This week’s cold spell may have reduced the yellow rust threat and bought growers some time, but the threat remains and susceptible varieties may need treating once it warms up.

Last week Frontier agronomists highlighted there had been a spate of yellow rust reports in Lincolnshire and Cambridgeshire and warned that farmers may need to go on with a pre-T0 spray.

Christine Lilley, technical support manager for Frontier, says the late start to the season has added extra disease pressure, with the true T0 timing probably some weeks away.

But Miss Lilley did highlight that weather will be a big factor in determining whether or not a pre-T0 spray is needed.

“Last week’s warmer weather saw growers finding yellow rust fairly easily. However, the colder spell this week has nullified the threat for now and could well take us to the more conventional T0 timing, with no need for a pre-T0,” she says.

The end of March to the first week in April is the conventional T0, but it will be difficult to predict this year.

“Once it does warm up the disease will be there and could potentially be a big issue, so growers need to be aware of the threat,” she adds.

ADAS plant pathologist Peter Gladders also urges growers to look out for yellow rust. But he adds that the change in weather has bought growers a bit of time and resulted in a pre-T0 application being less important.

“I can’t see a pre-T0 being needed now. I think growers would be better off hanging on. There’s not going to be a lot of new activity until the end of the month at the very earliest,” he says.

Dr Gladders advises waiting until T0 to get a fungicide application on – only if it is needed. He stresses growers should avoid running into a five-spray programme rather than a three or four-spray approach.

Strutt and Parker agronomist Ryan Hudson says if there is a need to go on with a pre-T0 spray, Corbel (fenpropimorph) will carry the crop through to the normal T0 timing.

Although the need for a pre-T0 has declined following the cold spell, Mr Hudson says nothing can be taken for granted.

“We can’t afford to lose anything – any of the plant or any of the leaf. I think where we’ve got thinner plant stands, every single leaf on the plant is going to contribute towards yield this year.”

In the next two weeks he will be looking at getting some sort of fungicide on, even on the backward wheat crops.

“If growers choose not to go with a pre-T0 then the T0 will be important for yellow rust and also septoria.

“Generally the view is that it will be a triazole plus chlorothalonil product, so Cherokee (chlorothalonil + cyproconazole + propiconazole) will be the backbone of our T0 programme.”