Top tips for T0: Spraying variable and fast-moving cereals

In this blog, AHDB’s Ollie Johnson comments on managing disease pressures in rapidly growing, variable crops of winter wheat.

With the second wettest August-to-February period since 1837, it is unsurprising that crop condition at the T0 timing has been compromised.

We believe that about 40% of the national winter wheat area could be described as ‘poor’ to ‘very poor’. The numbers are likely to be similar for winter barley.

As usual, some areas have been hit harder than others. Things appear to be particularly challenging across the Midlands and the Yorkshire and the Humber regions. Our next crop development report is out in a few days, which will provide further information on the condition of the major cereal and oilseed crops in the UK.

Where growers have managed to get their early nitrogen and sulphur applied, crops are picking up. The condition of roots remains a concern and could prove problematic, especially if conditions become much drier. ‘Diseases of old’, such as take-all or eyespot in second wheats, have the potential to become highly visible.

Today (27 March 2024), I visited one of our Recommended Lists (RL) winter wheat trials in the East Midlands, where foliar diseases are taking hold. Yellow rust and septoria tritici were prevalent in most varieties. In relatively susceptible varieties, disease was obvious at quite a distance.

I was particularly struck by the level of brown rust. Normally, the disease would not be seen for several more weeks. Where rusts (brown and yellow) are active, especially on varieties with relatively low disease resistance ratings at the adult plant stage, a robust T0 with good rust activity – such as tebuconazole or azoxystrobin – should be considered.

The latter active ingredient has some slight activity against take-all. Reduced active rooting (following waterlogging) and wet springs (which can encourage take-all development) mean it is worth bearing this in mind. We published a report on the effects of azoxystrobin on wheat take-all in 2001.

As always, spray timing is important. T0 is often applied from late tillering to the start of stem extension. However, things are really moving with the mild conditions, with many crops at GS30–31 (especially in the early varieties KWS Palladium and KWS Extase).