Fungal Disease and Fruit Quality in an Apple Orchard Converted from Integrated Production to Organic Production

Abstract

Interest in organic food is increasing among consumers, thus making it possible to improve the profitability of Swedish apples. One way to obtain a swift increase in organic apple production is to convert existing orchards to organic growing. The main objective of this study was to compare the horticultural performance of an apple orchard converted to organic growing with the previous Integrated Fruit Production (IFP). The trial was conducted in the south of Sweden during the years 2000–2002. The accumulated yield for organic ‘Aroma’ was 66.2 kg/tree compared with 77.9 kg and 99.5 kg for two IFP-treated sections. For ‘Karin Schneider,’ the yield was 20.7 kg/tree in the organic section, and 21.9 kg and 26.1 kg for the two IFP sections. The lower yield in organic sections was mainly due to a smaller amount of fruit. This reduction may have been caused by the use of a sulphur-containing fungicide, which could have had a fruit-thinning effect. The most important difference between treatments was apparently connected with the use of less efficient fungicides in the organic sections. In these sections, 10% of the fruit was damaged by scab, whereas less than 1% had scab in the IFP sections. Lack of efficient fungicides was also apparent after storage; 8% of organically grown ‘Aroma’ fruit was affected by the storage disease bull's-eye rot, compared with 0.4% in the IFP sections, while corresponding figures for ‘Karin Schneider’ were 4% and 0%, respectively. The two cultivars differed considerably from one another in various fruit quality parameters, but no major treatment effects were found in fruit covering colour, ground color, firmness, sugar content or malic acid content. Higher amounts of nitrogen and boron were found in fruit from the IFP sections, but this finding was probably caused by foliar spraying with nutrients.

KEYWORDS:

• apple scab
• bull's-eye rot
• Malus
• Monilia fructigena
• Neofabraea alba
• Neofabraea malicorticis
• organic growing
• Venturia inaequalis

ACKNOWLEDGMENT

The authors thank Paul Ilg, Ibrahim Tahir, Jan-Eric Englund, Ingemar Jönsson, Asta Jönsson and Lars Jönsson for providing valuable assistance.