Mechanical harvesting of plum fruit cuts drastically costs of production. ‘Elena’ plum trees were planted, at a high density (4 × 1.0 m and 4 × 1.5 m) and trained to a horizontal canopy. The trees, trellised on wires 1 m above the ground, created a continuous, open-texture, fruit-bearing horizontal surface, 2 × 200 m long. Plum trees planted at the distance 4 × 1.5 m and 4 × 2.0 m trained to the standard leader tree served as the control. In the fifth to seventh year from planting (2012–2014), plums from the horizontal canopy were harvested with a tractor-driven, canopy-contact harvester. Fruits from the standard leader trees, having a height of 2.8 m, were harvested with a self-propelled canopy-contact straddle harvester. The mean volume of a horizontally trained tree was 3.6 m³, compared with 7.4 m³ of a standard leader tree. The efficiency of mechanical fruit harvesting of control trees was 40 times higher than of hand picking. The efficiency of fruit harvesting of horizontal canopy trees was 25 times higher than of hand harvesting. The effectiveness of fruit collecting of standard leader trees was 86–94% against horizontal canopies 72–80%. Plums harvested with the small tractor-driven harvester were of good quality. After grading, 80% of them were suitable for the fresh market. Plums harvested with the large straddle harvester were of medium quality. After grading only 50% of them were suitable as dessert fruits.

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