Thousand Acre Farm:
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.
The first question that must be asked when planting a high density orchard is “Why?” The first answer is increased early production. In today’s markets, many “new” cultivars are selling for 4-5 times the price of standard cultivars. Having orchards that can be established and cropped significantly in the first 2-3 years is a very good reason to consider high density systems. Because of the early production and higher returns many higher density orchards are breaking even in 6-7 years compared to 10-12 years for traditional systems.
Efficient use of labor to harvest and prune from the ground or from a short stool is another advantage of using a high density system. It is difficult to find employees who are willing to climb ladders to work in traditional orchards in today’s market, not to mention the liability that must be assumed for those employees. Another advantage is the potential to have higher quality fruit for a longer period of time by maintaining light interception in the smaller trees of higher density orchards. Pesticide application efficiency may be much higher in higher density orchards as well.