A worrying yellow rust presence – fuelled in part by a reliance on some varieties – coupled with manganese deficiency, means growers will need to be ultra-vigilant in the next few weeks.
According to Dr Tudor Dawkins, technical director for agronomy firm ProCam, the Borders and parts of Northern England have septoria building as temperatures rise, with yellow rust now also being found in a number of crops. 
Further into Scotland, he said that septoria and mildew are most prominent, with no yellow rust as yet, though this should not be ruled out. Manganese deficiency is now also appearing, he added.
“Around 20% of winter wheat varieties in the ground this year are at risk from yellow rust, with 30% having a significant vulnerability to septoria and 55% having susceptibility to eyespot,” pointed out Dr Dawkins.
“Check crops regularly. Disease levels and nutrient deficiencies need addressing before, not after, they become yield-limiting. As an industry, we have traditionally focused heavily on the later spray timings of T1, T2 and T3, and been more reluctant to also include earlier T0 fungicides. 
“However, now we have septoria populations that have become more difficult to control and new yellow rust races that are eroding confidence in variety ratings, early disease prevention has become more important.”
Pointing to ProCam trials, Dr Dawkins said consistent benefits have been seen from including a T0 application over recent years.
“Even in 2016, when a lack of sunshine in June and July curtailed yield, we still saw a yield response of 0.5 t/ha from including a T0 fungicide,” said Dr Dawkins. “At current wheat prices, that's a return of around £50/ha nett of fungicide cost. 
“T0 is also a useful time to include anti-resistance fungicides against septoria. But it’s not just the standalone benefit from controlling disease there and then that is important. Growers with a large area to protect can buy time by applying a T0, which gives a bit more flexibility with the T1 application,” he argued. Admitting that not all crops would benefit from a T0, he believed that omitting it can add later pressure. 
“Growers who have planted a more resistant variety and delayed sowing into November to reduce blackgrass pressure, or sown the crop later following root crops, may be able to omit a T0,” he argued.
“However, the timing of the T1 will need to be spot on if they do this and T1 may need to be more robust to ensure disease doesn’t become established..
“Fungicide programmes are a good investment, typically giving potential returns of £2 back for every £1 invested and T0 should be considered an integral timing in the programme, not just an add on,” he concluded.