It has been discovered that irradiating the cut side of sugarcane billets, preferably 2-50 mm, with UVB or UVC light or combinations thereof initiates stilbene production, particularly resveratrol and piceatannol. In an embodiment the cut sides of sugarcane billets of a predetermined thickness are irradiated with Ultraviolet-C or Ultraviolet-B light or combinations thereof at an intensity and for a duration of time sufficient to produce a significant increase in a level of one or more stilbenes in the irradiated billets compared to a level of stilbenes in billets that are not irradiated; and the irradiated sugarcane billets are maintained for at least about three days up to about 20 days, to optimize stilbene levels.