Global warming has resulted in phenomenal rise of aggressive microbial pathogens which target agricultural plants with inestimably high consequences on yield and quality of affected crops. To combat these extensive infections of pathogenic diseases in plants, it is critical to develop sustainable materials that do not rely on the traditional agricultural practices. Nanomaterials of renewable sources provide a straightforward and clear solution to pest and disease control in plants. These innovations are transforming the scientific and industrial spheres. Nano-based materials hold enormous promise in agriculture, notably for the production of potent formulations that assure idyllic distribution of fertilizers, nutrients, pesticides, and growth regulators for increased usage efficiency. Of great significance in green agriculture development is the use of cellulose materials. The abundance of cellulose as a natural biomaterial is one of the numerous advantages of employing cellulose as the base material in plant disease control. In nanocomposite preparation, the availability, turnability, biocompatibility, and nontoxic nature of cellulose raw material make it handy. The presence of prevalent hydroxyl groups allows the preparation of metal nanocomposites of cellulose that can have therapeutic effects on the plant. This chapter describes the potential of cellulose nanomaterials for use in plant disease management. New developments and advances of cellulose in agriculture are also considered.