Multi-site disease protection needed at T1 too

This year the T1 fungicide timing needs to be earlier than normal as most winter wheats are more advanced and the T0 sprays were applied earlier too.

It is important to protect the crop from foliar diseases including Septoria and yellow rust at this stage. The T1 fungicide treatment in wheat will be needed to deliver effective broad-spectrum disease protection plus a multi-site mode of action to manage the question of resistance management.

Andrew Gilchrist of Scottish Agronomy reports that there is a lot more yellow rust and eyespot in crops this year and his T1 treatment will be based around boscalid and epoxiconazole (Tracker) plus a multisite protectant such as chlorothalonil or mancozeb. "T1 sprays are applied to control diseases already present as well as to prevent any further disease developing in the subsequent four week period. It is important not to exceed a 4 week gap between T0 and T1, particularly in ’rusty’ varieties such as Oakley, Robigus and Viscount."

His choice of multisite protectant where rust is a factor is mancozeb. "We used to use a lot of this many years ago, but its usage fell off, partly because the powder formulations were not very user friendly. Now that we have a very easy to use liquid formulation in Quell Flo, it has come back on the scene. I have always preferred mancozeb over chlorothalonil where rust was a threat as it is a stronger protectant. Multisite fungicides play an increasingly important role in resistance management, helping to protect the activity of the current systemic fungicides."

We need to be careful as the fungicide armoury we have currently is good and it needs protecting with more multi-site fungicide usage, says Dr. David Stormonth, Technical Manager for Interfarm UK Ltd.

"But you also need a multisite fungicide that adds to disease control in its own right. Quell Flo delivers excellent protection against Septoria as well as mildew, yellow and brown rust. He reports that its efficacy has been demonstrated in trials where Quell Flo on its own resulted in a useful 30% control of Septoria tritici 18 days after treatment, similar to 1.0 l/ha of chlorothalonil. But for other diseases such as yellow rust, Quell Flo gave 28% control compared to 18% from chlorothalonil and 27% of brown rust compared with chlorothalonil at just 7% control. Quell Flo also gave superior control of mildew, 57% compared with 21% for chlorothalonil. Quell Flo is a significant contender when it comes to mixing with a triazole or triazole and carboxamide coformulation at T1 timing. And it won’t interfere with uptake or action of other fungicides in the tank," he says.

"A lot of crops in England and Wales are drought-stressed at a critical time when the ears are trying to maintain grain sites."