333 Organic Fruit Production in Humid Climates of Europe: Bottlenecks and New Approaches in Disease and Pest Control Lucius Tamm, Andy Häseli, Jacques G. Fuchs, Franco P. Weibel and Eric Wyss Research Institute of Organic Agriculture (FiBL) Ackerstrasse, Postfach CH-5070 Frick Switzerland Keywords: apple, cherry, organic, cultivar, scab, brown rot Abstract The organic market has grown exponentially in Europe during the last ten years. However, the organic fruit industry has shown the lowest growth rates (1-5% market share) compared to other commodities. One major reason is the high production risk due to high disease and pest pressure in humid climates. Key pests and diseases in apple and pear include scab, sooty blotch, and fire blight as well as rosy apple aphid, pear sucker, and codling moth. In cherry, damages due to brown rot (Monilinia) and the cherry fruit fly make organic production almost unfeasible. In an ideal organic system, all possible measures that lead to improved stability of the system must be implemented. In fruit production, such measures include (i) use of resistant varieties (scab), (ii) active promotion of predators (rosy apple aphid), (iii) sanitation (cherry monilinia), (iv) microclimate management (planting density, covering trees), and (v) strengthening the plant self-defence system (e.g. building up of soil fertility, bio-dynamic preparations). At present, most organic orchards have been designed for conventional production and, therefore, lack most stabilising components. In consequence, organic fruit production still depends largely on direct pest and disease control methods. These include traditional pesticides such as copper, sulphur, and lime sulphur, pyrethrin, oil and soap preparations. More recently, new pest control compounds and techniques have been developed including neem products, granulosis virus, and mating disruption. New tools for disease control are less spectacular and focus on the replacement of copper (e.g. with clay powders and resistance inducers). The introduction of new equipment, materials, and Decision Support Systems (DSS) will further improve yield stability. However, other limiting factors such as weed competition, crop load regulation, and conventional market demands need innovative solutions. INTRODUCTION The organic market has grown exponentially in Europe during the last decade. However, organic fruit production has not kept pace with market growth despite the growing interest of consumers (Hamm et al., 2002). Pest and disease management, including the management of ‘novel’ noxious organisms such as fire blight, is the key bottleneck hindering growth of the organic fruit industry in Europe’s humid climates. As a result of the high production risks conventional fruit growers are hesitant to convert their farms to organic production. Further bottlenecks include increasingly strict standards for exterior fruit quality and the growing difficulty in development and registration of pesticides acceptable for organic farming (Tamm, 2000). This paper aims to identify some key pests and diseases in organic apple (Malus x domestica), pear (Pyrus communis), and cherry (Prunus avium) production and to discuss the current control strategies as well as the potential of novel techniques. Bottlenecks and Current Crop Protection Strategies Crop protection materials that are compatible with organic standards tend to be less efficient than modern synthetic pesticides. Formulas approved for organic production are often efficient at low disease pressure, but may be much less efficient under high Proc. XXVI IHC – Sustainability of Horticultural Systems Eds. L. Bertschinger and J.D. Anderson Acta Hort. 638, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA)