A NEW grower survey has given a '2020 vision' into what wheat diseases will be giving growers most grief this coming year.

It's key findings are that controlling the UK’s number one wheat disease, septoria; the loss of multi-site fungicide chlorothalonil (CTL); having fewer fungicide active ingredients in general; and control of yellow rust, will feature prominently.

Those are the very real challenges facing wheat disease control in 2020, according more than 100 respondents to the survey – and these were mainly farmers plus a handful of advisors.

Conducted independently for Syngenta, the results showed almost every respondent was highly concerned about the revocation of chlorothalonil – which has a 'last chance sallon' date for use of May 20, this year.

Chorothalonil is the backbone of septoria tritici management, mainly because resistance or reduced sensitivity has appeared in other fungicide groups, such as strobilurins and triazoles, and for protecting SDHI fungicides, pointed out Syngenta's fungicide campaign manager, David Ranner.

Accordingly, its loss is expected to have a major impact in several areas, the survey revealed. These included: Higher levels of septoria and septoria resistance; a need to use less effective alternatives, or more expensive fungicide chemistry; plus lower yields and higher costs of production.

“Certainly, the loss of chlorothalonil will change how we have to tackle septoria tritici,” said Mr Ranner. “Two-thirds of advisors and 40% of farmers spontaneously mentioned the loss of chlorothalonil and fungicides in general as challenges or concerns for wheat disease control in 2020.

“Typically, septoria tritici causes yield losses of up to 20%, but losses in the wetter west can be higher. We’ve already seen with black-grass how growing wheat becomes more difficult when resistance gets out of hand. It is important to continue to delay the escalation of septoria tritici resistance once chlorothalonil has gone,” he argued.

While there was some confusion in the survey as to which fungicide might be used to replace chlorothalonil in wheat, Mr Ranner says there was an indication that the multi-site folpet was the favoured option.

“Even with new fungicides coming along, it is important they are protected in programmes and not left exposed to resistance,” he stressed. “Because a multi-site fungicide controls disease at multiple points in its metabolism, including one can help to delay resistance development.

“For a cost-effective strategy against septoria tritici resistance, start with a multi-site as the foundation for the programme, before deciding which other fungicides to add to it based on available budget. Our guidance is to continue using chlorothalonil, if available on farm, as the multi-site of choice until May 20, switching to folpet thereafter.”

Other strategies highlighted by the survey that respondents are most likely to use once chlorothalonil can no longer be used included changing to varieties more tolerant to septoria, even if that meant compromising yield potential or other characteristics, and increasing the doses of SDHI or triazole fungicide products.

“Variety resistance provides a foundation for reducing disease. The recent introduction of varieties with improved septoria tritici resistance – such as Graham and Gleam – has now proven extremely timely,” added Mr Ranner.