Plant infections critically limit yields and significantly reduce crop production, therefore posing substantial threats to food security and remaining a paramount concern in agriculture. While chemical measures are still the primary strategy to mitigate the spread of plant diseases, their excessive application can lead to reduced pathogen susceptibility. Moreover, excessive spraying can have adverse effects on soil microorganisms and ecosystem contamination. Thus, the development of effective diagnostic approaches for the early detection of phytopathogens is imperative to ensure agricultural sustainability and food security. Purposely, numerous molecular techniques have been adopted for rapid phytopathogen detection. This chapter explores various direct and indirect methods for such an aim including nanotechnology, biosensors, microfluids, among others. The utilization of nanotechnology in managing agricultural diseases is a significant research area. Nanotechnology can be considered a promising and potential tool to enhance sensitivity, precision, and speed in identifying plant pathogens while also facilitating high-throughput analysis.