STORAGE OF SEED POTATOES IN PALLET BOXES .2. CAUSES OF TUBER SURFACE WETTING

In a paper to establish how different store ventilation systems affect the population of tuber borne Erwinia, periodic reductions in tuber s kin resistance occurred (Pringle & Robinson, 1996). To help understand these changes, tuber skin resistance data was collected simultaneousl y from two stores nearby. All reductions were due to condensation when tubers were colder than the dew-point temperature of the surrounding air. Warm humid air from newly harvested or sprouting potatoes below c ondensed on the cooler surface tubers in naturally, but not periodical ly forced ventilated? boxes. Condensation occurred in both naturally v entilated and forced ventilated boxes when ambient air, under both fan pressure or wind induced leakage, and with a dew-point temperature ab ove that of the stored tubers, entered the store. Individual tubers in trays, simulating the surface layer of boxes, received condensation w hen Ventilation stopped. Warmer humid air from the rest of the crop co ndensed on these preferentially cooled tubers.