High Density Apple Orchard Management
From a historical perspective, a high density orchard is defined as any orchard with more than 150-180 trees per acre. However, many highly productive commercial orchards today have 150-180 trees per acre and higher density could be anything over 180 trees per acre. For the purposes of this publication, there are several characteristics in addition to tree number that are included in a high density orchard system. Besides having an increased number of trees per acre, a high density orchard must come into bearing within 2-3 years after planting. To achieve this early production, it is essential to use a precocious dwarfing rootstock. Although it is possible to restrict the growth of trees on semi-dwarf rootstocks, they do not have the genetic capacity for early bearing.
Consistent early fruit production is essential to offset the increased establishment costs. It is also very costly to hold trees on more vigorous rootstocks in an allotted space required for a high density orchard. To maximize the production of a high density orchard, it is also necessary to modify the training system and training and pruning techniques from traditional methods. Since trees will be bearing fruit early, a permanent tree support system is also required.
It is essential to crop trees very early in the life of the orchard to offset the costs of establishment and to aid in managing vegetative growth. Early production is directly related to the number of trees planted per acre. The greater the tree number, the greater the light interception by that acre of land early in the life of the orchard. To the extreme, there are orchards planted in Europe and the Pacific Northwest with 5,000-9,000 trees per acre. Although, these orchards may be very productive early in their life, it is doubtful that they would be profitable, or manageable, under economic conditions in the Southeast. So the next question that must be addressed is “What is the most profitable tree density for a high density orchard?” Research conducted at Cornell University’s Geneva Research Station in New York found that for the first seven years of an orchard, the yield increased with tree density, independent of the size-controlled rootstock used. The most dwarfing rootstocks produced significantly larger yields in the third year. As tree density increased, profitability increased up to approximately 1,000 trees per acre. Preliminary studies in North Carolina indicate that tree densities of 450-600 trees per acre are most profitable for the Southeast given the climate, soils, and markets.