Anthracnose is the major pre- and postharvest disease of mango which caused by Colletotrichum gloeosporioides. In-vitro and in-vivo studies were done to evaluate the antifungal activity of Pennisetum purpureum weed extract on control of C. gloeosporioides. Result: The in-vitro result showed that methanol crude extract of P. purpureum exhibited the best antifungal activity against C. gloeosprioides with an average minimum inhibition concentration value of 3.13 mg/ml and it had the highest total activity (5.28 ml/g) on inhibition of C. gloeosprioides. Meanwhile, the in-vivo result demonstrated that the fruits coated with alginate incorporated crude extract at a concentration of 18 mg/ml were most effective in retaining fruit firmness and had the smallest size lesion in diameter (0.34 cm) as compared to other treatments. The phytochemical assay of methanolic crude extract revealed the presence of phenolic compound (tannins), alkaloids and flavonoids but steroids, saponin, amino acid and oil were absent. Conclusion: This study has demonstrated that alginate based coating incorporated with methanolic crude extract of P. purpureum could be used to inhibit anthracnose pathogen of C. gloeosporioides, thereby extending the shelf life of mango fruits. Keywords: anthracnose, coating, compound, plant extract, mango