With chlorothalonil (CTL) no longer available for cereal disease control, growers are looking at what alternatives they can use.
The easy answer is the multisite folpet, says Hutchinson’s technical director Dr David Ellerton.
He said: “It is not as consistently strong as CTL, but it offers similar activity as far as septoria is concerned and has an additional impact on rusts too. However, it is more expensive than CTL.”
Folpet can also be used to give protectant control of ramularia in barley.
“As far as multisites go, it is a useful alternative to CTL,” says Dr Ellerton.
Some biostimulants, for example Scyon, a complex of metabolites designed to maximise nutrient health within the plant, although not a fungicide, can help the plant to overcome septoria by stimulating its inherent disease resistance, says Dr Ellerton.
“However, the most obvious CTL multisite alternative is folpet, while sulphur and mancozeb could also be considered,” he says.
On wheat, the earlier folpet, which has protectant activity, can be applied, the better, says Dr Ellerton.
“For septoria in wheat the optimum timing is usually at T0 or T1 while for ramularia in barley the disease normally comes in later in the season, so apply at T1 and/or T2,” he adds.
While folpet can be less consistent than CTL, in trials the crop often yields just as well, he adds.
Looking further into the season and into other crops, Cambridgeshire farmer Russell McKenzie is concerned about control of chocolate spot in beans without CTL.
He says: “I haven’t seen a lot that will be as effective, so that’s a concern. I don’t think we will know the real ramifications [of loss of CTL] until we see a season that will push the diseases that it would have been key for.”
Although growers will go to folpet as a multisite, it is not as good as CTL and many growers will use less multisite chemistry, believes independent agronomist Patrick Stephenson.
He said: “With a variety like KWS Barrel in a wet season and where there is a lot of disease, multisites help existing chemistry.
“But with varieties like Extase and Firefly, with improved septoria resistance, it is more difficult to
“With newer chemistry coming on stream, instead of including them in every spray application, growers will be more selective depending on variety and key positions [in the programme].”
Of other remaining multisites, Mr Stephenson says mancozeb’s future is uncertain and that sulphur is a product growers have ‘fallen out of love with’.
“It is used more commonly in France where there are a lot more restrictions on pesticide use,” he said.
“We may see it start to play more of a role going forward.
“There are no new multisites on the horizon. Folpet is much more expensive than CTL – up to 50 per
cent more expensive.”
He points to the fact that new fungicide Inatreq from Corteva may gain regulatory approval and become available this spring, but no earlier than T2. Further ahead, Syngenta and Bayer also have new fungicides
in the pipeline, he adds.