Research Article published by Scientific Research Publishing Inc.The objective of this study was to evaluate the efficacy of plant extracts in managing late blight disease in tomato, in vitro. Crude extracts were from Plectranthus barbatus , Tephrosia vogelii , Sphaeranthus suaveolens and Lantana camara . These were compared with commercial formulations Otiva fungicide and untreated as negative control. Their effectiveness was determined by measuring the inhibition zone of the mycelial growth of the pathogen recorded in triplicate at 48 hours and 72 hours. The results showed significant differences (P ≤ 0.001) among the extracting solvents on percentage inhibition of Phytophthora infestans . Methanol was superior in inhibiting the growth of mycelial growth of P. infestans as compared with ethyl acetate. Furthermore, all plants tested showed antifungal activity against P. infestans . The P. barbatus, L. camara and S. suaveolens were comparable with the commercial fungicide in inhibiting the growth of P. infestans . In this study, T. vogelii extract showed poor results in inhibiting the mycelial growth of P. infestans as compared with other plant extracts. Also, it was observed that, there were significant (P < 0.05) interactive effects between solvent and plant extracts and between incubation time and plant extracts.