Survival of Botrytis cinerea conidia on kiwifruit

Experiments were conducted over two seasons (1995 and 1996) to determine the survival of Botrytis cinerea conidia applied to the fruit surface of kiwifruit (Actinidia deliciosa, cv. Hayward). In 1995, potted vines were exposed for nine weeks to controlled environments at the National Climate Laboratory and to natural conditions in a shadehouse. In 1996, field experiments were carried out over a period of 16 weeks at two research sites. Change in number of conidia (enumeration), viability (germination) and vigour (germ-tube length, 1995; infection of host tissue, 1996) of conidia were assessed over time. In both years, the number of conidia/fruit declined significantly over time. However, conidia remained viable on the fruit surface throughout the two experiments. In both seasons, approximately 40% of the conidia recovered still germinated after field exposure and the vigour of viable conidia remained constant over the duration of the two experiments. The results of the research showed that B. cinerea conidia are able to survive on fruit surfaces of kiwifruit, remaining viable and infectious throughout the growing season.