Abstract: An in-the-field seed treating method and apparatus in which a treating fluid, such as an emulsion containing an insecticide, fungicide, or bactericide or the like, is sprayed onto seeds as they move from a seed hopper to a planting tube and into a planting furrow. The system is particularly directed to a plateless planter using an air pick-up system, either positive or negative pressure relative to atmosphere, for selecting seeds from a rotating drum or an intermediate pick-up chamber. In one form, the system permits air, heated by compression, to flow over the coated seeds to dry the coating as they rotate in a planting drum or disk; thus, the coating is dried on the seeds before introduction into the planting tube so that coating is not lost and the planting tubes remain clean. A hydraulic control circuit is disclosed for regulating flow of treating fluid from a "bypass" nozzle to an exceptionally low range, from about 0.2 to 5 gallons per hour.