Latest trends in insect and disease management in organic apple systems in the Midwestern USA and New Zealand.

In the USA in 2005, organic apples were produced on 2788 ha in the drier climates of Colorado and eastern Washington State, but significant production also occurred in the Midwestern USA. In Midwestern organic markets, scab (Venturia inaequalis)-resistant cultivars have gained increased acceptance as the most environmentally acceptable method of organic apple production, due to concerns about copper and sulfur applications in susceptible cultivars. Typically, key pests, such as codling moth (Cydia pomonella), have been managed to damage levels below 5% through the use of codling moth granulosis virus (CMGV), mating disruption, kaolin clay, and spinosad-based insecticides. In an experimental organic apple orchard in Iowa, killing frosts in 2007 destroyed up to 80% of fruit production, leading to a resurgence of codling moth and plum curculio (Conotrachelus nenuphar) under a no-spray program. This resurgence emphasizes the need to manage pests even in low crop years. Similar pest management systems have been developed by apple-exporting countries like New Zealand in order to comply with export standards and quarantine requirements. In New Zealand, significant progress has been made in achieving greater fruit firmness after 3-month storage in advanced scab-resistant selections with 'Pinkie' background compared to 'Pinkie' or 'Liberty' apples. Future pest management strategies in organic apple production will continue to focus on the development of scab-resistant cultivars with enhanced storage capability, and the use of controlled atmosphere (CA) treatments to reduce inputs associated with negative environmental and health effects.