The proposed model was trained for 100 epochs using the EfficientNetB0 backbone and custom dense layers (Fig 3). The training and validation performance improved steadily over time. In the initial phase (Epoch 1), the training accuracy was low at 19.86% and the loss was high at 2.9853. The validation accuracy at this point was 20.35%, with a loss of 2.3289. By Epoch 25, the model had significantly improved. It achieved a training accuracy of 98.28% and a validation accuracy of 98.64%. Corresponding training and validation losses were 0.6777 and 0.6316, respectively. This shows that the model was able to learn useful features and generalize well by the mid-point of training.
At Epoch 50, the model continued to perform well. The training accuracy reached 99.75% and the validation accuracy improved to 98.84%. The training loss reduced to 0.4466 and the validation loss dropped to 0.4522. This indicated that the model was not overfitting and maintained stability across epochs. By Epoch 75, the training accuracy was 99.66% and validation accuracy remained at 98.84%. Training and validation losses further reduced to 0.3011 and 0.3186, respectively. This confirmed consistent performance over time. At the final epoch (Epoch 100), the model reached 99.95% accuracy on the training set. The validation accuracy peaked at 99.22%, showing excellent generalization. Final losses were 0.1818 for training and 0.1963 for validation. The gap between training and validation losses remained small, which indicates minimal overfitting. Overall, the model demonstrated strong learning capacity and robustness. The EfficientNetB0 backbone with the added dense layers contributed significantly to high accuracy and low validation loss. The early stopping callback helped prevent overfitting and ensured optimal weight retention.
The confusion matrix in Fig 4 highlights the performance of the proposed EfficientNetB0-based model on the groundnut leaf disease classification task. Each row represents the actual class and each column indicates the predicted class. The model correctly classified 130 samples of Alternaria Leaf Spot without any misclassifications. All 179 healthy leaf images were accurately identified. For the Leaf Spot (Early and Late) category, 139 images were correctly classified, while 3 were mistakenly predicted as Alternaria Leaf Spot. In the case of Rosette disease, 20 images were correctly classified and only one was misclassified as Healthy. Rust disease was perfectly predicted for all 44 samples. These results demonstrate strong class-wise performance, with very few errors occurring mainly between visually similar diseases. Overall, the model exhibits high reliability in distinguishing between multiple groundnut leaf diseases.
The classification report further validates the effectiveness of the proposed model across all five groundnut leaf classes (Table 2). For Alternaria Leaf Spot, the model achieved a precision of 0.9774 and a perfect recall of 1.0, resulting in an F1-score of 0.9886 across 130 test images. Healthy leaves were classified with extremely high precision (0.9944) and perfect recall, yielding an F1-score of 0.9972 over 179 samples. The Leaf Spot (Early and Late) class recorded a precision of 1.0 and a recall of 0.9789, producing an F1-score of 0.9893 for 142 samples. In the Rosette category, the model achieved perfect precision but a slightly lower recall of 0.9524, which led to an F1-score of 0.9756 for 21 images. Rust classification was flawless with 1.0 scores across all metrics for 44 samples. The model attained an overall accuracy of 99.22% on the test dataset. The macro average precision, recall and F1-score were 0.9944, 0.9863 and 0.9901, respectively, indicating balanced performance across all classes. The weighted average, which accounts for the number of samples per class, remained consistent at 0.9922 for both recall and F1-score. These results confirm that the model is robust, consistent and well-suited for multi-class classification of groundnut leaf diseases.
The ROC curve in the image shows excellent model performance for all classes (Fig 5). Each class achieves an AUC close to or equal to 1.0. Specifically, Healthy, Rosette and Rust have an AUC of 1.0000, indicating perfect class separation. Alternaria Leaf Spot and Leaf Spot (Early and Late) also perform well, with AUC values of 0.9999. The curves rise sharply toward the top-left corner, confirming high true positive rates and low false positive rates across all categories.
The precision-recall (PR) curve shows that the model performs well across all classes (Fig 6). Average precision (AP) for Healthy, Rosette and Rust is 1.0000, indicating perfect balance between precision and recall. Alternaria Leaf Spot has an AP of 0.9998 and Leaf Spot (Early and Late) achieves 0.9997. The curves remain close to the top-right corner, reflecting high confidence in predictions and minimal false positives or false negatives.
The F1-score vs. threshold plot demonstrates stable and high F1-scores for all five classes across most threshold values (Fig 7). Scores remain above 0.9 between thresholds of 0.1 and 0.95, showing the model maintains a good balance between precision and recall. A sharp drop is observed near thresholds 0 and 1, which is expected. All classes, Alternaria Leaf Spot, Healthy, Leaf Spot (Early and Late), Rosette and Rust, exhibit similar trends, confirming model consistency.
Fig 8 presents the classification outcomes of groundnut leaf samples using the proposed EfficientNetB0-based model. In the first row, the model accurately predicted a healthy leaf with 99.99% confidence, showing its ability to recognize disease-free foliage. It also correctly identified a Rosette-infected leaf with 99.98% confidence, characterized by leaf curling and discoloration. An Alternaria Leaf Spot case, showing distinct dark lesions, was also correctly predicted with high certainty (99.85%).
In the second row, three additional Alternaria Leaf Spot cases were correctly classified with confidences ranging from 99.95% to 99.98%, demonstrating the model’s consistent ability to detect different symptom severities and lighting conditions. A second healthy sample was also accurately predicted with 99.97% confidence, reinforcing the model’s robustness in classifying non-infected leaves. In the final row, a Leaf Spot (early and late) case showing circular lesions was recognized with 99.99% confidence, indicating the model’s sensitivity to early-stage symptoms. Another Alternaria-infected leaf, despite dense clustering of lesions, was accurately classified with 99.95% confidence. Lastly, a leaf affected by Rust was identified correctly, supported by a high prediction confidence of 99.94%. Overall, these results highlight the model’s reliability and precision across diverse leaf diseases.
Table 3 presents a comparison of the presented work with the existing literature. The modified EfficientNetB0 model proposed in this study achieved an impressive accuracy of 99.22% using a real-world dataset collected under natural lighting conditions
(Sasmal et al., 2024), surpassing the performance of several existing approaches.
Abhilasha et al., (2023) used ResNet50 on images from the Durgapur Agriculture Research Centre and reported only 82.30% accuracy.
Bama and Priyadharsini (2022) achieved higher accuracies, with SVM reaching 99.84%; however, their dataset included PlantVillage images, which may lack real-world variability.
Rakholia et al., (2022) employed a CNN with progressive resizing and achieved 96.12% accuracy using a dataset from Gujarat. Similarly,
Maheswaran et al., (2022) trained a CNN on multi-disease samples and reached 96.50% accuracy.
Paramanandham et al., (2024) proposed the LeafNet architecture, which attained 97.23% on a large dataset of 10,361 images. Despite the effectiveness of these models, the customized EfficientNetB0 used in this study, with added dense layers, regularization and batch normalization, proved to be both accurate and lightweight. This makes it especially suitable for real-time field applications and mobile-based disease detection tools.
Furthermore, the proposed EfficientNetB0-based model demonstrates strong potential for real-time deployment in mobile-based disease detection applications. The model can be integrated with a user-friendly mobile interface, enabling farmers to capture leaf images and receive instant disease predictions. In addition, the classification output can be linked to an expert system module, which associates each detected disease with appropriate management recommendations, including pesticide application, cultural practices and preventive measures. Such integration would enhance the practical utility of the model by providing decision support to farmers, thereby facilitating timely intervention and improving crop productivity. This combined framework of deep learning and expert systems can serve as an efficient tool for precision agriculture and sustainable crop management.