Mango fruit diseases severity estimation based on image segmentation and deep learning

Plant disease severity is the ratio between the surface area of disease symptoms and the total surface area of the plant unit (e.g. fruit, leaf). It is related to plant disease diagnosis and has several advantages for farmers. It is therefore a key element in the protection and management of plant diseases. In the literature, there are three proposed categories of plant disease severity determination solutions: solutions based on segmentation algorithms, solutions based on classical ML algorithms and those based on DL algorithms. Despite their several advantages, these solutions have a number of limitations, including i) subjectivity in data labeling, ii) loss of information on disease lesion contours during (manual) data labeling, and iii) the proposed solutions have focused on estimating plant disease severity from leaves, although diseases can also affect other parts of the plant, such as fruits. In this paper, we present a solution for estimating the severity of four mango fruit diseases, namely Alternariose, Anthracnose, Aspergillus rot and Stem rot. This solution is based on ResNet50 CNN and uses a dataset automatically labeled by a proposed algorithm based on two segmentation algorithms such as image color space segmentation and image thresholding. The solution has achieved an accuracy, a precision and a F1_score of 97.82%, 97.09% and 97.79%, respectively, on test data It is then deployed in a mobile application with a diagnostic solution we previously proposed. This mobile application will help mango growers, particularly those in Sahelian countries like Senegal, to manage their mango diseases earlier. This article presents a solution for estimating the severity of mango diseases, not on leaves, but on fruit. This solution uses two image segmentation algorithms to automatically label the dataset used, in order to avoid any errors that might result from manual labeling. The proposed solution uses deep learning, in particular the CNN ResNet50 model, to estimate the severity of four mango diseases (alternaria, anthracnose, aspergillus rot and stem rot) according to four severity stages: healthy, early, intermediate and final. It is finally deployed in a mobile application for mango growers.