Navigating the Post-Tebuconazole Era: The Search for Better Alternatives

Recent stringent re-evaluations in Europe has led to restrictions and bans on several triazole fungicides due to concerns over environmental impact, endocrine disruption, and human health environmental impact, endocrine disruption, and human health risks in 13, with insufficient data to rule out endocrine effects on humans and wildlife. Consequently, the demand for safer alternatives has grown, particularly as older products are withdrawn from the EU market. Tebuconazole, now a candidate for substitution due to its reproductive toxicity, faces possible deregistration in 2026, highlighting the urgent need for effective replacements given the vital role of triazoles in crop protection.

Registration Status of Major SBI-I Fungicides in the EU

(Among the eleven major SBI-I products, those currently in the “not approved” status all had their re-evaluation processes prematurely terminated due to the applicants’ own decisions.)

Of the potential alternatives, from our perspective, Prothioconazole and Metconazole stand out as the most promising ones. Prothioconazole has already proven its worth in the market, while Metconazole, though less recognized, is emerging as a strong contender. A recent assessment by the European Food Safety Authority (EFSA) in August 2023 found no critical areas of concern in Metconazole’s re-evaluation, extending its approval in the EU until August 2031. This assessment not only confirms the fungicide’s safety but also removes previous restrictions, solidifying its role in the market for years to come.

To identify the most promising alternatives, a comprehensive evaluation of the latest cereal fungicides is essential. The table below highlights that the newest fungicides are primarily within the SBI-I and SDHI categories, many of which still enjoy long patent protection. Limiting our focus to those compounds that could be commercially viable right now or within the next five years, we find viable options being Prothioconazole, Metconazole, Bixafen, Benzovindiflupyr, and Fluxapyroxad. However, the latter three have narrower applicability compared to Metconazole and Prothioconazole. For example, they all have lower effectiveness against Fusarium Head Blight (FHB) while Bixafen and Benzovindiflupyr are unsuitable for seed treatments. The biggest problem for Benzovindiflupyr and Fluxapyroxad are their currently high costs. Prothioconazole and Metconazole emerge as the most broad-spectrum and cost-effective choices, both showing high efficacy against FHB. As capacity of Metconazole ramps up in China, its price is expected to fall below that of Bixafen in the near future. Prothioconazole and Metconazole can be used in rotation to manage resistance, with Metconazole also aiding Prothioconazole in the treatment of specific challenging diseases.

New Cereal Fungicides Evaluation

While global sales of Metconazole have declined in recent years, its usage has remained stable at around 600 tons annually (equivalent to technical concentrate), indicating consistent demand. Currently, it is primarily used for FHB in wheat and Sclerotinia stem rot in canola, with some seed treatment applications in North America. However, its potential remains largely untapped. Future opportunities lie in expanding its use to other crops and diseases, as well as in seed treatments, where studies have shown Metconazole to be one of the most effective triazoles for seed treatment. Additionally, the development of mixed formulations presents further potential, given Metconazole’s excellent compatibility with other compounds, but BASF’s extensive patent coverage poses a certain risk.