<p>Dwarf mistletoes are important forest parasites that negatively affect host performance but positively contribute to community biodiversity. The dual parasitism observed in central Mexico, where <i>Arceuthobium globosum</i> and <i>A. vaginatum</i> share hosts, influences the population dynamics of both dwarf mistletoe species. This study aims to evaluate the impact of co-infection, where both dwarf mistletoe species parasitize the same host tree, on seed production. Seed production of mistletoes, with and without co-infection by the other species, was compared, along with the effect of tree diameter at breast height (dbh) and mistletoe dry weight on seed production. Co-infection significantly affected seed production; <i>A. globosum</i> produced more seeds alone, while <i>A. vaginatum</i> showed increased seed production in the presence of the other species. Both mistletoes benefited from larger tree dbh and mistletoe dry weight in terms of seed production. Interspecific interactions play a crucial role in dwarf mistletoe reproduction, influencing seed production and altering population dynamics. This has implications for management planning, as these interactions can either inhibit or facilitate seed production, thereby shaping the overall dynamics of dwarf mistletoe populations.</p>