MECHANICAL HARVESTING AND DISEASE MANAGEMENT IN CITRUS PRODUCTION; AN ENGINEERING APPROACH

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1003530
• Project Start Date: Jul 11, 2014
• Project End Date: May 31, 2019
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
Citrus Research and Education Center, Lake Alfred

Non Technical Summary
In recent years, citrus production has been seriously affected by the emergence of exotic diseases such as HLB, citrus canker and citrus black spot (CBS). Citrus production costs have increased from $800 per acre in 2004 to $1,800 per acre in 2012. This $1,000 increase in production cost in less than ten years is mainly due to additional costs to manage citrus HLB and other exotic diseases. Harvesting is another major citrus production cost that accounts for more than 50 percent of production costs. These increased production costs put citrus growers at a disadvantage in the global market. To maintain this important industry, production costs need to be reduced and disease need to be detected and managed better. The long term goal of this research program is to enhance the profitability and global competitiveness of citrus production in Florida through new engineering technology that reduces harvesting costs as well as controls and minimizes losses caused by diseases. The specific goals are: 1) to reduce harvesting costs by enhancing existing mechanical harvesting machines or developing new alternative harvesting approaches, 2) To develop both aerial- and ground-based robotic sensing equipment that will facilitate early detection of diseases and stress within a commercial citrus block and 3) To develop novel approaches for physical disease treatment such as thermal treatment and other non-traditional disease treatment methods.

Animal Health Component

80%

Research Effort Categories

Basic

(N/A)

Applied

80%

Developmental

20%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
402	0999	2020	75%
404	0999	2020	25%

Knowledge Area
404 - Instrumentation and Control Systems; 402 - Engineering Systems and Equipment;

Subject Of Investigation
0999 - Citrus, general/other;

Field Of Science
2020 - Engineering;

Keywords

unmanned aerial vehicle

mechanical harvesting

heat treatment

Goals / Objectives
The long term goal of this research program is to enhance the profitability and global competitiveness of citrus production in Florida through new engineering technology that reduces harvesting costs as well as controls and minimizes losses caused by diseases. The specific goals are:1) To continue the development and improvement of the existing mechanical harvesting machines in terms of enhancing their performan while lessening tree damage, and to develop new equipment designs and alternative harvesting approaches.2) To develop both aerial- and ground-based robotic sensing equipment that will facilitate early detection of diseases and stress within a commercial citrus block.3) To develop novel approaches for physical disease treatment such as thermal treatment and other non-traditional disease treatment methods.

Project Methods
The details of the approach for each of the three main objectives are as follows:Mechanical HarvestingEnhancing performance of existing mechanical harvesting systems1) Improve the design of fruit removal tines on the commercially available harvesters to reduce tree structural damage and improve fruit recovery percentage a. Validating and comparing the performance of proposed alternative designs b. Refining the existing analytical model that quantifies interaction of the harvester with tree limbs. c. Performing experimental based design optimization of shaker based on the information from the field trials. d. Automating some of the harvesting tasks to increase the efficiency of the machine operators.2) Develop a fruit recovery system for the Oxbo 3210 a. Designing a catch frame to avoid fruit drop from harvester; b. Designing citrus removal of under canopy to middle row for ease of pick-up either by hand or machine.Developing innovative fruit removal system for over-the-row harvesting machinesDisease and Stress Management Systems using UAV1. Innovative crop stress sensing and monitoring systemThe sensor platforms, sampling system, sensors and machine learning algorithm will be a part of the cooperative robot network for detecting abiotic stress and exotic diseases.1) Investigate appropriate sensing tools for UAV-based plant stress detection.2) Develop ground-based plant stress detection platform and corresponding machine learning algorithms to complement the aerial imaging.3) Generate geo-referenced crop help mapping system.2. Experimental validation in realistic orchard environmentThe flight conditions (flying height, spatial resolution, spectral resolution, etc.) of the multi-rotor will be optimized in the experiment for collecting high-resolution data based on the stress type in the model crops.Novel Approaches for Physical Disease TreatmentThermo-treatment approach1) Develop a simple in-field system to raise tree canopy temperature a. Structure design-It includes different shapes and forms, from a simple tent-like cover with solar heated system to a self-propelled heating tunnel with auxiliary heat and temperature control system. b. Determine system operating parameters.This step includes determining the best source of supplementary heat for each application.2) Determine the optimal time-temperature treatment for in-field Ca. L. asiaticus inactivation.3) Modeling heat transfer for effective and efficient treatment based on tree size and trunk size.Other non-traditional physical treatment approachesOther non-traditional physical treatment approaches such as canopy surface modification will be also investigated under this objective and their environmental impact will be evaluated.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The audiences for this program includecitrus extension agents, citrus producers, managers, consultants, and potential users of new technology for applications in agriculture. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?This project ended in 2017 due to leaving the main PI from the University of Florida.

Impacts
What was accomplished under these goals? In 2017, research and extension activities were conducted under the main objectives of this project. The following is a brief description of the main project activities: 1- Under the goal ofdevelopment and improvement of the existing mechanical harvesting machines, field experiments were conducted to experimentally study thevibrational acceleration of different shaking tines used in citrus canopy shaker. 2- Under early disease detection goal, filed and laboratory studies conducted to develop a techniquefor detection ofLate blight, Target and Bacterial spots in tomato using a spectral based sensor.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Wetterich, C. B., R. F. O. Neves, J. Belasque, R. Ehsani, and L.G. Marcassa. 2017. Detection of Huanglongbing in Florida using fluorescence imaging spectroscopy and machine-learning methods. Applied Optics. 56(1): 15-23.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Liu, T., R. Ehsani, A. Toudeshki, X. Zou, and H. Wang. 2017. Experimental study of vibrational acceleration spread and comparison using three citrus canopy shaker shaking tines. Shock and Vibration, vol. 2017, Article ID 9827926, 9 pages, 2017. doi:10.1155/2017/9827926.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Lu, J., Y. She, R. Ehsani, A. Decastro, and Y. Xu. 2017. Field detection of strawberry Colletotrichum disease using hyperspectral technology. Computers and Electronics in Agriculture. 135:289-299.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Citrus growers, Crop consultants, Citrus processors, extension agents, scientific community. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Outreach and extension activities and accomplishments in 2016 Gavea half-day workshop on thermotherapy. More than 60 people attended the workshop which was held at Southwest Florida Research and Education Center. Gave presentations on thermotherapy at Citrus Engineering conference. Participated and gave demonstration and talk at Citrus Expo and Florida citrus show. Gave several invited keynote speeches on applications of Unmanned Aerial Vehicles (UAV) in agricultural. Participate as UF representative on a multi-state project on applications of UAV in Agriculture. Participate the meeting and contribute to the discussions. Consulted with several growers about how to build a thermotherapy system. Co-organizing an international conference for precision horticulture for 2018 through ISHS. Conducted several planning meetings and selected the organization and academic teams. Outcomes and Impacts: In 2016, more than three million tree heat-treated statewide which is the results of Dr. Ehsani's work in this area What do you plan to do during the next reporting period to accomplish the goals?We plan to contintue working and making progress on the objectives of on-going projects.

Impacts
What was accomplished under these goals? In 2016, research and extension activities were conducted under four externally funded projects. The following isa brief discription of each project with their goals, objectives, and accomplishment. These projects areall in line with the overal goals and objectives of this program. Steam-generated Supplementary Heat Thermotherapy as an Immediate Treatment for Prolonging Productivity of HLB-infected Citrus Trees: This four-year multi-state multi-disciplinary research and extension project aims to address the urgent need of citrus growers in Florida to an immediate treatment for HLB-affected citrus trees by utilizing steam for rapid thermotherapy. The overall goal of this project is to provide an immediate scalable technique using steam as well as synthesize scientific explanations on how the technique works in mitigating HLB and prolonging the production life of infected citrus trees. Dr. Ehsani is the project director and main PI for this project. In 2016 we did largely field trails and collected data based on the proposed research plan. Two full time and one part time PhD students are working on this project. Automated stress and disease detection in vegetable and tree crops using a cooperative ground and aerial vehicle network and optical sensors: Dr. Ehsani is a Co-PI in this project with the University of Central Florida. The idea is to develop a ground and an aerial robot that will cooperatively look for early detection of disease in citrus and strawberry fields. An optical spectrometer was modified to be installed on an end-effector of autonomous robot and be able to communicate with the robot. In-Field Mechanization Initiative for Cocoa Farms. This is a three-year project funded by MARS Global Chocolate Science & Technology. We are in the second year of project now. The overall goal of this project is to identify appropriate in-field mechanized systems for labor intensive portions of cocoa production. The specific objectives are: Specific objectives: a) Collect sufficient information on prospective scalable mechanization efforts for use in cocoa farming practices. b) Determine appropriate specific technologies for implementation in cocoa growing and harvesting practices. c) Recommend mechanization tools and machinery together with the success and design criteria for potential use in existing and future cocoa farms. A sensor was designed to determine the fruit maturity and tested in the field. The sensor need more modification to be able address the need of growers. Collaborative research: robot swarms and human scouts for persistent monitoring of specialty crops: This is a collaborative effort between Dr. Vijay Kumar at the University of Pennsylvania and Dr. Ehsani. This project will use a swarm of small robots flying at very close range to the tree canopy to detect pests and diseases and well as yield for tomato, citrus, and blueberry. A sensor was designed for detecting the physiologically mature tomato under filed condition. More field trials are planned for 2017.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Gupta, S.K., R. Ehsani, and N.H. Kim. 2016. Optimization of a citrus canopy shaker harvesting system: Mechanistic tree damage and fruit detachment models. Transactions of the ASABE. 59(4): 761-776.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Defterli, S. G., Y, Shi, Y. Xu, and R. Ehsani. 2016. Review of Robotic Technology for Strawberry Production. Applied Engineering in Agriculture. 32(3): 301-318. DOI: 10.13031/aea.32.11318.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Sarkar, S. K., j. Das, R. Ehsani and V. Kumar. 2016. Towards Autonomous Phytopathology: Outcomes and Challenges of Citrus Greening Disease Detection through Close-range Remote Sensing. Proceedings of IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Choi, D., W.S. Lee, R. Ehsani, and F.M. Roka. 2016. Detection of dropped citrus fruit on the ground and evaluation of decay stages in varying illumination conditions. Computers and Electronics in Agriculture.110:221-232.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Abdulridhag, J., R. Ehsani and A. de Castrop. 2016. Detection and differentiation between Laurel Wilt disease, Phytophthora Disease, and Salinity Damage Using a hyperspectral Sensing technique. Agriculture 6 (56): 1-13
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Zolfagharnassab, S., C. N. Vong, A. R. Mohamed Shariff, R. Ehsani, H. Jaffar, and I. Aris. 2016. Comparison of mean temperature taken between commercial and prototype thermal sensor in estimating mean temperature of oil palm fresh bunches. International Food Research Journal. 23(Suppl):91-95
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Al-Jumaili, A. p, and R. Ehsani. 2015. Mobile batch heat treatment system for treating HLB-infected citrus trees. ASABE Annual International Meeting in New Orleans, Louisiana, USA. Paper No. 152190319. 6 pages.
• Type: Other Status: Accepted Year Published: 2016 Citation: Ehsani, R., and J. Das. Johnson. 2016. Yield estimation in citrus with SUAVs. Citrus Industry. 97(2) 16-18.
• Type: Other Status: Published Year Published: 2016 Citation: Ehsani, R., M. Dewdney and E. Johnson. 2016. Controlling HLB with thermotherapy: what have learned so far. Citrus Industry. 97(9) 26-28.
• Type: Other Status: Published Year Published: 2016 Citation: Ehsani, R., D. Wulfsohn, J. Das and I. Z. Lagos. 2016. Yield estimation a low hanging fruit for application of small UAVs. Resource engineering and technology for a sustainable world. July/August 16-18.
• Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: Ying She. Application of high resolution aerial imaging for inventory management in nurseries and citrus groves. August 2016.
• Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: Fazly M. M. Design and development of a precision soil drenching machine for tree roots. August 2016.
• Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: J Abulidha. Detection of laurel wilt disease for avocado trees using multispectral imaging and a spectrodiometer. December 2016.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: M. Fazly Mail, Saman Souri, Hesam Zaeri, Reza Ehsani. 2016. Development of a soil drencher system for delivery of nutrients and chemicals to citrus tree roots. ASABE Annual International Meeting, July 17-20, 2016 Orlando, FL
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Pertiwi, Cininta, Ehsani, Reza, and Ingram, Keith. "Identifying Mechanization Options for Use in Cocoa Farms: Lessons Learned from Site Visits to Indonesia and Brazil," presented at the 2016 ASABE Annual International Meeting, Orlando, July 17-20, 2016.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Citrus growers, crop consultants, citrus processors, extension agents, scientific community Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Program activities and accomplishments in 2015 Organized a one-day workshop on applications of UAV in agriculture at the Citrus Research and Education Center. More than 80 people attended the workshop. There were13 speakers from seven different institutes. Gave presentations on thermotherapy at two main citrus events (Citrus Growers' Institute, Citrus Expo)and thermotherapy field day Participated and gave demonstration and talk to group of more than 60 growers in thermotherapy Field Day in Lake County. Gave several invited keynote speeches on applications of Unmanned Aerial Vehicles (UAV) in agricultural. Developed a website www.crec.ifas.ufl.edu/heat for the heat treatment of HLB-infected trees to provide latest information on application of heat treatment for citrus trees affected by HLB Outcomes and Impacts: In 2015, two citrus growers and three commercial companies built thermotherapy equipment based on Dr. Ehsani's concept. The growers used their heat treatment machines to heat treat several hundred trees in their groves. Also, commercial companies now actively build these machines and sell their services to citrus growers. Dr. Ehsani's group heat treated more than 2,500 citrus trees in three counties in response to growers' requests for the machine that he developed. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? New projects in 2015: Collaborative research: robot swarms and human scouts for persistent monitoring of specialty crops: This is a collaborative effort between Dr. Vijay Kumar at the University of Pennsylvania and Dr. Ehsani. This project will use a swarm of small robots to detect pests and diseases and well as yield for tomato, citrus, and blueberry. On-going projects in 2015: Steam-generated Supplementary Heat Thermotherapy as an Immediate Treatment for Prolonging Productivity of HLB-infected Citrus Trees: This four-year multi-state multi-disciplinary research and extension project aims to address the urgent need of citrus growers in Florida to an immediate treatment for HLB-affected citrus trees by utilizing steam for rapid thermotherapy. The overall goal of this project is to provide an immediate scalable technique using steam as well as synthesize scientific explanations on how the technique works in mitigating HLB and prolonging the production life of infected citrus trees. Dr. Ehsani is the project director and main PI for this project. Automated stress and disease detection in vegetable and tree crops using a cooperative ground and aerial vehicle network and optical sensors: Dr. Ehsani is a Co-PI in this project with the University of Central Florida. The idea is to develop a ground and an aerial robot that will cooperatively look for early detection of disease in citrus and strawberry fields. Development of citrus black spot sensing system using multispectral imaging: This project was on developing technique for detecting citrus black spot disease. Dr. Ehsani was a Co-PI on this project. Harnessing Unmanned Aerial vehicles (UAVs) in Specialty Crops: This planning project brought a team of scientists and engineers from the University of Georgia, Georgia Tech, the University of Pennsylvania, Clemson University, and the University of Florida together to write a large proposal on application of UAS in pecan and peach production. This proposal is written and submitted and is pending now. The following projects were funded by the USDA-APHIS-MAC program to build different types of heat treatment systems, based on the original heat treatment machine developed by Dr. Ehsani's group, and demonstrate them to growers. A compact, mobile, and improved tree steaming system for thermal therapy of individual medium-sized citrus trees Ag Harvesters citrus steam machine Integrated management of HLB for sustainable citrus production in Florida using an integrated management approach

Publications

• Type: Other Status: Published Year Published: 2015 Citation: Ehsani R. and P. Brown. 2015. Precision agriculture for citrus: Opportunities and challenges. Citrus Production Manual. University of California  Agricultural and Natural Resources. Publication 3539. pp 403- 408.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Castro, A. I. p, R. Ehsani, R.C. Ploetz, J.H. Crane, and J. Abdulridha. 2015. Optimum spectral and geometric parameters for early detection of laurel wilt disease in avocado. Remote Sensing of Environment. 171:33-44.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Katti, A.R., W.S. Lee, R. Ehsani, C. Yang. 2015. Band selection using forward feature selection algorithm for citrus. Journal of Biosystems Engineering. 40(4):417-427.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Gupta S.K. g, R. Ehsani, and N.H. Kim. 2015. Optimization of a citrus canopy shaker harvesting system: Properties and modeling of tree limbs. Transactions of the ASABE 58(4):971-985.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Castro, A. I. p, R. Ehsani, R.C. Ploetz, J.H. Crane, and S. Buchanon. 2015. Detection of laurel wilt disease in avocado using low altitude aerial imaging. PLoS ONE. DOI:10.1371/journal.pone.0124642.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Choi, D., W.S. Lee, R. Ehsani, F.M. Roka. 2015, A machine vision system for quantification of citrus fruit dropped on the ground under the canopy. Transactions of the ASABE 58(4):933-946.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Pourreza, A., W.S. Lee, R. Ehsani, J.K. Schueller, E. Raveh. 2015. An optimum method for real-time in-field detection of Huanglongbing disease using a vision sensor. Computers and Electronics in Agriculture, Elsevier.110:221-232.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Li, XH., W.S. Lee, M. Li, R. Ehsani, A. Mishra, C. Yang, and R. Mangan. 2015. Feasibility study on Huanglongbing (citrus greening) detection based on worldview-2 satellite imagery. Biosystems Engineering. 132:28-38.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Lee, W.S. and R. Ehsani. 2015. Sensing systems for precision agriculture in Florida, Computers and Electronics in Agriculture.112:2-9.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Al-Jumaili, A. p, and R. Ehsani. 2015. Mobile batch heat treatment system for treating HLB-infected citrus trees. ASABE Annual International Meeting in New Orleans, Louisiana, USA. Paper No. 152190319. 6 pages.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Abdulridha, J. g, R. Ehsani, A. de Castro p, R. Ploetz, and J. Konkol. 2015. Differentiate Laurel wilt disease and nutrient deficiency in avocado trees using Vis-NIR spectroscopy. ASABE Annual International Meeting in New Orleans, Louisiana, USA. Paper No. 152189572. 5 pages.
• Type: Other Status: Published Year Published: 2015 Citation: Ehsani, R., and C. Pertiwig. 2015. Tenting and supplementary heat for thermotherapy of HLB trees. Citrus Industry. 96(8) 8-12.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Li, N., C. Remeikas, Y. Xu, S. Jayasuriya, and R. Ehsani. 2015. Task assignment and trajectory planning algorithm for a class of cooperative agricultural robots. Journal of Dynamic Systems, Measurement and Control. 137:510041-9.

Progress 07/11/14 to 09/30/14

Outputs
Target Audience: Citrus growers, crop consultants, citrus processors, extension agents, scientific community Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? The results have been presented ina growers meetingand at two professional conferences. What do you plan to do during the next reporting period to accomplish the goals? Objective-1: The submitted papers will be revised based on the reviewers' comments. A high speed camera will be utlized to study the performance of different fruit removal systems. Objective-2:The spectral characterestics of laurel wilt disease in avocado will be studied, and a band selection technique will be usedtodetermine the most important spectral bands. Based on the results from band selection,a multi-band camera will be used to obtained multi-band aerial image. The aerial image and an appropriate classification technique will be used for early detection of laurel wilt. Objective-3: A portable heat treatment machine will be developed and used to field tests and to evaluate the possibility of heat treatment with supplemental heatfor heat treatment ofa large numberHLB-infected citrus trees.

Impacts
What was accomplished under these goals? The following activities were accomplished under each main objective as listed below: Objective-1) To continue the development and improvement of the existing mechanical harvesting machines in terms of enhancing their performance while lessening tree damage, and to develop new equipment designs and alternative harvesting approaches. Sub-objective-1: Improve the design of fruit removal tines on the Oxbo harvesting machines so as to reduce tree structural damage. A blueberry harvester provided by Oxbo International was used to evaluate two types of fruit removal systems (slappary and sway type) for dwarf citrus trees. The experiments were performed on dwarf citrus trees at the CREC grove. Static and dynamictests were conducted at four different shaking frequencies (2.5, 3.7, 4.8, and 5.9 Hz). For each test, the number of fruits removed and remaining on the tree were counted. This process was repeated on five trees. Eight accelerometers were attached to the tree before the testcommenced to gather the acceleration data. The finite element analysis indicated that the slapper system produced lower stresses and deflections in the branches. It was also found that the natural frequency range of the dwarf trees was significantly higher than the excitation frequency range of the machine. The fruit removal ratio for both mechanisms was also much lower than required. The data analysis part is not completed yet, and the work on it is in progress; but overall, the slapper system has higher fruit removal and less tree damage compared to the sway system. Sub-objective (2): Developing a fruit recovery system for the Oxbo 3210 Anew modified sweeper and fruit pick-up machine was developedand installed on an Oxbo 3220. The fruit pick-up machine consists of a sweeper and fruit pick-up head. The sweeper system has two major components: (1) A main base with a suspension and flotation system, (2) A sweeper system with flexible rods attached to rotating wheel collectors equipped with flaps. This system is designed to allow free movement of the sweeping arm on the ground irrespective of the position of the fixed platform which is attached to the vehicle. This design allows the sweeping arm and the wheels to follow the contour of the ground. In addition, the sweeping arm is pivoted to the main base which allows the system to swing to the left or right through a hydraulic cylinder controlled by the operator. The wheel is rotated by a hydraulic motor through a chain system. To follow the ground contour, a concave disk is installed under the sweeper wheel. This allows the sweeper to float on the ground and can follow the contour of the ground. The disk under the sweeper wheel is able to rotate freely, independent of the sweeper. Since the disk does not rotate with the wheel, it is very stable during the operation and easily follows the ground contour. The developed system has the following advantages over existing commercial systems. The system has a simple design, and most components are commercially available which makes the overall cost of production lower than the competitors. The system is very rugged and suitable for agricultural applications. Flexible tines are not damaging the tree trunk or main branches even if they hit the trees. The flexibility in the flaps caused a very little disturbance in the soil and produces very little dust when it is operating in the field. The system can operate in loose sandy soil where regular sweepers cannot operate easily. The sweeper head has a very low-profile which makes it suitable for sweeping leaf litter and fruits from under the trees that are not skirted and that have very low hanging branches. The sweeper had a cleaning performance of 90 to 98 percent. The damage to the irrigation line was minimal; however, it could knock over the sprinkler nozzles. This will not be an issue if the nozzles are installed next to the tree's main trunk. Objective-2) To develop both aerial- and ground-based robotic sensing equipment that will facilitate early detection of diseases and stress within a commercial citrus block. A plan of the field work was developed to study the effects of water stress on thermal and spectral signature of citrus and strawberry plants. It was expected that a combination spectral and thermal data will improve the accuracy of detecting water stress. Objective-3) To develop novel approaches for physical disease treatment such as thermal treatment and other non-traditional disease treatment methods. Field trials wereinitiated to evalaute the effect of heat treatment using steam as a suplimental heat. In addition, a research proposal was developed to study the engineering, biology and economics of heat treatment as an immediate technique for prolonging the productive life of HLB-infected trees. Impact of accomplishments towards overall goals: Objective -1): The results of this study can help us to choose a better fruit removal system for dwarf citrus trees. The performance of the sweeping and pick-up system was very satisfactory. These two main components now can be used on smaller and lower cost fruit pick-up machines. Objective -2): Understanding the effect of drought on thermal and spectral signature could lead to developing more accurate sensors for UAV systems. Objective-3): Developing an efficientand scalable heat treatment system could lead to an effective short term solutionfor HLB-infected citrus trees and could potentialy save the citrus industry in Florida.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Jadhav, U., L. R. Khot, R. Ehsani, V. Jagdale, J. K. Schueller. 2014. Volumetric mass flow sensor for citrus mechanical harvesting machines. Computers and Electronics in Agriculture. 101: 93-101.
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Aksenov, A. A., A. Pasamontes, D. J. Peirano, W. Zhao, A.M. Dandekar, O. Fiehn, R. Ehsani and C. Davis. 2014. Detection of Huanglongbing Disease Using Differential Mobility Spectrometry. Analytical Chemistry. 86(5):2481-2488. DOI: 10.1021/ac403469y
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Khot, L. R., R. Ehsani, G. Albrigo, W. Swen, J. C. Neto, J. Campoy and C. Wellington. 2014. Validation of variable rate spray decision rules in intricate micro-metrological conditions. Precision Agriculture. CIGR Journal. 16(1): 90-98
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Khot, L. R., R. Ehsani, J. M. Maja, J. M. Campoy, C. Wellington and A. Al-Jumaili. 2014. Evaluation of deposition and coverage of an air-assisted sprayer, and two airblast sprayers in citrus orchards. . Transactions of the ASABE. 57(4): 1007-1013
• Type: Book Chapters Status: Accepted Year Published: 2014 Citation: Sankaran, S., L. R. Khot, R. Ehsani. 2014. Mid- and far-infrared spectroscopy. In Alahakoon et al. (Eds.), Imaging with Electromagnetic Spectrum: Applications in Food and Agriculture. Springer, IX, 290p. ISBN 978-3-642-54887-1
• Type: Book Chapters Status: Accepted Year Published: 2014 Citation: Ehsani R. and P. Brown. 2015. Precision Agriculture for Citrus; opportunities and challenges. Citrus Production Manual. University of California  Agricultural and natural Resources. Publication 3539. Pp 403- 408
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2014 Citation: Pertiwi, C., S. Leavitt, R. Ehsani, and W. Pelletier. 2014. Heat transfer model development for thermal treatment of huanglongbing-infected citrus trees. ASABE and CSBE/SCGAB Annual International Meeting in Montreal, Quebec Canada. Paper No. 141913935 doi: 10.13031/aim.20141913935
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2014 Citation: Yunjun X. , Ehsani R., Kaplan J., Ahmed I., Kuzma W., Olandi J.,Nehila K., Waller K., Defterli S.G. 2014. An octo-rotor ground robot network for autonomous strawberry disease detection-Year 1 status update. Proceedings of the second international conference on robotics, associated high-technologies and equipment for agriculture (RHEA-2014), Madrid. pp 141-148.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2014 Citation: She, Y., R. Ehsani, J. Robbins, J. N. Leiva and J. Owen. 2014. Applications of small UAV systems for tree and nursery inventory management. Proceedings of 12th International Conference on Precision Agriculture (ICPA). July 20-23, Sacramento, CA
• Type: Other Status: Accepted Year Published: 2014 Citation: Roka F.M. , R. Ehsani, S.H. Futch, and B.R. Hyman. 2014. Citrus mechanical harvesting systems--Trunk shakers. EDIS Publication No. FE950. http://edis.ifas.ufl.edu/fe950
• Type: Other Status: Other Year Published: 2014 Citation: Roka F.M., R. Ehsani, S.H. Futch, and B.R. Hyman. 2014. Citrus mechanical harvesting systems--Continuous canopy shakers. EDIS Publication No. FE951. http://edis.ifas.ufl.edu/fe951
• Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Gupta, S.K., R. Ehsani, N.H. Kim. Optimization of a citrus canopy shaker harvesting system: Properties and modeling of tree limbs. Transaction of the ASABE
• Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Gupta, S.K., R. Ehsani, N.H. Kim. Optimization of a citrus canopy shaker harvesting system: Mechanistic tree damage and fruit detachment models. Transaction of the ASABE.