For the past decades, the worldwide population has continued to grow rapidly, and ensuring a food supply has become a serious matter. Besides, agricultural production was considered a major pole of development and research oriented to better food quality, important yields, and above all, ensuring plant protection using common ancestral practices and products. Indeed, more attention was given to new methods that combine both minimum time consumption and efficiency. Unfortunately, as agriculture involves difficulties that can become more decisive, one of the factors that hinder the agricultural system is food losses due to pathogen infections, which are the main cause of yield reductions resulting in a significant decrease in financial returns. To overcome this challenge, researchers in the plant pathology field take care of developing fast and accurate early detection methods, notably for emerging diseases or tough pathogens that reside more and spread fast and wide. To overcome this challenge, researchers in the plant pathology field take care to forge fast and accurate early detection methods, especially for novel diseases or persistent infections that survive alive for a long time and spread faster. Therefore, the use of recent molecular detection tools has enabled fast and real-time diagnosis of plant diseases, in addition to artificial sensors that are capable of simultaneously monitoring the plant's health status over time. In this chapter, an overview will be provided of the state-of-the-art, recent, and innovative tools applied in the early detection of emerging diseases. Moreover, a deep comparison between conventional and recent diagnostic methods for phytopathogens will be made. Interestingly, this review emphasizes the control strategies of plant diseases and the transition from less-effective practices and harmful chemicals to more fast and eco-friendly strategies resulting in reliable, productive, and sustainable agriculture.