The experiment was carried out to survey for incidence and prevalence of purple blotch disease which ranged from 30.49 to 51.76 percent. Isolation, identification of pathogen and determination of pathogenicity were conducted as well; In-vitro evaluation of some botanical extracts, some commercial fungicides and some antagonistic microorganisms against Alternaria porri were performed. At 5 percent concentration of Adhatoda vasica extract showed the maximum of 91.11% inhibition of mycelial growth of A. porri followed by 60 % and 55.33% of inhibition due to Azadirachta indica and Ocimum sanctum extract respectively. At 10 percent concentration showed similar patterns of mycelial inhibition. The antagonistic effects of four biocontrol agents viz., Trichoderma viride, T. koningii, T. harzianum, Bacillus sp. on mycelia growth of A. porri were studied and maximum reduction in colony growth of A. porri was observed due to T.viride. All the concentrations (0.1g/100 ml; 0.2g/100 ml; 0.3g/100 ml) of Bavistin DF and Companion applied fully inhibited the growth of A. porri.