This invention relates to methods and compositions for improving plant health. The present invention includes methods for making an enriched library of treatments capable of improving plant health, methods for an making an enriched library of plants capable of being improved by a treatment, and methods of marketing a plant treatment, as well as synthetic compositions comprising treatments produced by the methods of the present invention, synthetic compositions comprising endophytes capable of improving plant health, and nucleic acid probes and nucleic acid detection kits that may be used in the methods of the present invention.