In vitro efficacy of guava plant (Psidium Guajava) leaf and bark ethanol crude extracts against fungal pathogens (Fusarium Oxysporum) associated with tomato (Solanum lycopersicum L.) fruits

Tomato wilt, caused by Fusarium oxysporum, is a significant agricultural problem, leading to substantial yield losses. Although chemical fungicides are used to eliminate the severity of the disease, their continuous use poses a negative effect on the environment health. Therefore, bio-fungicides are frequently employed due to their eco-friendly properties and cost-effectiveness. This study focused on evaluating the antifungal properties of crude extracts derived from the leaves and bark of the guava plant (Psidium guajava) against Fusarium oxysporum. The leaves and bark of the experimental plant were collected from Gubrye and around Wabe river. The collected plant parts were brought into the laboratory and water rinsed properly, dried under shade, and milled to powder. The bioactive components were extracted from the powder using ethanol. The antifungal activities of the extracts against tomato wilt disease (Fusarium oxysporum) were estimated by using the Potato Dextrose agar (PDA) Agar well diffusion method. The minimum inhibitory concentration (MIC) of the leaf and bark extracts of P. guajava was determined using the agar diffusion method. The standard antifungal drug, amphotericin (10 mg) was used as positive control whereas distilled water was used as negative control. The bioassay examination of the crude extracts was conducted at four different concentrations (50, 100, 150 and 200 mg/ml). In the current study, the presence of phytochemicals such as alkaloids, phlobatannins, saponins, tannins, and terpenoids in P. guajava leaves and the bark were confirmed and flavonoids were only found in the leaf extract. The effect of guava plant leaf and bark ethanol crude extracts of P. guajava was determined and significant antifungal activities against F. oxysporum in a concentration-dependent manner was observed. The ethanol crude extracts of leaf and bark had a high growth inhibitory effect at a concentration of 200 mg/ml with zones of inhibition of \(9.5\pm\) $9.5\pm$ 0.33 mm and \(7.98\pm\) $7.98\pm$ 0.08 mm respectively. The positive control amphotericin at 10 mg/ml concentration exhibits fungal growth inhibition by a mean zone of inhibition of 12.62 ± 0.14 mm. The P. guava leaf and bark crude extracts of ethanol showed the lowest minimum inhibitory concentration (MIC) at 1.25 and 2.5 mg/ml respectively. The results of this study indicate that ethanol extracts of P. guajava leaves and bark exhibit promising antifungal activities against F. oxysporum. Therefore, these findings suggest that ethanol extracts of P. guajava leaves and bark could be considered as an alternative strategy for the management of potato wild disease. Highlights

Guava (Psidium guajava) plant are known for their medicinal application