Studies of Warburgia ugandensis lyophilized crude extract with Trichoderma asperellum on tomato blight pathogens

Abstract

Early and late blights in tomatoes are among the most destructive diseases. The causative agents are Alternaria solani and Phytophthora infestans respectively. Warburgia ugandensis extracts have been demonstrated to have wide prophylactic and curative use as biocontrol agents against fungal and bacterial pathogens in animals but not in plants. Trichoderma species have been used as biocontrol agents for many phytopathogens. Warburgia ugandensis stem bark samples were air-dried ground, weighed then soaked in distilled water. The soaked material was then filtered and filtrate lyophilized to obtain crude extract which was screened against A. solani and P. infestans both in vitro and in vivo. All assays were performed in triplicate. Preliminary phytochemical analysis of the extract and minimum inhibitory concentration (MIC) were determined. Data on the inhibition by the extract was analyzed using ANOVA and the differences between means separated by Tukey’s test (p<0.05). Warburgia ugandensis extract in diffusion wells showed significant inhibition (P= 0.001) of the pathogens with no recovery. The MIC for A. solani was 1.25 mg/ml while for P. infestans was 2.5 mg/ml. Treatment with combined Warburgia and Trichoderma showed the least disease severity at 27.81 % for P. infestans and A. solani. This was closely comparable with the commercial fungicide which had disease severity of 33.21 %. The current study suggests that Warburgia lyophilized crude extract and Trichoderma have potential use as antifungal prophylactic biocontrol against both Phytophthora infestans and Alternaria solani. Further research is needed to analyze the bioactive compounds responsible for Warburgia activity against these pathogens.