The timing of your appropriate fungicide at T1 can impact the rest of your fungicide programme. T1 sprays should be applied to target final leaf 3 fully emerged and applying too early can be as detrimental as delayed applications as you don’t hit the target properly.
What to do
Where applications have been made in good time (i.e final leaf 3 fully emerged) as part of a robust spray programme, Proline275 0.55 L/ha + multisite remains the economic choice at T1, providing comparable disease control and yield to the latest SDHI options. By combining the most effective systemic azole with a protectant multi-site you are able to protect your fully emerged final leaf 3 from Septoria, yellow rust and mildew infection. With added activity on true eyespot and early season Fusarium inoculum management.
Where treatments have been delayed or a T0 has been missed it is likely that your crop will be in a curative situation at T1 and you will benefit from using a SDHI co-form. If you are planning on using an SDHI then 1 L/ha Aviator 235Xpro +/- multisite is your best option. With the benefit of an 80% dose of prothioconazole and the power of bixafen you are covering all your diseases concerns with additional benefit of the Leafshield formulation.
Is it really final leaf 3?
Ensuring the T1 application is targeted at final leaf 3 is essential to ensure the full benefits of this spray timing are achieved.
Following guidance from the AHDB cereal growth guide, it is clear that there is room for ambiguity as final leaf 3 can emerge anytime between GS 31 and GS 33. Simply counting the nodes present on the stem can be used as a ‘crude’ assessment of growth stage but will not identify exactly which leaf has most recently been exposed. To be sure final leaf 3 is present at application of T1, it is essential to dissect the plant and count the number of leaves rolled up internally within the stem.
Source: AHDB Cereal Growth Stages – a guide for crop treatments