Automatic Segmentation and Classification System for Foliar Diseases in Sunflower

Obtaining a high accuracy in the classification of plant diseases using digital methods is limited by the diversity of conditions in nature. Previous studies have shown that classification of diseases made with images of lesions caused by diseases is more accurate than a classification made with unprocessed images. This article presents the results obtained when classifying foliar diseases in sunflower using a system composed of a model that automatically segments the leaf lesions, followed by a classification system. The segmentation of the lesions was performed using both Faster R-CNN and Mask R-CNN. For the classification of diseases based on lesions, the residual neural networks ResNet50 and ResNet152 were used. The results show that automatic segmentation of the lesions can be successfully achieved in the case of diseases such as Alternaria and rust, in which the lesions are well-outlined. In more than 90% of the images, at least one affected area has been segmented. Segmentation is more difficult to achieve in the cases of diseases such as powdery mildew, in which the entire leaf acquires a whitish color. Diseased areas could not be segmented in 30% of the images. This study concludes that the use of a system composed of a network that segments lesions, followed by a network that classifies diseases, allows us to both more accurately classify diseases and identify those images for which a precise classification cannot be made.