Absorption and translocation of 14C-propiconazole associated with two adjuvants in young coffee plants.

BACKGROUND: This study evaluated the absorption, translocation and distribution of 14C-propiconazole applied alone or combined with two biodegradable adjuvants for coffee rust control. Solutions containing 0.5% (v/v) adjuvant were applied to the adaxial leaf surface and absorption was quantified by liquid scintillation counting (LSC) and semi-quantitatively assessed by autoradiography. RESULTS: The treatment 14C-propiconazole-DPS showed the highest absorption rate, reaching 0.16% h-1. In contrast, the treatments of pure 14C-propiconazole and 14C-propiconazole-WS exhibited lower absorption rates, with 0.055% h-1 and 0.028% h-1, respectively. Although maximum translocation did not exceed 1.0% of the applied amount in any treatment, qualitative analysis revealed distinct patterns: pure 14C-propiconazole translocated to opposite leaves and to leaves below the treated leaf, demonstrating radial transport, whereas 14C-propiconazole-WS showed limited translocation after 96 h after application. CONCLUSION: The biodegradable adjuvants demonstrated complementary effects: one adjuvant enhanced the initial absorption of propiconazole, whereas the other contributed to product persistence on the leaf surface and delayed translocation. Both adjuvants showed potential for improving fungicide performance, representing promising alternatives for more efficient and sustainable control of coffee leaf rust. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.