October 11, 2016
Succeeding with Late-Drilled Wheat
Wheat drilling on heavy ground in the second half of October can deliver excellent yields as well as first class black-grass control. But success demands more attention to agronomic detail than earlier autumn planting and a different nutritional approach to traditional wheats after roots.
This is the experience of specialists from Agrii’s Stow Longa black-grass technology centre near Huntingdon where the crucial importance of late-October sowing for black-grass control has been shown in modern cereal rotations over more than a decade.
“Year after year we’ve seen delayed drilling delivering huge advantages in both black-grass control and wheat performance,” stressed the company’s head of agronomy,
Colin Lloyd who has led the Stow Longa work since its start in 1999.
“In the same season in adjacent plots in the same heavy clay field, though, we’ve had late-sown wheats delivering similarly good levels of black-grass control but yielding as much as 12.8 t/ha and as little as 4.6 t/ha. This underlines how important it is to manage everything right.”
“Late drilling leaves much less room for error,” pointed out trials manager, Steve Corbett. “After all, there’s a month less time and around 400 fewer day degrees on average to achieve the strong establishment we need ahead of the winter.”
“At the same time, we know conditions can rapidly turn against us at this time of year,” added regional technical adviser, David Felce. “Especially so, on heavy ground and with the sort of weather variability we’re seeing these days.”
Under these circumstances, the Agrii specialists identify a number of key factors for successful late wheat drilling – from seedbed conditions, fertilisation and sowing practice through variety choice, seed rate and seed treatment to early weed and pest control, crop nutrition and growth regulation.
As with everything, the team insists that soil must be the first consideration driving management; specifically soil in a fit condition to drill.
“Your soil must be able to take water and allow you to create a decent seedbed,” insisted Steve Corbett. “Stay off the land until you can drill to an even depth without clods or you’ll have big problems with pre-em activity and slug control, not to mention the seed-to-soil contact essential for the best early crop growth.
“And if you can’t get the right conditions stay off until the spring. Whatever you do, don’t maul the crop in. With margins as tight they are today it simply isn’t worth it.”
Wherever soils are fit after mid-October, Steve Corbett advises drilling without delay and with minimal soil movement so the least amount of black-grass is woken up.
“More haste less speed is essential here,” he said. “You need to drill at a consistent 3-4 cm so the seed’s deep enough to be out of the way of residual chemistry but shallow enough to get out of the ground as rapidly as possible.
“Good consolidation is also vital if you’re to minimise any slug damage, early take-all development and manganese deficiency. And, wherever possible, you should place phosphate with the seed or apply it early to encourage rooting.
“Sufficient phosphate is vital for early root development and its availability is reduced in cold wet soils. So it’s well-worth using a specialist availability-enhancing coating with your fertiliser. Averaged across fertiliser rates, adding P-Reserve to TSP increased feed wheat yields by 0.64 t/ha from early November-drilling in our trial work for a cost of just £8/ha.”
What you drill is every bit as important with late-sown wheat as how you do drill it, in Colin Lloyd’s experience. As well as fast development, he advocates varieties with the greatest weed competitiveness and seed of the highest quality for the best germination and early vigour.
“The latest Agrii Advisory List produced from our own national trial work as a complement to the Recommended List shows the quality wheats, Skyfall, KWS Trinity and Cordiale are particularly well suited to late-drilling,” he reported. “Among feed wheats, Evolution and Dickens stand out. With the exception of Cordiale, all these varieties have proved relatively competitive against black-grass in our Stow Longa testing.
“What’s more, they can all safely be sown to the end of January. But if you want even more flexibility, we’ve found a spring wheat like Mulika can perform as well as many winter varieties from late sowing.
“With germination and early vigour so critical in the late drilling slot, unless you can be completely sure of its quality I wouldn’t use farm-saved seed here,” Colin Lloyd continued. “I’d also be using certified seed with MasterSeeds levels of quality that go well beyond European standards as extra insurance.
“Effective seed treatment is crucial too. In particular, Deter to protect against slug hollowing and BYDV carrying aphids; Take-off or manganese dressings to encourage early rooting; and Latitude where there’s a particular take-all risk.”
Regardless of variety, Colin Lloyd explains that reduced tillering potential from later-drilling means higher plant populations are needed to produce the target of at least 400 ears/m2 – 320 plants/m2 in the spring against 260-280/m2 from earlier drilling. Which, in turn, means sowing rates of 400-450 seeds/m2, depending on conditions.
“Later sowing can be extremely valuable in the most cost-effective management of septoria, yellow rust and BYDV as well as black-grass” noted Bedfordshire farmer and Agrii regional technical adviser, David Felce. “However, failing to manage your most important yield robbers sufficiently well from the start can be extremely costly. Not least as spray days become increasingly limited by ground and weather conditions.
“It’s vital to spray-off black-grass and other weeds with glyphosate as close to drilling as you can, for instance. And if you have to leave a week or more between spraying- off and drilling, it’s best to include a permitted glyphosate with your pre-em to deal with already emerged but often hard-to-spot weed seedlings.
“While late October sowing gives much better flufenacet residuality, the herbicide must go on as a pre-em because you may not have much in the way of peri-em or post-em spraying opportunities. That’s why decent seedbeds are so important.
“Also important in ensuring the greatest herbicide activity and crop safety by holding the residual in the narrowest possible band, I’ve found, is a specialist pre-em adjuvant like Backrow.
“Earliest is best with slug control,” he insisted. “Assess the pressure and always kill before you drill. Giving slugs the choice of pellets or nothing is far more effective than pelleting alongside juicy young wheat seedlings.
Despite the very late aphid activity seen in recent mild winters, David Felce doesn’t believe Deter-treated crops should require a follow-up insecticide. Without the seed treatment, though, he stresses that it may be needed but prove impossible due to the weather, underlining the importance of building-in BYDV protection from the start.
“As well as getting late-drilled wheats off to the best possible start, you’ve got to keep them going strongly as they come through the winter,” he added.
“Unlike traditional wheats after roots, they’re unlikely to have plenty of available nutrition in the soil and, in many cases, they have to cope with the extra nutrient drain of incorporated straw.
“So, just like second wheats, a good early dose of nitrogen will be important to maximise tiller retention. By which I mean 60-80 kg N/ha in mid-February if conditions permit, ideally accompanied by fresh phosphate, some potash to support shoot development and sulphur to balance the nitrogen.
“Then you should come back with the nitrogen regularly to keep the crops going,
so you don’t leave a ‘hungry gap’. And once they’re growing away apply an early, low temperature-active PGR. This will help tiller retention, promote rooting and counteract the tendency for thick crops with thinner shoots to be more prone to lodging.
“Our trial work suggests early foliar zinc and boron can also be very valuable at early PGR time. And early spring rolling to deal with any frost lift can pay dividends too.
“It’s all a matter of appreciating the inherent drawbacks of later drilling and doing everything possible to counteract them so you can take full advantage of its immense value in managing black-grass.”
Ten Top Tips for Late-Drilled Wheat
- Stay off the land until you can drill to an even depth without clods, even if this means waiting until the spring.
- Move as little soil as possible when drilling, sow to a consistent 3-4cm depth, place enhanced availability P with the seed, if possible, and consolidate well.
- Use the best quality seed available from fast-developing varieties with a high black-grass competitiveness.
- Treat the seed against slug hollowing and BYDV-carrying aphids, to boost root development and, where necessary, to combat take-all.
- Sow at 400-450 seeds/m2, depending on conditions, to achieve spring populations of around 320 plants/m2.
- Spray off weeds and volunteers as close to drilling as possible and include a permitted glyphosate with the pre-em, if necessary.
- Use a flufenacet-based pre-em, including a specialist adjuvant to improve activity and crop safety.
- Assess slug pressure well ahead of sowing and achieve the best possible kill before drilling with targeted pelleting.
- Apply a good dose of early spring N, accompanied by P,K and S where possible and maintain regular top-dressing ahead of earlier plantings
- Consider early spring rolling, an early low temperature active PGR and early foliar Mn, Zn and B.