THE EVOLUTION TOWARDS MORE COMPETITIVE APPLE ORCHARD SYSTEMS IN THE USA

The USA apple industry continues to modernize with higher density orchards of new premium varieties. Over the last 20 years, most growers have increased their planting density from 400 trees/ha to between 1,500 and 3,000 trees/ha. Our economic analysis has shown that with the relatively high price of trees in the USA the optimum planting density in the USA is currently around 2,500 trees/ha. However, with less expensive trees and high fruit prices of new premium varieties the optimum planting density is around 5,000-6,000 trees/ha. Currently, a few growers who grow their own nursery trees or plant sleeping eye or bench grafts, plant up to 5,500 trees/ha. At the lower end of the current planting densities, the most common training system is the Vertical Axis using M.26 or G.30 rootstocks, while at the higher end of the range the most common training systems are the Tall Spindle, V-Tall Spindle and Super Spindle on M.9, B.9, G.16, or G.11 rootstocks. More recently, researchers and growers are attempting to improve the competitive position of US apple producers by reducing production costs per packed box by either improving yield and/or reducing labor costs. The effort to improve yield has focused on improving yield of premium sized fruit by increasing planting density, planting higher quality trees which require little or no pruning for the first 4 years and by more precise fruit thinning. The effort to reduce labor costs is currently focusing on partial mechanization of pruning, thinning and picking. This effort is focusing on designing tree canopies that are very thin and have a simple repeating structure. The mechanization efforts have been on evaluating mechanized platforms which position workers to improve labor efficiency. Longer term efforts are aimed a developing machine vision and robotic machines to mechanize pruning and harvest.