Recent research in agriculture focuses on classifying agricultural plant diseases using images of their leaves. This will minimize the dependence on farmers to protect the plants. Coconut trees fall prey to a variety of pests and diseases due to fungi, bacteria, viruses and nematodes. Many researchers are increasingly turning to metaheuristic algorithms because of their success in finding optimum solutions in solving real-world issues. This paper proposes a unique nature- inspired meta-heuristic optimization algorithm, referred to as Whale Optimization algorithm (WOA) based Deep Neural network to classify the Coconut tree diseases.