More benefits from fungicides

The inclusion of both strobilurin and SDHI fungicides means that other physiological benefits can be delivered by well-timed programmes, helping crops to give additional responses and achieve higher yields.

"Despite the introduction of new SDHIs this year, the principles for the 2011 season remain the same," he says. "Triazoles should form the basis of any fungicide strategy, with added disease control coming from niche products if required and added value coming from fungicides which improve greening, nitrogen uptake and stress tolerance."

Cereal growers must be aware that they can't get this additional yield from a triazole-based programme alone, he notes.

"You need to make use of mixtures for the extra yield. And you also need to put enough fungicide on."

 The three factors which limit yield potential are poor timing, insufficient dose and incorrect product choice, warns Mr Clark.

"If fungicide timing goes awry, it is difficult to get good results. And there's every chance that T1 treatments will be applied too late this year, because growth stages are all over the place after such a cold winter."

That will make a T0 spray essential, he believes.

For this year, the presence of yellow rust in susceptible varieties means that a triazole should be included at T0 and will be essential to stopping the disease at T1, he advises.

Applying insufficient is another limiting factor, notes Mr Clark. "National surveys show that rates are commonly reduced by more than half, with epoxiconazole being used at 0.49 of the average label dose.

"That's madness, as you don't get any yield benefit at that level. Today's high yielding varieties give better responses to fungicides, but there's no benefit without the right dose being applied."

Product choice also makes a difference, he comments. "There's plenty of information available on the performance of different fungicides, both in protectant and eradicant mode. And there are new formulations available this year, all of which are improvements."

Strobilurins have a place at both T2 and T3, as they prolong grain filling, he explains. "They're especially valuable with high yield potential crops. They maintain green leaf area, delay senescence and increase nitrogen uptake. They're also very useful for rust control."

The two new SDHIs have a similar physiological effect to strobilurins, although the mechanism is different. "They too have additional effects over and above disease control, which is why yield responses from them have been so impressive. They have an obvious place at T2, but their persistency means they mustn't be exposed to resistance by delaying the T3."