By Long He – A feature piece from our Fall-Winter 2023 issue of the Lancaster Thriving Publication!
The U.S. tree fruit industry (non-citrus) contributes approximately one-fourth ($15.4 billion) of all total economic value of specialty crops ($60 billion), and apple is an important component of the tree fruit industry, contributing approximately $2.75 billion (USDA-NASS, 2020). The tree fruit industry is currently facing two major challenges, one is its highly labor-intensive tasks and associated labor shortage and high cost, and the other one is the massive application of agricultural materials (water, fertilizers, and chemicals) and its associated big waste and environmental impact. Precision agricultural technologies including artificial intelligence (AI) have been showing promises on addressing these challenges at some extend.
- Precision and robotic crop load management for apples
Crop load management for apples starts from branch pruning in the dormant season, and blossom and green fruit thinning in spring season. To achieve a good crop yield and fruit quality, it is critical to demonstrate a well-planned crop load management approach throughout the season. AI-based machine vision systems have been investigated for precision crop load management in recent years. In our studies, AI-based deep learning models were developed for early flower buds, blossoms, and green fruits detection in an orchard environment. For blossom thinning, a robotic chemical thinning system was developed with integration of a machine vision system to detect flower clusters, a nozzle control system to target spray the detected flower clusters, and an unmanned ground vehicle (mobile robot) to automatically drive in an orchard to conduct chemical thinning. Also, a robotic green fruit thinning system was developed with the integration of a machine vision system for green fruit detection, and a green fruit removal mechanism with a robotic manipulator for excessive green fruit removal.
- Precision spraying technologies for tree fruit orchards
Sensor-guided precision sprayer technology has been developed and used in recent years. Three sensor types commonly used in pesticide sprayer development are ultrasonic sensors, digital cameras, and laser scanning sensors. A LiDAR sensor was used to detect tree canopy density, and then the sprayer nozzles were controlled to apply chemical rates based on the density of the canopy. The research results showed that the chemical saving can be significant (i.e., over 50%) if canopy density is considered during spraying. Meanwhile, an inlet airflow control system was added to the sprayer, and the inlet air amount was controlled based on the canopy density. The results showed that spray drift can be dramatically reduced if the inlet airflow is controlled, especially for these small and narrow trees.
- Precision and automatic irrigation for tree fruit orchards
Soil moisture sensors have been proved to be effective for assisting the irrigation scheduling for tree fruit orchards. Precision irrigation based on soil moisture can determine when and how much to irrigate. An automatic irrigation system is capable of turning on/off water automatically or remotely as the crop needs, no longer requires going to the specific site. A soil moisture sensor based automatic irrigation system was developed and tested in apple and peach orchards. The system mainly includes an electrical pump station, three soil moisture sensors, solenoid valve and control, and a LoRaWAN based internet of things (IoT) system. In this system, a solenoid valve locates closely to the orchard block for an irrigation zone will be remotely or automatically turn on/off for irrigation. The IoT system connects sensors and irrigation decisions through cloud servers, and the irrigation starts when the sensor reading reaches the dry threshold, and stops when it comes to soil water capacity level.
Figures:
- Robotic chemical blossom thinning for apples
- Robotic green fruit thinning for apples
- Precision spraying technologies for tree fruit orchards
- Precision irrigation system for tree fruit orchards
Author:
Long He, PhD, Assistant Professor
Department of Agricultural and Biological Engineering, Pennsylvania State University
Fruit Research and Extension Center
luh378@psu.edu
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