Influence of grapefruit extract (GE) on mycelial growth, spore germination, population density of Fusarium oxysporum f. sp. cyclaminis and F. oxysporum f. sp. dianthi and its effectiveness in the control of Fusarium wilt of carnation and Fusarium corm rot of gladiolus (F. oxysporum f. sp. gladioli) was studied. Amendment of PDA with 40 μg ofGE/cm3 inhibited mycelial growth about 50%. Drenching of carnation with 165 μg of GE/cm 3, immediately after planting, resulted in drastical decrease of colony forming units number of the pathogen and increased healthiness plant stand about 50%. Applied as gladiolus corm soak, GE at cone. 660 ug/crrr' decreased development of Fusarium rot of gladiolus clones at least twice.