When the growth regulator ethephon is applied to walnuts at maturity and when packing tissue between kernel halves turns brown, hull dehiscence and nut loosening are advanced. Harvest can generally begin 7 to 10 days following treatment, which may be 1 to 3 weeks before normal harvest. The possible advantages of an earlier harvest are: improved kernel quality, less insect infestation , greater nut removal, greater hullability, and a more efficient harvest. In the course of University of California experiments and subsequent grower use of ethephon, reports have appeared claiming both longer and shorter nut drying times. The purpose of our investigation was to measure nut drying time after ethephon treatment.