Among various pests, damaging crops qualitatively as well as quantitatively, soil-borne plant pathogenic fungi Sclerotium rolfsii and Macrophomina phaseolina pose a serious threat to a wide range of major food and cash crops throughout the world. Harmful impacts associated with use of current chemical control measures and limitations of botanical products have necessitated to explore alternative pathways for development of antifungal agents which are environmentally benign, at the same time as effective as the existing ones. In this regard our previous studies have highlighted the superiority of synergistic combination of synthetic chemicals and natural products over the use of components alone. A compound 1,5–bis(2–hydroxyphenyl)pent–1,4–diene–3–one(A1) was identified which can be synthesized by safer reaction using no toxic solvent or catalyst and enhanced in vitro antifungal activity of nicotinic acid manifolds with its synergistic effect. In haemolytic analysis it is also found less toxic to human beings. In continuation, the combinations of A1 with naturally occurring biologically important acids viz., ascorbic (vitamin C); usnic acid(extracted from lichen in our laboratory); tartaric acid(antioxidant) and oleic acid(Fatty acid) were screened in vitro against Sclerotium rolfsii ITCC5226 and Macrophomina phaseolina ITCC0482 at 200,100 and 50ppm. At 200ppm, 1:1 combination of A1 with tartaric and ascorbic acid, against M.phaseolina and with usnic acid against S.rolfsii were found to be most effective synergistic formulations. Other formulations also showed significant fungicidal activity. Current study gives an opportunity to develop environment friendly fungicides.