In vitro and in vivo bio-assay of phytobiocidal effect of plant extracts on Alternaria solani causing agent of early blight disease in tomato

Abstract

The efficacy of six locally available plants extract was evaluated for their phytobiocidal effect on Alternaria solani the causal agent of early blight (EB) disease of tomato and was compared with commercial fungicide mancozeb under in vitro and in vivo conditions. Under in vitro conditions, Eucalyptus globus and Datura alba were found to be ineffective, while the remaining plants extract (Allium sativum, Curcuma longa, Melia azedarach, Zingiber officinale) significantly reduced A. solani growth on PDA. Increasing concentrations of A. sativum (0–25%) were found negatively correlated with growth of A. solani on PDA. Among the tested plants, A. sativum extract at 20% concentration was found most effective against A. solani witnessed by both in vitro and in vivo experiments result. It reduced EB disease up to 75.11% over positive control. Similarly, among the different plants extract, maximum plant height (76.25 cm), fruit size (57.50 cm3) and yield (511.30 g) were observed in A. sativum sprayed treatments (20%), beside mancozeb and negative control. Upon phytochemical analysis of these extracts, flavonoids, alkaloids, saponins, tannins, terpenoids, glycosides and steroids were detected. Present study showed that 20% concentration of garlic extract has the potential to reduce EB disease severity, while having no noticeable phytotoxicity.