Resumo. Basal stem rotting (BSR), caused by Fusarium spp., has been observed in peach palm (Bactris gasipaes Kunth. var. gasipaes Henderson) plantations in Brazil since 2000. The disease is a limiting factor to peach palm farming, damaging plants of different ages. The pathogen presence has been verified in seeds. The objectives of this study were: to evaluate the sanitary and physiological quality of eight commercial lots of peach palm seeds from Porto Velho, state of Rondonia, in Brazil; to compare two detection methods for Fusarium spp. in peach palm seeds; to evaluate pathogenicity and to compare aggressiveness of Fusarium spp. isolates from peach palm seeds; and to evaluate the chemical treatment of two peach palm seed lots for controlling Fusarium spp., about their effects on: a) sanitary effect; b) germination and vigor. The Fusarium spp. pathogenic may be transmitted by seeds to seedlings causing BSR disease. The paperboard methodology for Fusarium spp. detection proved to be more efficient for recovering this pathogen in peach palm seeds. The Chlorothalonil + Thiophanate Methyl and Thiophanate Methyl fungicides achieved the effective control over the target pathogen Fusarium spp. in peach palm seeds. Fusarium oxysporum and Fusarium proliferatum isolated from seed and seedling, respectively, were pathogenic to peach palm.