Plants are very important to the earth and all living things. Plant diseases are a kind of destruction of the normal state of plants, which can interrupt or change their life functions. Leaf disease is the most common disease in most plants. One of the ultimate key factors in reducing production is the onset of disease. Peanut plant diseases, such as fungi, soil-borne and viruses. In this article, the software certainty to automatically classify peanut leaf diseases is used. This method will increase the yield of crops. It includes the number of steps. Various image processing techniques use K nearest neighbours (KNN). In order to improve the performance of existing algorithms, the SVM classifier is replaced with KNN classification. n order to improve the speed and accuracy of the network for identifying and classifying different disease-infected areas on peanut leaves, a classic neural network algorithm is used. In this article, the KNN classifier algorithm is used to classify 4 different diseases