Tree Fruit Production in High Tunnels: Current Status and Case Study of Sweet Cherries

Multi-bay, three-season high tunnels can provide production advantages for high value tree fruits, particularly those for which a protected environment can add significant crop or market access value. A key challenge for tunnel production of such woody perennial crops is the efficient utilization of space within the tunnel as well as containment of the tree canopy within the limited dimensions of the structure. Sweet cherries (Prunus avium) have excellent potential for tunnel production, as they are among the temperate zone tree fruits having the highest value as well as the highest production risks. Relatively recent advances in dwarfing rootstocks and high efficiency training systems for cherries provide critical tools for successful tunnel production. The covered environment of the high tunnel protects ripening cherry fruit from rain-induced cracking, improving growers' ability to consistently supply cherries for high value wholesale, pick-your-own, or farmers markets. Rain exclusion also reduces some diseases, such as cherry leaf spot (Blumeriella jaapii). The tunnel structure facilitates enclosure of sides and ends in spring for improved frost protection (with supplemental heat) and more rapid accumulation of growing degree days to promote earlier ripening, as well as netting of open sides and ends during harvest for protection from birds. Prevalence of some insects, such as Japanese beetle (Popillia japonica), is also reduced. Tree growth is significantly enhanced under tunnels, and fruit quality (size and flavor) is excellent, with reduced wind-bruising. Pruning of trees for good light exposure throughout the canopy is important for quality, especially the development of red blush on the skin of premium yellow-fleshed cherry cultivars like 'Rainier'.