Hot water treatment to control Gloeosporium disease on apples during long-term storage

Synthetic fungicide treatments are not allowed in organic apple farming orchards a few weeks before harvest in order to reduce post-harvest diseases during long-term storage. Hot water treatments (53 °C, 2 minutes) of organically farmed apples are able to control Gloeosporium disease, the most dangerous fungal disease of organically produced apples during storage. A reduction of Gloeosporium rot below 10 % after a storage time of five to six months could be achieved with hot water treatments after harvest, irrespective of storage conditions (cold storage or controlled atmosphere storage). In comparison we found over 90 % disease on untreated apples stored at 1 °C in air, and even 40 % of these apples stored under controlled atmosphere showed the typical Gloeosporium rot after five to six months of storage. Investigations on the internal quality of hot water treated apples showed no difference between the treated apples and the untreated control-apples.