Animal species likely have different strengths of host habitat preference (HHP) that might be cha... more Animal species likely have different strengths of host habitat preference (HHP) that might be characterized by a standardized index ranging from 0 (no preference) to 1 (maximum preference). We hypothesized that in some species, HHP may result from individuals dispersing out of the host habitat having a probability of turning back at the boundary, or after entering host habitat by reducing speed or increasing size of turning angles. Computer simulations of individuals moving between various sized patches of host and nonhost habitat were conducted based on these three behaviours hypothesized to affect HHP. In the rebounding model, simulations resulted in equilibria of animal numbers inside and outside of host habitat that depend on sizes of these areas, initial number and the rebounding probability. Curvilinear regression of simulation results suggested an equation that predicted numbers in the host habitat and was solved for rebounding probability. A modified equation that sampled po...
Highlights Medjool date fruit bunches can be modeled in 3D based on structural decomposition and ... more Highlights Medjool date fruit bunches can be modeled in 3D based on structural decomposition and the use of Bezier curves. The 3D model can be used for generating artificial image datasets of Medjool fruit bunches. The annotated image datasets can be used to develop robust algorithms for robotic Medjool date thinning. Algorithms for determining the required thinning length are a prerequisite for Medjool date thinning automation. . Medjool is a premium date cultivar, and the market demands high-quality fruits, for which specific horticultural practices, including timely and efficient fruitlet thinning, are required. Currently, thinning the fruitlets is one of the most labor-intensive tasks in the Medjool cultivation cycle, and there is a need to develop methods for automating the thinning process. An algorithm determining the required thinning is a prerequisite for advancing toward thinning automation. An annotated Medjool fruit bunch image dataset is necessary for developing such an...
The lesser date moth (LDM) Batrachedra amydraula is a significant pest of date palm fruits. Previ... more The lesser date moth (LDM) Batrachedra amydraula is a significant pest of date palm fruits. Previously, detection and monitoring of the pest was inaccurate due to high costs of sampling with lifting machines. We report a practical system for detection and monitoring of LDM based on pheromone traps and relevant models. Dose–response experiments with LDM pheromone traps indicated a 1 mg lure is optimal for monitoring. Delta traps with adhesive covering their entire inner surface gave the highest captures while trap colour was unimportant. Sampling pheromone traps throughout the night indicated male flight began at 1:00–2:00 and reached a peak 2 h before sunrise. Monitoring traps exposed all year long in Israel revealed three generations with different abundance. Trapping transects in a date plantation indicated interference from a monitoring trap became minimal at distances >27 m away. Inter-trap distances closer than this may lower efficiency of monitoring and mass trapping in con...
Control of pollination and fertilization in date palm is essential for the development of high-qu... more Control of pollination and fertilization in date palm is essential for the development of high-quality fruit. Pollen is harvested from male trees and mechanically applied to inflorescences on female trees. An overly high rate of fruit set may cause excessive fruit load, requiring expensive fruit thinning to prevent reduction in fruit size and marketability. On the other hand, inefficient pollination results in lower yield. Although the female flower has three separate carpels, only one develops into a fruit; the others degenerate. Non-fertilized flowers may develop into parthenocarpic singlet or triplet fruit, which have no commercial value. Environmental conditions affect fertilization and fruit development. The current study characterizes fertilization and early fruit development in date palm under different temperature conditions. The date palm is a very large tree. To study environmental effects on its reproductive biology, special units, termed “modular phytotrons”, were designed for this research. They were assembled on pollinated inflorescences of whole ‘Medjoul’ date trees in the orchard, enabling modification of temperature regimes in planta. Pollen-tube growth, fertilization, fruitlet formation and carpel degeneration, as well as early development of parthenocarpic fruit were defined and characterized by macro- and microscopic analyses. Relatively low temperatures applied during plant fertilization significantly decreased pollen germination rate, enhanced formation of parthenocarpic fruit and reduced normal fruit development. The significance of these results to horticultural practices during fertilization and fruit thinning is discussed.
In July 1998, a sudden wilt of Star Ruby grapefruit (Citrus paradisi Macf.) occurred in Israel in... more In July 1998, a sudden wilt of Star Ruby grapefruit (Citrus paradisi Macf.) occurred in Israel in a region with a warm Mediterranean climate. The wilt of the middle and upper canopy of main limbs was accompanied by gum oozing from the affected branches. The bark of these branches attained a dark colour and the epidermis sloughed off easily revealing a mass of black powder, resulting from copious sporulation of dark conidia. Both the bark and the xylem were intensively colonized with mycelium. The fungus was identified as Scytalidium lignicola Pesante, based on the characteristic mixture of some colourless and dark conidia, produced in branched chains by conversion of the vegetative hyphae. Artificial inoculations induced typical disease symptoms and the fungus was reisolated, thus confirming Koch's postulates. Similar symptoms appeared in Star Ruby interim segments which had been cut and top grafted with various citrus cultivars. This is the first detailed report of pathogenicit...
The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a ... more The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a serious pest of date palms, Phoenix dactylifera. The release of volatiles from both males and females was investigated using sequential SPME/GC/MS analysis. Males release a complex mixture of compounds in a circadian rhythm during the night between 03:00 and 05:00 hr. Six compounds were identified: benzaldehyde, sulcatol (6-methyl-5-hepten-2-ol), geranyl acetone [(E)-6,10-dimethyl-5,9-undecadien-2-one], phenylacetaldehyde, 2-phenylpropenal, and (R)-fuscumol [(R)-(E)-6, 10-dimethyl-5, 9-undecadien-2-ol]. Benzaldehyde, sulcatol, and geranyl acetone were found only in trace amounts. These compounds were in glands located in the forewing of males only. Small amounts of acetoin and 2,3-butanediol were found sporadically in the SPME/GC/MS analyses of volatiles from females, and these compounds probably originate from microorganisms. This is the first finding of a circadian release of male-specific compounds in moths. GC/EAD analyses with synthetic standards of compounds released by males showed that the female antenna is stimulated by all six compounds, while the male antenna responded only to phenylacetaldehyde. A possible pheromonal role for the male-specific compounds is suggested by the circadian rhythm of their release and the EAD response of females to them. However, trapping tests with the main male-specific compounds in screen cages in the laboratory or in the field did not reveal any significant behavioral responses from females or males. Copulation in the laboratory was observed only in the presence of date palm tissue, thus suggesting that sexual communication and mating of GDM moths probably occurs in the crown of date palms.
Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automatio... more Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automation can significantly reduce labor and improve efficiency. An image processing apparatus developed for robotic Medjoul thinning is presented. Instance segmentation based on Mask R-CNN was applied to identify the fruit bunch components: spikelets and rachis. Motion planning parameters were extracted using the derived masks: rachis center point (RCP), rachis orientation angle, and spikelets remaining length. RCP and rachis orientation angle were computed geometrically, spikelets remaining length was estimated with a convolutional neural network (CNN) and a deep neural network (DNN). Instance segmentation results were accurate, especially for spikelets, for low intersection over union (IoU) (0.3 IoU, fruit determined for thinning identification, spikelets: 98%, rachises: 73%). However, only 66% of the rachises were correctly matched to spikelets. The segmentation of all spikelets and rachises in the images was of medium quality for low IoU (0.3 IoU, F1, spikelets: 0.67, rachis: 0.77), where both precision and recall dropped for higher IoUs. RCP and rachis orientation angle were accurately estimated (0.3 IoU, error, RCP: 2.2 cm, rachis orientation angle: 5.0°). Spikelets remaining length estimation using CNN resulted in better performance than DNN (0.3 IoU, error, CNN: 19.7%, DNN: 24.6%). Spikelets segmentation results are suitable for thinning automation. However, rachis segmentation and matching the rachis and spikelets may still require human intervention during run-time. RCP and rachis orientation angle estimation errors are acceptable, while spikelets remaining length estimation errors are acceptable only for preliminary motion planning and mandate additional tuning during motion execution.
Animal species likely have different strengths of host habitat preference (HHP) that might be cha... more Animal species likely have different strengths of host habitat preference (HHP) that might be characterized by a standardized index ranging from 0 (no preference) to 1 (maximum preference). We hypothesized that in some species, HHP may result from individuals dispersing out of the host habitat having a probability of turning back at the boundary, or after entering host habitat by reducing speed or increasing size of turning angles. Computer simulations of individuals moving between various sized patches of host and nonhost habitat were conducted based on these three behaviours hypothesized to affect HHP. In the rebounding model, simulations resulted in equilibria of animal numbers inside and outside of host habitat that depend on sizes of these areas, initial number and the rebounding probability. Curvilinear regression of simulation results suggested an equation that predicted numbers in the host habitat and was solved for rebounding probability. A modified equation that sampled po...
Highlights Medjool date fruit bunches can be modeled in 3D based on structural decomposition and ... more Highlights Medjool date fruit bunches can be modeled in 3D based on structural decomposition and the use of Bezier curves. The 3D model can be used for generating artificial image datasets of Medjool fruit bunches. The annotated image datasets can be used to develop robust algorithms for robotic Medjool date thinning. Algorithms for determining the required thinning length are a prerequisite for Medjool date thinning automation. . Medjool is a premium date cultivar, and the market demands high-quality fruits, for which specific horticultural practices, including timely and efficient fruitlet thinning, are required. Currently, thinning the fruitlets is one of the most labor-intensive tasks in the Medjool cultivation cycle, and there is a need to develop methods for automating the thinning process. An algorithm determining the required thinning is a prerequisite for advancing toward thinning automation. An annotated Medjool fruit bunch image dataset is necessary for developing such an...
The lesser date moth (LDM) Batrachedra amydraula is a significant pest of date palm fruits. Previ... more The lesser date moth (LDM) Batrachedra amydraula is a significant pest of date palm fruits. Previously, detection and monitoring of the pest was inaccurate due to high costs of sampling with lifting machines. We report a practical system for detection and monitoring of LDM based on pheromone traps and relevant models. Dose–response experiments with LDM pheromone traps indicated a 1 mg lure is optimal for monitoring. Delta traps with adhesive covering their entire inner surface gave the highest captures while trap colour was unimportant. Sampling pheromone traps throughout the night indicated male flight began at 1:00–2:00 and reached a peak 2 h before sunrise. Monitoring traps exposed all year long in Israel revealed three generations with different abundance. Trapping transects in a date plantation indicated interference from a monitoring trap became minimal at distances >27 m away. Inter-trap distances closer than this may lower efficiency of monitoring and mass trapping in con...
Control of pollination and fertilization in date palm is essential for the development of high-qu... more Control of pollination and fertilization in date palm is essential for the development of high-quality fruit. Pollen is harvested from male trees and mechanically applied to inflorescences on female trees. An overly high rate of fruit set may cause excessive fruit load, requiring expensive fruit thinning to prevent reduction in fruit size and marketability. On the other hand, inefficient pollination results in lower yield. Although the female flower has three separate carpels, only one develops into a fruit; the others degenerate. Non-fertilized flowers may develop into parthenocarpic singlet or triplet fruit, which have no commercial value. Environmental conditions affect fertilization and fruit development. The current study characterizes fertilization and early fruit development in date palm under different temperature conditions. The date palm is a very large tree. To study environmental effects on its reproductive biology, special units, termed “modular phytotrons”, were designed for this research. They were assembled on pollinated inflorescences of whole ‘Medjoul’ date trees in the orchard, enabling modification of temperature regimes in planta. Pollen-tube growth, fertilization, fruitlet formation and carpel degeneration, as well as early development of parthenocarpic fruit were defined and characterized by macro- and microscopic analyses. Relatively low temperatures applied during plant fertilization significantly decreased pollen germination rate, enhanced formation of parthenocarpic fruit and reduced normal fruit development. The significance of these results to horticultural practices during fertilization and fruit thinning is discussed.
In July 1998, a sudden wilt of Star Ruby grapefruit (Citrus paradisi Macf.) occurred in Israel in... more In July 1998, a sudden wilt of Star Ruby grapefruit (Citrus paradisi Macf.) occurred in Israel in a region with a warm Mediterranean climate. The wilt of the middle and upper canopy of main limbs was accompanied by gum oozing from the affected branches. The bark of these branches attained a dark colour and the epidermis sloughed off easily revealing a mass of black powder, resulting from copious sporulation of dark conidia. Both the bark and the xylem were intensively colonized with mycelium. The fungus was identified as Scytalidium lignicola Pesante, based on the characteristic mixture of some colourless and dark conidia, produced in branched chains by conversion of the vegetative hyphae. Artificial inoculations induced typical disease symptoms and the fungus was reisolated, thus confirming Koch's postulates. Similar symptoms appeared in Star Ruby interim segments which had been cut and top grafted with various citrus cultivars. This is the first detailed report of pathogenicit...
The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a ... more The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a serious pest of date palms, Phoenix dactylifera. The release of volatiles from both males and females was investigated using sequential SPME/GC/MS analysis. Males release a complex mixture of compounds in a circadian rhythm during the night between 03:00 and 05:00 hr. Six compounds were identified: benzaldehyde, sulcatol (6-methyl-5-hepten-2-ol), geranyl acetone [(E)-6,10-dimethyl-5,9-undecadien-2-one], phenylacetaldehyde, 2-phenylpropenal, and (R)-fuscumol [(R)-(E)-6, 10-dimethyl-5, 9-undecadien-2-ol]. Benzaldehyde, sulcatol, and geranyl acetone were found only in trace amounts. These compounds were in glands located in the forewing of males only. Small amounts of acetoin and 2,3-butanediol were found sporadically in the SPME/GC/MS analyses of volatiles from females, and these compounds probably originate from microorganisms. This is the first finding of a circadian release of male-specific compounds in moths. GC/EAD analyses with synthetic standards of compounds released by males showed that the female antenna is stimulated by all six compounds, while the male antenna responded only to phenylacetaldehyde. A possible pheromonal role for the male-specific compounds is suggested by the circadian rhythm of their release and the EAD response of females to them. However, trapping tests with the main male-specific compounds in screen cages in the laboratory or in the field did not reveal any significant behavioral responses from females or males. Copulation in the laboratory was observed only in the presence of date palm tissue, thus suggesting that sexual communication and mating of GDM moths probably occurs in the crown of date palms.
Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automatio... more Laborious fruit thinning is required for attaining high-quality Medjoul dates. Thinning automation can significantly reduce labor and improve efficiency. An image processing apparatus developed for robotic Medjoul thinning is presented. Instance segmentation based on Mask R-CNN was applied to identify the fruit bunch components: spikelets and rachis. Motion planning parameters were extracted using the derived masks: rachis center point (RCP), rachis orientation angle, and spikelets remaining length. RCP and rachis orientation angle were computed geometrically, spikelets remaining length was estimated with a convolutional neural network (CNN) and a deep neural network (DNN). Instance segmentation results were accurate, especially for spikelets, for low intersection over union (IoU) (0.3 IoU, fruit determined for thinning identification, spikelets: 98%, rachises: 73%). However, only 66% of the rachises were correctly matched to spikelets. The segmentation of all spikelets and rachises in the images was of medium quality for low IoU (0.3 IoU, F1, spikelets: 0.67, rachis: 0.77), where both precision and recall dropped for higher IoUs. RCP and rachis orientation angle were accurately estimated (0.3 IoU, error, RCP: 2.2 cm, rachis orientation angle: 5.0°). Spikelets remaining length estimation using CNN resulted in better performance than DNN (0.3 IoU, error, CNN: 19.7%, DNN: 24.6%). Spikelets segmentation results are suitable for thinning automation. However, rachis segmentation and matching the rachis and spikelets may still require human intervention during run-time. RCP and rachis orientation angle estimation errors are acceptable, while spikelets remaining length estimation errors are acceptable only for preliminary motion planning and mandate additional tuning during motion execution.
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