September 13, 2016
Succeeding with Late-Drilled Wheat
Drilling in the second half of October is invaluable in managing black-grass, but it leaves us much less room for error. After all, we have a month less time and around 400 fewer day degrees on average to achieve the strong establishment needed ahead of winter.
At the same time, we know conditions can rapidly turn against us at this time of year on heavy ground and with the sort of weather variability we’re seeing these days. This makes it more important than ever to get our agronomy right.
First and foremost, our soil must be able to take water and allow us to create a decent seedbed. We need to stay off the land until we can drill to an even depth without clods or we’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 we can’t get the right conditions we should hold-off until spring. With margins as tight they are today, it simply isn’t worth mauling crops in.
We need to drill at a consistent 3-4 cm too so the seed is deep enough to be safe from residual chemistry but shallow enough to get out of the ground as rapidly as possible. Equally, we must sow with as little soil movement we can to wake-up the least amount of black-grass.
Good consolidation is important to minimise any slug damage, early take-all development and manganese deficiency. And, wherever possible, phosphate placement with the seed or early seedbed application is advisable.
Sufficient phosphate is crucial for early root development and its availability is reduced in cold wet soils. So it’s well-worth employing a specialist fertiliser coating. In our trial work, adding P-Reserve to TSP has increased feed wheat yields by 0.64 t/ha from early November-drilling for a cost of just £8/ha.
What we drill is every bit as important with late-sown wheat as how we drill it. The latest Agrii Advisory List produced from our national trial work as a complement to the Recommended List highlights winter wheats especially well-suited to the slot and most competitive against black-grass in our Stow Longa testing. And for the greatest 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 essential in the late drilling slot, unless I can be completely sure of its quality I wouldn’t use farm-saved seed. I’d also insist upon a MasterSeeds level of certified seed quality that goes well beyond industry standards.
Effective seed treatment is vital 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, reduced tillering potential from later-drilling means higher plant populations are needed for optimum ear numbers – 320 plants/m2 in the spring against 260-280/m2 from earlier drilling. This means sowing rates of 400-450 seeds/m2, depending on conditions.
Later sowing can be extremely valuable in managing septoria, yellow rust and BYDV as well as black-grass. However, failing to manage our most important yield robbers from the start can be extremely costly as spray days become increasingly limited by ground and weather conditions.
While late October sowing gives much better flufenacet residuality, the herbicide must go on as a pre-em because we 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 adjuvant like Backrow.
Earliest is always best with slug control too. Having assessed the pressure we should always kill before we 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, Deter-treated crops shouldn’t require a follow-up insecticide. Without the seed treatment, though, it may be needed but prove impossible due to the weather, underlining the importance of building-in BYDV protection with our seed.
As well as getting late-drilled wheats off to the right start, of course, we’ve got to keep them going strongly as they come through the winter with early spring fertilisation; an early, low temperature-active PGR with foliar zinc and boron, if possible; and, early spring rolling to tackle any frost lift.
It’s all a matter of appreciating the inherent drawbacks of later drilling and doing everything possible to counteract them so we can take full advantage of the immense value it offers in our black-grass management.