<p><i>Rumex lunaria</i> is a translocated native species with invasive character in the island of Lanzarote (Canary Islands), threatening the fragile landscape of Timanfaya National Park and Los Volcanes Natural Park and altering the natural process of primary succession. This study explores the potential of <i>Fusarium</i>-derived compounds, particularly fusaric acid, to weaken <i>Rumex lunaria</i> populations. The effects of three different <i>Fusarium</i> strains culture filtrates (<i>F. languescens, F. annulatum</i> and <i>F. acuminatum</i>) were assessed, under greenhouse conditions, using leaf photosynthetic rate (assimilation of CO₂ and intracellular CO₂), transpiration rate, stomatal conductance, membrane permeability, chlorophyl <i>a</i> and <i>b</i> content and plant biomass. All three culture filtrates induced symptoms like chlorosis, wilting and burned or scorched leaves, a low biomass trend and a higher percentage of <i>Rumex lunaria</i> affected leaves. Plants treated with only mineral-based nutrient medium (Czapek) exhibited similar outcomes compared to treatments, in all measured variables. The mineral salts in this medium are likely responsible for inducing physiological stress in <i>Rumex lunaria</i> plants. Yet, in the field trials, only the culture filtrate strain 701 (<i>Fusarium languescens</i>) significantly increased the number of affected leaves and, in the greenhouse, showed a higher number of affected leaves than the other two culture filtrates and control with nutrient medium. This approach demonstrates the potential use of a fusaric acid-enriched medium to debilitate plants with invasive behaviour, particularly those already struggling to cope with harsh environments. By specifically targeting <i>Rumex lunaria</i>, this method could contribute to future control strategies aimed at eradicating populations from protected parks.</p>