Further yield gains needed in disease-resistant wheats

Do disease-resistant wheat varieties stack up on yield and economics? James Andrews investigates.

Feed wheat growers can either opt for out-and-out yield or disease resistance when selecting varieties, but so far there is little to offer those who want both.

KWS Santiago offers bumper yields at 108% of the control and Stigg from Limagrain boasts fantastic disease resistance. But the former demands high inputs and flawless agronomy, while yield potential of the latter is uninspiring.

JB Diego, Duxford, Grafton and Humber are some that sit in the middle, offering more attractive yields and better agronomics than the top-yielders. But they, too, represent a bit of a compromise.

On paper, yield potential puts Santiago at the top of the group, even though fungicide inputs can be almost double that of Stigg. But if breeders could squeeze an extra 3-4% yield from Stigg-type varieties, they could be a far more attractive prospect when browsing the Recommended List (see graph at end of article).

Lee Robinson, Limagrain’s director of arable marketing, says the firm is working hard to combine both traits by crossing Stigg with higher-yielding varieties. “We could be producing varieties with Stigg-like levels of resistance and 3-4% higher yields in the next few years.”

Breeding varieties with both these traits was complex, as disease resistance genes often compromise yield potential, but improved breeding technology means cycles have been reduced from more than 10 years to about seven, he says.

“We’re also trying to build up multi-level disease resistance, as sustainability is key.”

RAGT seeds should also have a higher-yielding Group 4 variety, with a similar resistance profile to Group 3 Warrior, available in two-to-three years, says senior wheat breeder Ed Flatman.

The breeder is identifying resistance genes that have the smallest impact on yield potential and these are being stacked to give robust disease resistance and better yields, he says.

“We have a couple of coded varieties in National List trials at the moment. One of these is a soft potential Group 4 that should yield 104-105% of the control and have similar resistance to Warrior.”

The firm also has Relay, a hard Group 4 variety that is up for Recommended List approval this year. This offers similar yields to the coded variety at about 105% of the control as well as good disease resistance.

But growers need to consider varietal performance in the field as well as looking at figures quoted on the Recommended List, says Andrew Wade, an Agrovista agronomist based in Shropshire.

“With varieties like Oakley you’re likely to get the big yields but, in some cases, going for something with slightly lower yields is more sensible.”

For example, missed fungicide or growth regulator timings can cause yields to drop lower than some of the other varieties on the list, he says. “Sometimes you need to question how much more yield you really get.”

For those who do opt for Santiago and Oakley, it is crucial to spread risk by planting them alongside more robust varieties. “I’ve got one grower who is growing 50% Santiago and 50% JB Diego to try to get the yields, but cut risk at the same time.”

AICC agronomist Bryce Rham believes growers are better off opting for more stable varieties such as Grafton or Humber.

In his area of Shropshire, Grafton is a popular option for the early drilling slot, Humber for slightly later drilling and JB Diego in the second wheat position.

The problem with some of the higher-yielding varieties such as Oakley and Santiago is that they can easily catch growers out, he says. “With those two you need to be spot on [with agronomy] and they’re not for the faint-hearted.”

He is a fan of Grafton as it is particularly early and performs well as a second wheat. “I grow Grafton as a tool as I don’t think you could ever get it to fall over.”

ProCam agronomist Nick Brown says Oakley’s fungicide spend is roughly 25% higher than Duxford and Grafton, but at current prices, the yield premium still outweighs the increased input cost. “If the wheat price went down to £120/t, the more robust varieties such as Stigg might stack up better.”

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