Infection of blackcurrant flowers and fruits by Botrytis cinerea in relation to weather conditions and fruit age

Abstract

Experiments were conducted to investigate infection of blackcurrant flowers and fruits in relation to environmental conditions and fruit age on cvs. Baldwin and Ben Hope. The two cultivars did not differ significantly in the susceptibility of flowers to Botrytis infection. Nearly 75% of flowers were infected or abscised 1 week after inoculation and nearly all remaining flowers failed to develop into mature fruit. Fruits were inoculated at different growth stages and then incubated under different initial conditions: 10, 15, 20 and 25 °C each with four wet periods (4, 8, 12 and 24 h). Infection of fruit was not significantly affected by the temperature and duration of wetness. The two cultivars differed significantly in their responses to Botrytis infection depending on the fruiting stage at the time of inoculation. Inoculation of young fruitlets resulted in nearly 50% of fruits aborted on cv. Baldwin, compared to ca. 10% on cv. Ben Hope. Inoculation of fruit near harvest resulted in significantly fewer fruit aborted. The incidence of latent infection decreased with increasing fruit age at the time of inoculation. Sampling of blackcurrant fruit and spraying timing trials in planting of these two cultivars in open-field and under-protected conditions supported the main conclusions drawn from the controlled inoculation studies. Thus irrespective of weather conditions, strategies must be adopted to reduce inoculum and the extent of flower infections.