LATE DRILLING: THINGS TO CONSIDER
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THINGS TO CONSIDER
With harvest almost complete attention must now turn to autumn drilling. Near perfect conditions mean that for those able to get on early drilled crops should get off to an excellent start. For those who need, or prefer, to wait a while longer, they must hope that the weather holds long enough for them to complete the task ahead.
Over the past decade there has been a marked trend towards later drilling of autumn sown wheats. The over-riding reason for this has been to aid grassweed control through spraying off an early flush of weeds, with black-grass a particular concern.
Research by the AHDB has found that “delayed sowing of winter wheat by three weeks from mid/late-September to early/mid-October reduced black-grass infestations by 33% on average. In addition, heads and seeds per plant, were reduced by an average of 49%.”
It added that: “the most important finding was the better black-grass control achieved by the pre-emergence herbicides (240g flufenacet/ha†+ 60g diflufenican/ha†plus 1600g prosulfocarb/ha) when applied in later-sown crops. This mean benefit, an additional 26% control (above the 47% achieved at the first sowing date), was substantial. Most of these benefits came from delaying sowing by about three weeks to early-mid October, with relatively smaller additional benefits from delaying sowing until late October/early November.”
Many growers will, however, choose to use glyphosate. It is indiscriminate, quick to act and inexpensive to apply. But that does not mean it should be applied without care and consideration.
Worldwide, 31 weed species have been reported to have developed resistance to glyphosate. This has led the Weed Resistance Action Group (WRAG) to produce guidelines to help agronomists and growers maintain efficacy.
High-risk practices identified by WRAG that should be avoided include:
- multiple glyphosate applications;
- sub-lethal doses; and
- sub-optimal application timings.
Having decided to delay drilling, whether it is for enhanced grassweed control or simply because earlier conditions didn’t allow, it is important to choose a suitable variety. The AHDB recommended List should be the first starting point as most varieties are sown in into trial in October, but beyond this and the variation between varieties becomes apparent.
Below is an analysis of the KWS varieties that we believe are suitable for late drilling, the trials results below from 2015 and 2016 show the varieties that have performed in terms of yield as well as their speed of development. In addition KWS Lili, KWS Crispin and KWS Silverstone have high specific weights which make them well suited to this drilling slot.
Beyond mid-November and the list of suitable varieties dwindles rapidly. Conqueror was a past favourite of late drillers and often did well in this slot after roots. More recent introductions, such as KWS Siskin, KWS Crispin and KWS Silverstone have been found to do similarly well in this position, but with better yield performance.
Slugs and other pests are, of course, a significant threat to late drilled crops, but there should time to establish the level of risk and decide on appropriate course of action well in advance of sowing.† For example, where a molluscicide is required, then growers will have time to consider whether metaldehyde-based pellets are suitable or whether a switching to a ferric phosphate-based alternative would be more sensible.† Whichever product is used, opt for a pasta-based wet process pellet for greater durability and persistence. Application research performed by AHDB suggests broadcasting pellets to the surface after drilling is likely to be more effective than applying them with the seed this makes it harder for the pest to locate the bait.† Similarly, the number of baiting points required is also often overstated.† Just 32-35 pellets per square metre is sufficient to achieve effective control with standard size pellets.