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 t ubers infected with silver scurf (Helminthosporium solani). The electr ical resistance measured across the skin of tubers from the top of the chambers was consistently lower than that from the bottom of the cham ber, and this was reflected in an increased number of H. solani spores produced by the top tubers. An increase in the length of the condensa tion period resulted in the skin resistance remaining lower for a long er period and also resulted in higher numbers of spores. Tubers held a t relatively high ambient temperatures (15 degrees C) required a short er period of condensation to cause an increase in spore count. This in vestigation highlighted the need for close monitoring of store environ ments so that condensation events can be quickly identified and the tu bers dried.