“…Asexual spores, called sporangiospores, are generally viable for only a few hours; however, with temperatures near 20 "C, attached or detached spores of P. tabacina have been found to survive for as long as 1 to 2 weeks (KrC)ber, 1965;Hill, 1969a, b). Viability of spores decreases with increasing ultraviolet radiation loads (Shepherd, 1962;Shepherd et al, 1971). Sporangiospores lose much of their ability to germinate when sprayed on leaves and allowed to dry immediately (Cohen and Rotem, 1971;Cohen et al, 1974).…”