Managing late sown crops
25 Feb 2021
Dr Jon Helliwell, Business Development Manager
Conditions during Autumn drilling and recent weather events have led to a very varied national cereal crop. If any late sown or more backward crops are managed well, there is no reason why they should not deliver reasonably.
The temptation following the unique 2020 season is to write off many later sown crops as having low potential. However, this is a self-fulfilling prophecy – crops deemed low potential and treated accordingly will not achieve their potential. If these crops are managed well, there is no reason why they should not deliver reasonably – maybe not to their full yield potential that would have been achievable from being sown in October, but certainly combined with a buoyant grain price, returns per hectare could well be similar.
Vigilance and attention to detail this spring will be crucial, for both disease control and wider inputs. The wetter than usual winter and continued rainfall recently will have increased the risk of nutrient leaching for example, particularly nitrates. Coupled with the high levels of nitrogen likely present in residues of lower yielding 2020 crops, appropriate SNS quantification as we approach T0 timing will be crucial.
End of tillering/GS30 T0
In many cases a T0 will only be technically justified if yellow rust and/or mildew are present. With the loss of CTL, this timing should be focussed around a rust active triazole for early eradication of yellow rust in high risk scenarios. It is also important to ensure the crop has an adequate supply of nitrogen, as well as appropriate PGR use to maintain tillers.
GS 31-GS32 T1
Later drilled cereals or those held back by recent weather will move through growth stages more quickly than usual. Therefore, as we approach the traditional T1 timing, the main focus will be accurate growth stage assessment. More backward crops will have produced far fewer leaves over winter and may visually look sparse. However, crop development is largely driven by day length (modified to some extent by temperature), and so stem extension and final leaf three emergence can occur in deceptively small plants. Careful dissection is required to determine which leaf layer has emerged in mid-April – reliance on nodes can be deceptive. Final leaf three can emerge at GS31 (rather than the normal GS32). This can have important consequences for fungicide timing to ensure adequate protection of yield influencing leaf 3, and PGR applications where label growth stage restrictions may affect applications.
GS 39 T2
There is no reason to believe that by this time that the crop’s developmental stage will be far off normal, and that the flag leaf will emerge around the same time. The disease epidemic may be slightly delayed, but history tells us that Septoria continues to be the main focus regardless of season.