Spring wheat was the best gross-margin performer in the second year of one agronomy group’s field-scale rotation blackgrass trials – outperforming spring barley and late autumn-sown wheat.

In addition, the crop delivered the most effective control of blackgrass in this 5ha heavy land trial, but crop experts highlight that it must be managed correctly to ensure the crop delivers.

Colin Lloyd, the head of agronomy at Agrii, and Jim Carswell, the group’s northern research and development manager, underline the importance of maximising blackgrass control, securing a milling premium and avoiding problems from rust, barley yellow dwarf virus, ergot and gout fly to grow a successful crop.

See also: The best spring cropping options for 2017

Across the rotational trial block at Agrii’s Stow Longa blackgrass technology centre in Cambridgeshire, last season’s mid-March sown crop of the spring wheat variety Mulika averaged 7.83 t/ha to deliver a gross margin of £534/ha and a summer blackgrass population of 24 ears/sq m.

This compared with 6.32 t/ha, £404/ha and 37 ears/sq m from spring barley sown on the same date and 7.6 t/ha, £237/ha and 37 ears/sq m from the best crop of the most blackgrass competitive winter wheat, Edgar, sown in late-October.

Mulika showed the best average crop performance in 2015/16 Stow Longa rotational study

Potential yield 

“Yields of more than 9 t/ha and protein contents of over 14% in other recent trials across our research network underline the clear potential of Mulika, which commands the lion’s share of today’s spring wheat market,” says Mr Lloyd.

But he has seen crops badly hit by gout fly giving little more than 2t/ha. Equally, cleaning out ergot typically adds £10-15/t to production costs, while the AHDB quality survey shows only 23% of Mulika samples from harvest 2016 made the Group 1 milling specification.

Like all spring crops, the short growing season means few, if any, opportunities to compensate for setbacks, which puts a premium on the earliest and best possible start.

This is especially important with spring wheat to minimise competition from blackgrass and avoid the worst effects of both gout fly and ergot. Setting up the ground well in the autumn – either as a cultivated stubble or with a cover crop – leaving it undisturbed through the winter and drilling with minimal soil movement is the preferred recipe.

Waking up blackgrass seed by moving too much soil at drilling has, indeed, been shown to reduce Mulika yields by almost 2t/ha.

Timely treatment 

“Timely glyphosate treatment is essential to eliminate both cover crop and weed growth ahead of drilling. We like to follow up our initial spray to kill any cover with a second treatment just before sowing or as a pre-em to target blackgrass previously shielded by the canopy,” says Mr Carswell.

He adds that slower glyphosate action at low temperatures makes it important to spray off cover crops some three to four weeks ahead of intended drilling for the best results.

“Kill before you drill also has to be the watchword with slugs to avoid what can be devastating problems on heavy ground coming into the spring. Just like winter crops, effective rolling after drilling is invaluable here, as well as in achieving the best seed-to-soil contact,” he says.

Unlike spring barley, growers don’t need to wait for the ground to warm up for spring wheat, so growers should sow it as soon as they get decent seedbed conditions.

Last year, the three spring wheats in Agrii’s Throws Farm alternative wheat drilling date trials in Essex averaged 9.34 t/ha from sowing in the first week of February and 7.74 t/ha from mid-March, while earlier sowing also produced noticeably higher specific weights.

Sow before April 

“In any event, you should always sow before April. As well as making the crop far more vulnerable to gout fly damage, late drilling invariably means extended flowering and far greater opportunities for ergot infection – which can be especially problematic in bad blackgrass ground, given the weed’s particular ability to host the disease,” he says.

The group’s trials show no consistent performance differences between Mulika sowing rates of 350 and 500 seeds/sq m. 

On this basis, some 400-450 seeds/sq m is considered about right under most circumstances, suggesting this may be increased to 500 seeds/sq m to maximise crop competitiveness where blackgrass populations are high.

On soils prone to manganese deficiency, a quality manganese seed dressing is recommended, while a seed treatment and/or a low temperature-active plant growth regulator can provide an early boost to rooting.
 
With a large amount of barley yellow dwarf virus seen following the recent run of mild winters and the extent to which it can damage later-sown spring wheats, a pyrethroid at GS13-21 is recommended too, as is extra foliar manganese and zinc where necessary.

“Our most recent spring wheat nutrition work highlights a yield advantage of around 0.5t/ha from 50-60 kg/ha of phosphate in seedbed. For the greatest value, our trials underline this should be drilled below the seed rather than surface applied after drilling,” says Mr Lloyd.

Nitrogen needs

Looking at nitrogen, Mr Lloyd says the group’s work suggests 160-200 kg/ha is quite sufficient, with
40-70 kg/ha (depending on sowing date) applied in the seedbed and the bulk at GS12.

“Higher levels than this have given us significant grain protein boosts – to 14% and beyond. But as there is nothing to gain from proteins of more than 13%, they really don’t make sense unless you generally struggle to achieve the milling specification,” he says.

A two-spray fungicide programme is advised for spring wheat, with strobilurins included at both T1 and T2 to target rust and support grain quality. These regimes gave an average response of 0.5t/ha from March-sown Mulika in 2016 trials, together with a specific weight increase of almost 2 kg/hl.

Mr Carswell says he has not seen a sufficient benefit from a T3 spray to justify the extra cost, so a modest fungicide programme is adequate unless there’s a major disease challenge.

“Instead, the key focus of investment with the crop must be on drilling it into the best possible conditions early enough and getting it away well enough from the start,” he adds.