Host factors related to fruit rot of sweet cherry (Prunus avium L.) caused by Botrytis cinerea

Fungal rot of sweet cherry fruit leads to reduced yield and quality at harvest. This study investigated a range of host factors related to cherry rot and also identified the main species present in latently infected-fruit and fruit with visible rot at harvest in a Tasmanian orchard. There was a significant effect of tree cultivar on total rot found at harvest, with the cultivar “Sweetheart” associated with almost double (approx. 25 % infection) the amount of rotten fruit compared to “Regina” and “Simone” (approx. 13 %). Harvest date may have had some influence on this result, as Sweetheart fruit were harvested 2 weeks later than the other cultivars, and there was a large rainfall event just before Sweetheart harvest (rainfall can increase disease spread and infection). Crop load did not influence the amount of rotten fruit found at harvest for any cultivar, although crop load was low in this season at this site. Removing fungicide application from the point of 50 % full bloom onwards did not significantly alter disease incidence. The study found that Botrytis cinerea was the dominant rot pathogen in cherry fruit at this site and season. No evidence of Monilinia species was found in this study with the methods used, despite it being typically associated with rot of stone fruit. Fruit quality characteristics were not indicators of disease susceptibility, as very few characteristics observed to correlate with disease at harvest.