NC140: Improving Economic and Environmental Sustainability in Tree-Fruit Production Through Changes in Rootstock Use

(Multistate Research Project)

Status: Active


The NC-140 Regional Research Project addresses economically and environmentally sustainable development in temperate fruit production by focusing on rootstocks and root systems. The NC-140 project meets the guidelines presented by the North Central Regional Association (NCRA) in Guidelines for Multistate Research Activities (July, 2014) by addressing high priorities within the crosscutting research areas of agricultural production, processing, distribution, genetic resource development and manipulation, integrated pest management, and economic development and policy. The project involves researchers and extension specialists from multiple disciplines in multiple states as well as international collaborators. Researchers involved in this project have leveraged federal and state dollars to add significant financial and in-kind resources to address this important research area. Lastly, outreach is integrated within the project and includes electronic information transfer through web sites, written material for growers and other stakeholder groups, on-farm demonstrations, and numerous educational programs conducted at a local, national and international level. 

Needs Identified by Stakeholders

The needs of the stakeholders addressed in this project have been identified through various sources and surveys.  Many of the members of this project have Cooperative Extension appointments and serve as educational liaisons with the tree fruit industries in their respective states working directly with their stakeholders in identifying and addressing needs. Additionally, a national needs assessment was initiated in 2009 to identify research needs of tree fruit growers.  Between 2009 and 2012, multiple meetings of tree fruit representatives, including growers, allied industries, researchers, and extension specialists were held.  Through this process a list of stakeholder research and extension priorities was compiled.  Among the greatest needs identified were integration of rootstocks into management systems, and root and soil interactions (replant/soil-borne problems); these are encompassed in the updated NC-140 objectives.   

Importance of the Work and Consequences if it is Not Done. 

Tree-fruit growers must adopt economically and environmentally sustainable orchard management strategies to remain competitive in both national and international markets, to meet consumer demand for high quality fruit, to address the pressure to reduce chemical use, and to enhance production efficiency. The root system, or rootstock, is a key orchard component to address these issues.  The rootstock provides control of tree vigor and final tree size, allowing for closer tree spacing and more trees per land area resulting in high density plantings.  Higher density plantings lead to earlier production and greater yield potentials. To stay profitable, growers must establish higher-density orchards of cultivars in demand by consumers and having higher market values.   However, establishment costs for high-density orchards are 10 to 20 times more per land area than lower-density plantings, thus greatly increasing economic risk. Potential economic returns of high-density orchards, however, can far exceed orchards at a lower-density, particularly during the first 10 years. Past NC-140 research has successfully identified reliable size-controlling, early-bearing rootstocks for apple and cherry, and led to the integration of their use in high-density production systems to reduce tree size, labor costs and significant tree and/or production losses from disease and environmental stresses. Although size-controlling rootstocks are currently in the relatively early stages of development for peaches, pears, apricots, and plums, this project seeks to identify and evaluate potential size-controlling rootstocks and associated orchard strategies to increase production and sustainability in these tree fruits as well.

In addition to tree size, the rootstock profoundly affects sustainable productivity, fruit quality, pest resistance, amenability to mechanization technologies, adaptability to different soil types, stress tolerance, and ultimately profitability. Many commercially available rootstocks have inherent weaknesses and have not been evaluated thoroughly for potential problems in different production environments. Continued tree losses due to cold temperature injury, disease, scion incompatibility, and poor soil conditions are an economic cost for the industry that can be ameliorated by improving rootstock genotype options.  There is a concomitant demand by growers for timely research that solves production problems and provides information for the prevention of costly mistakes.

Technical Feasibility

Success with new orchard systems depends on reliable recommendations for a wide range of conditions which can be best accomplished with coordinated multistate research. Since the inception of the NC-140 project, U.S. tree fruit growers have received reliable rootstock recommendations that have transformed their industry into one of the most productive in the world.  New pome- and stone-fruit rootstock recommendations are based on multi-site research investigating soil and climatic adaptability, root anchorage, size-control, precocity, productivity, and pest resistance. Tree fruit are long-lived perennial plants, so a minimum of eight years is necessary to develop a thorough understanding of rootstock performance and to accurately assess the potential for improved profitability, reduction of grower inputs, and enhancement of production efficiency. With multi-state research, new rootstocks are quickly and systematically exposed to widely varying soil and climatic conditions to shorten the time necessary for a thorough evaluation as well as to help develop site specific recommendations across this range of growing environments. Consequently, the vast majority of growers rely on research-based NC-140 recommendations as their primary resource for rootstock selection. 

Changes in orchard systems have occurred over the past ten years to address profitability and the increasingly high cost and shortage of labor. Using size-controlling rootstocks, the apple and cherry industries have adopted high-density orchard systems that facilitate tree maintenance operations from the ground or mobile platforms, eliminating dangerous ladder use. Increased adoption of mechanization, and even the exploration of robotics, for pruning and harvesting is also underway, which is influenced by the orchard system implemented. Consumer interest in new varieties of apple, pear, peach, plum, apricot, and cherry creates a demand for highly productive and precocious rootstocks and an opportunity for growers to select rootstocks that are better adapted to these industry changes and to regional climate and soil considerations.

If the U.S. temperate-zone tree fruit industry is going to remain competitive in international markets and meet increasing consumer demands, new genetic materials will need to be identified, evaluated, and adopted to address emerging problems. Through traditional plant breeding methods and novel genomic tools, researchers have incrementally incorporated insect and disease resistance into existing rootstock germplasm, as well as developed rootstocks with enhanced horticultural performance and stress tolerance. Obtaining potentially improved rootstock genotypes from research programs throughout the world for testing by NC-140 cooperators has been an integral part of the project.  Promising clonal materials for new rootstocks for pear, peach, apricot, plum, and cherry have been obtained both domestically and internationally. Development and use of genetic markers can speed up the selection process, but are dependent on coordinated evaluation of economically important traits in multiple environments.  Meanwhile, rootstock breeding programs have generated many new elite selections that may be preferentially adapted to specific regions of North America. These new rootstocks require coordinated testing under diverse North American climates and soil types, and training and pruning techniques must be modified to match rootstock traits with local growing conditions.

Advantages of a Multistate Effort

Collaborative research by the NC-140 project team has demonstrated that tree fruit rootstock growth characteristics can differ widely across North American production regions. Low or high temperatures, soil conditions, and susceptibility to endemic pests can limit the adaptability of some rootstocks in certain regions. A greater understanding of stress factors and physiological mechanisms behind these responses, as well as rapid screening of genotypes for susceptibility or tolerance, will improve tree survival and productivity in diverse soils and climates.

Outreach is integral to the NC-140 project ( Using eXtension, in addition to regionally and state-focused web sites, NC-140 members will expand the digital availability of rootstock information. Other outreach efforts will include written materials for growers and other stakeholder groups, as well as video and on-site educational programs in individual states and at national and international grower and scientific meetings. On-farm research and demonstration trials, including farm tours and field days, are very effective for disseminating NC-140 research results directly to growers.

Collaborative evaluation of new and existing rootstocks by NC-140 researchers continues to generate financial support from fruit and nursery industries for the propagation and establishment of cooperative plantings, as well as grants for specific rootstock research. Individual researchers use support from industry as seed money to leverage and seek state, federal and private foundation grants (competitive and non-competitive) for associated studies. It is anticipated that over the term of the current project (2012-2017), approximately $2,000,000 will have been generated to support NC-140 research as seed funding/matching and/or direct support from sources other than universities, Hatch funds, and RRF funds, and more than half of this total will come from grower organizations. Additionally, more than $4 million in USDA-SCRI funding has recently been procured (by a team that includes NC-140 members) for intensive apple rootstock-related studies that are dependent upon the existing NC-140 trials as a unique research resource.

Likely Impacts

As evidenced in the previous work and performance of this project, the proposed and on-going research will enhance the economic viability of growers through improved selection of rootstocks that lead to greater production efficiency and improved fruit quality. Orchard labor and land will be utilized more efficiently, with fewer tree losses to pests and environmental stresses, leading to a faster and greater return on investment.

A compelling need exists to initiate new coordinated research on a large scale for temperate-zone fruit tree rootstocks as new genetic materials are developed or made available. Many new rootstocks will require a change in orchard cultural practices. Continued testing will provide a thorough evaluation of promising rootstocks, multiple genetic systems, and planting and training system efficiencies. This research project will continue to develop sound research-based recommendations for growers and nurseries that are based on extensive and collaborative multi-state work, providing an increased understanding of rootstock adaptability and performance.

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