Syngenta fungicide uses new chemical class

Swiss chemical giant Syngenta’s new molecule – code-named 520 – is a fungicide based on a new class of chemistry, the benonorbenes, reports Farmers Guardian. Syngenta plans to bring the new molecule, given the common name isopyrazam, to the market in time for next season’s winter cereal crops. The single-site compound’s actual mode of action is being assessed by the Fungicides Resistance Action Committee (FRAC) this winter. According to Syngenta Crop Manager Rod Burke, its key characteristics are persistence and a broad spectrum of activity. The new product will be recommended only as a mixture partner, most likely with the triazole epoxiconazole.

“Isopyrazam is a respiration inhibitor, in the same way that strobilurins are, but is effective on triazole and strobilurin-resistant disease strains,” describes Burke. Syngenta says isopyrazam’s key strengths are on septoria – with efficacy claimed to be better than straight epoxiconazole – and on rusts in wheat, as well as on ramularia in barley. Isopyrazam’s activity is largely protectant, but it also displays some curative action; in trials, says Syngenta, its effects were still visible on one sample seven weeks after treatment. At ten weeks, another sample showed only 7.5% disease intrusion, suggesting that isopyrazam offers one to two weeks’ longer protection than triazoles.