Arable
Take T2 action to maximise wheat potential
• Yellow rust is priority this season • Septoria tritici influence by rainfall • Stick to correct T2 spray timings
H
igh grain prices and variable spring weather mean finalis- ing T2 or flag leaf fungicide de- cisions in winter wheat must be care- fully assessed this season. Grain prices of over £170/t make it worth protecting crop output proper- yl, says Syngenta senior field techni- cal manager Iain Hamilton. At these prices, just an extra 0.25 t/ha from a fungicide is worth a healthy addition- al £42/ha, he points out. “Even when we had low disease pressure last year, fungicides still lift- ed yield by 2 t/ha on average across dif- ferent wheat varieties over the season. This year, disease pressure is proba- bly higher.”
With yellow rust very much the main disease after a dry early spring, Mr Hamilton says it could remain a key target for T2 – particularly as out- breaks are less predictable with the appearance of new races. Similarly, brown rust thrives when there is a warm, dry end to the season, so growers and agronomists should check the brown rust resistance of any varieties.
Septoria risks
“If rust is your main concern, Elatus Era has been proven in independent trials to be an outstanding SDHI/tri- azole combination for both these dis- ease, with significant yield benefits and return on investment.” After a slow start and cold, dry ear-
ly spring, development of Septoria trit- ici will be influenced heavily by rain- fall levels between T1 and T2 – and by variety resistance. Mr Hamilton says development tends to be slower on va- rieties with greater resistance, such as Graham.
“If you are in a situation of prevent- ing Septoria tritici, various SDHI- based fungicides are available – and the differences in products are much smaller than with rusts.”
Growers trying to cure infection
may need to increase the dose of the SDHI treatment or look at a newer fungicide with more curative activity at an appropriate rate. In both cases, remember that long-lasting activity will help protect grain-filling.
Weather effects
Rainfall increases Septoria, says Mr Hamilton, but do not be lulled into a false sense of security if dry. Growers should also consider how the weather
8 ANGLIA FARMER • JUNE 2021
Long-lasting activity
protects grain- filling, says Iain Hamilton
Left: Flag leaf protection is key to optimise yields
after T2 will influence diseases. Two years ago, deluges in June sparked a late-season Septoria epi- demic. On the other hand, rusts like drier weather. If it does turn into a dry end to the season, certain fungicides have also been shown to have physio- logical benefits. In trials, a T2 application of So-
latenol – the SDHI in Elatus Era – gave an extra 0.23 t/ha over untreat- ed wheat in drought situations, even without visible disease.
Slow leaf emergence due to the cold spring meant the growth stage for T1 fungicides was often later than normal this season, says Mr Hamilton. But growers should not delay the T2 fun- gicide – because doing so could leave the flag leaf unprotected for too long. “For maximum protection, the cor-
rect T2 spray timing is still as soon as the flag leaf has fully emerged,” says Mr Hamilton. “If the T1 to T2 interval was short, view this as a bonus for pro- tection. If rain delayed the T1 even fur- ther, then timely T2 spraying becomes even more important.”
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