Orchard History: Fruit Monoculture and Orchard Intensification, 1946-Present

This article is an excerpt from Part I, Chapter 4 of Fruitful Legacy: A Historic Context of Orchards in the United States, with Technical Information for Registering Orchards in the National Register of Historic Places.

Internationalism, dwarf trees, and high-density management systems

The trend towards higher density, dwarf fruit tree orchards in the period from World War II to the present was fueled by the need to lower costs of production in an increasingly competitive marketplace. The development overseas of clonal rootstocks (genetically cloned, standardized rootstocks) influenced American horticultural practices by exposing American growers to more sophisticated horticultural technologies.

The discovery by European researchers that select dwarfing rootstocks could produce greater yields of higher quality fruit than seedling rootstocks led to the development of clonal dwarfing rootstocks. First developed for apple before World War II, clonal dwarfing rootstocks were then created for pear, plum, cherry, apricot, and citrus. These rootstocks provided multiple benefits for growers, including more quality fruit per unit of wood production, earlier fruit bearing, disease resistance, and easier orchard management. By the 1960s, semi-standard M. 7 and M. 106 clonal rootstocks had been adopted for apple orchards throughout the United States, with tree spacing transformed from 30 by 30 feet (40 trees per acre) before World War II to 10 by 18 feet (240 trees per acre).

Clump of pale green and yellow apples on tree branch covered in dark green leaves, with grass and red cliffs in the background.
Ginger Gold apples in the Jackson Orchard at Capitol Reef National Park.

NPS / Jamie Mansfield

A row of fruit trees grow in an agricultural landscape, pruned into an open bowl shape.
The orchard at Eisenhower NHS Landscape was planted around 1955. By 1969 the orchard contained twenty-four fruit trees, including sixteen apples, six peaches, and two nectarines. Although planted at this time, it lacks the characteristics of commercial orchards during this period of orchard history.


By the late 1980s, new apple orchards were planted on the most clonal dwarfing rootstocks M. 9 and M. 111, requiring staking or training systems to support the tree. The adoption of high-density management systems accompanied the use of clonal dwarfing rootstocks, using trellises to grow dwarf spindle trees at 2-5 by 6-10 feet spacing (1,000 to 2,000 trees per acre). Following suit, clonal dwarf rootstocks for pear, plum, apricot, and citrus have been discovered since World War II and adopted since the 1970s. Only peach does not have an accepted clonal dwarfing rootstock. With all orchards, the mass planting of singular varieties (with the exception of rows of pollenizer trees) became the norm for management efficiency, resulting in vast monoculture orchards over thousands of acres.

By the late 1970s, pear, peach, plum, apricot, and citrus were grown at tighter spacing, with hedge systems being explored in concert with clonal dwarfing rootstocks for fresh market fruits. Hedge systems had very close tree spacing within the rows and wider spacing between the rows, though still tighter spacing than before World War II. Hedge systems co-evolved with mechanical pruning systems invented during the 1960s. Mechanical harvesting systems, also developed in the 1960s, promoted less density in orchards grown for food processing to provide space for the "shake and catch" equipment.

Gradually, the movement towards higher density management systems affected all orchard fruits that would be hand-picked for the fresh market. Fruit varieties grafted to clonal rootstocks rather than clonal dwarfing rootstocks would also be planted at tight spacing and be maintained as compact trees by summer pruning and newly developed chemical growth regulators. Other trends included the adoption of spur-type mutations of several apple and pear varieties and the popularity of red sports of apple and pear varieties between the 1950s and the 1970s. Development in the 1960s of Controlled Atmosphere storage fueled the overproduction of Red and Golden Delicious apple varieties. Their ultimate loss in popularity and value in the 1980s was a response to new global competition.

New varieties and new imports devalued Red and Golden Delicious and stimulated a trend towards the growing of a broader range of apple varieties. A new round of peach varieties was developed in the 1970s, with earlier fruiting and more red-color characteristics, superseding the dominant Elberta variety. The range of pear, plum, apricot, and citrus varieties did not expand significantly in the late 1900s, with early 20th century commercial varieties continuing to dominate.

Diagram showing traits common in fruit trees and orchards during the period 1946-present
Characteristics common to fruit trees and orchards during the period 1946-present. Variety trees were grafted onto (clonal) dwarfing rootstock. Orchards were planted with regular geometry, short  threes, and tight spacing.

NPS / S. Dolan

At the turn of the 21st century, global market forces are shaping the work of orchardists and horticultural researchers. The new frontier appears to be the patenting of varieties that will be licensed to growers and be superseded every 10 years by other new patented varieties. New orchards will be grown on clonal dwarfing rootstocks in high-density management systems, which will produce the greatest quantity of highest quality fruit for the majority of the ta-year life span of the orchard. These new rotational orchards are planned to keep pace with the concept of variety obsolescence.

As a result of the trends in orchard history since World War II, earlier orchards with widely spaced trees on seedling rootstocks have come to represent archaic horticulture. Thousands of varieties have been lost as a result of the decreased number of varieties grown, and the new patented varieties are distinct from those of earlier periods. These changes have distinguished the older orchards in national parks dating prior to World War II, which represent earlier periods in the history of American horticulture. Historic orchards in national parks and elsewhere are now the repositoriesof rare varieties or strains of varieties, and are becoming rare examples of extant old fruit tree forms and layouts. Orchards have changed radically since World War II, and the rate of change can be expected to continue to grow.

Change in Orchard Spacing Between 1945 and the Present

Fruit Species Historic Orchard Spacing, 1800-1945 (feet) Historic Number of Trees per Acre Contemporary Orchard Spacing (feet) Contemporary Number of Trees per Acre
Apple 30 x 30 40 10 x 18 (M. 7 / MM. 106)
2-5 x 6-10 (M. 9 / MM. 111)
Apricot 20 x 20 100 10 x 20 200
Cherry 25 x 25 60 2-5 x 6-10 1000-2000
Grapefruit 30 x 30 40 20-25 80
Lemon / Lime 20 x 20 100 12-15 x 18-20 140-180
Orange / Tangerine 30 x 30 40 15 x 20 140
Pear 30 x 30 40 12 x 20 180
Peach 15 x 20 140 8 x 10 500
Plum 20 x 20 100 10 x 20 200

Last updated: April 5, 2023