 Müller researched and published on a wide range of topics in viticulture and winemaking, including the biology of vine flowering, assimilation of nutrients by the vine, vine diseases, alcoholic fermentation of wine, breeding of strains of yeast with specific properties, malolactic fermentation, development of wine faults, and methods for producing alcohol-free grape juice.During his time in Geisenheim, Müller created the grape variety Müller-Thurgau in a breeding programme initiated in 1882, by crossing Riesling with Madeleine Royale, although for a long time it was erroneously assumed to be Riesling x Silvaner.Müller's goal was to combine the aromatic properties of Riesling with the earlier and more reliable ripening of Silvaner.