Alternaria solani causes early blight in plants belonging to family Solanaceae. It severely infests agriculturally important crops like tomato and potato at different developmental stages. We havescreened eighty one extracts of twenty seven medicinally important plants for their antifungal activity against A. solani. Twelve extracts of eight plants (Cinnamomum zeylanicum, Syzygiumaromaticum, Ferula foetida, Inula racemosa, Hemidesmus indicus, Rubia cordifolia, Glycyrrhizaglabra and Saussurea lappa) possessed marginal to excellent antifungal activity. Hexane (Hx) andmethanol (MeOH) extracts of C. zeylanicum showed complete inhibition of A. solani in vitro at adose of 3 ml/lit water. Formulation trials conducted in shade house using MeOH extract of C. zeylanicum at a dose of 2 ml/lit water were highly effective against A. solani infesting tomatoplants. TLC, HPTLC and GC-MS analysis confirmed the presence of Eugenol, Cinnamaldehydeand 2H -1- Benzopyran -2- one in MeOH extract of C. zeylanicum. These secondary metabolites were isolated by preparative TLC to further confirm antifungal activity and probable structures byGC-MS. 2H-1-Benzopyran-2-one, a coumarin has been reported for the first time as an antifungal against A. solani in present study. An effective lab-scale formulation was developed and testedagainst A. solani.