The effect of condensation on sporulation of Helminthosporium solani on potato tubers infected with silver scurf and held in simulated store conditions

Chambers were designed to simulate environmental conditions present in commercial potato stores and were used to introduce condensation to tubers infected with silver scurf (Helminthosporium solani). The electrical resistance measured across the skin of tubers from the top of the chambers was consistently lower than that from the bottom of the chamber, and this was reflected in an increased number of H. solani spores produced by the top tubers. An increase in the length of the condensation period resulted in the skin resistance remaining lower for a longer period and also resulted in higher numbers of spores. Tubers held at relatively high ambient temperatures (15 degrees C) required a shorter period of condensation to cause an increase in spore count. This investigation highlighted the need for close monitoring of store environments so that condensation events can be quickly identified and the tubers dried.