It was likely that the later drilled winter wheat plots at Hinton Waldrist wouldn’t fully vernalise, and that has proved to be the case.
All February drilled plots have varying degrees of vernalisation, the number of ears that have formed depends on the variety and how far into the month it was drilled. One potential surprise is Nelson – a variety noted for a drilling window as wide as September to the end of February. Even early drilled February plots have incomplete ear emergence, despite stems extending.
Extase fared a little better than most but site manager Ben Giles suggests it’s better to err on the side of caution when it comes to latest sowing dates.
Another interesting aspect with Extase was the short interval between leaf emergence over different drilling dates. Leaf three emergence between late October and late November drilled plots was only six days apart, flag leaf emergence less at just three.
The trial also highlighted that drilling date does have a bearing on yellow rust severity, as later drilled untreated JB Diego plots are carrying more of the disease than earlier drillings. However, all treated plots are clean regardless of what azole and SDHI combinations were used.
All varieties regardless of drilling date are now beyond full flag leaf emergence at Hinton Waldrist, and the anthers are emerging on October sown fast developers like Skyfall, Extase and Graham.
For site manager Ben Giles he cannot recall a season recently where the anthers have been out so soon after T2 application at Hinton Waldrist. It has taken him a little by surprise and he wonders if plant stress has been a factor in the race to flower and then start grain fill.
But whatever the reason it doesn’t change the situation for growers, the time between GS39 and GS63-65.
Where the target is foliar top up, Mr Giles says it isn’t a critical issue, as there is more timing flexibility. Indeed, with low disease pressure at the moment he questions whether growers need to spray at all unless covering a late brown rust infection. “As you’re not specifically targeting the ear you can time the application for when the T2 spray might be running out of steam. This is likely to be around 2 – 3 weeks after it went on, depending on what was used.”
But for those wanting a safeguard against Fusarium and mycotoxins he says timing is everything with such a narrow window. “You have to spray at the first sign of anthers emerging from the middle of the ear. Miss that and Fusarium protection can be compromised.”
Growers urgently need to check their fast-developing varieties for flag leaf emergence.
Extended day length usually means the differences seen in winter wheat leaf emergence at GS32 iron out by GS39. But not in this strangest of seasons. At Hinton Waldrist in Oxfordshire leaf three emergence ranged widely across variety and drilling date, and flag leaf emergence is likely to vary considerably too.
October-drilled fast developers have continued to ‘romp on’, in particular Extase plots drilled on 21 October. Despite T1 sprays only being applied on April 27, the flag leaf was almost fully emerged on site manager Ben Giles’s visit on 8 May. “If the T2 spray is going to fully protect the most important leaf of the pack, then it will be going on within the next few days.”
That is a gap from GS32 of just over two weeks, which is incredibly short, he notes. “Growers need to be vigilant as those expecting a four-week stretch from T1 will apply their T2 well beyond the optimum timing, with the risk of disease already established.”
October drilled Gleam and Diego are a whole leaf behind, but later drilled Extase plots are catching up. “Leaf three emerged in November drilled Extase around the turn of the month. Flag leaf emergence isn’t that far away, again the gap to GS39 will be short.”
Watch Ben Giles video for the latest progress from the Hinton Waldrist Field Day site in Oxfordshire. Around 50mm of rain has helped crops take up nitrogen and grow quickly in recent weeks. T1s were applied to these plots on 26 April.
Watch the video to look at disease levels in various key varieties.
Slower developing varieties have suddenly got moving at the Bayer trial site at Hinton Waldrist, Oxon, as rain kicked things into life, meaning regular assessment is required to make sure T1 fungicide timings are hit accurately.
After 20mm of rain the latest visit on April 24 revealed leaf three is ‘on the way’ for less vigorous varieties such as J B Diego. January drilled late developers are still behind, but plots drilled in November and December are moving faster than perhaps anticipated. “In these plots leaf three ranges from a third to half fully emerged, and plants have obviously dropped a leaf or two. It’s worth checking later drilled fields regularly at the moment because it is so important to get that final leaf 3 T1 timing correct.”
KWS EXTASE - Drilled 21/10/19
KWW EXTASE - Drilled 20/11/19
JB DIEGO - Drilled 21/10/19
JB DIEGO - Drilled 20/11/19
Don’t assume that late November or early December drilled wheat will be much behind those drilled in mid-October by the time T1 sprays need applying. That’s the warning from Bayer’s Hinton Waldrist trial site manager Ben Giles.
Extase drilled on October 21st is at leaf three full emergence, with sprays due around ANZAC Day – April 25th. Naturally, January or February drilled Extase is some way behind and leaf three emergence is more likely into early May. But early and late November drilled plots have caught up, with T1 sprays probably due only 5 to 7 days beyond October drilled plots. “Quick developers like Extase and Skyscraper have rapidly narrowed the gap in drilling dates and there is a danger that leaf three full emergence might be sooner than growers anticipate.”
At Hinton Waldrist Septoria is currently confined to the base of plants, which should ease the pressure on T1 sprays. But parts of the south including Hinton Waldrist received sufficient rain last Friday/Saturday to cause rain splash further up the canopy.
With showers possible he cautions against complacency. “Elsewhere in the country, leaf 3 is likely to be under less pressure as the disease hasn’t established on new growth. But any change in the weather combined with a delay to a T1 application could leave it exposed, and open to infection. We saw last season how quickly the situation can change as Septoria severity rose rapidly on the back of late season rainfall.”
KWS Extase - drilled 21/10/2019
KWS Extase - drilled 30/10/2019
KWS Extase - drilled 20/11/2019
Here’s why using nodal growth stages will not be a good indicator of leaf three emergence this season. These Extase plants were drilled on eight different dates between 21st October and 21st January at Bayer’s Hinton Waldrist demo site – with it hopefully obvious that the latest drilling date is on the left.
The combination of light ground, excess winter rainfall and recent dry conditions have caused restricted rooting and this has slowed tiller production. October drilled plots have at best got five tillers, meaning there could be a shortfall in ear number compared to the AHDB benchmark of approx. 450/m2.
Currently, all crops are not yet at true GS30 but the later drilled ones will drop leaves and leaf three is likely to emerge at GS31 rather than the more usual GS32. If T1 applications are delayed on these later crops until GS32 then leaf three, or even leaf 2, may have been out for some time.
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