Despite proper soil health management, pests and diseases control is also an important task in corn farming for improving both the quality and the quality of the crops production. One way to address this challenge is to identify the emerging symptoms accurately to help define the appropriate solution. Downy, Leaf Blight, Rot midrib, Rot Stem, Leaf Rust, Burnt, Dwarf, Leaf spot are among the common symptoms on corn crops. Failure to identify these symptoms in the early stage could result adverse effects on the corn crops and reduce the production in the long run. This study therefore aims to classify corn disease symptoms to know the real disease. In this study, Decision trees and Frequent Pattern Growth (FP Growth) are employed. Analysis from the data indicated accuracy values of decision tree J4.5 (ID3) of 95%, J.48 of 96% and Random Forest of 95%. While for the relation pattern with 9 attributes and 2 classes, obtained the most often arise rule is the mycelium symptom or cotton with the leaves color turning red / brown / ash / chlorotic with accuracy of 92%.