COLD AND wet weather may have compromised many T0 spray timing, so growers are being urged to 'reset' their programmes and centre on the GS32 fungicide spray.

Bayer’s Tim Nicholson told The SF that after many T0s were abandoned or applied late on winter wheat, now the focus should be on fully protecting leaf 3 – and timing is essential for that.

“It’s the first key yield producing leaf, so protection through to flag leaf emergence is important. The correct timing is when leaf three has just fully emerged.

"Too early and you might only protect the leaf tip and any fungicide could run out of steam ahead of GS39. Too late and leaf three is exposed to potential infection ahead of application.”

That advice, he added, doesn’t alter for those that got T0 sprays on. “The T0 is designed to protect leaf 4 from septoria spreading from the base and strike at yellow rust if needed. If a T0 goes on late, the T1 should still go on at the conventional time. It is a chance to reset the programme,” he advised.

In his view azole + CTL still has a place at the T1, but not where a T0 was omitted. “For many, weed control took priority, with black-grass herbicide efficacy compromised by CTL and severe frosts removing yellow rust in many cases, the T0 was dropped.

"With septoria present in the lower canopy, an SDHI at T1 is inevitable. They are our best septoria protectants, and offer some kick-back if needed.”

He added that farmers should control urges to increase rates. “Aviator (prothioconazole + bixafen) applied at the 1.0 l/ha rate with CTL will provide robust activity and an 80% rate of azole to help protect the SDHI. Growers must heed azole rates to reduce SDHI selection pressure as much as possible.

"Money saved at T0 should be reinvested at T1 to ensure products are used at appropriate rates,” he added.

PANEL

Finding leaf three:

A sharp knife is essential but also is the need to identify main tiller, pointed out Crop Management Partners agronomist, Richard Cromie.

Working back from the ear will allow growers to identify the emerging leaf once the main tiller is separated. “After separating the main tiller, split it in half from top to bottom cutting through the leaf layers. As you move down the tiller you should feel the nodes.

“Then gently lift everything out from the inside until you get to the top node in the plant. At this point you can discard the remainder of the tiller and then working from the ear, count backwards from the flag leaf to identify which leaf is currently emerging,” he advised.