Source: FLORAPULSE CO submitted to NRP
IN-PLANT PROBE OF WATER POTENTIAL FOR FEEDBACK CONTROLLED MANAGEMENT OF WATER STATUS IN FRUIT CROPS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
SMALL BUSINESS GRANT
Reporting Frequency
Annual
Accession No.
1017306
Grant No.
2018-33610-28825
Cumulative Award Amt.
$599,977.00
Proposal No.
2018-03164
Multistate No.
(N/A)
Project Start Date
Sep 1, 2018
Project End Date
Aug 31, 2021
Grant Year
2018
Program Code
[8.4]- Air, Water and Soils
Recipient Organization
FLORAPULSE CO
170 LOUISE LN
DAVIS,CA 95618
Performing Department
(N/A)
Non Technical Summary
Water is a critical and growing issue for our planet in both human use as well as the need for food production to feed a growing world population. Agriculture plays a dominant role in this challenge as the single largest user of water, accounting for an estimated 70% of all use by humans. There are 680 million acres of irrigated agriculture in the world (FAO) and 55 million acres of irrigated crops in the US alone. With climate change and increasing drought frequency, improving agricultural water use efficiency is truly a critical global issue. To optimize water use efficiency requires the ability to measure how much water stress the crop is experiencing and limit the amount of water used in irrigation without detrimental effects on crop yield or quality. Precision irrigation is one of weakest components of precision agriculture due to a lack of ways to directly monitor crop water stress. This project is a collaborative effort between nanotech engineering and applied plant science that has developed an innovative new technology, called a microtensiometer, for continuously monitoring water stress in plants. This is a micro-chip based on a well-understood principle of measuring the water. Due to the design and manufacturing method, this microtensiometer has a huge range of accurate measurement, faster equilibration times (seconds), and much smaller size than existing systems. Such a tiny sensor can be embedded directly inside the stems of plants, especially woody crops, and provide continuous real-time data on water stress wirelessly to growers. We have been testing the sensor inside grapevines, almond trees and apple trees and have proven that this technology works over many months in the harsh commercial field environments. The measurements give the same values as a current standard, but manual and slow, method. The continuous monitoring of crop stress will provide unprecedented actionable information to growers for efficient decision-making in smart management systems in multiple agricultural, forestry and ornamental uses. This will be key to improving irrigation efficiency, reducing environmental damage due to leaching, optimizing product yield and quality, and maintaining sustainability for irrigated crops.
Animal Health Component
40%
Research Effort Categories
Basic
10%
Applied
40%
Developmental
50%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1021131202060%
4041131202020%
1111212202020%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 111 - Conservation and Efficient Use of Water; 404 - Instrumentation and Control Systems;

Subject Of Investigation
1212 - Almond; 1131 - Wine grapes;

Field Of Science
2020 - Engineering;
Goals / Objectives
The Major Goals of the project are to:Develop a sound, rugged and cost-competitive scientific tool to continuously and accurately measure the water potential directly inside plants over long periods. Since this combination of capabilities does not currently exist, this sensor will provide unique insights into the physiology of plant water relations.Develop, test and prove the microtensiometer to be reliable as a commercial product to give growers real-time data on crop water status. This data stream will guide when and how much to irrigate and will provide precise data for variable rate irrigation to maximize revenues.Develop a platform for data analysis, delivery and user interface for valuable recommendations to growers based on the unprecedented stream of data.We aim to provide data-driven, actionable, precise guidance to the grower, with the ultimate goal of enabling a completely automated irrigation system.The Major Objectives of the project are to:System integration and manufacturing - Generate a next version of microtensiometers of smaller size and improved sensitivity and develop new packaging options. These characteristics will improve sensor performance, extend applicability to low stress scenarios, as in soils, and younger vines and trees, and lay the groundwork for future manufacturing.Robust, do-it-yourself protocol for installation and operation. In close coordination with continued field trials in almond, grape, and apple, we will develop tools and protocols with supporting video instructions to allow for sensors to be shipped to non-expert users for installation and operation. This is critical to broaden the market from only the areas that we have a physical presence.Wireless datalogger and user interface. We will continue development of the wireless electronic interface, with an emphasis on reducing power consumption and robustness with respect to multi-year deployment in the field. In parallel, we will develop a suite of user interfaces for web and mobile access to data for customers.Data analytics and crop modeling to provide high value services to growers. We will continue to mature our models of coupling between micrometeorology and plant hydraulics for various crops or varieties that have different optimal water status regimes (red vs white wine grapes, almonds, apples, etc.). These will provide growers with actionable guidance to understand and utilize the data streams in user-friendly formats on web-based and mobile platforms.
Project Methods
Efforts in this project fall into 4 main categories: (1) design and fabrication of the MEMS sensor, (2) development of robust sensor packaging for environmental protection, (3) testing of embedding strategies and (4) development of a grower user interface and crop-specific water management models.MEMS developmentEffort: FloraPulse will fabricate another batch of MEMS sensors with improved characteristics. Through our work in the cleanroom, we will simplify the sensor fabrication process, decreasing the number of steps (and cost) by ~30%, along with improving the sensor sensitivity and ease of packaging. In particular, we will add a glass or fiber 'cap' to the sensor that will increase overall accuracy through elimination of external sources of noise. We also aim to change the sensor metal stackup to allow direct, easy soldering of the microchip directly to a printed circuit board.Evaluation: After fabrication, we will measure the following device characteristics: total number of fabrication steps, functional yield, accuracy of fully-packaged devices and drift in the sensor electronics. Improvements in the fabrication process should also decrease our time to build a sensor by 30-50%.Environmental packagingEffort: FloraPulse will continue iterating on the method to package the device, with the goal to streamline this process, increase yield of functional devices, and produce devices that are robust and last for years embedded in plant tissue. We will thus fine tune our current encapsulation method by designing machined containers for the sensor and testing ways to increase the encapsulation quality. Attempts here will include applying vacuum during encapsulation, applying high pressures to collapse undesired encapsulation bubbles, and vibrating the encapsulant to remove bubbles. Further improvements will be made in the sensor printed circuit board design. Finally, we seek to streamline subsequent preparation steps, such as sensor pressure and temperature calibration, sensor filling, and sensor storage.Evaluation: Packaging methods will be evaluated by testing the resulting devices in water for multiple weeks, looking at the stability and drift of the electrical output. We will further count the amount of time it takes to prepare devices with the new methods, and compare said number with our current record.Sensor installationEffort: FloraPulse, in collaboration with the Stroock group, will continue testing and iterating on how to best install sensors in multiple woody species--such as almonds, grapes, walnut and apple. We will install sensors on a regular basis, with the goal of making the sensor installation easier and more reliable. Given that currently installation requires highly skilled and trained workers, installation equipment and video guidance will be developed to facilitate the sensor installation by third parties.Evaluation: Our progress in improving the sensor installation will be measured through 3 metrics: (1) accuracy of installed sensors as compared to the Scholander chamber, (2) time for an untrained user to correctly install the sensor, and (3) overall cost of performing an installation. We aim to have sensors agree with the Scholander chamber within 1 bar*, be installed in less than 15 minutes, and cost less than $100 to install.*Although the Scholander pressure chamber is the current standard method, the sampling of leaves within a tree or vine canopy gives some inherent variability to Scholander measurements that is not exactly the same as measured by our sensor in the trunk. Thus, the two measures should be highly, but not perfectly, correlated.Grower interfaceEffort: We will continue developing the user interface for our data stream in collaboration with our beta testers. As part of this effort, we will test different ways of visualizing the water stress data and recommending actions to growers. This may lead to a suite or multi-layered interface as technical specialists, orchard/vineyard managers and irrigation workers will likely prefer different levels of data and formats. Besides display, the data will be analyzed and plant water status will be compared against current standards for fully irrigated crops and for imposed water stress regimes found to be effective at improving product quality (grape and other fruit crops) and harvest efficiency (almonds). Current understanding will be integrated with new understanding gained from our sensor data stream to improve models and recommendations for irrigation management. This will be done in collaboration with water relations scientists, irrigation advisors and leading growers as new data is accumulated.Evaluation: The ease of use and the effectiveness of the user interface will be determined from feedback from our beta-testers, our industry advisors who have offered to help our development, and from all users varying in technical skills and needs.Current models of optimal irrigation based on infrequent or indirect data (weekly pressure chamber, soil moisture, weather effects, etc.) will be tested against the new data stream to determine how accurate and robust they are. As the database of continuous dynamic water status develops, we will be able to refine or abandon the current models and provide improved real-time models appropriate to the crop and the desired product outcome.In addition to testing models with current modeling approaches, we will collaborate with data analytic scientists in academia and industry on using "big data" approaches. Our data stream, with available continuous weather and soil moisture data will provide an unprecedented opportunity to apply such powerful methods to the critical practice of water management.

Progress 09/01/18 to 08/01/21

Outputs
Target Audience: Plant scientists who study plant physiology of water relations - particularly through email communications and presentations at a scientific conference. Graduate and post-doctoral students studying plant science through collaborations with UC Davis faculty and the Stroock group at Cornell. Fruit and nut growers who have access to the water-stress information we are gathering in their field and are using it to improve their farming. We further corresponded and collaborated with growers and scientists in multiple countries outside the US. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?At least 6 interns have been hired to work in this project and learn about agriculture, engineering and microfabrication. How have the results been disseminated to communities of interest?The work will be presented at the 2021 ASHS conference. Furthermore, our collaborators (in particular prof. Ken Shackel from UC Davis) regularly present our data in conferences. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objective #1: system integration and manufacturing Multiple issues were solved with the microfabrication of the microtensiometer chip. In particular, we dramatically increased the sensor speed by patterning the backside oxide before producing the nanoporous silicon. We now have a robust, repeatable process to build 1000+ microtensiometer chips in ~7 days. The microtensiometer probe was extensively redesigned to be less expensive to produce and easier to manufacture. We developed a process for a technician to consistently build probes at a rate of 100 probe per 40 hours. We added a plastic capsule that makes the sensors easy to ship and move while keeping them wet. Objective #2: DIY protocol for installation The installation method was dramatically improved, after multiple iterations, to work consistently in a variety of crops. We successfully tested the new installation method in 12 crops. We recorded an instructional video on how to install the sensor - this video is posted on our website and has been used by 10+ scientists and growers to install our sensors successfully. We wrote a manual that explains how to install the sensor. A sensor installation can be performed in 5 minutes. Much faster than our previous method. Objective #3: Wireless datalogger and user interface The dataloggers developed under this award have been shown to work for 2+ years in the field. The power and electronics are robust enough to work without issues. A user interface was developed that shows the continuous water potential data, and also a simplified version. The simple version shows the midday water potential, along with recommended levels for 3 crops (grape, almond, prune). This interface can be viewed from a PC or smartphone. Objective #4: Data analytics and crop modeling Our main focus was on developing the hardware and ensuring that it worked consistently. We succeeded at those goals. We started preliminary work on this objective by providing the growers with recommendations based on the guidelines published by the University of California.

Publications

  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2021 Citation: Presentation at the American Society of Horticultural Science Annual Conference, 2021, Denver CO â¿¿Microtensiometer sensor for accurate, long-term water potential measurement in trees and vines⿝. Michael Santiago


Progress 09/01/19 to 08/31/20

Outputs
Target Audience:Target audiences Plant scientists interested in plant physiology, agricultural efficiency, and sensing systems and their graduate students. We have ongoing collaborations scientists at UC Davis and Cornell University, and this year sold product to scientists in California and Washington for testing. The microtensiometer developed under this award is now available available to scientists in the USA and many other countries. Fruit and nut growers, particularly of almonds and winegrapes. The microtensiometer is now available as a commercial product and various growers have purchased our systems to try them out. We have made efforts to communicate with these and other growers about our product, how it works, and how to use it. Undergraduate and graduate engineering students, who are working at FloraPulse as interns developing the technology and acquiring experience. Delivery efforts We have given presentations about the microtensiometer to scientific meetings: International Society for Horticultural Sciences 9th International Symposium on Irrigation of Horticultural Crops in Matera, Italy. Two papers, one invited and one contributed are in press. American Society for Horticultural Sciences annual meeting, Washington, DC - invited presentation. To universities: University of Bologna and University of Napoli, Italy Cornell University - guest lecture in course on horticultural physiology To Extension and Grower Groups: The International Fruit Tree Association annual meeting, Rochester, NY Cornell Shaulis Symposium on Digital Viticulture, Geneva, NY Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Hired two interns from UC Davis. They are getting experience in building the electronics and software part of our system, along with seeing how a small company is run and develops. The research collaboration with Cornell University has provided research training for several graduate students in the Stroock Lab with sensor development and data analytics. How have the results been disseminated to communities of interest? We have disseminated information and results from the microtensiometer to several interested communities. First, plant researchers who have tried to continuously monitor plant stress for decades without success. They are highly interested, knowledgeable about the potential and difficulties. Many have indicated their interest in purchasing sensors to test, but we currently have limited numbers and many researchers are in other countries. We are exploring the import/export issues for international sales. Second, we have given presentations to growers who understand the general value of such data. However, they are typically skeptical (frankly due to too many" miracle technologies" being hyped) until research and extension specialists, crop consultants or leading growers they trust confirm its value and ruggedness. Also, they and even researchers are not entirely sure how to use continuous data for management as it has never been available before. What do you plan to do during the next reporting period to accomplish the goals? We continue working on simplifying the sensor build process, improving sensor yields, and increasing overall system reliability with field data and perpsectives from growers and consultants. In particular, there are still existing challenges with microfabrication of the microtensiometer chips (yield losses due many chips becoming 'slow'), the packaging of probes (similarly, yield losses due to probes becoming 'slow'), and installation of sensors (the plant wounding response sporadically causes sensor failure). Thus, we will continue building and installing devices with the goal of continually improving our microfabrication, packaging and installation yields. We will also continue improving the user interface by implementing feedback from current customers.

Impacts
What was accomplished under these goals? Objective #1: Build next generation microtensiometer with improved characteristics During the past year, the company has continued fine-tuning and improving the processes involved in building microtensiometers. We went through 3 rounds of microfabrications to build microchips and decreased the time and cost to fabricate chips by 25%, and increased the sensor sensitivity by 30%. There were issues with yields of chips due to blockage of the nanoporous membrane and we began experiments to better understand this issue and fix it. During our testing, we built over 300 probes while continually tweaking and improving the probe building process. Probe packaging was simplified substantially and now takes approximately 40% less labor and half the time. To achieve these improvements, we developed software protocols for the sensors to effectively calibrate themselves with respect to temperature, and software that analyzes sensor data and detects problems. Objective #2: DIY protocol for installation and operation This year FloraPulse launched a product based on this award, where customers themselves received and installed the product. We continued to improve the sensor installation methods and recorded a detailed, easy to follow installation video that was sent to customers. Over 95% of customer installations went well, which shows that the DIY protocol developed is effective. The installation method has further continued to mature. A step was added to remove phloem tissue and seal between the plant cambium and the sensor installation with silicone caulk. This extra sealant step helps prevent the infiltration of wounding gels into the sensor installation, which previously prevented measurement or led to slow sensor response. This particular improvement was necessary for accurate measurement in crops where the wounding gels have low viscosity, such as prune and mango. Objective #3: Wireless datalogger and UI The datalogger received multiple small improvements: hardware parts were changed to improve ease of assembly; loggers can now be charged directly through USB; loggers now automatically enable themselves and start running after installation without user input; the logger firmware was updated for increased reliability. A brand new user interface was developed to help customers interpret and use the data. The new UI simplifies the sensor data and only shows the most relevant information, the daily lowest measured water-status, along with the recommended levels for water status according to the crop. The UI also automatically downloads weather data from nearby weather stations and calculates the crop 'baseline', or water status expected when the crop is fully hydrated. More recently, we implemented input boxes for the customer to record and visualize manual measurements of water status and irrigation events. Objective #4: Data analytics and crop modeling Multiple year-long datasets have been acquired--these will continue to be used for building and improving models. Our system now has the capability of automatically processing sensor data to extract key metrics such as the daily maximum, daily minimum, and running average. An alarm system has been coded that automatically reads the sensor measuremets every day, detects common issues, and sends out a relevant alert. This alarm system will continue maturing to include more complex analyses of the data and will be modified to implement the data-analysis algorithms being developed.

Publications

  • Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Lakso, A.N., S. Zhu, M. Santiago, K. Shackel, V. Volkov and A.D. Stroock. 2020. A microtensiometer sensor to continuously monitor stem water potentials in woody plants - design and field testing. Acta Horticulturae, In press.
  • Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Lakso, A.N. and D.S. Intrigliolo. 2020. Plant-based sensing for irrigation management in the field. Acta Horticulturae, In press.


Progress 09/01/18 to 08/31/19

Outputs
Target Audience: Plant scientists interested in plant physiology, agricultural efficiency, and sensing systems and their graduate students. We have ongoing collaborations with these groups in UC Davis and Cornell University. The story of the development of the microtensiometer and FloraPulse have been featured in Cornell engineering undergraduate classes as examples of sensor engineering and related progress toward commercialization. Fruit and nut growers, particularly of almonds and winegrapes. Through our ongoing collaboration and field testing, these growers receive data to help improve their operations. Although the sensor is not yet commercially available in quantity, the FloraPulse team have been invited to speak to growers about the future for precision irrigation. Also, this project will be featured as a cover story for the American Fruit Grower, a key trade publication. Undergraduate and graduate engineering students, who are working at FloraPulse as interns developing the technology and acquiring relevant experience. The interns have learned about building datalogging hardware, algorithms and user interface engineering. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Hired two interns from UC Davis. They are getting experience in building the electronics and software part of our system, along with seeing how a small company is run and develops. How have the results been disseminated to communities of interest? As written previously, the FloraPulse team and collaborators regularly present at plant science conferences, such as ASEV and Acta Horticulturae. Our collaborators from Cornell University are writing a refereed journal paper based on our measurements in apple, grape and almond. It will be submitted this year. Three articles are being published on FloraPulse this summer (Wine Business Monthly, UC Davis Engineering Progress Magazine, American Fruit Grower Magazine). What do you plan to do during the next reporting period to accomplish the goals? Now that we can reliably produce and install sensors, we are focused on making sensors and installing them at customer sites during the 2019 growing season. Secondary goals are to (1) continue improving the sensor packaging for reliability, (2) fine-tune the UI to meet customer needs, (3) simplify the installation procedure, record how-to videos and test unsupervised sensor installation with new customers, (4) develop a system for easier transport of sensors, (5) begin to modify the datalogger to use LoRa for lower system cost, and (6) raise private funds to push product development and get ready for launch in 2020.

Impacts
What was accomplished under these goals? IMPACT Water is the largest input to agricultural fields and directly affects plant health, crop yield and crop quality; inefficient use of water also creates problems of fertilizer leaching and aquifer depletion. Unfortunately, fruit and nut growers lack adequate tools to manage irrigation, to know when, where and how much to irrigate optimally, and consequently lose out on yield and quality improvements, while causing unnecessary environmental impact. Specifically, there are no methods to measure plant water status directly, automatically, and robustly over long periods in commercial fields until now. FloraPulse has developed a sensing probe that directly and automatically measures the water status, or 'thirst' of a woody plant, information that allows growers to irrigate with maximum precision, according to the needs of the plant, and produce maximum crop yield and quality, while using the minimal amount of water. During the award period, the FloraPulse team collaborated with academic and industry researchers to produce sensors and install them in multiple vineyards and orchards. They showed that the sensor can reliably measure plant water status for over a year in grapes, almonds and apple trees. They also developed a user-friendly method to install sensors, which will allow growers to receive sensors over the mail and install it themselves at lower cost. These results pave the way for the company to start building sensors at scale and sell them commercially in 2020. With this technology, growers will irrigate with maximum precision, maintain healthier fields, and will produce more, better quality produce, with less water. Objective #1: Build next generation microtensiometer with improved characteristics Chip fabrication - Microchip R&D was moved from Cornell University to UC Davis to be closer to our headquarters and allow faster development. We designed and fabricated two full iterations of the microtensiometer, and ended up with 200% increased yield, 50% higher sensitivity, and improved reliability. Experimental versions of the microchip - We built experimental versions of the microchip with 10x higher sensitivity and thicker glass-backing for improved tolerance to external mechanical stresses. These improvements pave the way to measure water stress in soils and producing devices that remain accurate for years in the field. Chip packaging - We improved sensor packaging by fine-tuning the cleaning and encapsulation procedures to enhance encapsulant adhesion and decrease packaging-induced stress. Various encapsulants were tested to find an ideal mix of adhesion and softness. We further developed two different packaging strategies - "flip chip" where the chip is soldered directly to a PCB, and "wirebonding" where PCB-sensor electrical connections are made through aluminum wirebonds. These improvements solved a longstanding issue with sensor drift and noise; our newest probes can now reliably measure plant water-status, drift-free, for months to years. Process flow - We developed a standardized and well documented process flow for chip fabrication, packaging and installation. This documentation will enable us to outsource sensor manufacture and train new employees to build devices. Post-install sensor accuracy - Due to improvements in the sensor packaging and installation method, our latest batch of sensors reliably measure plant water status and agree with the gold standard manual measurement, without the need for in-field calibration. This improvement greatly simplifies use of the sensor, since no manual measurements are needed to calibrate each sensor. Sensor longevity - Many of the sensors installed in 2018 are still giving accurate measurements, even after going through the winter period of plant dormancy. These results show that multi-season measurement of plant water status is feasible. Objective #2: DIY protocol for installation and operation Wrote a manual on how to install the sensor for customer use. Built toolbox and equipment for customers to self-install sensor. Had customers successfully install sensors with our supervision. Designed and tested custom-machine parts that allow a sensor to be installed in less than 10 minutes. This used to take over an hour. We are seeking patent protection on this method. Objective #3: Wireless datalogger and UI The datalogger previously developed has shown to be robust and reliable, with only a 3% failure rate over the last year. This year we are on track to have 60+ loggers installed and running before the end of the season. We now have an in-house assembly line where the dataloggers can be assembled reliably by inexpensive labor. The UI previously developed has shown to be robust, reliable, and easily extensible. We added inputs where the grower can add in manual measurements of plant water status and irrigation, then see this extra data along with sensor measurements in the FloraPulse UI. Modified UI to show multiple sensors in the same screen for easier viewing of the information. Objective #4: Data analytics and crop modeling We have added weather analytics to help the growers better understand and use the sensor data. The UI automatically polls weather data, analyzes it, and outputs a 'fully irrigated' baseline that shows the grower how far away they are from fully irrigated. Installed sensors at Clos De La Tech, a California vineyard with automated irrigation capabilities. The owner is working with us to use the microtensiometers to drive his irrigation valves, for our first proof of concept for closed-loop irrigation with our sensors.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Chao Shang, Wei-Han Chen, Abraham Duncan Stroock, Fengqi You, Robust Model Predictive Control of Irrigation Systems With Active Uncertainty Learning and Data Analytics. IEEE Transactions on Control Systems Technology 10.1109/TCST.2019.2916753 (2019).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Keynote presentation by A.D. Stroock: ⿿Learning to listen to plants⿝. Gordon Research Conference on Physics and Chemistry of Microfluidics. Hong Kong. June 2019. Keynote presentation by A.D. Stroock: ⿿Learning to listen to plants - tools for efficient water use⿝. American Association for the Advancement of Science (AAAS) Meeting 2019. Washington DC. April 2019. Keynote presentation by A.D. Stroock: ⿿Microtensiometer ⿿ a tool for optimizing water management in fruit & nut crops⿝. Empire State Fruit & Vegetable Expo. Syracuse, NY. January 2019. Keynote presentation by A.D. Stroock: ⿿Water Dynamics in Plants and the Innovations for Agriculture They Inspire⿝. American Institute of Chemical Engineering Annual Meeting. Pittsburg, PA. November 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Invited presentation by A. Lakso ⿿Water use, water stress and water management in trees⿝, to the International Fruit Tree Association annual conference 2019 Poster at the 2019 American Society for Enology and Viticulture National Conference, Napa CA. ⿿A Micro-tensiometer sensor for continuous monitoring of stem water potential in grapevines⿝ Ken Shackel, Vadim Volkov, Nate Kane, Abraham Stroock, Alan Lakso, Michael Santiago. Presentation to the 9th International Symposium on Irrigation in Horticultural Crops; Paper submitted to proceedings to be published in Acta Horticulturae, ⿿A microtensiometer sensor to continuously monitor stem water potentials in woody plants ⿿ design and field testing⿝ Alan Lakso, Siyu Zhu, Michael Santiago, Ken Shackel, Vadim Volkov and Abraham Stroock.