Most plant species produce thousands of living root 'border' cells, secretory cells programmed to separate from the root tip into the rhizosphere. Border cell signals regulate behavior, growth, and gene expression in populations of pathogenic and symbiotic bacteria, fungi, and nematodes. The goal of this research is to systematically test the hypothesis that the delivery of border cells into the rhizosphere fosters plant health by regulating relationships with soilborne microbial and nematode populations. If our model is correct, border cells can be employed to provide targeted delivery of chemicals needed for crop protection, with minimal environmental impact.