antimicrobial potential of Controller, Impose, Phostrol, Ridomil Gold plus, and Roxyl Plus was determined for Pectobacterium atrosepticum and Streptomyces scabies. The cidal effect against P. atrosepticum was only shown by the fungicide Controller. S. scabies was highly affected by Controller, Impose and Roxyl Plus compared to RidomilGold plus, and Phostrol that did not inhibit the growth. The MIC of Controller was found to be 4000 ppm for P. atrosepticum and S. scabies. On the other hand, the MICs of Impose and Roxyl Plus were found to be 4000 ppm and 3000 ppm respectively for S. scabies. Application of Controller against blackleg significantly decreased the incidence of the disease in potted potato plants. Application of Controller, Impose and Roxyl Plus at 3.0g/l to control common scab significantly decreased the disease. Conclusive results were obtained by the 4.0 g/l application. Residues of ingredients of these fungicides in potato tuber 60 day after application were below the approved maximum residue level (MRL).