T0 fungicides a useful insurance policy

Applying a T0 fungicide to wheat crops will still be a worthwhile investment, despite lower disease incidence – particularly rust – than last year, agronomists advise.

“The fact there’s any disease about at all means the T0 is a valuable insurance, especially on ‘rusty’ varieties,” Agrovista’s Mark Hemmant says. “It might be lower risk than last year, but we’ve seen quite a bit of septoria about and a bit of brown and yellow rust, which is worth treating. There are reports of quite bad yellow rust in some regions, so we need to watch out.”

Scottish Agricultural College technical director Keith Dawson says T0’s are an “absolute prerequisite” at current grain prices as they can make disease control easier later in the season.

There are a lot of products available, but he says keep it simple and match product to variety. “For septoria-susceptible varieties, Opus (epoxiconazole) is the best option, probably with a mixture of Bravo (chlorothalonil) in there if crop biomass warrants it. For brown rust, Folicur (tebuconazole) is probably a better option on varieties like Alchemy, but in most situations Opus is best.”

Mr Hemmant says chlorothalonil is important for controlling septoria, but growers should avoid mixing it, and any other T0s or PGRs, with Atlantis (iodosulfuron + mesosulfuron). “There will be the temptation to mix Atlantis, as quite a lot didn’t go on due to poor weather. But you need to avoid mixing it if you can, otherwise you do get a drop-off in efficacy.”

Mildew is also worth treating early and if needed, he suggests including metrafenone with he T0.

Tod Hunnisett says until last year, his T0s had traditionally just targeted septoria with chlorothalonil. “But last year we saw the value of including a triazole against brown rust.”

So this season he plans to use either 1 litre/ha Cherokee (chlorothalonil + cyproconazole + propiconazole) or 0.25 litres/ha Opus plus 1 litre/ha Bravo. “A bit of triazole at T0 allows you to delay the T1 and if needed it lets you do a straddle T2/T3 spray.”

Not all crops will receive a T0, he adds. “Late (November)-drilled wheats are still at mid-tillering, so I will probably just go with the traditional T1 at growth stage 31-32, which isn’t likely to be until the last week of April.”