EFFICACY OF CERTAIN ALGAE EXTRACTS TO CONTROL DRY ROT OF POTATO

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 o C. 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 storage conditions (7±2°C) 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 decrease 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