The aim of this study was to evaluate four the antifungal activity of aqueous plant extracts (Laurus nobilis, Dianthus caryophyllus, Cinnamomum verum, and Thymus vulgaris) as an alternatives to chemical fungicides (Imazalil and Thiabendazole) against Alternaria alternata which causing black spot of sugar mango fruits. Antifungal activities of plant extracts and chemical fungicideswere tested both in vitro and in vivo conditions. The in vitro assay showed maximum inhibition of radial mycelial growth of A. alternata (100%) by D. caryophyllus extract, at concentrations of 2.5, 5, and 10% Similarly, the in-vivo assay showed a marked reduction in lesion diameter (2.5, 1.5, and 0.9 mm) and decreasing disease severity by 95.46, 97.04 and 98.22 %, respectively on the mango fruits treated with this extract. While the in vitro assay with Imazalil fungicide showed inhibition of radial mycelial growth of A. alternate by 82.13, 85.22, and 89.35%, respectively at 50, 100, and 200 ppm, respectively and reduced disease severity by 86.37, 88.90, and 93.43%, respectively. The residual activity of post-harvest treatment with imazalil (IMZ) and thiabendazole (TBZ) was studied at different dip lengths and different cold storage times on mango fruit. IMZ and TBZ residue decreased with the number of cold storage days for all treatments and the residue increased with the duration of dipping for all treatments. Both fungicides residues were lower than MRL set by codex and EU Pesticides Database.