Data are from three experimental trials examining pre-existing water stress on Xylella fastidiosa infections and possible associated shifts in host chemistry, including free sugar, amino acid, and phenolic compound measurements. Trials A and B were utilized in the manuscript, whereas Trial C was data from an experiment whereby the water stress treatment was not significant enough to affect plant physiology or bacterial progression (but included for completeness). Predawn water potentials and photosynthesis were provided for trial B to show methodology worked (and for trial C to show the failure to reach water stress). Resources in this dataset:Resource Title: Pre-infection water stress effects on Xylella fastidiosa progression and grapevine chemistry. File Name: Preinfection Water Stress Effects on Xf Data.xlsxResource Description: Data represent affects of water stress on Xylella titers and Pierce's disease progression, as well as changes in grapevine stem amino acid, sugar, or phenolic compounds. Data were from three trials. Two of these were deemed from successful experiments with water stress obtained (Trials A and B), but the last trial (Trial C) did not appear to have induced water stress, based on pre-dawn water potentials. Data were summarized in a manuscript submitted for publication.