Apple varieties susceptible to mouldy core generally have an open sinus extending from the calyx into the core that allows saprophytic fungi colonising senescing flower parts to enter the core region. Many varieties of apples are affected worldwide especially Red Delicious and Red Delicious types. In the UK the problem is mainly associated with the varieties Cameo and Bramley’s Seedling but is also found in Ida red, Braeburn, Gloster and certain cider apple varieties.