of your rapeseed will probably be off.


We’ll only know once all the yields are analysed, of course, but travelling around my feeling is that this is a season likely to favour later-maturing varieties more than the earlier ones. It’s also one in which the northernmost crops are, again, set to outshine those further south. And it should really highlight the value of the best structured, most resilient soils.


Crop height

Unsurprisingly perhaps after such a late spring, all our trial crops – with the obvious exception of semi-dwarf, low biomass hybrids like DK Secret – are notable for their shortness. On average, indeed, across comparable sites they’re just over 20cm shorter than last season.


As expected, the tallest varieties in our replicated plots are DK Exclaim and DK Expansion at a similar height to the widely-grown non-DEKALB hybrid and pure line varieties we include for comparison, though clearly shorter than the tallest variety on the RL we also have in our plots.

Visibly shorter at around the same familiar height as DK Extrovert is DK Expedient with DK Exception and DK Imperial CL slightly taller and DK Impressario CL rather shorter.

Both the club root resistant varieties are shorter than most, DK Pliny being about the same height as DK Impressario CL, and DK Platinium shorter than all but the low biomass hybrids.


Standing ability


With the possible exception of the very earliest varieties on the highest fertility sites, lodging has been notable by its general absence this season. Across our 28 variety farm-scale strip trials and replicated small plot trials we’ve recorded an average lodging score of under 3.0 (on a 1 to 9 scale where 1 is the best).

While most varieties have lodging scores similar to the generally ‘bullet-proof’ low biomass hybrids, one of the two tallest, DK Exclaim has really underlined its strength by outdoing even these and posting the best average lodging score possible.


Disease levels


With the exception of Scotland and the north, we’ve certainly seen less light leaf spot in our trials this season, with an average all-variety score of less than 2.5 (again on our 1-9 scale where 1 is the best).

Encouragingly, DK Exclaim, DK Expansion, DK Expedient, DK Imperial CL, DK Impressario CL, DK Pliny and DK Platinium have all scored much the same as benchmark light leaf spot resistant varieties, DK Extrovert, DK Exalte and DK Secret.

Early indications suggest we’re seeing a similar verticillium pressure to previous years, although the extent of infections will only really be evident in our immediate pre-harvest and stubble assessments. Varieties standing out for below average early verticillium scores include DK Exalte, DK Expedient, DK Impressario CL, DK Pliny and DK Platinium.


Early European harvest results


The main UK varieties we have in this year’s pan-European trials appear to have stood-up well to the equally challenging summer weather being experienced across the continent.

Topping our first 11-variety trial to be harvested in south western France, DK Expansion stood out for delivering an average 4.85 t/ha, nearly 7% ahead of the next most promising high output hybrid and 9% up on the trial average.


The variety also topped the first German trial to be reported at 5.05 t/ha or 104% of the trial average, with DK Imperial CL not far behind at 4.71 t/ha.


Across the next three French trials for which we have results on notably lower yielding sites DK Expansion at an average 4.22 t/ha was outperformed by DK Exception producing 4.42 t/ha.


DK Exception also outperformed DK Expansion in the first 26 variety trial to be harvested in Germany, leading the field at 120% of the average yield with DK Expansion in third place at 114% and DK Imperial CL also comfortably above the trial average.