The investment required to establish a new apple orchard is one of the most important factors in lifetime profitability. The decisions made at planting time have a large influence on the future profitability of the orchard. Thus, design phase of the orchard is critical in the long-term profitability with important decisions such as variety, planting density, training system and rootstock all having a large effect. Previous economics analyses showed that with different apple varieties the selection of the rootstock (Gonzalez Nieto et al., 2024; Lawrence et al., 2025) and the training system were the most important factors in the final profitability of the orchard (Gonzalez Nieto et al., 2023; Ho et al., 2024). Several studies of horticultural and economic performance of new orchards showed that training system and rootstock can improve yield and profitability of the orchard (Gonzalez Nieto et al., 2023; Lordan et al., 2019a, 2018a, 2019b; Reig et al., 2020, 2019; Robinson, 2007; Robinson et al., 2007). There are several studies that evaluated mineral nutrient profiles of different rootstocks (Reig et al., 2018; Fazio et al., 2018, 2019, 2025), the effect of rootstocks on fruit disorders (Donahue et al., 2021; Islam et al., 2022; Valverdi and Kalcsits, 2021) or resistance to different apple pest (Kviklys et al., 2016; Leinfelder and Merwin, 2006; Norelli et al., 2003; Russo et al., 2007), hormone concentrations (Kalcsits et al., 2019; Lordan et al., 2017; Van der Krieken et al., 1993) and organic management (Bradshaw et al., 2015; Fazio et al., 2025). However, all these articles evaluated agronomical parameters and not the long-term economic implications. One exception was Lordan et al. (2019b) that evaluated the economic effects in two cultivars at different tree densities and five rootstocks. They observed both high and medium planting density systems and found that M.9 and B.9 offer a more favorable balance between tree vigor, productivity, and profitability than more vigorous rootstocks. Another study by Ho et al. (2024) evaluated eleven rootstocks in four training systems at different planting densities and three cultivars in two locations. They found that the most profitable training system was Tall Spindle at 3230 trees per ha with the best rootstocks being G.11, G.16, G.41, M.9 and B.9. in ‘Gala’, ‘Honeycrisp’ and ‘Fuji’. However, there are no economic studies specifically focused on the ‘Delicious’ cultivar, particularly evaluating the interaction between multiple rootstocks and training systems over the long term, which represents a significant gap in the literature that our study aims to address.

‘Delicious’ is one of the most important varieties in USA and in other areas of the world. In 2024 the USA production was 789,918 t (41.4 million bushels) and was the second most produced variety (Industry Outlook report 2025, www.usapple.org). The production of New York was 43,260 t (2 million bushels) and is one of the top 10 varieties in the state (Industry Outlook report 2025, www.usapple.org). We initiated this project to study the economics new orchards of this important variety since its spur-type clones have a very different growth habit than other varieties such as ‘Gala’, ‘Honeycrisp’ and ‘Fuji’ which we have already studied.

Among planting systems which we have not previously evaluated long-term economic performance is the multi-leader system. In the current study we chose to evaluate a triple leader system we named the triple axis spindle (TAS). Muli-leader systems of 2, 3 or more leaders have been proposed as a method of obtaining the desired number of leaders (trunks) per hectare with fewer trees per hectare thus reducing the initial establishment costs of high density orchards. The spur-type growth habit of ‘Delicious’ is optimum for such multiple leaders which can be spaced every 40 cm along the row. In this study we compared the TAS to both lower and higher density systems which utilized a single leader per tree. We also evaluated each system on a number of rootstocks to evaluate the interaction of rootstock and planting system. Building on this foundation, our objective was to evaluate the long-term economic performance and the interaction between ten different rootstocks and four training systems using a popular spur-type clone of ‘Delicious’: Super Chief. The horticultural results of this project were previously published by Reig et al. (2020), providing critical insights into tree growth and productivity. By extending this work to include an economic analysis, the present study offers practical guidance for optimizing orchard profitability and sustainability, which is essential for apple production systems in the Northeastern United States.

This study is a continuation of the series of studies our group has conducted to determine the economics of varying planting density and rootstock with several varieties (Robinson et al., 2004; Lordan et al., 2018b; Gonzalez Nieto et al., 2023; Ho et al., 2024). This current study was done with a variety with a strong spur-type growth habit (Type 1) (Lespinasse, 1977) while all our previous studies were done with Type 3 varieties. Spur-type ‘Delicious’ has much shorter internodes and is lower in vigor than Type 3 varieties, thus, high-density plantings of spur-type ‘Delicious’ with M.9 have not been successful in commercial orchards. The unique growth habit of spur-type ‘Delicious’ presents challenges to producing spur-type ‘Delicious’ trees in modern high-density commercial orchards and is the reason this study was initiated.

The results of this study demonstrate that training system and rootstock play a crucial role in determining the long-term economic viability of ‘Delicious’ apple orchards, as assessed through NPV over a 20-year period. Among the systems we evaluated, the high-density planting configurations of SS and TS, consistently yielded the highest profitability. In contrast, the VA, characterized by its lower planting density, resulted in the least favorable economic returns, while the TAS occupied an intermediate position. These findings align with and expand upon previous research. For instance, Lordan et al. (2018b) demonstrated that the TS system provided optimal profitability for ‘McIntosh’ apples at a similar planting density, although their study did not include the SS system. The agronomic analysis by Reig et al. (2020), based on the same ‘Delicious’ dataset, showed that SS had the highest cumulative yields, followed by TS, with TAS and VA trailing behind. This yield hierarchy directly correlates with the economic outcomes observed in our study, reinforcing the conclusion that systems with higher cumulative yields tend to generate greater long-term profits. Our data further supports the conclusions from Mitre et al. (2011), who found that TS outperformed VA and Solaxe in terms of productivity across various apple cultivars. Our findings with ‘Delicious’, clearly show that TS and SS are economically superior due to their higher yield potential. Additionally, Weber (1998) compared SS with the traditional Slender Spindle system and concluded that although SS required a higher initial investment, it delivered significantly greater profits after a decade. Our study extends this observation over a 20-year horizon, confirming that despite the elevated establishment costs associated with high-density systems like SS and TS, their long-term profitability is substantially higher.

Our results with the Triple Axis Spindle system indicate that lowering the number of trees per acre and developing multiple leaders (trunks) on each tree resulted in lower cumulative NPV than single stem trees of TS or SS both planted at higher densities than the TAS. The planting density of the TAS was 2,343 trees per hectare resulting in 6,729 leaders per hectare which was greater than the SS which had 5,382 leader (trunks) per hectare or the TS which had 3,662 trees per hectare yet the TAS had lower profitability. Thus, our results indicate that it is a false promise that a multi leader tree will allow a reduction in the number of trees per hectare resulting in similar profitability as higher density single stem trees. Our result also indicates that the idea of developing more leaders per tree to allow lower planting densities to reduce the initial establishment costs of the high density systems such as TS or SS systems, negatively affects lifetime profitability. Underlying this result is the basic principle that profitability is strongly tied to planting density up to 3,000-5,000 trees per hectare as we have previously reported (Lordan et al., 2019b). The curvilinear profitability curve we previously reported for 4 Type 3 cultivars showed profitability maximized at around 3,000 trees per hectare. The current study with spur-type ‘Delicious’ indicates that the optimum density (depending on rootstock) is probably ~4,000 trees per hectare.

There was a significant interaction between rootstock and training system, indicating that the economic performance of a given rootstock varied depending on the training system, which supports findings previously reported by Ho et al. (2024) and Gonzalez Nieto et al. (2024), who observed similar interaction between training system, rootstock and variety. This finding showed that profitability cannot be optimized by considering rootstock or training system in isolation. For example, while M.9 consistently ranked among the least profitable rootstocks overall, its slow early growth, despite being a precocious rootstock, limits early yields; however, it showed greater profit under SS than under VA, suggesting that high-density systems can partially offset this disadvantage. In this line, Lawrence et al. (2025) reported similar results for ‘Delicious’ with M.9T337 where this rootstock was among the least productive in a 17-year trial comparing 18 rootstocks, further confirming its limited economic potential in long-term orchard systems. Interestingly, M.7 had the poorest results with SS despite performing moderately in lower-density systems, highlighting that vigorous rootstocks that are non-precocious may not align well with high-density plantings. Cline et al. (2025) had similar results with ‘Honeycrisp’ in a multilocation trial in the US. In our study, G.11 and G.41 emerged as top performers with the SS system, whereas G.11 was the best with TS, and B.118 provided the highest returns in VA, reflecting the adaptability of the different rootstocks to specific structural and management conditions. These patterns reveal that rootstock traits such as vigor and precocity interact strongly with system design, influencing the profitability of the orchard, as mentioned by Fazio (2021). This author noted that the recent advances in apple breeding programs have greatly enhanced the capacity to tailor rootstock performance to specific orchard conditions, including scion cultivar, soil characteristics, water availability, disease pressure, and training system architecture. Therefore, economic sustainability in apple orchards depends on a tailored approach that matches rootstock characteristics with the chosen training system, rather than relying on general recommendations. This interaction of training system and rootstock genotype highlights the complexity of orchard design decisions and reinforces the need for integrated strategies that consider both biological and economic factors to maximize long-term profitability.

In our study, large differences in establishment costs were associated with each training systems, as shown in previous work (Robinson et al., 2004; Lordan et al., 2018b; Gonzalez Nieto et al., 2023; Ho et al., 2024) and several other papers. This early negative balance with all systems reflects the implementation costs of orchard establishment. VA showed the smallest initial deficit, followed by TAS and TS, while SS experienced the most negative NPV during the early years. This is logical because the most intensive apple orchards had higher implementation cost because the number of trees, and materials (irrigations lines, post, wires, etc.) was higher for high density systems compared to low density systems. However, this initial disadvantage was offset by greater early yield of high-density systems leading to a rapid recovery of cumulative NPV observed in SS and TS, which demonstrated the steepest upward trajectory in cumulative NPV after the establishment phase. This result coincides with the results of Weber (1998). This pattern of the more rapid improvement of cumulative NPV’s highlights the economic advantage of high-density systems, where early and sustained yield compensates for higher upfront costs, ultimately leading to superior long-term profitability. In contrast, lower-density systems such as TAS and VA exhibited slower NPV recovery rates, reflecting their reduced capacity for early production and lower cumulative yields. These results are consistent with the findings of Quamme et al. (1996) who showed how the high-density systems like slender spindle and VA are more productive and economically beneficial than low density systems especially in the early years of orchard establishment, despite slightly higher labor demands. These findings reinforce the principle that orchard profitability is strongly influenced by the balance between initial investment and the speed of revenue generation, favoring high-density systems for long-term economic sustainability.

Among rootstocks, the SS system with rootstocks like G.210 and G.935 reached break-even in just 8 years, confirming their strong compatibility with intensive planting. Conversely, M.7 showed the slowest recovery, requiring 11 years, likely due to its vigor and delayed fruiting. With the TS system, the fastest break-even was with M.26 in 7 years. However, G.11, G.30, and G.935 need 8 years, reinforcing their adaptability to high-density configurations. M.9 and G.41 required longer recovery times, suggesting that despite their compatibility, their lower early productivity can delay profitability. Lordan et al. (2018b) concluded that the faster break-even with M.9 for ‘McIntosh’ (9 years) and B.9 and M.9 for ‘Honeycrisp’ (7 and 8 years respectively). Their conclusion with ‘McIntosh’ and ‘Honeycrisp’ was different from our results with M.9. This was likely due to the extremely low vigor of ‘Delicious’ with M.9 which resulted in small trees that did not fully fill the space as with the varieties in the Lordan et al. (2018b) study. This result supports the concept of matching scion vigor with a precocious rootstock that will fill the allotted space rapidly.

The lower density systems, TAS and VA showed significantly longer break-even periods, ranging from 9 to 13 years. Bechtel et al. (1995) reported a break-even year of ‘Delicious’ with central leader and M.7 and M.26 between 11 and 14 years in Washington state. Our results with TAS showed that more vigorous rootstocks such as B.118, G.210, G.30, and G.935 reached break-even in 9 years, while M.9 performed poorly, requiring 13 years. The lowest density system we evaluated was VA which consistently showed the longest break-even times, with dwarf rootstocks like M.9 and G.16 penalized due to limited early yield potential.

The regression analysis between planting density, as determined by the training system, and cumulative NPV over 20 years revealed that economic performance is improved by increasing planting density up to an optimum density which varies considerably among rootstocks. B.118 was the only rootstock that showed a negative correlation between planting density and NPV, with the highest profitability observed at the lowest density evaluated (1,656 trees/ha). This negative relationship was likely due to excessive vigor of this stock which required excessive pruning in the high density systems. The excessive pruning was counterproductive to fruit production. These findings are consistent with those reported by Lo Bianco et al. (2003), who concluded that apple tree growth is influenced by both rootstock vigor and tree spacing. Their study demonstrated that the same rootstock exhibited different growth patterns depending on the planting density, which aligns with our results indicating that each rootstock has a specific optimal tree planting density that maximizes productivity and profitability.

While this study did not evaluate the effect of rootstock and training system on fruit size, external and internal quality, and storability other studies have reported rootstock effects on fruit size (Lawrence et al., 2025) and on fruit quality (Al Shoffe et al., 2025; Gonzalez Nieto et al., 2025; Valverdi and Kalcsits, 2021). It is likely that the rootstocks we evaluated in this study, had important effects on fruit size and fruit quality. However, those effects are unlikely to have a significant effect on orchard profitability which is largely driven by price and yield. Fruit size can have an important effect on crop value but it is largely controlled by crop load (Gonzalez Nieto et al., 2025). We actively managed crop load in this study so that each year each system and rootstock had a commercially acceptable crop load, which minimizes differences in fruit size.

Recognizing the limitations of this study (recorded data only through year 11 and estimated data of yield for years 12–20 and the lack of data on fruit quality and size), this study is the first study in ‘Delicious’ apples to evaluate the interaction between rootstock and tree density from an economic perspective. Our results suggest that for rootstocks such as G.11, G.210, G.30, G.41, and M.9, profitability was positively related to planting density with highest planting density producing the greatest profitability, particularly for G.41. This indicates that high-density planting is critical to achieving the maximum economic potential for this rootstock. Ho et al. (2024) reached similar conclusions in a comparable analysis, reporting that the optimal planting density ranged between 2,500 and 3,000 trees per hectare for M.9, G.41, and G.16 in ‘Fuji’, ‘Honeycrisp’, and ‘Gala’. However, for ‘Fuji’ grafted on G.41, the optimal density was below 1,000 trees/ha, highlighting that the same rootstock may perform differently depending on the scion cultivar. In our study, B.118 was the only rootstock which performed best at the lowest density evaluated (1,656 trees/ha). Meanwhile, G.16, G.935, M.26, and M.7 achieved their highest economic returns at an intermediate density of 3,262 trees/ha in the TS system, with no additional gains observed beyond this threshold over a 20-year period. No previous studies have directly examined the relationship between tree spacing and economic performance of ‘Delicious’ for these Geneva rootstocks.

This study provides the first comprehensive economic evaluation of the interaction between rootstock and planting density with spur-type ‘Delicious’ apple orchards, using NPV over a 20-year period. The results demonstrate that both the training system and rootstock significantly influence long-term profitability, and that their interaction must be considered when designing economically sustainable orchard systems.

High-density training systems, particularly SS and TS, consistently outperformed lower-density systems in terms of profitability, despite higher initial establishment costs. These systems had faster break-even points and greater cumulative NPV, especially when combined with rootstocks such as G.11, G.210, and G.935. In contrast, Vertical Axis (VA) and Triple Axis Spindle (TAS) systems exhibited slower economic recovery and lower overall returns.

Rootstock profitability was highly dependent on planting density and training system. G.41, G.11, and G.210 showed strong economic performance under high-density systems, while economic performance of B.118 was optimum at lower densities. However, M.9 and M.7 demonstrated limited economic potential with spur-type ‘Delicious’, particularly for intensive systems. These findings confirm that rootstock vigor and precocity must be aligned with training system and scion variety vigor to optimize orchard profitability.

The study shows that orchard design should be adapted to the unique conditions of each orchard. Rather than relying on generalized recommendations, growers should consider the specific interactions between rootstock, scion cultivar, training system, and site conditions. This integrated strategy is essential for maximizing long-term economic returns and sustainability of modern apple production systems.