The AHDB has released performance data for the newly authorised cereal fungicide Plaxium, developed by Bayer CropScience.
According to testing, the product showed useful broad-spectrum efficacy in winter wheat and barley and will provide a useful option to manage several diseases.
It was approved for use by the Health and Safety Executive (HSE) in November 2024 and is a three-way formulation comprising two succinate dehydrogenase inhibitors (SDHIs) – fluopyram and isoflucypram (also known as iblon) – and the demethylation inhibitor (DMI) prothioconazole.
ADAS’ Jonathan Blake, who works on the trials, said: “We test products under code and can release independent performance data soon after approval for use has been granted.”
Trials are held in high-risk areas, using highly susceptible varieties and a single spray timing.
Winter wheat
Wheat trials focused on septoria tritici, brown rust and yellow rust. Plaxium was found to be highly effective against septoria, comparable to existing standards such as Revystar XE and Univoq and ahead of Ascra Xpro.
A comparable yield increase of 0.3t/ha was also noted.
For yellow rust, it was above both Ascra Xpro and Revystar, and comparable to Univoq and Elatus Era, with the performance carrying through to harvest.
In brown rust, Plaxium was seen to offer superior control compared to other mixtures and was comparable to Imtrex and Elatus Plus. The yield response was comparable to Revystar and higher than other products tested.
The AHDB quantified the brown rust findings, noting that since 2021 changes in the brown rust population have led to reduced activity from benzovindiflupyr, with it being unclear if other SDHIs are affected.
NIAB’s Stuart Knight, who also works on the trials, said: “The wheat trials indicate a clear efficacy and yield-response advantage for Plaxium compared to Ascra Xpro. This reflects the boost to foliar disease activity provided by isoflucypram, in place of bixafen, in this three-way mixture.”
Winter barley
Plaxium was also tested against rhynchosporium, net blotch, ramularia and powdery mildew, showing good efficacy against all four.
SRUC’s Fiona Burnett, one the trial partners and chair of the UK Fungicide Resistance Action Group (FRAG), said: “Plaxium adds another robust mixture option for the control of barley diseases and is carefully stewarded to manage resistance risk.”
Against rhynchosporium, both in protectant and eradicant situations, it gave excellent disease control, comparable or better than Siltra Xpro and Ascra Xpro, and similar to Miravis Plus.
Even at 50% of the label rate, Plaxium was shown to perform comparably with Miravis Plus and Ascra Xpro against net blotch, while in ramularia it matched Revystar and was slightly better than Ascra Xpro.
In powdery mildew, it gave the highest level of protection, although the AHDB notes that pressure was relatively low in these trials.
Resistance management
Plaxium is limited to a single application per crop and supports resistance management strategies as it contains two modes of action.
As well as winter and spring wheat, it can be used in barley, rye, triticale, spelt and oats, with applications taking place up to growth stage 61. A maximum dose of 75g/ha isoflucypram may be applied every two years.
