Isolation spore production and Kochs postulates of <i>Elsinoe pyri</i>

Abstract

Elsinoe leaf and fruit spot is a minor disease of apple and pear Very little is known of the biology and life cycle of the causal agent Elsinoe pyri The fungus was isolated from spots on apple fruit and grew very slowly on potato dextrose agar (PDA) The conditions needed for spore production were examined using different culturing media plating techniques and culture ages When small pieces of a 2 to 6weekold culture from PDA were subcultured onto corn meal agar for 2 days viable conidia were produced Conidial germination occurred between 10C and 26C with the highest germination percentage at 20C and 26C and greatest germination tube elongation at 20C At least 200 conidia per leaf were required to infect Royal Gala leaves Typical elsinoe spots were visible 6 weeks after inoculation Four months after inoculation conidia from the spots were reisolated onto PDA and grew into typical colonies of E pyri