A fungicide from a chemical group with the potential to become the cornerstone of future fungicide programmes is in development with a view to launching in 2010, approval permitting.

Isopyrazam, coded 520 by its manufacturer Syngenta, has the same mode of action as boscalid, but when used appropriately in programmes would help provide a “step forward in yield”, the firm’s David Ranner says.

Key to that is strong activity against a wide range of cereal diseases from a largely protectant mode of action, which has given an extra one to two weeks’ protection over triazole fungicides against the key wheat disease, Septoria tritici, in initial trials.

In one trial last season, for example, designed to test the protectant activity of individual active ingredients, epoxiconazole and prothioconazole started to break down to septoria six to seven weeks following the single full rate spray at GS32-33, while 520 lasted for eight to nine weeks.

Despite these encouraging results, 520 will not be recommended as a stand-alone product. Part of the reticence comes from the fear of resistance developing as it did with strobilurins.

You should see the untreated! Fungicide 520 has shown very impressive septoria protection in trials, according to Syngenta.

Like that group, 520 works at a single site within the fungus, and therefore is unlikely to be classified as a low-risk compound when the Fungicide Resistance Action Committee classifies it sometime this winter, Mr Ranner says. “This product will not be used alone. We hope ourselves and the market have learned from the strobilurin experience.”

In other trials in wheat, the mix approach has also added to disease control and yield levels. For example, a two-spray programme of 520 gave an extra 0.5t/ha over a triazole programme, while a mix of 520 and a triazole gave an additional 0.5t/ha, he says.

Both rust diseases are also controlled by 520, with activity “at least as good as the strobilurins”, while the product also gives some control of eyespot, mildew and michrodochium.

In barley, a mix with cyprodinil looks promising too. While in trials 520 alone doesn’t quite match up to industry standard Fandango (prothioconazole + fluoxastrobin) against key diseases rhynchosporium and net blotch, the mix does. “Across 16 trials yields are also comparable,” Mr Ranner says.

The active isn’t just being developed for cereal crops, Rod Burke, product manager for Syngenta says. “We’re most advanced [other than cereals] on oilseed rape, but also looking at vegetable crops.”