Author(s): Falade MJ and Oyelakin FO

Abstract: Anthracnose of water melon is an important fungal disease reducing yield by 20-100% when not controlled. Field experiment was carried out to evaluate the effect of time and sequence of application of infective conidia and extracts of three plants: Physalis angulata, Nicotiana tabacum and Hyptis suaveolens on disease incidence, severity and fungal infection of water melon inoculated with Colletotrichum orbiculare. Three concentrations of the extracts (20, 40 and 60%) were used in the study. Total area of the farm (625m2) was divided into three sub plots in a factorial experiment. The first plot was sprayed with extracts of the three plants at the tested concentrations and after 48 hours inoculated with the conidia of the fungus. The second plot was sprayed with the conidia of the fungus followed by application of the different extracts after 48 hours. The third plot was treated simultaneously with the different concentrations of the extracts and the inoculum of the fungus. Control plot in each case was sprayed with distilled water. The result showed that all the extracts were effective in reducing the incidence and severity of the disease and values obtained were significantly (p≤0.05) lower than the control. At 20, 40 and 60% concentration of P. angulate extract, disease incidence in percentages were 23.5, 22.7 and 18.3% compared to the control (75.4%) when extracts were applied two days before inoculation. Similarly, percentage germination of seeds was 81.9, 84 and 92.7% when extracts of P. angulata were applied at 20, 40 and 60% concentrations respectively compared to the control (53.7%). In terms of disease severity, trace infections of symptoms were noticeable on treated plots compared to the control (severe infection). Extracts of P. angulata were the most effective followed by N. tabacum and H. suaveolens. The study demonstrated that the extract of the plants can be used in the management of anthracnose disease of water melon.

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