Citrus greening (Huanglongbing) is an invasive disease in citrus plants that is devastating the largest citrus industry in the United States. This disease causes significant crop loss for citrus growers because of the increased premature fruit drop and the reduced fruit quality. There is a need for investigating the low-cost, easily accessible, and efficient nanomaterials which have potential applications in treating the Huanglongbing (HLB) disease. One of the potential candidates is a zinc oxide (ZnO) nanomaterial which has the ability to produce reactive oxygen species as well as Zn ions in solution. Theoretical modeling and simulations at multiscale can provide insights into the mechanism of producing reactive oxygen species and the interaction between ZnO particles and molecules (simple to complex).