The Control of Powdery Mildew in Watermelon Using Home-made Fungicide Containing Campuloclinium macrocephalum Extract

Background: Fungal plant diseases are a big problem to farmers and food markets. These infections reduce the plant’s production and yield, negatively affecting the food supply. The Curcubitaceae family is very susceptible to most fungal diseases, especially powdery mildew. Campuloclinium macrocephalum (pom-pom weed), an invasive exotic in South Africa, has antifungal properties. Aim: To investigate the effectiveness of pom-pom weed extract in controlling watermelon powdery mildew (Podosphaera xanthii) fungal disease. Methods: Watermelon plants grown in plastic pots, were irrigated with a Hoagland nutrient solution. The plants were organised in a randomised block design. The treatments were: negative control, no treatment (Treatment A), positive control, plants sprayed with commercial fungicide (Treatment B), plants sprayed with buffered plant extract (Treatment C), plants sprayed with plant extract of 0.1 mg/ml (Treatment D) and plants sprayed with plant extract of 0.2 mg/ml (Treatment E). Foliar application of the different treatments on the watermelon plants was done once per week for five weeks. Results: The negative control (Treatment A) had the highest mildew leaf coverage at 77.69%. This was followed respectively by Treatment C at 13.10%, Treatment E at 7.56%, Treatment D at 2.05%, and lastly by Treatment B at 0%. There was a significant difference (p< 0.05) amongst the treatments. Conclusion: The results of the study showed that pom-pom weed extract at a minimum concentration of (0.1 mg/ml) can be used to control powdery mildew in watermelons, thus reducing the usage of chemical fungicides.