Results of a recent survey suggest that more than two thirds of farmers think that T0 fungicide in winter wheat has become more important that five years ago.
The survey, conducted by cereal growers Syngenta, showed that 68 per cent of survey respondents felt this was the case.
The main reason, given by over half of the respondents, was that Septoria tritici and yellow rust have become more difficult to control if not prevented early.
Almost a third said that T0 gives some insurance against T1 delays, but despite the importance attached to T0, 17 per cent of respondents had still cut back on T0 in winter wheat in 2016.
Andrew Curtis, Syngenta cereal fungicide campaign manager, said: "The key point with winter wheat disease control nowadays is that we have to take a more preventative approach.
“Shifts in the sensitivity of Septoria tritici to the curative effects of azole fungicide chemistry mean it has become more difficult to regain control later if allowed to establish.
"Similarly, we saw last year just how quickly the latest yellow rust races can develop, and how difficult they can be to get back under control.
“Even if crops appear clean at T0, which is typically in March or early April, it is impossible to accurately predict future disease pressures.
“For example, new trial results from 2016 in what was a high pressure situation, showed yield was increased by 0.7 t/ha across three different winter wheat varieties from a T0 application of the chlorothalonil plus azole treatment, Cherokee.
"That was despite a robust follow-up fungicide programme being used.
“As the survey highlighted, you also have to consider the benefit of having applied a T0 if your follow-up T1 fungicide is delayed.
"T1 and T2 fungicides, which protect the main yield-building leaves, give better results if applied to clean crops.
“The chlorothalonil treatment Bravo is a popular option at T0 against Septoria, but if there’s a risk of rust as well, you’re going to need more than this.
“Cherokee is cost-effective because it provides a high loading of chlorothalonil plus two leaf-mobile azoles – including cyproconazole which is noted for its yellow rust activity.
"Usefully, it also targets disease with different azoles to epoxiconazole and prothioconazole, which are frequently used later at T1 and T2.”