Participatory Ecological Assessment of Farmer Perspectives on Management of Invasive <i>Ageratina adenophora</i> in Eastern Bhutan

<i>Ageratina adenophora</i>, a native plant to Mexico, has rapidly invaded Bhutan's landscapes from subtropical foothills to subalpine zones. This has resulted in suppressed native plant biodiversity, impacts on economically important plants, altered soil properties, and crop yield losses. Although impacted farmers managing this weed possess deep, experiential knowledge, their insights remain under-quantified and under-utilized. We aimed to assess farmers' perspectives on the impacts and management of <i>A. adenophora</i> in eastern Bhutan. A focus group discussion with village leaders was held in Kanglung to refine nine literature-derived themes into five farmer-relevant priority areas: (1) weedy characteristics, (2) growth habit, (3) competitive effects, (4) control methods, and (5) awareness. A structured questionnaire was administered to 91 randomly selected farmers to rank five sub-themes under each priority area on a five-point scale. Responses were analyzed using Kruskal-Wallis rank tests and weighted-average calculations. Farmers assigned the greatest weight to characterizing <i>A. adenophora</i> as a weed (weedy characteristics) (28%), followed by control methods (24%), competition (20%), growth habit (16%), and awareness (12%). Sub-theme rankings differed significantly within each priority area (<i>χ</i> ² ≥ 78.95, <i>p</i> < 0.001). Farmers identified the species abundance, prolific seed production, and rapid seedling growth as key drivers of its aggressive spread. They perceived <i>A. adenophora</i> as both ecologically damaging and economically harmful, prioritizing management via uprooting, burning, and burying over slashing or herbicide application. By bridging the gap in quantified farmer-perspective data through focus group discussion, structured ranking questionnaires, and non-parametric analysis, this study uses a participatory approach for integrated invasive-weed management. It is replicable to similar agroecological landscapes, aligning scientific strategies with local knowledge to enhance sustainable control of <i>A. adenophora</i> to protect productivity of the farming lands.