The debate over whether to apply a T3 fungicide to wheat crops has intensified after southern and eastern regions saw their first significant spring rainfall earlier this week.
Strutt and Parker agronomist Jock Willmott said the recent rains and cooler temperatures had made growers feel better about their crops, with some late uptake of nitrogen and slowing of crop development reducing the slide in yield potential caused by the drought.
Despite continuing low disease pressure, the Cambridge agronomist believed most growers in eastern regions will still apply a T3.
Septoria levels are low this year because there has not been much infection on leaves pre-T2.
But crops of Oakley have shown high levels of yellow rust all year and brown rust could be round the corner on susceptible varieties, he warned. “Having got this far, we can’t lose yield potential to indiscriminate late disease, almost irrespective of how crops look.
“If the season turns cooler, grain fill could be quite a long period, continuing through June and into July, allowing some crops to recover potential. Therefore, it’s essential to keep these crops alive for as long as possible.”
Mr Willmott said given the low disease pressure, there may be scope to reduce T3 fungicide rates by as much as half, depending on location, interval from T2, and disease susceptibility.
He is recommending Folicur (tebuconazole) because he believed it is “good value for money”. Where required, a trace element and/or an insecticide, depending on aphid risk, may need to be added to the tank-mix, he suggested.
Growers are also facing a tricky decision over whether to apply late liquid nitrogen, to boost protein contents in milling wheats, said Mr Willmott.
“At £35-40/ha it’s a big call – but milling premiums are there to go for.”
Cambridgeshire grower David Felce was due to start his T3s this week after strong winds and the subsequent rainfall delayed his timing.
His wheat crops on light land have died in patches, but on heavy land they are still showing potential despite the drought.
Most crops will receive a robust rate of metconazole, rather than a more expensive prothioconazole-based fungicide, he said.
“My product choice will, hopefully, cover all bases – rusts, fusarium and septoria to a lesser extent,” he explained.
Herefordshire AICC agronomist Antony Wade says applying a T3 still makes sense for most this season, despite the low disease pressure.
“With the wheat prices being so high it’s worth spending the money and trying to get every last bit of yield out of crops,” he reckoned.
“I’m advising to go with a T3, but to make it as economical as possible.”
His recommendations will be based on prothioconazole. “I’ll be going cheap and cheerful if I’m following Aviator (bixafen + prothioconazole). But if not, depending on variety, it will probably be Prosaro (prothioconazole + tebuconazole).”
Growers in Shropshire, Herefordshire and North Wales are generally on top of disease control and septoria levels are low due to a lack of rainfall.
“Instead of foliar diseases, I’m focusing more on fusarium to prevent mycotoxins,” he added.