A manual / robotic device for early detection of diseases and abiotic stresses in plants

Abstract

A method and system for detecting disease in a plant, the method including: obtaining a baseline electrical impedance or resistance measurement of a plant organ by applying an electrical signal via a plurality of electrodes in contact with the plant organ and measuring a response to the applied electrical signal; obtaining one or more subsequent electrical impedance or resistance measurements of the plant organ or another plant organ of the plant, each subsequent measurement obtained after a time interval from a previous measurement; comparing the one or more subsequent electrical impedance or resistance measurements with the baseline electrical impedance or resistance measurement to detect a deviation indicative of a developing disease in the plant; and generating an alert in response to detecting the deviation indicative of the developing disease.

Description

[0001] APPLICATION FOR PATENT

[0002] Inventor(s): Avital Bechar, Ran Gorali, Lavi Rosenfeld, Aviv Dombrovski, Assaf Yaakobovitch

[0003] Title: A MANUAL / ROBOTIC DEVICE FOR EARLY DETECTION OF DISEASES

[0004] AND ABIOTIC STRESSES IN PLANTS

[0005] This patent application claims priority from, and the benefit of, U. S. Provisional Patent Application No. 63 / 734,884, filed December 17, 2024, which is incorporated in its entirety as if fully set forth herein.

[0006] FIELD OF THE INVENTION

[0007] The present invention relates to robotics, disease, and abiotic stresses detection in plants and more specifically to a manual / robotic device that can detect diseases and abiotic stresses in plants through physical contact with the plant leaf which measures electrical characteristics of the plant which are a high indication of the presence of diseases in the plant.

[0008] BACKGROUND OF THE INVENTION

[0009] Viruses of the Tobamovirus genus caused severe losses in many economically important crops, such as pepper, tomato, and cucurbits. Disease symptoms of the Tobamovirus tomato brown rugose fruit virus (ToBRFV) are visually detected about 10-14 days postinfection by experts. During the “latent” asymptomatic period, infected plants constitute a primary source for virus spread to the entire crop via workers’ hands and tools. This is merely one example of disease that farmers have to deal with.

[0010] Conventional methods for testing plants today include physical visual examination by experts (phytopathologists) 12-14 days after infection, laboratory tests, and / or hyperspectral photography 6-8 days after infection. The lab tests are expensive and take a number of days to receive the results.

[0011] Early discovery of infection / disease is important as it reduces the number of plants that get infected and need to be treated / destroyed. SUMMARY OF THE INVENTION

[0012] The present invention successfully addresses the shortcomings of the presently known configurations by providing a new technology for detection of diseases and abiotic stresses in plants.

[0013] According to the present invention there is provided method for detecting disease in a plant, the method including: obtaining a baseline electrical impedance or resistance measurement of a plant organ by applying an electrical signal via a plurality of electrodes in contact with the plant organ and measuring a response to the applied electrical signal; obtaining one or more subsequent electrical impedance or resistance measurements of the plant organ or another plant organ of the plant, each subsequent measurement obtained after a time interval from a previous measurement; comparing the one or more subsequent electrical impedance or resistance measurements with the baseline electrical impedance or resistance measurement to detect a deviation indicative of a developing disease in the plant; and generating an alert in response to detecting the deviation indicative of the developing disease.

[0014] According to further features, the electrical signal is an alternating signal applied over a range of frequencies, and each electrical impedance measurement comprises an impedance spectrum.

[0015] According to still further features, the plurality of electrodes are coupled to the plant organ via a clamping mechanism.

[0016] According to still further features, obtaining the one or more subsequent electrical impedance measurements includes obtaining a plurality of subsequent measurements at regular time intervals.

[0017] According to still further features, wherein the deviation includes a change in impedance magnitude or phase exceeding a predetermined threshold.

[0018] According to still further features, the disease is a biotic disease caused by a pathogen.

[0019] According to still further features, the predefined interval is at least one day. According to still further features, the predefined interval is between half a day and a day and a half.

[0020] According to another embodiment there is provided a device for measuring electrical impedance or resistance of a plant organ, the device including: a plurality of electrodes; a clamping mechanism mechanically coupled to the plurality of electrodes, wherein the clamping mechanism is configured to releasably secure the device to a plant organ such that at least one of the plurality of electrodes is in electrical contact with a surface of the plant organ or penetrates the plant organ; and a processor in electrical communication with the plurality of electrodes, the processor configured to apply an electrical signal between at least two of the plurality of electrodes and measure an electrical impedance or resistance of the plant organ based on a response to the applied electrical signal.

[0021] According to further features, the clamping mechanism includes a movable clamping member slidably mounted on a frame for linear sliding movement toward and away from the fixed clamping member.

[0022] According to still further features, the clamping mechanism includes a clamping element mounted for reciprocating linear movement within the clamping mechanism.

[0023] According to still further features, the clamping mechanism includes an adjustable jaw threadedly engaged with a screw rotatably engaged with a motor, where rotation of the screw causes linear movement of the adjustable jaw.

[0024] According to still further features, the electrical signal is an alternating current or voltage signal, and the processor is configured to perform electrical impedance spectroscopy over a range of frequencies.

[0025] According to still further features, at least one of the plurality of electrodes has a needlelike form factor configured to penetrate the plant organ. According to still further features, wherein the clamping mechanism comprises a first jaw supporting a first electrode and a second jaw supporting a second electrode, the second jaw being movable toward and away from the first jaw to clamp the plant organ therebetween.

[0026] According to still further features, the device further includes a display or a wireless transmitter configured to output the measured electrical impedance or a plant status derived therefrom.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various embodiments are herein described, by way of example only, with reference to the accompanying drawings, wherein:

[0029] FIGS. 1A-1D are various views of a detection device according to an example embodiment of the present invention;

[0030] FIG. 2 is a pictorial illustration of an example embodiment of a handheld device 200 of the instant invention;

[0031] FIG. 3 is a pictorial illustration of automated vehicle 300 with a robotic arm 310 (mobile robot) with the present sensing mechanism 100 attached to the distal end of the arm;

[0032] FIG. 4 is a flow diagram 400 for a method for detecting disease in a plant;

[0033] FIG. 5(a) is an image of the contact pads formed on a tomato leaf and the equivalent measurement circuit of two-points I-V measurement;

[0034] FIG. 5(b) a graph indicating the resistance obtained for two-points, four-points, and impedance measurements on healthy plants;

[0035] FIGS. 6(a)-6(d) are graphs illustrating I-V curves of four specimens of healthy tomato plants;

[0036] FIGS. 7(a)-7(d) are graphs illustrating I-V curves of four specimens of unhealthy tomato plants; FIG. 8 illustrates an average electrical resistance of (a) healthy and (b) infected tomato plants during the first two days (light bars) and days 3-6 (dark bars). The error bars represent the standard deviation of the averaged resistance.

[0037] DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The principles and operation of a manual / robotic device that can detect diseases and abiotic stresses in plants according to the present invention may be better understood with reference to the drawings and accompanying description.

[0039] There is disclosed herein a new technology for detection of diseases and abiotic stresses in plants through physical contact with the leaf. The instantly disclosed systems, devices, and methods employ a specialized mechanical mechanism detailed hereafter. Inter alia, there is a mechanism employed for leaf grasping while applying uniform pressure on the leaf and / or puncturing it with one or more micro-electrodes. Further, there is a mechanical mechanism for safely releasing the leaf, as well as an electrical properties-sensing unit for detecting electrical properties of the leaf / plant. The test is non-destructive is so much as it does not adversely affect the health of the plant or leaf. The electrical properties sensed by the electrical properties sensing unit are processed to determine the health state of the plant.

[0040] In one non-limiting example embodiment, it has been proven that ToBRFV-infected tomato plants undergo changes in their electrical characteristics. Approximately three days postinfection, the infected plants demonstrate changes in the I-V curve (I and V are the current and voltage, respectively) and a significant reduction of their electrical conductivity. This phenomenon is not specific to tomato plants or ToBRFV disease but rather occurs in all plant life (vegetable plants, fruit trees, etc.) as a result of contracting any type of disease, be it viral, bacterial, and / or fungal.

[0041] Accordingly, there is natural phenomena whereby infection causes changes in the electrical properties of plants a relatively long period before the same plants begin to display visual symptoms of the infection. Therefore, the instant detection method and system is able to detect infections in plant life much earlier legacy detection methods that rely mainly on visual inspections looking for visible symptoms.

[0042] Early detection reduces the primary infection source, minimizes the secondary spread of the virus, improves yield quality, and minimizes economic losses. The present invention tests the electrical properties of a leaf of a plant and is able to determine, within three days of infection, if the plant has been infected. This capability outperforms all the known methods of disease detection in plants to date.

[0043] When a plant contracts a disease, be it bacterial, viral, or fungal, the bio-chemical makeup of the plant begins to change. On the molecular level, materials are moving inside the plant and within plant organs to cope with the disease, for example, by shutting off "areas" and so on. These changes, and possibly other types of changes, cause changes in the electric properties of the plant. The “electrical profile” of the plant changes as the plant changes from healthy to diseased. These changes can be detected using electrical sensors, as will be detailed hereafter.

[0044] Referring now to the Figures, Figures 1A, IB, 1C, and ID provide various views of a detection device according to an example embodiment of the present invention. Fig. 1A is an isometric front view of a device 100. Fig. IB is a side view of the device 100. Fig. 1C is a front view of device 1C. Fig. ID is an exploded view of detection device 100. Detection device 100 is an example embodiment of the invention. The device is part of a detection system that can be employed to effect a method of sampling plants in order to detect, at a relatively early stage, a developing infection. It is made clear that the detection method can be carried out with variations of the example embodiment depicted in the figures. In embodiments, the detection device is a device for measuring electrical impedance or resistance of a plant organ.

[0045] The example device depicted in the Figures 1A-1D can be modified or adapted to be a handheld device (see Fig. 2) or a robot-mounted device (see Fig. 3).

[0046] Eooking at Fig. ID, the following components are listed according to their reference numbers: 1 - A motor adapter.

[0047] 2 - A motor (e.g., high torque hybrid stepping motor SY28STH32-0674A by Pololu Robotics and Electronics, Las Vegas, Nevada).

[0048] 3 - A top bearing.

[0049] 4 - A leadscrew. The leadscrew (or lead screw) is a threaded that converts the rotary motion of the motor 2 into precise linear motion.

[0050] 5 - A frame.

[0051] 6 - A base of the top section.

[0052] 7 - A top assembly.

[0053] 8 - A coupling. Coupling 8 is a mechanical device that connects two shafts to transmit power (torque and rotation) from a drive to a driven component. In the example embodiment, coupling 8 connects motor 2 to leadscrew 4.

[0054] 9 - A microswitch button.

[0055] 10 - A holder for the electrodes.

[0056] 11 - A shelf dividing between the top section and the bottom section.

[0057] 12 - A microcontroller frame.

[0058] 13 - Electrodes.

[0059] 14 - A controller board.

[0060] 15 - A microcontroller board (e.g., a single-board microcontroller from Arduino®).

[0061] 16 - A cover for the bottom section. In Figs. 1A-1C the cover has been removed.

[0062] 17 - A bottom bearing.

[0063] The detection device includes a top section and a bottom section. These sections are delineated by the shelf component 11. The frame of the device is rigid and fixed. The motor 2 is fixed into the bottom section by the motor adaptor 1. The leadscrew 4 is coupled to the motor 2 via the coupling 8. In the top section of the device, the top assembly 7 is threadedly mounted on the leadscrew 4. The top end of the leadscrew 4 is slotted inside the top bearing 3 which is attached to the top of the frame 5 via four screws. The lead screw rotates freely inside the bearing. When the motor rotates, the top assembly rides up or down the leadscrew, where a portion of the top assembly is in the top section and a portion of the assembly is in the bottom section. The linear movement of the top assembly defines a clamping motion, which, in this case, is the linear translation of a movable clamping element (top assembly 7) towards and away from a fixed clamping element (the base 6).

[0064] Said another way, the clamping mechanism includes an adjustable jaw threadedly engaged with a screw rotatably engaged with a motor, where rotation of the screw causes linear movement of the adjustable jaw.

[0065] The top assembly is seated in the base 6 of the top section. The holder 10 for the electrodes is also seated in the base 6. The top assembly moves up and down on the screw 4. When the assembly comes down, the leaf is clamped between the inner surface of an upper ledge 18 of the top assembly 7 and the holder 10 for the electrodes and the base. The electrodes 13 are disposed inside the holder and are in electrical communication with each other and with the processor. They also draw energy from a power source. In some embodiments the power source is the same power source that powers the motor. In other embodiments, a separate power source powers each component.

[0066] In the example embodiment, there are four electrodes disposed in the holder 10. The number of electrodes (four) is merely an example number of electrodes, and more or less could be used.

[0067] In some example embodiments, the plant organ, e.g., a leaf, is clamped / pressed onto electrodes by a clamping mechanism mechanically coupled to the plurality of electrodes, where the clamping mechanism is configured to releasably secure the device to a plant organ such that at least one of the plurality of electrodes, and preferably all of the electrodes, is / are in electrical contact with a surface of the plant organ. In some cases, the device is capable of successfully measuring electrical activity by pressing electrodes to the leaf. It appears that the measurement of electrical properties is very dependent on the degree of pressure on the leaf surface, which needs to be carefully calibrated due to different leaf thicknesses, leaf stiffness, etc., to prevent inconsistent results. In such embodiments, the electrodes would be flat or - if they protrude above the surface of the holder - they would be rounded and not needle-like.

[0068] In other embodiments, four micro-electrodes are used to pierce the leaf. This method shows increased consistency / stability in receiving measurements of the electrical properties. The microelectrodes are very thin, needle-like, about 100 microns or less in diameter and do not cause damage to the leaf, merely temporary micro-penetration. These measurement methods and mechanisms are considered non-destructive, in as much as they do not materially affect plant health.

[0069] The electrodes pass an electrical signal through the leaf and monitor conductivity etc. A processor (e.g., a microcontroller board 15 coupled to a controller board 14) in electrical communication with the plurality of electrodes, the processor configured to apply an electrical signal between at least two of the plurality of electrodes and measure an electrical impedance or resistance of the plant organ based on a response to the applied electrical signal

[0070] According to some embodiments, two electrodes touch the leaf, one positive and one negative. In other embodiments, such as in the example device, four electrodes, i.e., 1 negative and 3 positive electrodes. Each positive electrode is activated individually to check different places on the leaf. The mapping of the resistance in different parts of the leaf can teach different things about the disease.

[0071] In some embodiments, the electrical signal is an alternating current or voltage signal, and the processor is configured to perform electrical impedance spectroscopy over a range of frequencies. In some embodiments, having a slightly different configuration, the clamping mechanism includes a first jaw supporting a first electrode (at least) and a second jaw supporting a second electrode (at least). Like in the depicted configuration, the second jaw is movable toward and away from the first jaw to clamp the plant organ therebetween.

[0072] Referring back to the embodiments whereby the electrodes have a needle-like form factor that is adapted to penetrate the plant organ, it will be appreciated that even when the mobile clamping element (i.e., the top assembly) moves away from the fixed element, the leaf / plant organ would still remain attached to the needle-like electrodes. To solve this issue, a pushing element is needed to push the leaf off the electrodes in order to release the leaf.

[0073] The top assembly includes two J-shaped pieces that extend out of a distal section of the upper ledge. The J-shaped pieces each have a longer leg on one side of the J and a shorter leg on the other side of the J. The pieces are each attached by their longer legs to the upper ledge and the tops of the shorter legs are connected to each other, forming a push bar 19. When the top assembly moves upwards to the roof of the device, the push bar comes up through the opening in the electrode holder 10. If a leaf or other plant organ is stuck on the electrodes, the push bar pushes the leaf off the electrodes, thereby releasing the leaf.

[0074] The bottom section is generally enclosed by the cover 16. Cover 16 has two slots formed in the front face of the cover. When the top assembly moves, the J-shaped legs move in and out of the slots.

[0075] In other example embodiments, the clamping mechanism includes a movable clamping member slidably mounted on a frame for linear sliding movement toward and away from the fixed clamping member.

[0076] In example embodiments, the clamping mechanism includes a clamping element mounted for reciprocating linear movement within the clamping mechanism.

[0077] Figure 2 is a pictorial illustration of an example embodiment of a handheld device 200 of the instant invention. Device 200 is a variation of the detection device 100, depicted in Figs. 1A- ID has been adapted with a handle for manual portable use. An activation button has been installed on the handle for ease of actuation.

[0078] Figure 3 is a pictorial illustration of automated vehicle 300 with a robotic arm 310 (mobile robot) with the present sensing mechanism 100 attached to the distal end of the arm. The vehicle may be remotely controlled or self-driving. The self-driving embodiment, as well as remote controlled embodiments where the device is not controlled under line-of-sight directions, the robotic arm and / or the vehicle include sensors (imaging, proximity, etc.) for navigation of the vehicle and remote control of the robotic arm. In other embodiments, the vehicle may be controlled by a wired or wireless controller.

[0079] In example embodiments, the device(s) includes a display or a wireless transmitter configured to output the measured electrical impedance / resistance or a plant status derived therefrom. The data may be collected in the device itself and / or stored in a central computer which includes a program for cataloging the readings from identified plants and maintaining a log of electrical data per plant. The software is tasked with comparing the presently attained sensor data with the historical data.

[0080] The process for monitoring and detecting disease in a plant includes a number of steps using the aforementioned detection device or variations thereof, where the electrical sensor data is obtained as described above.

[0081] Figure 4 depicts a flow diagram 400. The flow diagram outlines the steps for a method for detecting disease in a plant. In step 410, a baseline electrical impedance or resistance measurement of a plant organ is obtained by applying an electrical signal via a plurality of electrodes in contact with the plant organ and measuring a response to the applied electrical signal. In some example embodiments, the electrical signal is an alternating signal applied over a range of frequencies, and each electrical impedance measurement comprises an impedance spectrum. In some example embodiments, the electrical signal is a direct current charge. In some example embodiments, the plurality of electrodes are coupled to the plant organ via a clamping mechanism. In step 420, one or more subsequent electrical impedance or resistance measurements of the plant organ or another plant organ of the plant is obtained. Each subsequent measurement is obtained after a time interval from a previous measurement. In some embodiments, a plurality of subsequent measurements are taken at regular time intervals. These time intervals may be approximately a day. Alternatively, the time intervals may be between half a day and a day and a half. In some cases, the intervals may be longer and in other cases they may be shorter.

[0082] In step 430, the one or more subsequent electrical impedance or resistance measurements are compared with the baseline electrical impedance or resistance measurement to detect a deviation indicative of a developing disease in the plant. In example embodiments, the deviation may be a change in impedance magnitude or phase exceeding a predetermined threshold.

[0083] In step 440, an alert is generated in response to detecting the deviation indicative of the developing disease. In example embodiments, the disease is a biotic disease caused by a pathogen. In example embodiments, the disease is a virus, a bacteria, and / or a fungus.

[0084] While the instant detection device is often described as sampling a plant leaf, it is made clear that any plant organ, not only leaves, can be used to obtain an electrical profile of the plant. As such, it is to be understood that every mention of a leaf equally or similarly, mutatis mutandis, applies to any applicable plant organ. The term plant organ includes, but is not limited to, roots, stems, leaves, flowers, and fruits. An organ is defined as a structure made of different tissues that are joined and organized to perform a specific function. A leaf contains dermal, ground, and vascular tissues arranged to carry out photosynthesis, gas exchange, and transport, so it fits this definition of an organ. Any element of plant life that fits the definition of plant organ is included in the scope of the term. In fact, many biology texts explicitly state that the leaf is a plant organ, along with the root, stem, flower, and fruit.

[0085] It is noted that by applying a DC signal or measuring only the resistive component, then one is measuring resistance. Applying an AC signal (usually at various frequencies) and analyzing both magnitude and phase (or real and imaginary parts), one is measuring electrical impedance. Many plant disease detection studies use impedance because tissue capacitance (from cell membranes) changes with disease, providing richer diagnostic information than resistance alone. However, the present device, system and method are directed at early detection of disease (e.g., in order to take appropriate action to quarantine the infected plants and prevent spread of the disease and / or to allow early intervention to save or destroy the infected plants), as such, it is the comparative change relative to prior readings that is an important factor in the instant system, device, and method.

[0086] Background and Experimental Support

[0087] Case study - S. K. Reddy et al., "Early Sensing of Tomato Brown Rugose Fruit Virus in Tomato Plants via Electrical Measurements," in IEEE Sensors Leters, vol. 6, no. 5, pp. 1-4, May 2022, Art no. 1500304, doi: 10.1109 / LSENS.2022.3161595.

[0088] An experiment consisting of two treatments was conducted in tomato plants cv. Ikram. In the first treatment, four tomato plants were infected by ToBRFV. The second treatment (the control) consists of four healthy tomato plants. Tomato plant cv. Ikram, infected with ToBRFV, served for the sap-mechanical inoculation of the virus. It is made clear that the discussion regarding tomato plants is merely an example or a fruit or vegetable plant / tree and is not intended to be limiting in any way. Similarly, the discussion of ToBRFV is merely an example disease and not intended to be limiting in any way.

[0089] Fig. 5(a) illustrates an image of the contact pads formed on a tomato leaf and the equivalent measurement circuit of two-points I-V measurement. Fig. 5(b) illustrates a graph indicating the resistance obtained for two-points, four-points, and impedance measurements on healthy plants. Inset: image of the four-points contact pads.

[0090] In the experiment, selected leaves were grounded in 10 mM phosphate buffer pH = 7.0. The extract was rubbed on leaves of tested tomato plants. The plants of both treatments were at the same age and watered every day at the same time with the same amount of water. The researchers first formed electrical contact pads that enabled interfacing with the leaves. The researchers applied a thin layer of adhesive silver paste to which they also connected metallic wires. Removing the contacts is prone to harm the leaves, thus these contact pads are stationary, and were not peeled off during the experiments. The measured electrical resistance strongly depends on the distance between the contact pads (length of the electrical path) and their area. Consequently, by maintaining stationary contact pads, the researchers ensured that the distance and the contact area remained constant during all days of measurements and that the changes measured in the resistance were attributed to changes that occur in the plants. The researchers used a high precision source measurement unit (SMU, Keysight B2900A) to apply a controlled voltage while measuring the corresponding electrical current, thereby acquiring the I-V curves (I and V are the current and voltage, respectively) of the leaves. The I-V measurements were conducted automatically using the SMU instrument software. The researchers applied a bias voltage of -6 V and increased the voltage by steps of about 0.11 V, until reaching +6 V (overall, 110 I-V data points were acquired in a few seconds of acquisition time). The applied voltages induced low currents, in the order of several micro- Amperes, which were harmless to the leaves.

[0091] The I-V tests were conducted on all plants every day at the same time during the day, for six days from infection of the plants in the first treatment. The researchers acquired the I-V curves by means of two-points measurements.

[0092] Four-points measurements were compared to two-points measurements conducted on a leaf and found that the resistance of the four-points measurements was lower. Also, the researchers compared their resistance measurement to that obtained in impedance measurement and found that the latter was similar to the two-point measurement. Nevertheless, it was shown that since the electric resistance of the leaf tissue is relatively large, the resistance changes due to the ToBRFV can be easily observed using two-points measurements. In addition, two-point measurements are preferred since two contact pads (in contrast to four) minimize the exposure of the leaves to adhesive materials. Importantly, it was noted that the two-points measurement scheme was much simpler than the four-points I-V scheme and impedance measurements.

[0093] Results and discussion

[0094] The researchers showed the I-V curves of the healthy (uninfected) and infected tomato plants in Figs. 6a-d and 7a-d, respectively. Figs. 6(a)-(d) illustrate I-V curves of four specimens of healthy tomato plants (where each figure is a different plant). Insets illustrate the electrical resistance. Figs. 7(a)-(d) illustrate I-V curves of four ToBRFV infected tomato plants (each figure is a different plant). Insets illustrate electrical resistance calculated for voltages above 2 V. The arrows emphasize the reduction of the conductance after day 2.

[0095] The measured I-V curves are not always antisymmetric with respect to the zero-voltage axis. The researchers attribute this electrical behavior to energetic barriers and small charge accumulation that might exist in the electrical contacts. The researchers extracted the resistance of the leaves from the inverse of the linearized slopes of the I-V curves, see insets of Figs. 6 and 7. Notably, in most cases, the resistances of the healthy plants were roughly constant along the whole range of the applied voltages (i.e., between -6 and +6 V), while the infected leaves demonstrated I-V curves that in most cases somewhat deviated from linear behavior. Thus, the researchers showed their resistance for voltages above 2 V, as in this range they exhibited behavior that is closer to linear, see insets of Fig. 7. Also, they noted that the distance between the electrical pads in their experiments [Fig. 5(a)] was larger than that used for the comparison shown in Fig. 5(b). As a result, the resistance values shown are relatively large (in the mega-ohm range).

[0096] The researchers pointed out several significant differences between the electrical measurements of the healthy and infected plants. First, healthy plants demonstrated rather stable and similar electrical behavior during all days of measurements. Namely, they showed similar I- V measurements, which are indicated by the semi-transparent boxes in Fig. 6. Accordingly, the healthy plants also showed similar electrical resistances during all measurement days, as presented by the insets in Fig. 6. In contrast, infected plants show a significant reduction of their conductivity, as demonstrated in the insets in Fig. 7. The resistance measured in the first two days was significantly smaller than that of the following days. The resistance in the first two days was of similar magnitude to that measured in the healthy plants, namely, between 1 and 2 MQ. However, after two days of measurement, the resistance increased significantly and most infected plants demonstrated resistances that sometimes exceeded 10 MQ. Notably, the I-V curves of the infected plants were also stabilized after the second day, as indicated by the semi-transparent boxes in Fig. 7. The R2 values of the linear fits applied to the I-V measurements show good fit as most healthy plants show R2 values higher than 0.97, while most infected plants show R2 values higher than 0.80 for V > 2 V (Table of values not shown). These R2 values indicate a good linear fit that implies that the differences between the healthy and infected plants measurements originated from their different physical behavior and cannot be associated with statistical differences.

[0097] Fig. 8 illustrates an average electrical resistance of (a) healthy and (b) infected tomato plants during the first two days (light bars) and days 3-6 (dark bars). The error bars represent the standard deviation of the averaged resistance. The relative resistance changes are indicated in the graphs.

[0098] The researchers showed the evolution of the plant’s resistance in Fig. 8, where the averaged resistance of the plants during the first two days (light bars) and days 3-6 (dark bars) for healthy and infected plants is displayed. While the resistance of the healthy plants remained stable, the infected plants showed an increase in resistance of hundreds of percent.

[0099] Accordingly, the average resistance of all plants (healthy and infected) is ~ 1 MQ during the first two days of the experiments. However, the healthy plants exhibited a similar magnitude of resistance during days 3-6, while the resistance of the infected plants considerably increased, in some cases, up to ~ 10 MQ or more. It is made clear that the voltages, resistances, microamp currents etc. mentioned herein are merely examples and not intended to be limiting.

[0100] Implementation of the method and / or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and / or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

[0101] For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of method and / or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data and / or a non-volatile storage, for example, non-transitory storage media such as a magnetic hard-disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is provided as well. A display and / or a user input device such as a keyboard or mouse are optionally provided as well.

[0102] For example, any combination of one or more non-transitory computer readable (storage) medium(s) may be utilized in accordance with the above-listed embodiments of the present invention. A non-transitory computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non- exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable non- transitory storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electromagnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0103] As will be understood with reference to the paragraphs and the referenced drawings, provided above, various embodiments of computer-implemented methods are provided herein, some of which can be performed by various embodiments of apparatuses and systems described herein and some of which can be performed according to instructions stored in non-transitory computer-readable storage media described herein. Still, some embodiments of computer- implemented methods provided herein can be performed by other apparatuses or systems and can be performed according to instructions stored in computer-readable storage media other than that described herein, as will become apparent to those having skill in the art with reference to the embodiments described herein. Any reference to systems and computer-readable storage media with respect to the following computer-implemented methods is provided for explanatory purposes and is not intended to limit any of such systems and any of such non-transitory computer-readable storage media with regard to embodiments of computer-implemented methods described above. Likewise, any reference to the following computer-implemented methods with respect to systems and computer-readable storage media is provided for explanatory purposes and is not intended to limit any of such computer-implemented methods disclosed herein.

[0104] The flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustration, and combinations of blocks in the block diagrams and / or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0105] The descriptions of the various embodiments of the present invention have been presented for purposes of illustration but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

[0106] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

[0107] The word “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0108] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub- combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0109] The above-described processes including portions thereof can be performed by software, hardware and combinations thereof. These processes and portions thereof can be performed by computers, computer-type devices, workstations, processors, micro-processors, other electronic searching tools and memory and other non-transitory storage-type devices associated therewith. The processes and portions thereof can also be embodied in programmable non-transitory storage media, for example, compact discs (CDs) or other discs including magnetic, optical, etc., readable by a machine or the like, or other computer usable storage media, including magnetic, optical, or semiconductor storage, or other source of electronic signals.

[0110] The processes (methods) and systems, including components thereof, herein have been described with exemplary reference to specific hardware and software. The processes (methods) have been described as exemplary, whereby specific steps and their order can be omitted and / or changed by persons of ordinary skill in the art to reduce these embodiments to practice without undue experimentation. The processes (methods) and systems have been described in a manner sufficient to enable persons of ordinary skill in the art to readily adapt other hardware and software as may be needed to reduce any of the embodiments to practice without undue experimentation and using conventional techniques.

[0111] While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. Therefore, the claimed invention as recited in the claims that follow is not limited to the embodiments described herein.

Claims

WHAT IS CLAIMED IS1. A method for detecting disease in a plant, the method comprising: obtaining a baseline electrical impedance or resistance measurement of a plant organ by applying an electrical signal via a plurality of electrodes in contact with the plant organ and measuring a response to the applied electrical signal; obtaining one or more subsequent electrical impedance or resistance measurements of the plant organ or another plant organ of the plant, each subsequent measurement obtained after a time interval from a previous measurement; comparing the one or more subsequent electrical impedance or resistance measurements with the baseline electrical impedance or resistance measurement to detect a deviation indicative of a developing disease in the plant; and generating an alert in response to detecting the deviation indicative of the developing disease.

2. The method of claim 1, wherein the electrical signal is an alternating signal applied over a range of frequencies, and each electrical impedance measurement comprises an impedance spectrum.

3. The method of claim 1, wherein the plurality of electrodes are coupled to the plant organ via a clamping mechanism.

4. The method of claim 1, wherein obtaining the one or more subsequent electrical impedance measurements comprises obtaining a plurality of subsequent measurements at regular time intervals.

5. The method of claim 1, wherein the deviation comprises a change in impedance magnitude or phase exceeding a predetermined threshold.

6. The method of claim 1 , wherein the disease is a biotic disease caused by a pathogen.

7. The method of claim 1, wherein the predefined interval is at least one day.

8. The method of claim 1, wherein the predefined interval is between half a day and a day and a half.

9. A device for measuring electrical impedance or resistance of a plant organ, the device comprising: a plurality of electrodes; a clamping mechanism mechanically coupled to the plurality of electrodes, wherein the clamping mechanism is configured to releasably secure the device to a plant organ such that at least one of the plurality of electrodes is in electrical contact with a surface of the plant organ or penetrates the plant organ; and a processor in electrical communication with the plurality of electrodes, the processor configured to apply an electrical signal between at least two of the plurality of electrodes and measure an electrical impedance or resistance of the plant organ based on a response to the applied electrical signal.

10. The device of claim 9, wherein the clamping mechanism includes a movable clamping member slidably mounted on a frame for linear sliding movement toward and away from said fixed clamping member.

11. The device of claim 9, wherein the clamping mechanism includes a clamping element mounted for reciprocating linear movement within said clamping mechanism.

12. The device of claim 9, wherein the clamping mechanism includes an adjustable jaw threadedly engaged with a screw rotatably engaged with a motor, where rotation of the screw causes linear movement of the adjustable jaw.

13. The device of claim 9, wherein the electrical signal is an alternating current or voltage signal, and the processor is configured to perform electrical impedance spectroscopy over a range of frequencies.

14. The device of claim 9, wherein at least one of the plurality of electrodes has a needle-like form factor configured to penetrate the plant organ.

15. The device of claim 9, wherein the clamping mechanism comprises a first jaw supporting a first electrode and a second jaw supporting a second electrode, the second jaw being movable toward and away from the first jaw to clamp the plant organ therebetween.

16. The device of claim 9, further comprising a display or a wireless transmitter configured to output the measured electrical impedance or a plant status derived therefrom.

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