Tall Spindle Research Articles

Comparative study of five scab resistant apple cultivars

Vegetative and reproductive characteristics of five resistant apple cultivars budded on ‘М9-Т337’ rootstock were compared in the intensive orchard, planted at the density of 2380 trees per hectare (3.5 × 1.2 m) in the period 2017-2023. Trees were formed as tall spindle, under an insecticidal net against hail. Trees were grown under drip irrigation and sod-mulch system was applied. The cultivars FUJIONpbr and ENTERPRISE demonstrate greater trunk-cross section area, higher trees and greater crown volume to the tested cultivars. The smallest trees were noted in Cultivar GEMINI*. The lowest yield per unit area was obtained on cultivar FUJIONpbr. There was no significant difference among other cultivars. Despite of generally good characteristics the cultivar GEMINI* has relatively small fruits. Keywords: apple, vigor, productivity, fruit weight, yield

Comparative Spray Performance of a Solid Set Canopy Delivery System and an Airblast Sprayer in Modern Apple Orchards

Highlights Airblast sprayer applications in modern apple orchards can produce high off-target drift. A pneumatic spray delivery based solid set canopy delivery system (PSD-SSCDS) can be an alternative solution. PSD-SSCDS had comparable spray deposition, but lower spray coverage compared to airblast sprayer. Airblast sprayer had significantly higher losses to the ground and aerial drift. PSD-SSCDS confined ground drift within 4.1 m with minimal spray losses to air. Abstract. A pneumatic spray delivery-based solid set canopy delivery system (PSD-SSCDS) has been successfully configured for efficient spray applications in modern apple orchards typical of the state of Washington state. This study investigates the spray performance of optimized PSD-SSCDS against an axial-fan airblast sprayer in terms of spray deposition, coverage, and off-target drift in a tall spindle architecture of a commercial apple orchard. For field evaluation, mylar cards and water sensitive paper samplers were placed in different canopy zones on either side of the leaf surface, and 500 ppm of biodegradable fluorescent tracer solution was sprayed with PSD-SSCDS and an airblast sprayer. Additionally, aerial and downwind samplers were installed to evaluate ground runoff and drift, as well as aerial drift. The spray deposited on the mylar cards was analyzed using fluorometry, and spray coverage on WSPs was evaluated using image processing techniques. PSD-SSCDS (645.0 ± 94.7 ng cm-2, mean ± standard error) and an airblast sprayer treatment (661.6 ± 26.9 ng cm-2) had comparable mean spray deposition with no significant difference in different canopy zones for both treatments. However, the spray coverage was significantly higher for the airblast sprayer (32.7 ± 2.4%) compared to PSD-SSCDS (22.5 ± 3.1%). These differences are likely due to air-assist in airblast spraying, which is absent in PSD-SSCDS. Evidently, the airblast sprayer had significantly higher losses to the ground and aerial drift compared to PSD-SSCDS, as the ground drift for the latter was mostly confined within 4.1 m downwind of the sprayed row and spray losses to air were minimal. Keywords: Crop protection, Fixed spray delivery, Off-target drift, Pneumatic spray delivery, Spray coverage, Spray deposition.

Overall integrated navigation based on satellite and lidar in the standardized tall spindle apple orchards

Overall navigation in orchards is essential for autonomous production activities, however, most navigation studies, in orchards, focus on in-row scenes, and few of them pay attention to the headland transition or the overall navigation. This paper proposes an integrated navigation method based on satellite and lidar for overall orchards scenes, where the lidar was mainly used for in-row navigation and chassis position (CP) obtaining, whilst the satellite was utilized for headland transition as well as the assistant for in-row integrated navigation. Two overall integrated navigation modes were investigated: CMD-INT, which integrates the command signals from the lidar-based and satellite-based navigation systems, and BIAS-FUS, which combines the information of bias from the two navigation systems. The CP was used to detect the headland of the tree rows and achieve overall navigation integration. A position-ratio-based path planning method was also proposed, which enabled the chassis to maintain a proper constant offset from one side of the orchard. The refined pure pursuit algorithm was adopted for path tracking with good adaptivity on both the path curvature and tracking velocity. Both simulation and field tests with ten group parameters configuration in total were conducted to verify the performance of the system. The BIAS-FUS mode outperformed the CMD-INT mode, and the findings for the simulation experiments were consistent with that of the field tests. In the simulation experiments, the maximum value (Max), mean value (Mean), and root mean square error (RMSE) for the in-row process decreased by 0.0054 m, 0.0053 m, and 0.0062 m, respectively. Additionally, the corresponding heading deviation decreased by 0.3027°, 0.0050°, and 0.0256°, respectively. In the field tests, the Mean of the heading and lateral deviation for the in-row tracking process decreased by 0.3823°, and −0.0072 m respectively, and the corresponding deviations for the transition tracking process decreased by 2.8903°, and 0.0164 m respectively. Aiming at the standardized tall spindle apple orchards, this work contributes to an available overall integrated navigation method.

An image-based system for locating pruning points in apple trees using instance segmentation and RGB-D images

Intelligent pruning is an effective way to improve the efficiency of fruit tree pruning and reduce production costs, where the positioning of fruit tree pruning points is the key. In this study, a pruning point localisation method based on deep learning and red-green-blue-depth (RGB-D) is proposed for dormant tall spindle apple trees, which can quickly and accurately identify the pruning points on the primary branches. Firstly, red-green-blue (RGB) images and depth images of apple trees were acquired by using the Realsense D435i depth camera, and the SOLOv2 instance segmentation model was used to segment the trunks, branches, and supports in RGB images. Secondly, the manual pruning rules were adapted to improve the pruning methods; then using OpenCV image processing method, the junction points of branches and trunk and potential pruning points were gained, and the world coordinates of the points were obtained according to the coordinate transformation to calculate the length of branch diameter and spacing. Finally, the pruning points were determined according to the pruning rules. The results show that SOLOv2 has better segmentation effect compared with Mask R–CNN and Cascade Mask R–CNN. The mean absolute error between the estimated and manually measured values of branch diameter and spacing are 1.10 mm and 16.06 mm, and the recognition accuracy of pruning points is 87.2%, with a recognition time of about 3.8 s for each image. It is shown that the method can measure branch diameter and spacing and quickly locate pruning points with high reliability and accuracy, and the study provides a basis for the development of apple tree pruning robots.

Performance of ‘Gala Select’ and ‘Fuji Suprema’ grafted on Geneva series rootstocks under fallow land and replanting conditions in southern Brazil

BackgroundRootstocks less vigorous are among the most crucial management techniques to modernize fruit cultivation. Replanting with fallow land has become necessary due to a lack of land to establish new orchards. ObjectiveThe aim of this study is to determine the effect of various rootstocks of the American Geneva® series on the yield performance of the apple (Malus domestica Borkh) cultivars ‘Gala Select’ and ‘Fuji Suprema’ under replanting conditions in southern Brazil. Methods: After two years of fallow land, the experiments were initiated in 2017 and conducted during the 2018, 2019, 2020, and 2021 growing seasons in Painel and Caxias do Sul municipalities at the Santa Catarina and the Rio Grande do Sul State, respectively. The ‘Gala Select’ and ‘Fuji Suprema’ were grafted onto the G.202, G.814, G.210, and G.213 Geneva series rootstocks in a tall spindle training system using a randomized complete block design with four replicates. Principal component analysis (PCA) was used to assess the interrelationship among the variable's vigor, productivity, and fruit quality. ResultsThe PCA result showed significant differences in vigor, productivity, and fruit quality when the G.210 and G.213 and G.814 and G.213 Geneva series rootstocks were used in combination with Gala Select and Fuji Suprema cultivars, respectively. The PCA analysis clustered all cultivar/rootstock combinations into two groups, based on their vigor and productivity and the yield performance and fruit quality data, that differed significantly among combinations and regions. The ‘Gala Select’/G.202 and ‘Fuji Suprema’/G.213 combinations were less vigorous than the ‘Gala Select’/G.210 and ‘Fuji Suprema’/G.814 combinations. However, ‘Gala Select’/G.210 (semi-dwarfing) and G.213 (dwarfing) are the combinations with high yield performance, productive efficiency and fruit quality, being more reliable to the producer, and less vigorous, resulting in lower labor costs under replating conditions, with two years of fallow land, from 2018 until 2021 growing seasons.

Converting Tall Spindle Apple Trees to Narrow Walls with Summer and Dormant Hedging Plus Root Pruning

Recently, some commercial apple growers have been adopting hedging as an alternative or supplement to hand-pruning. With increasing labor costs across the United States, alternatives to hand-pruning and current training systems are being considered. One management strategy involves transitioning tall spindle trees to a narrow tree wall and simplifying labor-intensive activities of apple production, such as pruning, harvesting, and fruit thinning. The objective is to form the orchard system into a “fruiting wall” that makes fruit more visible and accessible, thus facilitating harvesting. Four management practices (tall spindle; narrow tree wall with manual pruning; narrow tree wall with dormant and summer hedging; and narrow tree wall with dormant hedging, summer hedging, and root pruning) were used to convert 12-year-old ‘Brak Fuji’ apple trees from the tall spindle training system to a narrow tree wall. Photosynthetically active radiation (PAR) and ultraviolet light levels within the canopies were improved by summer hedging, but they were still low for all treatments. Light within the canopy was improved most when root pruning was included. Specific leaf weight was not significantly impacted by hedging or root pruning. Detailed spur sampling showed that treatments had no effect on vegetative or reproductive growth on 2- to 3-year-old wood. Although dormant plus summer hedging alone did not affect shoot length, the combination of hedging and root pruning caused a significant reduction in terminal shoot length. Red fruit color was only improved with dormant hedging plus summer hedging plus root pruning. Compared with dormant plus summer hedging, dormant plus summer hedging plus root pruning improved fruit set and yield, but it reduced fruit size. Without root pruning, hedging had little effect on light, specific leaf weight, flower initiation, fruit set, and fruit quality. Conversion to narrow tree walls by manual pruning resulted in more poorly colored fruit and less highly colored fruit compared with maintaining the trees as tall spindles with manual pruning.

Reservoir Units Optimization in Pneumatic Spray Delivery-Based Fixed Spray System for Large-Scale Commercial Adaptation

A pneumatic spray delivery (PSD)-based solid set canopy delivery system (SSCDS) consists of in-line reservoirs and micro-emitter assemblies distributed throughout perennial crop canopies. The existing PSD-based SSCDS uses a large number of reservoirs, i.e., one unit per 3 m of linear spacing, which resulted in high installation and maintenance costs. These reservoirs also produces up to 25% post-spray chemical losses. Therefore, this study aimed to optimize the volumetric capacity and functionality of the existing reservoir for an efficient spray performance and the large-scale commercial adaptation of PSD-based SSCDS. Three reservoirs with volumetric capacities of 370 (1×), 740 (2×), and 1110 mL (3×) were developed to cover a spray span of 3.0, 6.1, and 9.1 m, respectively. Five system configurations with modified reservoirs and spray outlets were evaluated in the laboratory for pressure drop and spray uniformity. The three best system configurations were then field evaluated in a high-density apple orchard. These configurations had reservoirs with 1×, 2×, and 3× volumetric capacity and micro-emitters installed in a three-tier arrangement. Each replicate configuration was installed as a 77 m loop length encompassing 50 apple trees trained in a tall spindle architecture. A pair of water-sensitive paper (WSPs) samplers (25.4 × 25.4 mm) were placed on the abaxial and adaxial leaf surfaces in the bottom, middle, and top third of the canopy to evaluate the spray coverage (%). The PSD-based SSCDS showed no significant difference at the 5% level in terms of coverage among the three reservoir treatments. Coverage was more evenly distributed among the top, middle, and bottom zones for the 2× and 3× as compared to the 1× reservoir treatment. Overall, compared to the 1× reservoirs, the 2× and 3× reservoirs could potentially reduce the system costs by USD 20,000 and USD 23,410 ha−1, respectively, for tall spindle apple orchards and potentially reduce maintenance needs as well.

Pneumatic spray delivery-based solid set canopy delivery system for oblique banded leaf roller and codling moth control in a high-density modern apple orchard.

Pneumatic spray delivery (PSD)-based solid set canopy delivery systems (SSCDS) have demonstrated comparable spray deposition and reduced off-target drift compared with axial-fan airblast sprayers in high-density apple orchards. An important next step is to quantify whether PSD-based SSCDS can provide effective pest management. This study evaluated the biological efficacy of this fixed spray system variant and compared it with that of an axial-fan airblast sprayer. Partial field trials were conducted in a commercial apple orchard (cv. Jazz) trained in tall spindle architecture. Insecticides were applied at a rate of 935 L ha-1 (100 gallons per acre) for both application systems. Twenty-four hours after spraying, leaves and fruits were collected to prepare the laboratory bioassays enabling evaluation of efficacy against obliquebanded leafroller (OBLR) and codling moth (CM). OBLR mortality for SSCDS, airblast sprayer and untreated control treatments after 24 h of larval exposure was 91%, 98% and 4%, respectively and increased to 98%, 100% and 19% after 48 h. First-instar CM leaf bioassay mortality was 100% for SSCDS and airblast sprayer treatment, and 13% for the untreated control at 24 h post exposure. Larval CM mortality on fruit was 100% for SSCDS and airblast sprayer treatments, and 33% on the untreated control. Insecticides applied using SSCDS and an airblast sprayer had comparable larval mortality in all three assays, significantly higher than the untreated controls. These results suggest that PSD-based SSCDS may provide a viable alternative to axial-fan airblast sprayers in high-density apple orchards. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Costs and Profitability for Mechanized Pruning and Harvest in Two Cider Apple Orchard Systems

Growers need reliable information on costs and returns they can expect for a cider apple (Malus ×domestica) orchard suitable for mechanization because specialty cider apples can only be used for making cider, and returns are expected to be lower than for fresh table apples. This study estimates the costs, returns, and net profit that growers may realize by planting cider apples in either a freestanding or tall spindle system that use a mechanical harvester (both systems) and mechanical hedger (tall spindle system only). Results show that both production systems have positive net returns during full production, and their respective break-even returns are lower than the current market price, demonstrating that both systems are potentially profitable investments. Results also show that the tall spindle system is potentially more profitable due to the advantages of earlier start of fruiting and higher crop yield. The estimated net returns of the tall spindle system during full production are nearly 4 times higher than that of a freestanding system. At a discount rate of 10%, the net present value (NPV) of the tall spindle system is positive and payback period is 13 years, whereas the NPV of the freestanding system is negative. The discount rate represents the time value of money and reflects the perception of risk for the investment. The break-even discount rates (i.e., NPV = 0) are ≈6.88% for the freestanding system and 10.78% for the tall spindle system. Sensitivity scenarios found that when all else was constant, profitability increased as market price, crop yield, and production area increase and also when the cost of the harvester decreased. Because mechanical harvesters are expensive, profitability tends to be more favorable for larger farms due to economies of scale. Also, a high picking efficiency is important because fruit that falls on the ground is considered crop yield loss and reduces the gross income from cider apples.

Training Systems for Sweet Cherry: Light Relations, Fruit Yield and Quality

Semi-dwarfing rootstocks have enabled the adoption of high-density orchard systems for sweet cherry. Understanding the effects of training systems on light capture and fruit quality of lateral bearing cultivars early in tree/orchard establishment is lacking. The aim of this study was to investigate light interception and fruit quality over two seasons of 4–5 year-old ‘Kordia’ grafted to ‘Krymsk 5′ rootstock and trained to the 2D planar training systems of upright fruiting offshoot (UFO), super spindle axe (SSA), tall spindle axe (TSA), Bibaum (BB) and steep leader (SL). Average light interception over the two seasons was highest in UFO and SL (69%) followed by BB (66%). Average yield was highest for SSA (15.1 t ha−1) followed by SL (14.5 t ha−1) and UFO (12.7 t ha). There were negative correlations between crop load and fruit dry matter content (r2 = 0.67 and 0.84) and total soluble solids (0.92 and 0.42) in 2019–2020 and 2020–2021, respectively. Our results indicate that sufficient space is required between uprights for lateral bearing cultivars when trained to a planar training system to achieve optimal light interception and fruit quality. This study provides improved understanding to enable the adoption of planar training systems for lateral fruiting cherry cultivars at high-density plantings.

Investigation of Branch Accessibility with a Robotic Pruner for Pruning Apple Trees

HighlightsA branch accessibility simulation was performed for robotic pruning of apple trees.A virtual tree environment was established using a kinematic manipulator model and an obstacle model.Rapidly-exploring random tree (RRT) was combined with smoothing and optimization for improved path planning.Effects on RRT path planning of the approach angle of the end-effector and cutter orientation at the target were studied.Abstract. Robotic pruning is a potential solution to reduce orchard labor and associated costs. Collision-free path planning of the manipulator is essential for successful robotic pruning. This simulation study investigated the collision-free branch accessibility of a six rotational (6R) degrees of freedom (DoF) robotic manipulator with a shear cutter end-effector. A virtual environment with a simplified tall spindle tree canopy was established in MATLAB. An obstacle-avoidance algorithm, rapidly-exploring random tree (RRT), was implemented for establishing collision-free paths to reach the target pruning points. In addition, path smoothing and optimization algorithms were used to reduce the path length and calculate the optimized path. Two series of simulations were conducted: (1) performance and comparison of the RRT algorithm with and without smoothing and optimization, and (2) performance of collision-free path planning considering different approach poses of the end-effector relative to the target branch. The simulations showed that the RRT algorithm successfully avoided obstacles and allowed the manipulator to reach the target point with 23 s average path finding time. The RRT path length was reduced by about 28% with smoothing and by 25% with optimization. The RRT smoothing algorithm generated the shortest path lengths but required about 1 to 3 s of additional computation time. The lowest coefficient of variation and standard deviation values were found for the optimization method, which confirmed the repeatability of the method. Considering the different end-effector approach poses, the simulations suggested that successfully finding a collision-free path was possible for branches with no existing path using the ideal (perpendicular cutter) approach pose. This study provides a foundation for future work on the development of robotic pruning systems. Keywords: Agricultural robotics, Collision-free path, Manipulator, Path planning, Robotic pruning, Virtual tree environment.

Field Performance of a Solid Set Canopy Delivery System Configured for High-Density Tall Spindle Architecture Trained Apple Canopies

HighlightsVariants of a solid set canopy delivery system were evaluated in a high-density apple orchard.A pair of hollow-cone nozzles installed in three tiers had optimum spray performance for studied crop growth stages.A shower-down arrangement of emitters was the simplest design but had lesser deposition on abaxial leaf surfaces.Abstract. Optimally configured solid set canopy delivery system (SSCDS) based spraying has potential to improve tree-fruit crop pest and disease management by reducing application time and eliminating dependence on ground conditions. In such an effort, this study attempted to optimize SSCDS variants. Four different emitter types (E1 to E4) installed in different mounting configurations (C1 to C4) were evaluated for spray deposition and coverage in a high-density apple orchard trained in tall spindle architecture. Emitters E1, E2, and E4 had full circle spray patterns, and E3 had a hollow-cone pattern. Configuration C1 had a pair of E1 emitters spraying in a vertical plane and installed between two trees at 1.5 m above ground level (AGL). Another E1 emitter spraying in a horizontal plane was mounted atop each tree at 3.3 m AGL. Configurations C2 and C4 had emitters (E2 and E4, respectively) mounted atop each tree at 3.3 m AGL, and C3 had a pair of E3 emitters installed in a three-tier arrangement between two trees in the crop row. During field trials, a tree canopy about 3.0 m tall was divided into three zones (0 to 1.4 m, >1.4 to 2.2 m, and >2.2 to 3.0 m AGL) as bottom, middle, and top canopy zones, respectively. Mylar cards were used to quantify spray deposition using fluorometry, and water-sensitive papers (WSPs) were used to quantify coverage using image processing. Configuration C3 with 80° hollow-cone nozzles in a twin-emitter, three-tier arrangement had the highest overall spray deposition (581.1 ±77.8 ng cm-2, mean ± standard error) and coverage (18.4% ±4.1%). Moreover, C3 also had a significantly higher coverage on the abaxial surfaces of leaves compared to the other configurations. Configurations C1 was non-optimal because it lacked abaxial surface coverage as the canopy grew in the middle and late growth stages. Moreover, significant spray runoff from leaf surfaces was observed visually in the middle zone for C1 during the middle and late stages. This may be attributed to canopy growth around the emitters. Configurations C2 and C4, with emitters in a shower-down arrangement, had the highest deposition and coverage in the top canopy zone compared to the middle and bottom zones. Configurations C2 and C4 also had significantly higher spray coverage on the adaxial surfaces of leaves compared to the abaxial surfaces. Overall, despite the complex design of configuration C3 with six emitters per tree, it may be the most ideal arrangement for agrochemical application in an apple orchard trained in tall spindle architecture. For commercial feasibility, we recommend exploring this three-tier SSCDS configuration with low-cost emitter alternatives. Pertinent continuing efforts have been published by our group in which we successfully modified low-cost irrigation emitters, and the resulting three-tier SSCDS configurations had improved spray performance over expensive hollow-cone nozzles. Keywords: Fixed spray system, High-density apple orchard, Solid set canopy delivery system, Spray coverage, Spray deposition, SSCDS.

Long-term Performance of ‘Delicious’ Apple Trees Grafted on Geneva® Rootstocks and Trained to Four High-density Systems under New York State Climatic Conditions

We conducted a large (0.8 ha) field experiment of system × rootstock, using Super Chief Delicious apple as cultivar at Yonder farm in Hudson, NY, between 2007 and 2017. In this study, we compared six Geneva® rootstocks (‘G.11’, ‘G.16’, ‘G.210’, ‘G.30’, ‘G.41’, and ‘G.935’) with one Budagovsky (‘B.118’) and three Malling rootstocks (‘M.7EMLA’, ‘M.9T337’ and ‘M.26EMLA’). Trees on each rootstock were trained to four high-density systems: Super Spindle (SS) (5382 apple trees/ha), Tall Spindle (TS) (3262 apple trees/ha), Triple Axis Spindle (TAS) (2243 apple trees/ha), and Vertical Axis (VA) (1656 apple trees/ha). Rootstock and training system interacted to influence growth, production, and fruit quality. When comparing systems, SS trees were the least vigorous but much more productive on a per hectare basis. Among the rootstocks we evaluated, ‘B.118’ had the largest trunk cross-sectional area (TCSA), followed by ‘G.30’ and ‘M.7EMLA’, which were similar in size but they did not differ statistically from ‘G.935’. ‘M.9T337’ was the smallest and was significantly smaller than most of the other rootstocks but it did not differ statistically from ‘G.11’, ‘G.16’, ‘G.210’, ‘G.41’, and ‘M.26EMLA’. Although ‘B.118’ trees were the largest, they had low productivity, whereas the second largest rootstock ‘G.30’ was the most productive on a per hectare basis. ‘M.9’ was the smallest rootstock and failed to adequately fill the space in all systems except the SS, and had low cumulative yield. The highest values for cumulative yield efficiency (CYE) were with ‘G.210’ for all training systems except for VA, where ‘M.9T337’ had the highest value. The lowest values were for all training systems with ‘B.118’ and ‘M.7EMLA’. Regardless of the training system, ‘M.7EMLA’ trees had the highest number of root suckers. Some fruit quality traits were affected by training system, rootstock or system × rootstock combination.

Semantic segmentation of sparse 3D point cloud based on geometrical features for trellis-structured apple orchard

Orchard operations such as mechanical pruning and spraying are heavily affected by tree architectures. Quantified inputs (e.g., cutting locations for mechanical pruning, and canopy distribution and density for variable-rate precision spraying) are necessary information for achieving precise control of these orchard operations. Even in planar orchard systems, trees grow differently. Therefore, it is essential to measure the canopy at the individual tree level. A three-dimensional (3D) light detection and ranging (LiDAR) sensor imaging system was developed to estimate the main canopy specifications. The LiDAR sensor was installed on a utility vehicle and driven alongside tree rows in an apple orchard. A total of 1,138 frames of point cloud data were acquired from 69 apple trees in a tall spindle architecture. An algorithm was developed in the MATLAB environment to segment trellis wires, support poles, and tree trunks in these point cloud images. The results indicated that the proposed algorithm achieved overall accuracy values of 88.6%, 82.1%, and 94.7%, respectively, in identifying the corresponding three objects. Furthermore, canopy density and depth maps were created with the distribution of points in the point cloud images. The outcomes from this study provide baseline information for precision orchard operations such as mechanical pruning and precision spraying.

Comparison of tall spindle axes and vogel central leader systems in cherry

Comparison of tall spindle axes and vogel central leader systems in cherry

Long-term evaluation of rootstock effects on cropping and tree parameters of selected sweet cherry cultivars

The cropping of six sweet cherry cultivars that originated in the Research and Breeding Institute of Pomology at Holovousy, and a standard one, ‘Burlat’, were evaluated on three rootstocks in the period of 2007–2017. Trees planted in a spacing of 1.5 m × 5.0 m were trained as tall spindle axes utilising their natural tendency to develop a central leader. On the standard rootstock, P-TU-2, ‘Tim’ was the most productive with a mean total harvest of 47.6 kg per tree. ‘Sandra’ yielded the most on the PHLC rootstock with 56.2 kg per tree and ‘Helga’ yielded the most on Gisela 5 with a mean total harvest of 55.9 kg per tree. The mean impact of the rootstock on the tree vigour, measured upon the trunk cross section area, ranged from 148.4 cm2 on the standard rootstock P-TU-2 to 114.1 cm2 on the PHLC and 125.2 cm2 on Gisela 5 . On the standard rootstock P-TU-2, the most vigorous one according to this criterion was ‘Jacinta’ (178.0 cm2) whereas ‘Justyna’ (109.7 cm2) was the least vigorous. On the PHLC, the most vigorous was ‘Sandra’ (147.2 cm2) and the least was ‘Amid’ (94.0 cm2). The other tree characteristics were mainly dependant on the cultivar and minimally, or not at all, influenced by the rootstock vigour.

Branch Configuration Impacts on Production, Fruit Quality, and Leaf Minerals of ‘Aztec Fuji’ Apple Trees in an Upright Single Row High-Density Orchard System Over Five Years

Tree architectures play a critical role in the productivity of high-density orchards, but limited information is available in this subject. We studied effects of three branch configurations on tree growth, yield components, fruit quality and leaf mineral nutrients in ‘Aztec Fuji’ apple (Malus domestica Bork.) in a single row upright high-density system under southwest Idaho, USA conditions over 2012-2016. This study revealed that trees trained into a Tall Spindle (TS) had larger trunk cross sectional area (TCSA) than those with an Overlapped Arm (OA) system. Trees trained into a TS had higher number of fruit and yield per tree, three years after planting in 2012, than those with a Tipping Arm (TA) or OA system. However, in 2013, trees with a TA system had higher yield than those with a TS or OA configuration due to trees’ biennial bearing habit and higher spur formation in trees with a TA system. Trees receiving a TA training had lower biennial bearing index between all consecutive years. Trees with an OA training had smaller fruit than those with either a TA or TS training in all years between 2012-2016. Training systems did not have any effect on fruit color, soluble solids concentration, or starch degradation pattern at harvest. However, fruit from trees with an OA training had higher firmness and lower water core than those from trees with a TS or TA training. Leaves from trees receiving a TA training had greater leaf area, fresh weight, and potassium (K) and magnesium (Mn) concentrations than those with other trainings. Leaves from trees receiving an OA training had higher leaf iron (Fe), zinc (Zn), and copper (Cu) than those with a TS training. In this study, we concluded that training trees into a TA configuration rather than an OA system is recommended if the management and operation of apple production mandate the use of an “upright wall” structure to facilitate mechanical harvesting.

Evaluation of Shake-and-Catch Methods on Harvesting of Tall Spindle Apples

HighlightsBoth frequency and amplitude were influencing factors in analyzing the fruit removal efficiency and fruit damage.This research focused on tall spindle ‘Fuji’ apple trees, which enriched the study of the variety and architecture resources of apple trees.The advice for shake-and-catch harvesting was based on the analysis of amplitude and frequency from the perspective of energy consumption.Abstract. Almost all fresh-market apples are picked manually, and these apples rank among the most labor-intensive fruit crops to produce. Due to declining labor supply and rising labor costs, fresh-market apple growers are seeking mechanical harvesting solutions. Shake-and-catch is a potential method that has been well studied. However, because of fruit damage, this method cannot be widely used for fresh-market apples. The primary goal of this study was to investigate how the physical properties of the fruit tree and the shaker parameters affect fruit removal efficiency and fruit damage in an effort to help growers find solutions to the above-mentioned issues. A test system was developed, and its performance was evaluated in certain shaking modes. Based on the experimental results, the physical properties of the tree (length and diameter of limb, length and diameter of twig, and apple weight) and the frequency and amplitude of the shaker influenced the effectiveness of fruit detachment. When the amplitude of the shaker was 14.3 mm and the frequency was less than 15 Hz, the length of the twig had the greatest effect on fruit harvesting. However, with increasing frequency and amplitude, the effect of tree properties on fruit harvesting declined, and amplitude had a more significant effect on fruit harvesting than frequency. Moreover, the fruit removal rate reached 91.43% when the amplitude was 14.3 mm and the frequency was 20 Hz. The results of this study contribute to the development of an effective mechanical harvester that is adapted to tall spindle apple trees. Keywords: Amplitude, Apple fresh market, Frequency, Physical properties, Shake-and-catch, Tall spindle.

Development and Performance Evaluation of a Pneumatic Solid Set Canopy Delivery System for High-Density Apple Orchards

Abstract. Solid set canopy delivery systems (SSCDS) are fixed spray systems that consist of a network of permanently plumbed emitters in high-density tree-fruit orchard canopies. Most of the previously configured SSCDS worked on the principle of hydraulic spray delivery (HSD), which may not be suitable for large-scale installation due to the drop in operating pressure caused by frictional losses in the spray lines. Therefore, a pneumatic spray delivery (PSD) based SSCDS was developed in this study for potentially achieving uniform spray application at all locations along the spray lines. A reservoir subsystem was developed to contain a precisely metered amount of spray liquid. Once filled, compressed air pushed through the spray lines can pressurize the reservoir to help deliver uniform spray into the canopy through emitters. In this study, HSD and PSD systems of 91 m set length were installed in a high-density apple orchard. Both systems were evaluated for variations in operating pressure, spray output, and spray performance. Spray performance was quantified during the middle (BBCH 75) and late (BBCH 85) apple (cv. WA-38 on tall spindle architecture) crop growth stages. Deposition and coverage in three canopy zones and on both sides of leaves were evaluated using Mylar cards and water-sensitive papers (WSP) as samplers, respectively. The Mylar cards and WSP were respectively analyzed using fluorometry and image processing. Statistically similar operating pressure (p > 0.05) was observed for the HSD and PSD systems at 3 m (286.1 and 284.1 kPa, respectively), 33 m (268.4 and 270.5 kPa), 60 m (260.6 and 268.9 kPa), and 87 m (255.3 and 257.9 kPa) from the row inlet. Despite the operating pressure drop, the PSD system had uniform spray output along the 91 m spray line. Compared to the HSD system, about 4%, 3%, 5%, and 20% higher spray output was delivered with the PSD system at 3, 33, 60, and 87 m, respectively, along the spray line. Overall, the PSD system had significantly higher mean spray deposition (p < 0.01) compared to the HSD system during the middle (521 and 382 ng cm-2, respectively) and late (631 and 409 ng cm-2, respectively) growth stages. The PSD system also had numerically higher spray deposition compared to the HSD system for all the canopy zones and on either side of leaf surfaces. Spray coverage trends were similar to deposition; however, the differences were not significant. Overall, the PSD-based SSCDS shows potential for large-scale installation, with additional refinements, for uniform spray applications in high-density apple orchards. Keywords: Hydraulic spray delivery, Pneumatic spray delivery, Solid set canopy delivery system, Spray coverage, Spray deposition.

Gibberellic Acid<sub>4+7</sub> and Benzyladenine, Cambium Disconnection, Nitrogen, and Tip Removal Influence on Branch Induction in Newly Planted Poorly Feathered “Fuji” Apple Trees

The use of well-feathered nursery trees on dwarfing rootstocks is crucial for establishing high-density apple orchards to ensure early production. Training trees to develop a tall spindle canopy architecture has gained popularity in high-density orchards during the past decade. However, commercially produced nursery trees often lack feathers or are unevenly branched, making initial training decisions difficult and delaying precocious fruiting. In this project, we studied the vegetative meristem activation response to partial scoring or partial girdling of the bark cambium above the bud, with and without application of 500 ppm Promalin (gibberellin4+7 + benzyladenine), tip removal of the tree leader at the silver tip stage on April 23, 2019, Promalin spray at 500 ppm at post-bloom stage on May 7, 2019, and nitrogen (N) as UAN-32 (32% N) application at five levels (60, 80, 100, 120, or 140 g actual N/tree) on June 20, 2019, in newly planted un-feathered or unevenly branched “Aztec Fuji” trees on Budagovsky 9 (Bud 9) in southwest Idaho, USA. Grower’s Short Cut trees received a heading cut to the leader at 60 cm above the ground and resulted in the emergence of 5 - 6 strong branches near the heading cut. These trees had larger trunk cross-sectional areas than scored or girdled trees. Scoring or girdling, with or without Promalin, significantly improved branching by increasing the number of branches and bourse shoots. In many cases, the effects of partial scoring, with or without Promalin, were similar to those of bark girdling which is a more risky and time-consuming process. Branches induced by scoring and girdling had sharper crotch angles relative to the vertical leader. Spraying Promalin during the post-bloom stage at 500 ppm was not as effective as scoring or girdling to initiate branches. Additional N rates or removal of the leader tip did not significantly impact branch induction.