Thinning remains a critical yet challenging practice in apple production, especially for organic systems where chemical tools are limited. Since 2017, our research has evaluated the use of insect-exclusion netting as a sustainable, non-chemical strategy to simultaneously manage crop load and reduce pest pressure. What began as small-scale trials has expanded to commercial-scale implementation in Michigan, supported by USDA funding. Over the course of eight years, we evaluated netting on a diverse suite of cultivars including 'Gala', 'Fuji', 'SweeTango’, Liberty’ and 'Honeycrisp' in multiple locations. Canopies were enclosed at varying bloom stages, and results consistently demonstrated that netting significantly reduced fruit set in proportion to the amount of open bloom at the time of application. Cultivar-specific responses were observed: Gala’ and 'Fuji' achieved optimal crop loads when netted between 25% and 50% bloom, while ‘SweeTango’ and 'Honeycrisp' often required higher percentage of open bloom. In several trials, netted trees yielded commercial fruit numbers without requiring hand or chemical thinning. Fruit size and quality remained similar to conventional treatments, while seed content was reduced without negatively impacting fruit development. In many cases, trees netted at the ‘pink’ phenology stage produced adequate fruit set of low seed-content fruit despite the exclusion of pollinators. Importantly, molecular genotyping using 16 SNP markers revealed that seed parentage in netted canopies overlapped with known pollinizer genotypes. This ruled out self-pollination and suggested that wind, rather than insects, facilitated cross-pollination under netted conditions. Additionally, fruit retention was linked to seed content at the population level, not the individual fruit level, further supporting the viability of non-insect pollination under netting. In 2024, we implemented nets in commercial orchards in Michigan to validate scalability. Netting treatments at 30% and 60% King Bloom produced yields and fruit quality metrics comparable to conventional thinning. Pest monitoring confirmed male codling moth exclusion and reduced San Jose scale captures, though woolly apple aphid and flower thrips populations increased under nets given the exclusion of natural predators Collectively, our results indicate that exclusion netting is a promising, multifunctional tool for organic and sustainable apple production. Beyond thinning and pest control, netting systems enable effective crop set through wind-mediated pollination, challenging traditional assumptions of insect dependency. Adoption of this system may require revised orchard design to optimize pollen flow, but offers significant environmental benefits, including reduced chemical inputs, support for pollinator conservation, and improved climate resilience in Midwestern apple orchards.
