Mildew ‘threatens red wheat gross margins’

ATTRACTIVE margins from red wheat could be put at risk due to mildew this spring, an agronomist has warned.

Bedfordshire agronomist Andy Scott of Vass had a lot of interest from farmers wanting to grow red wheat this year. But a poorly managed fungicide programme could cost at least 0.5t/ha yield loss, he warned.

“Growers looking to grow red wheat will have to focus on their agronomy because the variety that has been selected for its quality goes through its growth stages much faster than a conventional crop.”

The red wheat variety A C Barrie is not on the NIAB recommended list but Mr Scott said it had a mildew susceptibility rating equivalent to about three, a point worse than Claire and two points below Humber, Duxford and Gallant.

In a conventional wheat-growing situation, a curative strategy based on a triazole plus appropriate morpholine should keep on top of mildew – so long as spray programmes started before the disease took hold.

But red wheat growers should not rely on a curative option, so a fungicide programme based on preventative control strategies was the only realistic option at a time when workload pressure was mounting.

“If mildew takes hold in red wheat it will be very difficult to contain,” said Mr Scott. “Any potential gross margin gain can be quickly wiped off in worst case scenarios.”

For winter drilled red wheat Mr Scott recommends a T0 spray of Justice (proquinazid) followed by a T1 application of Opus Team (epoxiconazole + fenpropimorph) at 0.75l/ha plus Justice at 0.15-0.25l/ha mixed with a PGR.

A second application two to three weeks later (GS 39) includes Mantra (epoxiconazole + fenpropimorph + kresoxim-methyl) at 0.5l/ha plus Hallmark (lambda-cyhalothrin) for gout fly. As a programmed approach, the lower rate for Justice should be enough to ensure long-term protection, said Mr Scott.

For spring drilled red wheat, growers should use the same sprays as for winter drilled crops, but to apply them at the T1 and T2 timing should provide appropriate levels of control.

“Proquinazid assists the plant in enhancing its own natural defence mechanism as well as helping to fight late infection by reducing the viability of spores. We have also found that when Justice is included in tank mixes with other triazoles it adds a percentage increase to the efficacy of the other products.”

A relative newcomer to the UK market, red wheat yields of between 4-5t/ha can make it more profitable than a 10t/ha feed wheat crop red wheat because of significant price premiums over conventional varieties.

Fixed price contracts of up to £310/t – giving a premium of £170/t over feed wheat – and input costs that are £100/ha lower have combined to make red wheat an attractive option.