Effect of Interrupted Wetness Periods on Spore Germination and Apple Infection byBotryosphaeria obtusa

Conidia of Botryosphaeria obtusa were allowed to germinate in water for 4 hr at 24 C, were air-dried, and were rewetted following dry periods ranging from 0 to 8 hr. No increase in germ tube length was observed 4 hr after rewetting in any treatment. Mean germ tube length was similar (approximately 126 μm) for all drying treatments. Mean germ tube length was 532 μm when conidia were allowed to germinate in water for 8 hr without interruption. Apple seedlings were inoculated with conidia of B. obtusa in aqueous suspension and were exposed to 24-hr wetness periods, which were interrupted after 12 hr for 1, 2, 3, and 4 hr (...)