Efficient Multi-location Testing of Scab Resistant Cultivars for Organic Apple Production in Switzerland

Summary

The market and production of organic apples is growing worldwide. Most of the production occurs on freshly converted orchards with cultivars very sensitive to apple scab (Venturia inaequalis) that in humid conditions need an intensive plant protection program. For the future development of organic fruit growing towards a credibly sustainable production it is necessary to replace these cultivars with scab resistant or tolerant cultivars. Cultivar testing under organic growing conditions is therefore an important task. We describe our testing concept that consists of precision trials where cultivars are tested with an without aphid control and with and without crop load regulation. In parallel, we carry out on-farm trials with the most promising cultivars on up to 10 commercial, certified organic farms in all apple growing regions of Switzerland. Our experience with the concept is mostly positive because recommendations for the organic growers can be made relatively fast and reliably. However the test system is costly and labor intensive.