Two tested acetone algae extracts of (Spirulina platensis and Chlorella vulgaris) in the present study significantly decreased radial growth (colony diameter) of the potato dry rot fungus, Fusarium sambucinum (isolate, F.s. 2), grown on PDA amended with the tested algae extracts,7days after inoculation and incubation at 25 oc. This effect increased with increasing the concentration where 160 mg/ml of any of the tested extracts completely (100%) inhibited the fungus growth. Meanwhile, treatments with the two tested acetone algae extracts (as dipping or coating in gelatinous substance) significantly decreased dry rot disease severity on the inoculated potato with F.s. 2 under cold 7±2°C storage conditions compared to the untreated inoculated control and the effect increased with increasing the concentration from 160mg/ml to 200 mg/ml. Also, coating tubers with the tested algae extracts was even more effective to decreased dry rot disease severity during storage. Spirulina extract treatments consistently decreased the developed dry rot severity compared to Chlorella treatments. This effect of algae extracts may be explained in view that the algae extracts treatments were accompanied with significant increase in total phenols as well as polyphenol oxidase and peroxidase activity in the treated tubers and also, this effect was accompanied with significant control for the tuber weight loss (%). This study clearly demonstrated that green alga such Spirulina platensis and Chlorella vulgaris can be a potential source of antifungal compounds useful in agriculture and plant diseases control.