T3 Timing Depends On Target

Base your T3 timing on target growers are being advised.


Rain has at last arrived in some areas and hopefully will refresh the potential in wheat crops, especially those drilled in the autumn. But it could also stir Septoria and Fusarium threats, and brown rust will have benefited from the warm weather.

The variation in crop potential makes T3 choices tricky, but so does the variation in leaf emergence. T2 spray dates ranged widely given the variability in flag leaf emergence between autumn and winter drilled wheat. In some cases the gap to GS63-65 could be a lengthy one.

In most seasons a stretched run into T3 sprays would cause alarm for Bayer’s Ben Giles, but this season it depends on the target.

Brown Rust

Where foliar disease is the focus he says there is some timing leeway, which could even be beyond flowering period. “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. There’s also plenty of options in terms of product and dose, which could be as simple as a modest dose of tebuconazole for brown rust.”

Bayer’s Ben Giles

But where Fusarium is a factor he points out timing is everything, as is product choice. “The window for Fusarium protection is the shortest and you have to spray at the first sign of anthers emerging from the middle of the ear. Miss that and Fusarium protection is compromised. The product options are short too with prothioconazole and tebuconazole as the only real choices.”

And targeting anther emergence doesn’t mean a compromise in foliar top up. “Most SDHIs are strong protectants for Septoria and brown rust and many growers will have still favoured this over an azole + multisite mix at T2. Growers with the likes of Crusoe and Lily will no doubt have concerns with brown rust but providing the disease hasn’t taken hold adding a product like tebuconazole or pyraclostrobin to a Proline (prothioconazole) T3 base will clean up any infection,” he concludes.

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