In the final article in our series, Dekalb trials manager, Anders Christensen pulls together harvest data from the company’s UK research network to assess how key varieties have performed where it matters.
I’ve been pleasantly surprised at how our farm-based trials have come through this past season. Like the country at large, yields have generally been below average. In just the same way too, we‘ve experienced wide variations between sites, depending on how badly they were affected by late winter waterlogging and pigeon damage, an unbelievably short spring and, of course, the summer drought.
Although flea beetle larvae definitely affected our sites, thankfully it wasn’t at the worrying levels reported by some, with crops struggling to grow away from the damage in the cold, wet spring. Even so, in both our replicated plot and field-scale strip trials this season we’ve been especially grateful for the initial establishment vigour of our hybrids, together with their ability to compensate for weather and pest setbacks.
An early, surprisingly smooth harvest means that, as I write in the second week of August, initial reports are in from all but our most northern sites. So far our field-scale strip trials managed by growers to their own farm regimes have yielded an average 4.20t/ha – albeit without headlands. This compares with the average of 4.62t/ha from an almost identical set of sites in 2017.
As well as lower seed yields than last year, we’ve seen much greater variation between sites – from a low of 2.43t/ha on land suffering particular waterlogging and pigeon problems, to a high of 5.46t/ha. In 2017, the range was from 3.21t/ha to 5.61t/ha.
We’ve also seen major performance differences in the fully-replicated farm plot trials benchmarking our portfolio against current RL and grower standards under commercial agronomy regimes. The highest yielding site here averaged 5.28t/ha while the lowest managed just 3.73t/ha. Interestingly, this was a complete reversal of fortunes from 2017 when the same two sites averaged 4.45t/ha and 5.61t/ha respectively.
Across the board, the best trial averages – 4.75 t/ha and above – have all come from sites where the soils have been in good heart, underlining the value of healthy soils in buffering extremes of wetness and drought and allowing crops to recover from pest damage.
The better performances have also come from our more western and northern sites, with heavy ground in the east appearing to suffer particularly from a season that was decidedly continental in its climate, with deep winter moving almost straight into high summer.
Under these circumstances, it hasn’t been surprising to see our more continental variety types like DK Exclaim, DK Expansion and DK Exception with a steadier growth pattern and later maturity performing strongly alongside the faster-developing, earlier maturing types that have traditionally better suited the UK’s Atlantic climate.
Indeed, RL Candidate, DK Expansion, topped our main farm strip trials with an average seed yield of 4.54t/ha and DK Exception averaged 4.33t/ha. However, the fastest developer in our current portfolio, DK Expedient did well too, also performing comfortably above the trial average at 4.39t/ha.
DK Exclaim was only included in one of these trials and one of the lowest yielding at that. Nevertheless, it out-performed every other variety on the site at 4.51t/ha – a massive 134 per cent of the trial average. It went on to underline its robustness in a 12ha field on our Yorkshire strip trial site where it averaged 5.62t/ha despite 6 weeks under water in the winter and a violent hail storm on the eve of harvesting.
The variety also stood out as the best performer in our replicated farm plot trials, averaging 4.83t/ha or 109 per cent of the highest gross output conventional variety on the East/West Recommended List, included as a benchmark. DK Expansion and DK Expedient performed strongly here at 106 and 105 per cent of the RL benchmark too, with DK Exception matching grower favourites, DK Exalte and DK Extrovert at 103%.
At the highest yielding farm plot site, DK Exclaim and DK Expansion both delivered an impressive 5.6t/ha (109 per cent of the East/West RL benchmark variety) just ahead of DK Expedient and DK Exception at 5.5t/ha (107 per cent).
Despite being badly hit by hail at early flowering – damaging pods, stripping buds and lacerating stems – DK Exclaim showed especially remarkable recovery abilities on the lowest yielding site, delivering 107 per cent of the 3.73t/ha trial mean and 108 per cent of the East/West RL benchmark.
CL varieties delivered
The two Clearfield varieties included in our farm plot trials – DK Imperial and DK Impressario – didn’t disappoint either. They averaged 4.36t/ha and 4.33t/ha respectively to stand within 2 per cent of the non-Clearfield East/West RL benchmark. And on the highest yielding site, they both delivered 5.0t/ha.
A final word about our especially impressive second current RL Candidate, DK Exsteel. This matched DK Exclaim at the top of our replicated farm plot trial table with a seed yield of 107 per cent of the mean and 109 per cent of the East/West RL benchmark. It also came joint top with DK Expansion in the farm strip trials in which it was included. So it’s clearly one worth watching.