Abstract :
Based on the results of interviews and direct observations to the Naura Farm Jember Gardens and the Pesanggaran Electric Dragon Fruit Agrotourism Garden, a total of 11 disease data, 6 pest data and 54 symptoms were obtained. The method used in this research is certainty factor, where this method works based on an expert's assessment of the belief of the symptoms. The result of this expert system is the percentage of pests and diseases that attack plants based on input in the form of symptoms that exist in dragon fruit plants. It also displays the possibility of other diseases that attack.