strobilurins

Strobilurins are a class of fungicides derived from natural products produced by the basidiomycete Strobilurus tenacellus; they were first isolated in the early 1990s. They function as QoI inhibitors, binding to the quinol oxidation (Qo) site of the mitochondrial cytochrome bc1 complex (complex III) in fungi, blocking electron transport and energy production, which leads to rapid growth suppression and death.

Commercial strobilurins include azoxystrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin, and fluoxastrobin, among others. They are valued for broad-spectrum activity against many plant-pathogenic fungi, with systemic and protective actions; many products are used preventively and can show translocation within the plant.

Strobilurins are designated FRAC Group 11. Resistance has emerged in some fungal populations, notably via mutations in cytochrome b (such as G143A) that disrupt QoI binding, causing high-level resistance and cross-resistance to other QoIs. Management emphasizes rotating with fungicides of different modes of action, using mixtures, and limiting repeated QoI use per crop cycle.

Environmental and safety notes: strobilurins generally have low to moderate persistence in soil and degrade under sunlight and microbial action. They can be toxic to aquatic invertebrates; label directions should be followed to minimize environmental impact.