Malic acid lowers the cytoplasmic pH of fungi and inhibits their ability to reproduce, it also encourages plant growth. Physico-chemical properties of malic acid, thiourea, and malic acid mixture with thiourea as an active ingredient were measured, then prepared as soluble powder formulation and passed successfully all specified tests. The efficacy of malic acid, thiourea, and the mixture of malic acid with thiourea (active ingredient) was tested against F. oxysporum under laboratory conditions, and their inhibition percent of mycelial growth values were: 49.6, 72.4, and 75.7% respectively at 2000 ppm, while their formulations (SP) displayed higher inhibition of mycelial growth and its values were: 86.9, 83.7 and 61.7% for malic acid thiourea mixture (SP), thiourea (SP) and malic acid (SP) at 2000 ppm respectively. A greenhouse experiment was done and the results revealed that malic acid with all tested concentrations decreased significantly the percentage of disease incidence and increased the percentages of plant survival followed by a mixture of malic acid with thiourea (SP) and thiourea (SP), where the efficacy values were: 94, 92 and 84% at 4000 ppm respectively, against fusarium wilt on cucumber plants.  Malic acid (SP) at 4000 ppm displayed the highest plant promotion  shown clearly in the results of parameters measured. Finally from the previous results malic acid (SP) could be used as safe alternative of chemical fungicides against fusarium wilt on cucumber plants after complete the needed studies.