In-vitro Evaluation of the Efficacy of Two Plant Extracts Allium sativum (Garlic) and Azadirachta indica (Neem) in the Control of Powdery Mildew Caused by Golovinomyces cichoracearum of Abelmoschus esculentus (Okra)

Aim: The aim of this study is to determine the efficacy of extracts of some selected plant materials in the control of Powdery Mildew of Okra plant.

Study Design: Completely randomized design.

Place of Study: This study was carried out in the Biology Laboratory of the Department of Plant Science and Biotechnology.

Methodology: Three Okra farms showing symptoms of powdery mildew disease were surveyed, disease occurrence was recorded, and disease incidence was calculated. Leaves of okra (Abelmoschus esculentus) showing symptoms of powdery mildew were collected from the farms. The disease incidence was recorded and the samples of infected leaves were collected from the farms and taken to the laboratory for microscopic examination. The fungus associated with the disease was isolated and cultured to obtain a pure culture. Pathogenicity test was carried out on a healthy okra plant. Extraction of the two plants were done using methanol and it was then diluted to different concentrations. The antifungal susceptibility test on Golovinomyces cichoracearum was carried out using the agar diffusion method and recorded at various concentrations of 50 mg/ml, 25 mg/ml, 12.5 mg/ml, and 6.25 mg/ml under in-vitro conditions. The minimum inhibitory concentrations and antifungal activity were recorded at these concentrations.

Results: Results of phytochemical analysis showed that Alkaloids, reducing sugars, carbohydrates, Flavanoids, Tannins and Resins were present in both Allium sativum (garlic) and Azadirachta indica (neem). These phytochemicals present are suspected to be responsible for the antifungal activity of the plants. Out of the two plants, neem leaf extract was found to be best in the inhibition of the fungus at 50 mg/ml with a significantly high inhibition of 26.77±0.50 after the treatment. At P<= 0.05 there was a significant difference in the antifungal activity of the extract of A. indica on Golovinomyces cichoracearum.

Conclusion: The extracts of both Allium sativum (garlic) and Azadirachta indic (neem) possess antifungal properties, and may have the potential for the production of biopesticides, that can be used for the control of fungi.