This paper presents a characterization of watermelon leaf diseases through the RGB color. The aim of this study is to perform identification of selected critical watermelon leaf diseases in Malaysia namely the Downy Mildew and Anthracnose diseases. Several samples of infected leaves images were put under digital RGB color extraction where the images were captured under standardized and controlled environment. This study involves 200 samples of infected leaves of which the classification of the diseases was carried out using Fuzzy Logic technique. Fuzzy Logic was used to handle the uncertainty and vagueness as it provides a means of translating qualitative and imprecise information into quantitative (linguistic) terms. The results have shown that the percentage of accuracy for both types of disease were more than 67%.