Growers are being advised to consider late season fungicide programmes carefully amid reports of low disease pressure this year.
Moderate disease levels in wheat due to the hot, dry summer in 2018 generally resulted in cost-effective but lower yield responses to fungicide programmes than the previous season, says Hutchinsons technical director David Ellerton.
"Despite the dry conditions later in the season, the largest yield increases were often in response to the flag leaf or T2 timing in Hutchinsons small plot trials, although drought and subsequent early senescence reduced the response in many cases."
In Hutchinsons winter wheat variety trials, the average yield response across sites and all varieties was 1.54 t/ha (17.28 % of final yield) compared to 2.64t/ha (28.48% of final yield) the previous season, said Dr Ellerton.
But there was a significant difference between varieties with Reflection giving a response 2.67 t/ha, while disease control in Santiago, Costello, Leeds, LG Rhythm and Gleam resulted in an increase in yield of over 2 t/ha.
"It is important to realise that the gap ween the flag leaf spray and the previous T1 fungicide should be a maximum of three to four weeks to continue disease protection, once the earlier spray begins to run out of steam," says Dr Ellerton.
For ear emergence T3 sprays, triazoles often form the base, including active ingredients with activity on Fusarium – favoured by warm, wet conditions – such as prothioconazole, tebuconazole or metconazole/epoxiconazole.
"Where Microdochium risk is high in cool, wet seasons, the emphasis should be on prothioconazole - although in last seasons' AHDB trials the multi-site product mancozeb was also found to give useful control."