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May 14, 2013

Better balanced feed wheat mix

The best possible varietal balance is crucial in modern UK feed wheat production to minimise the escalating agronomic risks from our increasingly variable and more extreme weather patterns. This has become crystal clear after another particularly challenging harvest, not to mention the most difficult winter and spring most growers can remember.

From the experience of last season, Agrii seed manager, Barry Barker highlights maturity, disease resistance and grain quality as areas requiring particular attention in the future feed wheat variety mix.

“Feed wheats certainly didn’t live up to their barn-filling reputation last year,” he observed. “But lack of sunlight is something no one can do anything about. In contrast, there’s a lot growers can do in their variety choice to address the other major issues thrown up by the season – serious harvest delays, substantial disease problems and very poor grain quality.”
Evaluations of wheat variety performance over the past two highly contrasting seasons by the Agrii R&D team highlight the danger of only growing relatively late ripening varieties.

These proved relatively more productive in the drier seasons of 2010 and 2011. Under the wet conditions of last year, however, in most cases the position was reversed, with earlier ripening varieties faring notably better.

This meant a major turn-round in the ranking of some varieties. For instance, KWS Kielder (ripening rating +3) topped the Recommended List performance rankings in both 2010 and 2011 but was one of the lowest yielding feed wheats in 2012. In contrast, Dickens – with an identical overall RL yield rating but ripening at the same earlier time as Solstice (0) – slightly under-performed Kielder in the dry years but had a 5% yield advantage in 2012 trials.

“Later ripening varieties were able to profit from the late summer rainfall in the previous two seasons while the earlier ripeners were beyond the point of no return by then,” explains Barry Barker. “But last year the tables were turned, favouring earlier ripening.

“In theory a two to three-day difference between varieties in average ripening doesn’t look much. But with sufficient moisture our agronomists know from experience across northern and western counties this can easily mean a week or more. So it can be very significant in practice, making it important not to put all your eggs into the later maturing wheat basket.”

This is, of course, made more difficult by the fact that all but four of the 19 feed wheats on the 2013/14 Recommended List and five of the six highest yielders are notably later ripeners, primarily because they have come through the testing system in seasons that have favoured them over earlier ripening varieties.
“For the most reliable performance across the seasons, I recommend earlier-ripening Dickens as complimentary to later-ripening KWS Santiago for growing alongside even later-ripening KWS Kielder,” Barry Barker suggests. “Or, for that matter, alongside any of the other top yielding feed wheats, most of which are relatively late to ripen.

“Such a combination will also help to ease autumn workload pressures and avoid the potentially damaging effects of delayed harvesting – particularly so on the critical early entry for oilseed rape. Indeed, as a notably strong second wheat, ahead of OSR the early ripener should enable wheat to continue being grown instead of the only real rotational alternative – barley.”
Disease resistance is another area in which the best possible balance is becoming more essential in feed wheat variety selection. All the more so, given the preponderance of current varieties with Robigus or Oakley in their ancestry.

A combination of early treatment to address yellow rust problems on susceptible varieties and extremely limited T1 and T2 spraying opportunities last year allowed Septoria tritici infections to take hold, causing a huge amount of damage to many crops.

“As well as underlining the value of both fluquinconazole seed dressing and robust T0 treatment, this really highlighted the importance of diversifying wheat varieties for disease resistance,” says Barry Barker.

Particularly worrying in this respect, he believes, is the extent to which feed wheat rust resistance ratings have slipped in recent years. For instance, while only three of the 14 Group 4 varieties on the 2009/10 Recommended List had yellow rust resistances of less than 7.5, no less than seven of the 19 currently Recommended varieties are rated less than 5.0.

“Large acreages of susceptible varieties create particular vulnerability because the spraying capacity on most farms is insufficient to ensure they’re all treated when they need to be – especially when the weather seriously limits spray days,” Barry Barker stresses. “As so many growers found to their cost last season, this can easily lead to excessive gaps between treatments, letting Septoria cycle to levels which seriously compromise crop performance.

“Just like diversification by ripening time, the best way of preventing this is to grow varieties with stronger disease resistance – and, if possible, also ones with resistance from different sources – alongside the more susceptible ones. That way they can safely be left for spraying until the more vulnerable ones have been prioritised, leaving fewer holes in the overall disease shield.

“The current Group 4 portfolio contains a number of varieties with good untreated yield ratings to allow this. “Cougar, Revelation and Myriad stand out for 90%-plus ratings in this respect among the soft feeds, as does Dickens in the hard category.”

With poor specific weights making such an impact on the bottom line through screenings and deductions last season, Barry Barker advises feed wheat growers to balance their variety mix equally carefully for grain quality in the years ahead.

While soft feed varieties have largely maintained or even increased grain quality levels in recent years – presumably in response to demand from distilling and other markets – the key grain quality requirement of hard feed wheats has fallen noticeably.

“All seven of the hard Group 4 varieties on the 2009/10 RL had specific weights of over 75 kg/hl, with Grafton, JB Diego and Timber particularly impressive at 77.0 kg/hl or more,” he points out.  “Yet almost half the nine hard feed varieties on the current List and all but one of the four top yielders are below this level, making grain quality a clear vulnerability in difficult seasons.

“Again, lowering the risk is a matter of getting a better balance in the mix. This will be most important for growers concentrating on hard feed production where the risk of quality problems is greatest.

“JB Diego has been a firm Group 4 favourite of our Throws Farm trials team for the consistency of its performance over the years,” he concludes. “This primarily comes from a combination of middle-of-the-road maturity, solid disease resistance and good grain quality – not to mention its ability to perform across different soil types and as a second wheat. This clearly emphasises the importance of these considerations in modern variety choice.”