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Pollination is essential for the production of most fruit and nut crops, yet it is often a limiting factor for both yield and product quality. Mechanical pollination (MP) systems offer the potential to increase productivity of a broad range of horticultural fruit and nut crops, and to manage the risk of reliance on current insect pollination services. To date, commercial MP systems have been developed for only a few crops (e.g., kiwifruit and date palm), suggesting that innovation in the use of MP systems has been stymied. Here, we review published and 'grey' literature to investigate the feasibility of MP systems of economically important tree fruit and nut crops. This review found that, whilst MP systems are a commercial reality for a wider range of fruit crops (e.g., sweet cherry) than nut crops (e.g., almond), promising results have been achieved at the experimental scale. Further we identified that the key barriers for progressing MP systems more widely include knowledge gaps in pollination biology, particularly of emerging fruit and nut species that are grown outside their native distributions, and access to proprietorial knowledge gained by commercial operators. What continues to remain unclear is detailed knowledge of the commercial development of MP systems and therefore, the opportunities to apply this knowledge to other tree crops where effective pollination limits yield and quality. [ABSTRACT FROM AUTHOR]

Intuitively, tree architecture will affect harvest efficiency of tree fruit crops, yet there are no empirical studies that document this. The objective of the current research was to investigate the role of training system on harvest rate of individual pickers in commercial sweet cherry (Prunus avium L.) orchards. We used a real-time labor monitoring system (LMS) with the ability to track and record individual picker efficiency in 11 orchards throughout the Pacific Northwest. Trees were trained to one of five different architectures: 1) upright fruiting offshoots (UFO), a planar architecture comprised of unbranched vertical fruiting wood; 2) Y-trellised, an angled dual planar architecture; 3) Kym Green Bush (KGB), a multileader bush; 4) central leader (CL); and 5) traditional multileader open center (MLOC), trees comprised of three to five main leaders. A consistent picking crew was used to facilitate comparisons among systems and eliminate variability in skill among pickers. The LMS calculated harvest rate, picking cost, weight of harvested fruit, number of harvested buckets, range in fruit weight per bucket/bin, and mean fruit weight per bucket/bin for individual pickers. Tests revealed a significant effect of canopy architecture on labor efficiency. The highest mean (± SE) harvest rates (0.94 ± 0.02 kg⋅min-1 and 0.78 ± 0.03 kg⋅min-1) were recorded in 'Cowiche'/'Gisela'®5' and 'Tieton7'Gisela®5' orchards trained to the UFO system, respectively. High harvest efficiency in these orchards was likely the result of the planar, simplified architecture and that most fruit were accessible from the ground. The third highest picking rate was recorded in the KGB system (0.73 ± 0.04 kg⋅min-1), a fully pedestrian orchard. Interestingly, harvest rate of slower pickers was improved to a greater extent (+132%) than skilled pickers (+83%) when comparing pedestrian and planar systems (e.g., UFO and KGB) with traditional architecture (MLOC). Furthermore, picking rate of individual pickers varied within 1 day by more than 100%, likely as a result of variability in fruit density within trees, tree size as well as fruit accessibility. We documented variability of more than 35 kg in final bin weight across all orchards and a range in bucket weight between ≈7 and 13 kg. These results suggest that architecture has a major effect on harvest efficiency and that current systems of piece-rate picker reimbursement are beset with inaccuracy. [ABSTRACT FROM AUTHOR]

Abstract: The formulation and evaluation of a model of radiation interception by fruit-tree orchards is presented. The model computes radiation interception based on the proportion of the orchard floor that is shaded by the trees at any given time, calculated from geometric relationships of the length of the shadow cast by the trees and the orchard configuration. Inputs include tree dimensions, orchard configuration, daily global solar radiation and a correction factor that accounts for within canopy gaps. Evaluation of the internal consistency of the model and a sensitivity analysis were carried out. Then, a test of the performance of the model was done, comparing simulated values of fractional PAR interception with field measurements from a range of orchard conditions (species, orchard design, tree dimensions, and location), including orchards on steep terrain. Despite simplifications made to reduce input data requirements as well as the inherent variability among the orchards, the model simulated reasonably well the fractional interception of radiation on an hourly time step (mean absolute error, MAE=10.08%; Willmott index of agreement, D =0.94). When evaluated on a daily basis, the performance of the model improved considerably (MAE=4.47%; D =0.98). In both time scales, the model performed similarly for the different orchard conditions considered. The model can be used to estimate both PAR and global solar radiation interception, including different types of orchard configuration such as hedgerow, overhead trained, or isolated trees planted in rectangular patterns. [Copyright &y& Elsevier]

Current mechanical harvesters for sweet cherry use either impact or vibration excitations to remove fruit. A comprehensive understanding of dynamic responses of cherry trees to vibratory excitation is therefore important for designing efficient mechanical harvest systems. This research quantified the distribution and dissipation of applied vibratory energy within the woody structure of cherry trees. Limb acceleration responses to either a band of sinusoidal excitations ranging from 2 to 40 Hz, or a series of impact excitations were monitored and analysed. The kinetic energy transmitted to all monitored locations was also compared between sinusoidal and impact excitations. The results indicate that all primary resonant frequencies could be detected within the prime branches of test trees. Branch waving displacement responses became larger as monitoring points were located further from the excitation point. Further, vibratory energy was amplified on branches with acute angles between the nodes caused by pruning, and on branches with few short lateral branches. This suggests that higher energy distribution along the branch, therefore higher harvest efficiency, could be obtained on such branches. [Copyright &y& Elsevier]