Abstract:
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.
