Evaluation of treatments to control mouldy core in apples

Abstract: Mouldy core is an internal rot of certain apple cultivars that have an open calyx whichallows saprophytic fungi colonising senescing flower parts to be washed into the core. Fungalgrowth then develops within the apple core and eventually rots the apple flesh. Core rots mayalso continue to develop in store and may then appear at the cheek, calyx or stalk end of the fruit.The main problem with mouldy core is that it can remain undetected until the fruit is eaten orprocessed. External symptoms in the orchard are rare but fruit may colour and fall prematurely.In the UK the problem is mainly associated with the cultivars Cameo and Bramley’s Seedling.The objective of the work described was to identify core rot incidence and the main fungiresponsible for the problem in Cameo and Bramley in the UK and to identify effective fungicideprogrammes to control them. The incidence of core rots was greater in 2009 than 2008 or 2010 inboth Cameo and Bramley and in general more core rots were found in fruit that had dropped fromthe tree than in fruit sampled from the tree. The main fungi identified included Fusarium spp,Alternaria spp. and Penicillium spp. Colletotrichum was also important on Bramley but notCameo. In 2009 and 2010 trials were established in Cameo and Bramley orchards located in Kentto evaluate the efficacy of fungicide products against mouldy core. The results indicated that bothBellis (pyraclostrobin + boscalid) and Switch (cyprodonil + fludioxonil) have some effect onreducing mouldy core when applied during blossom and petal fall but Systhane (myclobutanil)mixed with Scala (pyrimethanil) was ineffective.