The effect of a bio-product obtained from fique juice (Furcraea gigantea Vent.) in the management of late blight disease caused by Phytophthora infestans in two experimental crops of potato (Solanum tuberosum L.) was evaluated. A complete randomized block design with two factors was used, where the first factor corresponded to concentration: 5, 10 and 15 L.ha-1 and the second factor was the fermentation time: 2, 4 and 6 days (33oC) compared with a control test (water) and a commercial control (Cymoxanil 8% + Mancozeb 64%). From results of the severity values, incidence and yield the 15 L.ha-1 application and four days of fermentation showed a significant differences (P<0.05) with respect to control test, but with very low levels of protection. In a second trial the concentrations tested were increased in 20, 30 and 40 L.ha-1. After statistical analysis of treatments was determined that there are no statistics differences that prove the action of plant extract in crop protection.