JP2007195405A - Method and apparatus for treating plant disease - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for treating plant disease each free from possibility of environmental problems and killing pathogenic bacteria of a plant body while suppressing to the minimum damage of a plant body healthy area. <P>SOLUTION: This method for treating the plant disease comprises applying direct current high voltage to an electrode 7 and a plant body 1 and charging static electricity to the electrode 7 and/or the plant body 1 so as to generate corona discharge between the electrode 7 and the plant body 1 and kill plant cause bacteria sticking to or occurring on the plant body 1. The method for killing the plant cause bacteria based on charged voltage comprises setting a distance between the electrode 7 and the plant body 1 in a range so as not to wither a plant body 1 area which corona discharge reaches. The apparatus for treating the plant disease is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for treating plant diseases by killing mycelia, spores and / or spore handles present at a disease-infected site of a plant by corona discharge.

Plant pathogens (mainly molds) are transmitted from various parts such as leaves, stems, fruits and roots of plants. Many phytopathogenic fungi form next-generation spores on the above-ground surface of plants such as leaves and stems, and propagate to surrounding plants through wind, moisture, rain, and the like.
In the cultivation of agricultural and horticultural plants, many fungicides are used for the purpose of preventing the occurrence of plant diseases. However, due to the fact that phytopathogenic bacteria acquire drug resistance in a relatively short period of time and the types of drugs that can be used are limited depending on the plant, plant diseases of agricultural and horticultural plants in general can be reduced by using only drugs. It is difficult to control completely.

Commercially available germicides derived from chemically synthesized products include benzimidazole fungicides such as thiophanate methyl agents, acid amide fungicides such as mepronil agents, sterol synthesis inhibitors such as triflumizole agents, azoxystrobin agents There are methoxy acrylate fungicides such as All of these fungicides have a problem of the appearance of resistant bacteria, which is one of the causes for increasing the number of spraying of agricultural chemicals.
Examples of commercially available fungicides derived from natural products include acetic acid, sulfur agents, machine oil agents, and rapeseed oil agents. None of these agents induces resistance against phytopathogenic fungi, but their efficacy is low compared to fungicides derived from chemically synthesized products, and there are many cases in which phytotoxicity is a problem because they need to be sprayed at a high concentration .

  The application of the fungicide to the agricultural and horticultural plant is performed not only on the plant infected with the phytopathogenic fungus and the disease-infected site but also on the entire field. Therefore, there is a high possibility that the drug will be transferred to plants and soil other than the agricultural and horticultural plants to be applied, nearby agricultural water, rivers, and the like.

On the other hand, in the industrial field, in order to kill microorganisms such as bacteria and molds generated on the surface of an article without using a bactericidal agent, a bactericidal apparatus using pulse discharge has been proposed (for example, patent document). 1). In addition, a small-sized discharge device has also been proposed in order to enable sterilization treatment even for articles that cannot be moved (see, for example, Patent Document 2).
JP 63-318947 A Japanese Patent Laid-Open No. 11-047240

  However, both of the devices described in Patent Document 1 and Patent Document 2 are intended to kill microorganisms present on the surface of an article, and Patent Document 1 includes a gap between electrodes. It is described that a high voltage in the form of a pulse is applied to sterilize an object to be processed, and Patent Document 2 discloses that an AC voltage is applied to a discharge line covered with a dielectric material to form a coated discharge line. It is described that the sterilization is carried out by contact or sliding movement. If such a pulsed high voltage or AC voltage applied device is applied to a diseased plant body, the voltage and current will fluctuate greatly and the discharge will be unstable. There is a risk that not only the microorganisms at the site of disease infection but also the plant body itself in that part may be seriously damaged to cause the plant body in that part to die, and the whole plant body may be killed.

  Furthermore, since the devices described in Patent Document 1 and Patent Document 2 do not have a mechanism for limiting the range covered by corona discharge, the range covered by corona discharge spreads over a wide range. When applied to a plant that has developed, there is a risk that corona discharge will occur not only at the site of disease infection but also around it, causing significant damage to the area where the discharge of the plant has been caused and causing the region to die. Yes, there is a risk of killing the entire plant.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, a method for treating plant diseases that kills pathogenic bacteria in plants while minimizing damage to healthy areas of plants without fear of environmental problems and It is to provide a therapeutic device.

  In order to solve the above object, one embodiment of the method for treating plant diseases of the present invention is to apply a high direct current voltage to the electrode and the plant body, so that the electrode and / or the plant body is applied. By charging static electricity, a corona discharge is generated between the electrode and the plant body, and a phytopathogenic fungus attached to or generated on the plant body is killed.

  Here, the “phytopathogenic fungus attached to or generated in the plant body” may be a spore of a phytopathogenic fungus attached to the plant body or a mycelium, spore and / or spore pattern of the phytopathogenic fungus generated in the plant body. In other words, in this treatment method, not only treatment of plant diseases that have already occurred, but also treatment of prevention of plant diseases that may cause disease in the future can be taken.

As the material of the “electrode”, any material can be used as long as it is a conductor that can be charged or charged with a high voltage. For example, copper, aluminum, stainless steel, iron, tungsten, and the like are conceivable. Any shape can be used as long as the electrode can be discharged between the plant and the disease-infected site. For example, a flat plate shape, a cylindrical shape, a spherical shape, a linear shape, a protrusion shape, or a needle shape can be used. A shape having a sharp portion such as a shape is conceivable. However, considering the discharge efficiency, the shape of the discharge portion of the electrode is preferably linear or sharp, and more preferably has a plurality of fine lines or sharp portions.
The “high voltage” means a voltage at which corona discharge occurs between the electrode and the plant body. When the voltage is too high, the plant may be damaged by spark discharge or the like. For example, 1 to 100 kV can be considered, 5 to 80 kV is preferable, and 10 to 50 kV is more preferable. For high voltage, the voltage value can always be set to a constant value, or the voltage value can be changed according to the situation. It is also conceivable to change the voltage value to an optimum value during treatment.

  In this embodiment, either the electrode or the plant body is charged with high-voltage static electricity, or the electrode and the plant body are charged with static electricity so that a high potential difference occurs between them (for example, of different polarity). Causes corona discharge. More specifically, for example, using a high-voltage electricity generator, it is conceivable to charge a negative high voltage to the plant body and ground the electrode or connect it to the anode of the high-voltage electricity generator. Similarly, it is conceivable to use a high voltage electricity generator to charge a negative high voltage to the electrode and ground the plant body or connect it to the anode of the high voltage electricity generator. When the plant body is negatively charged, a cathode corona is generated in the plant body, and when the electrode is negatively charged, an anode corona is generated in the plant body.

  As described above, the polarity when the electrode or the plant body is charged can be selected according to the application, installation method, location, and the like. It is not preferable to apply an alternating voltage or a pulsed voltage because the stability of the discharge is lacking, and the area where the discharge of the plant body is killed, which may cause the whole plant body to die. In addition, as conditions for causing corona discharge and spark discharge, the shape of what causes the discharge, the magnitude of the voltage applied between those causing the discharge, and the distance between those causing the discharge are important factors.

  In this embodiment, the mycelium is a filamentous cell line constituting a nutrient body of a fungus, and the spore is for infecting an agricultural or horticultural plant with a disease, and is an exogenous spore (conidia) or spore sac. (Including endospores), dural spores and the like. The spore pattern is an organ that produces spores. As a treatment target of this embodiment, for example, powdery mildew, mycorrhizal disease, gray mold disease and the like can be considered.

  In this embodiment, the mycelium, spore and / or spore pattern of a phytopathogenic fungus generated in a plant can be effectively killed while suppressing damage to a healthy region of the plant. That is, the occurrence of disease can be apparently prevented by minimizing damage to the plant body, and further early treatment is possible. Moreover, the expansion of the infected part can also be suppressed.

  In another embodiment of the method for treating plant diseases according to the present invention, the distance between the electrode and the plant body is such that the phytopathogenic fungus is killed based on a voltage applied to the electrode and the plant body. However, it is characterized in that it is determined in such a range that the area of the plant body to which the corona discharge is applied does not die.

Here, the “distance between the electrode and the plant” refers to the discharge part of the electrode that generates discharge, for example, the tip of the electrode having a needle shape, and the surface of the plant that generates discharge, For example, it means the distance between the leaf surface and the surface of a cylindrical stem.
The conditions that cause corona discharge and spark discharge are important factors such as the shape of the discharge, the magnitude of the voltage applied between the discharge and the distance between the discharge. If a certain voltage is applied to the electrode and the plant using an electrode having a certain shape, a certain distance is reached when the distance between the electrode and the plant is reduced from the remote position. By the way, the discharge is started, and as the distance is further shortened, the discharge shifts to a discharge having higher energy, and finally the spark discharge is started. Here, it is considered that corona discharge is generated in a region from when discharge is started to when spark discharge is started. In the area where the corona discharge is generated, the discharge having a relatively small energy with a distance between the electrode and the plant body does not have an effect of killing the pathogen of the plant. In addition, by reducing the distance between the electrode and the plant body and shifting to a discharge with higher energy, damage to the area affected by the corona discharge of the plant body is minimized and the area is prevented from dying. However, it has the effect of killing pathogenic bacteria. When the distance between the electrode and the plant body is further reduced, spark discharge finally occurs, and the area of the plant body that is affected by corona discharge is greatly damaged and killed.

  In this embodiment, when an electrode having a predetermined shape is used, the phytopathogenic fungi are killed in accordance with the applied voltage, but the optimal range is such that the area to which the corona discharge of the plant body does not die. By determining the distance between the electrode and the plant body, pathogenic bacteria can be effectively killed while minimizing damage to the plant body.

  In another embodiment of the method for treating plant diseases of the present invention, the electrode is accommodated in a shielding member made of a non-conductor having an opening, and a corona is interposed between the electrode and the plant body via the opening. It is characterized by causing discharge.

  Here, as the “non-conductor”, any material that does not conduct electricity, that is, an insulator, can be used. For example, acrylic, vinyl chloride, polyethylene, polypropylene, urethane, polyester, Rayon, cellulose, rubber, etc. are conceivable.

The “shielding member having an opening” means a member having a hollow region that can surround the electrode and has an opening in part. Through this opening, corona discharge can be generated between the electrode surrounded by the shielding member and the plant body outside the shielding member. As the shape of the shielding member, for example, a cylindrical or columnar member with an open end, a spherical or box-shaped member with an opening provided in part, and the like are conceivable.
The electrode is “accommodated inside the shielding member” means that the electrode is surrounded by the shielding member except for the opening, and at least a part of the electrode is in contact with the shielding member And the case where the electrode and the shielding member are not in contact with each other is also included.

  Corona discharge generated from the electrodes (including both the anode and cathode corona) does not pass through the shielding member, but reaches the plant existing outside the shielding member through the opening provided in the shielding member. Therefore, since corona discharge is applied only to the region corresponding to the shape of the opening of the plant body, the mycelium, spore and / or spore pattern present at the site of disease infection of the plant body is killed, but the surrounding area is Damage to healthy areas of the plant body can be minimized. In addition, since the electrode is surrounded by a non-conductive shielding member, the occurrence of an electric shock is prevented, and the path of the corona discharge is guided by the inner wall of the shielding member, so that efficient corona discharge can be performed.

  As described above, according to the present embodiment, since corona discharge can be used for a disease-infected site of a plant body, the occurrence of the disease is apparently suppressed while minimizing damage to the plant body. It can be prevented and early treatment is possible. Moreover, the expansion of the infected part can also be suppressed.

  Another embodiment of the method for treating plant diseases of the present invention is characterized in that the opening has a size and shape corresponding to a disease-infected site of the plant body.

“Size and shape corresponding to the disease-infected site” is to prevent unnecessary corona discharge from affecting healthy parts of the plant other than the disease-infected site when corona discharge is applied to the disease-infected site. This means that the opening has an appropriate size and shape according to the disease-infected site.
As described above, the method for treating plant diseases of the present invention causes a corona discharge by charging static electricity, and the distance between the electrode and the plant body causes the plant pathogen to die but the plant body is killed. By determining the optimal value that does not cause the corona discharge to die, pathogenic bacteria can be effectively killed while minimizing plant damage.

  In this embodiment, since the opening has a size and shape corresponding to the disease-infected site of the plant body, the corona discharge will reach the region corresponding to the disease-infected site of the plant body, The hyphae, spores and / or spores can be surely killed while minimizing damage to healthy areas of the plant. If the disease-infected site is wider than the opening, damage to the healthy area of the plant can be done by repeating the corona discharge while shifting the position of the opening so that the discharge does not overlap at the same location. The pathogen can be killed while minimizing

  In another embodiment of the method for treating plant diseases of the present invention, the corona discharge is a brush corona discharge.

As described above, the conditions that cause corona discharge and spark discharge are important factors such as the shape of the discharge, the magnitude of the voltage applied between the discharge, and the distance between the discharge. . When a constant voltage is applied to the electrode and the plant using an electrode having a certain shape, the discharge that occurs when the distance between the electrode and the plant is reduced from the remote position is To explain according to the general classification, when a certain distance is reached, a glow corona discharge occurs, then a brush corona discharge with higher energy occurs, and when further approached, a spark discharge finally occurs .
Among the corona discharges, the brush corona discharge has higher energy than the glow corona discharge, so that the mycelia, spores and / or phytopathogenic fungi that have occurred in the plant body can be obtained without causing the corona discharge of the plant body to die. The spores can be killed more effectively.

  One embodiment of the apparatus for treating plant diseases of the present invention includes a shielding member made of a nonconductor having an opening, an electrode accommodated in the shielding member, a predetermined high voltage applied to the electrode and the plant body. A high voltage applying means for applying a voltage, and causing corona discharge between the electrode and the plant body through the opening to kill plant pathogens attached to or generated in the plant body. And

In this embodiment, the hyphae, spores and / or spore handle present at the site of disease infection of the plant body are killed, but a small size capable of minimizing damage to other healthy areas of the plant body. A therapeutic device can be realized.
For “predetermined high voltage”, the voltage value can always be set to a constant value, or the voltage value can be changed according to the situation. It is also conceivable to change the voltage value to an appropriate value during treatment.

  Another embodiment of the plant disease treatment apparatus of the present invention is characterized by further comprising a distance changing means for changing the distance between the electrode and the plant body.

  Here, as the “distance changing means”, any means can be used as long as it can change the distance between the electrode and the plant body. For example, a mechanism for moving the position of the electrode using screws or screws can be used, or a structure in which a plurality of spacer blocks having different dimensions are prepared and the position of the electrode is moved by changing the spacer block can be used. It can also be used. In addition, a mechanism for moving the position of the electrode using an actuator such as a solenoid, a cylinder, and an electric motor can be provided. In this case, it is conceivable that a control device is provided, and an arithmetic expression based on the shape of the electrode, the applied voltage, etc. is stored in the control device and the position of the electrode is automatically changed. It is also conceivable to perform feedback control based on detection data by measuring the voltage, current, etc. between the electrode and the plant body.

  In this embodiment, by providing distance changing means for changing the distance between the electrode and the plant body, the electrode and the plant body according to the shape of the electrode, the applied voltage between the electrode and the plant body, or the like. An optimal distance between the two can be set, and stable and effective corona discharge can be realized at all times.

  Another embodiment of the plant disease treatment apparatus of the present invention is characterized by further comprising voltage changing means for changing the value of the voltage applied to the electrode and the plant body.

In this embodiment, the voltage change means can change the value of the voltage applied to the electrode and the plant body to a desired value, so according to the shape of the electrode and the distance between the electrode and the plant body, An optimum voltage between the electrode and the plant can be set, and stable and effective corona discharge can be realized at all times.
In the present embodiment, it is also conceivable to perform feedback control in which the current value is measured and the voltage value is changed so as to achieve an optimal discharge state based on the detected data.

  In the plant disease treatment method and treatment apparatus of the present invention, when spores and / or spore stalks of phytopathogenic fungi are killed by corona discharge, only the disease-infected site of the plant body can be used. The occurrence of disease can be apparently prevented by minimizing damage to the plant body, and early treatment is also possible. Moreover, the expansion of the infected part can also be suppressed. In addition, plant diseases can be treated without burdening the environment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Description of the method for treating plant diseases of the present invention)
First, an embodiment of the method for treating plant diseases of the present invention will be described. In the present embodiment, a method for treating a plant disease is described in which a high voltage is applied to an electrode and a plant body, and plant pathogens attached to or generated on the plant body are killed by corona discharge. Here, the phytopathogenic fungus attached to or generated in the plant body may be a spore of the phytopathogenic fungus attached to the plant body or a mycelium, a spore and / or a spore pattern of the phytopathogenic fungus generated in the plant body. In other words, in the present embodiment, not only treatment of plant diseases that have already occurred, but also treatment of plant diseases that may cause disease in the future can be taken.
Specifically, a positive or negative terminal of a high-voltage electricity generator, which is a part of the high voltage application means, is connected to the soil portion of the plant body or the stem portion of the plant body and charged, and the electrode is connected to the plant body. A method for treating plant diseases can be performed by charging opposite to the charging. In addition, the positive or negative terminal of the high-voltage electricity generator is connected to the electrode and charged, and the plant soil treatment or the plant stem is charged opposite to the electrode charge, thereby treating plant diseases. Can also be performed. Here, charging means positively charging a high voltage, and charging means a state in which the high voltage is induced.

  More specifically, when a high voltage electricity generator is used to charge a negative high voltage to the plant body, it is conceivable that the electrode is grounded or connected to the anode of the high voltage electricity generator. Alternatively, when a negative high voltage is charged to the electrode using a high-voltage electricity generator, the plant body may be grounded or connected to the anode of the high-voltage electricity generator. That is, when the plant body is negatively charged, a cathode corona is generated in the plant body, and when the electrode is negatively charged, an anode corona is generated in the plant body.

The polarity when charging the plant body or the electrode can be selected according to the application, installation method, location, etc., but considering the ease of setting the treatment device when actually treating, It can be said that it is preferable to ground the plant and negatively charge the electrode. Corona discharge includes glow corona discharge and brush corona discharge. Among these, it can be said that it is desirable to use brush corona discharge having higher energy, but if a too high voltage is applied, there is a risk of spark discharge. The conditions for generating corona discharge and spark discharge will be described later with reference to FIGS.
Note that applying an AC voltage or a pulsed voltage to the electrode and the plant does not cause a stable discharge as compared with the case of charging static electricity as in the present invention. The risk of damaging and dying the area is not desirable.

  Here, the mycelium in the present embodiment refers to a filamentous cell line constituting a fungal nutrient. Spores are those that infect horticultural and horticultural plants and include exogenous spores (conidia), spore sacs (including endospores), dura mater spores, and the like. The spore pattern is an organ that produces spores.

  Examples of plant diseases that are targets of the present embodiment include powdery mildew (tomato, eggplant, pepper, wheat, cucumber, melon, watermelon, beans, grape, strawberry, rose, etc.), mycorrhizal disease (tomato, eggplant) , Cucumber, watermelon, radish, Chinese cabbage, cabbage, etc.) and gray mold disease (tomato, eggplant, pepper, cucumber, pumpkin, strawberry, pea, green beans, onion, leeks, etc.), leaf mold (tomato, etc.), rust (Eg, leek, onion, leek, asparagus, lettuce, etc.).

(Description of Embodiment of Treatment Device for Plant Diseases of the Present Invention)
One embodiment of the plant disease treatment apparatus of the present invention is shown in FIG.
The treatment device 5 of the present embodiment includes a cylindrical shielding member 6 made of a non-conductor and opened at both ends, an electrode 7 covered with a case 10 except for the vicinity of the distal end portion 7, and a rear end of the electrode 7. In order to charge the plant body 1 with a negative high voltage, the distance changing means 9 for changing the distance between the connected ground wire 12, the tip 7a of the electrode 7 and the tip 6a of the shielding member 6. The high-voltage electricity generator 8 and the connection member 11 that electrically connects the high-voltage electricity generator 8 and the plant body 1 are provided. The connecting member 11 includes a cable 11b extending from the high voltage electricity generator 8 and a terminal 11a connected to the tip of the cable 11b. Moreover, the high voltage electricity generator 8, the connecting member 11, and the ground wire 12 constitute a high voltage applying unit that applies a high voltage to the electrode 7 and the plant body 1.
Moreover, the plant body 1 is planted in the resinous pot 4, and the spore pattern 2 and the spore 3 of the phytopathogenic fungus are generated in the stem part.

In the present embodiment, the shielding member 6 is made of acrylic resin and has a cylindrical shape with both ends open. In principle, treatment is performed by causing corona discharge in a state where the distal end portion 6a of the shielding member 6 is in contact with a disease-infected site of the plant body 1 (site where the spore pattern 2 and spore 3 are generated).
The electrode 7 is formed by sharpening the tip of a copper rod in a needle shape and is covered with a case 10 made of acrylic resin except for the vicinity of the tip 7a, and the electrode 7 and the case 10 are in contact with each other. The case 10 covering the electrode 7 protrudes from the opening on the rear end side of the shielding member 6 to the outside of the shielding member 6. The ground wire 12 electrically connected to the electrode 7 is grounded. A clip-like terminal 11a attached to the tip of a cable 11b extending from the high-voltage electricity generator 8 is attached to the stem portion of the plant body 1, and the high-voltage electricity generator 8 and the plant body 1 are electrically connected. . Since the high-voltage electricity generator 8 has a function of changing the set voltage value, the applied voltage between the plant body 1 and the electrode 7 can be changed to a desired value.

Since the electrode 7 is disposed substantially at the center of the case 10 and the case 10 is disposed approximately at the center of the cylindrical shielding member 6, it can be said that the electrode 7 is disposed substantially at the center of the cylindrical shielding member 6. . Further, a distance changing means 9 composed of a screw screw is provided between the outer diameter of the case 10 and the inner diameter of the cylindrical shielding member 6, and the case 10 and the cylindrical shielding member 6 are connected to each other. By rotating, the case 10 and the shielding member 6 can be relatively moved. Accordingly, the distance changing means 9 can change the distance between the needle-like tip 7a of the electrode 7 and the tip 6a of the shielding member 6 to a desired value, so that the tip 7a of the electrode 7 The distance between the plant body 1 and the disease-infected site can be accurately set to an optimum value according to the applied voltage. Usually, when corona discharge is applied to the plant body 1, the distal end portion 6 a of the shielding member 6 is used in contact with a disease-infected site of the plant body 1, and therefore, the distal end portion 7 a of the electrode 7 and the distal end portion 6 a of the shielding member 6 are used. And the distance between the tip 7a of the electrode 7 and the disease-infected site of the plant body 1 coincide.
As described above, since the applied voltage can be changed to a desired value, the distance between the tip 7a and the disease-infected site of the plant body 1 is kept constant, and an optimum voltage value corresponding to the distance is obtained. It can also be changed.

  In this treatment device 5, the shape of the tip 7 a of the electrode 7, the voltage value (minus) charged to the plant body 1, and the distance between the tip 7 a of the electrode 7 and the plant disease-infected site are appropriately set. Corona discharge can be generated. Further, the inner diameter of the shielding member 6 is sized so as to correspond to the size of the disease-infected site of the plant body 1, and in FIG. 1, the opening provided in the tip 6 a is the site of the disease-infected site. The spore pattern 2 and spore 3 are covered.

In the above setting, by performing corona discharge, it is possible to kill the spore pattern 2 and the spore 3 at the disease-infected site of the plant body 1, and the tip portion 6 a of the shielding member 6 is brought into contact with the plant body 1. Since the corona discharge does not reach other healthy areas of the plant body 1 other than the disease-infected site, the damage to the plant body 1 is minimized. be able to.
In addition, when the diseased infection site of the plant body 1 is larger than the inner diameter of the shielding member 6, the pathogen is removed while minimizing damage to the plant body 1 by shifting the position of the shielding member 6 and repeating corona discharge. Can be killed.
The optimal distance between the tip 7a of the electrode 7 and the plant disease-infected site according to the applied voltage between the electrode 7 and the plant body 1 when the needle-shaped electrode 7 is used. This will be described later with reference to FIG.

    In FIG. 1, the spore pattern 2 and the spore 3 at the site of disease infection are schematically drawn, but the distance protruding from the surface of the stem of the plant body 1 is from the tip 7 a of the electrode 7. It is extremely small compared to the distance.

(Description of other embodiments of the treatment apparatus of the present invention)
In the above embodiment, the copper electrode 7 is used. However, the present invention is not limited to this, and any conductor that can charge or charge a high voltage can be used. For example, aluminum, stainless steel, iron, tungsten, or the like can be used.
Further, in the above embodiment, the shape of the tip of the electrode is a needle shape, but any shape can be used as long as the shape generates corona discharge. For example, a flat shape, a cylindrical shape, a spherical shape, a linear shape, a shape having a sharp portion such as a protrusion shape or a needle shape can be considered. However, from the viewpoint of efficient discharge, the shape of the discharge portion of the electrode is preferably linear or sharp, and more preferably has a plurality of fine lines or sharp portions.

  In the above embodiment, the acrylic resin is used as the material of the shielding member 6 made of a non-conductor. However, the material is not limited to this, and any material can be used as long as it is an insulator. it can. For example, vinyl chloride, polyethylene, polypropylene, urethane, polyester, rayon, cellulose, rubber and the like can be considered.

In the above-described embodiment, the shielding member 6 has a cylindrical shape having an opening at the end. However, the present invention is not limited to this, and the electrode can be surrounded and at least partially opened. Any shape can be used as long as it has a hollow region having a shape.
For example, a columnar shape having both ends opened as shown in FIG. 2A, a hollow spherical shape with an opening provided in a part thereof as shown in FIG. As shown in (c), a box-like shape in which an opening provided in a part is hollow is also conceivable.
Further, as shown in FIG. 2D, an arrangement in which the position of the opening and the direction of the electrode 7 are different is also conceivable, and a plurality of openings may be provided. In addition, when a shielding member without an opening is used to completely surround the electrode, it is not possible to employ it because discharge to a disease-infected site does not occur.

  In the above embodiment, the electrode is grounded and the plant body is charged with a negative voltage. However, the present invention is not limited to this, and the plant body is grounded and the electrode is charged with a negative voltage. You can also. Any other form can be applied as long as it is charged with static electricity so that a certain potential difference is generated between the electrode and the plant. For example, it is conceivable to charge a positive voltage to one of the electrode and the plant and ground the other electrode, or to charge static electricity to the electrode and the plant so that a potential difference is generated.

  FIG. 1 shows an embodiment in which the portion of the shielding member 6 in which the electrode 7 is accommodated and the portion of the high-voltage electricity generator 8 are installed in different locations, but the electrode 7 is accommodated. A high-voltage electricity generator 8 can be incorporated into the shield member 6 thus formed to form an integrated small-sized therapeutic device 5.

(Explanation of corona discharge and spark discharge conditions)
The conditions for generating corona discharge and spark discharge as described above are greatly influenced by the shape of the electrode, the magnitude of the voltage applied to the electrode and the plant, and the distance between the electrode and the plant.
Here, FIG. 3 shows an example of the result of a discharge test performed using a needle-like electrode and a plate-like electrode. FIG. 3 is a graph schematically showing the relationship between the applied voltage and the distance between the electrodes. The vertical axis shows the voltage applied between the electrodes, and the horizontal axis shows the distance between the electrodes. .

In this graph, for example, when the distance between the electrodes is constant and the voltage applied between the electrodes is gradually increased, a glow corona discharge occurs following the dark current state, and then has a higher energy. Brush corona discharge occurs, and finally spark discharge occurs. Similarly, when the voltage applied between the electrodes is made constant and the distance between the electrodes is gradually reduced from the separation position, when a voltage lower than about 20 kV is applied between the electrodes, the state of dark current continues. A glow corona discharge occurs, followed by a brush corona discharge with higher energy, and finally a spark discharge. In addition, when a voltage exceeding about 20 kV is applied between the electrodes, glow corona discharge occurs from the separation position (distance is about 26 cm), and when a voltage exceeding about 60 kV is applied between the electrodes, the separation position ( The brush corona discharge occurs from a distance of about 26 cm).
In the above test, discharge is performed between electrodes made of conductors, but when the treatment device of the present invention is used, needle-like electrodes made of conductors and plants that are considered to be flat or cylindrical. Since the discharge is performed between the two, the discharge tends to be slightly less likely to occur, but the basic characteristics are considered to be the same.

Next, FIG. 4 shows the test results for barley powdery mildew when the treatment device 5 of the present invention shown in FIG. 1 is used to discharge the leaves of the plant 1. In addition, the horizontal axis of FIG. 4 shows the distance (mm) from a leaf surface. In this test, the electrode 7 of the treatment device 5 was grounded (grounded), and the high voltage electricity generator 8 charged the plant body 1 with high voltages of minus 5 kV, minus 10 kV, and minus 20 kV, and the test was performed. At each voltage, the distance between the tip 7a of the needle-like electrode 7 and the diseased infection site on the leaf surface is changed to various values, and the discharge state and the healing state of the diseased site on the leaf surface are changed. I investigated.
The test was conducted in a dark room, and the start of discharge and the start of spark discharge were confirmed visually. In the test, when the distance between the distal end portion 7a of the electrode 7 and the diseased infection site on the leaf surface is gradually approached from the separation position, the start of discharge is confirmed visually, and then the spark discharge is visually observed. Until the start was confirmed, discharge weaker than spark discharge was performed almost stably. In this region, corona discharge is considered to have occurred.

  When the plant body 1 is charged with minus 5 kV, as shown in FIG. 4 (a), the discharge occurs when the distance between the tip 7a of the electrode 7 and the diseased part of the leaf surface reaches 9 mm. And spark discharge occurred when the distance reached 4 mm. Here, it is considered that corona discharge occurs when the distance between the distal end portion 7a of the electrode 7 and the diseased part of the leaf surface is 4 to 9 mm. Repeated tests were performed by varying the distance between the tip 7a of the electrode 7 and the diseased part of the leaf surface within a distance of 4 to 9 mm where this corona discharge occurs. As a result, the pathogenic bacteria at the disease-infected site changed in the distance between the tip 7a of the electrode 7 and the disease-infected site of the leaf surface between 4 and 6 mm, and the bactericidal effect by corona discharge could be confirmed. On the other hand, when the distance between the tip 7a of the electrode 7 and the disease-infected site was between 6 and 9 mm, no change was observed in the pathogenic bacteria at the disease-infected site.

  Similarly, when the plant body 1 was charged with minus 10 kV, as shown in FIG. 4B, the distance between the tip 7a of the electrode 7 and the diseased site of the leaf surface reached 11 mm. Discharge sometimes occurred, and spark discharge occurred when the distance reached 6 mm. Here, it is considered that corona discharge is generated when the distance between the tip 7a of the electrode 7 and the diseased site of the leaf surface is 6 to 11 mm. The test was repeatedly performed by varying the distance between the tip 7a of the electrode 7 and the diseased part of the leaf surface within a distance of 6 to 11 mm where the corona discharge occurs. As a result, the pathogenic bacteria at the disease-infected site changed in the distance between the tip 7a of the electrode 7 and the disease-infected site on the leaf surface between 6 and 9 mm, and the bactericidal effect by corona discharge could be confirmed. On the other hand, when the distance between the tip 7a of the electrode 7 and the disease-infected site was in the range of 9 to 11 mm, no change was observed in the pathogenic bacteria at the disease-infected site.

  Similarly, when the plant body 1 was charged with minus 20 kV, as shown in FIG. 4 (c), the distance between the tip 7a of the electrode 7 and the diseased part of the leaf surface reached 21 mm. Discharge sometimes occurred and spark discharge occurred when the distance reached 15 mm. Here, it is considered that corona discharge occurs when the distance between the distal end portion 7a of the electrode 7 and the diseased site of foliage is between 15 and 21 mm. The test was repeatedly performed by varying the distance between the tip 7a of the electrode 7 and the diseased part of the leaf surface within a distance of 15 to 21 mm where the corona discharge occurs. As a result, in the range of 15 to 17 mm between the tip 7a of the electrode 7 and the diseased infection site on the foliage, a change was observed in the pathogenic bacteria at the diseased infection site, and the bactericidal effect by corona discharge was confirmed. On the other hand, when the distance between the tip 7a of the electrode 7 and the disease-infected site was in the range of 17 to 21 mm, no change was observed in the pathogenic bacteria at the disease-infected site.

Summarizing the above test results, when the plant body is charged with minus 5 kV, the bactericidal effect is confirmed at a distance of 4 to 6 mm, and when the plant body is charged with minus 10 kV, the bactericidal effect at a distance of 6 to 9 mm. When the plant body was charged with minus 20 kV, the bactericidal effect was confirmed at a distance of 15 to 17 mm. If these results are summarized by empirical formulas, for example, it is considered that the applied voltage has a bactericidal effect in the range (distance) shown in the following formula in the range of 5 to 20 kV.
Range having a bactericidal effect (distance) L = L1 ± 1 to 1.5 (mm)
Center distance L1 = 0.056V ^1.79 +4 (mm)
Applied voltage V: Applied voltage (kV)
The calculation results of this empirical formula are shown in the table below. In the table below, calculation was performed assuming that L = L ± 1 (mm). Further, the empirical formula is not limited to the above formula, and any formula can be used as long as it is a formula showing the same relationship between the applied voltage and the distance. For example, the distance L can be expressed as a function between the first power and the second power of the applied voltage V.

As described above, in the treatment device 5 of the present invention, the distance between the tip 7a of the electrode 7 and the disease-infected site of the plant body 1 is set according to the voltage applied between the electrode 7 and the plant body 1. If the corona discharge having a bactericidal effect is set within a range, the disease of the plant body 1 can be treated.
In this test, the correspondence between the transition point from the glow corona discharge to the brush corona discharge and the distance between the tip 7a of the electrode 7 and the disease-infected site of the plant body 1 is not necessarily clear, but sterilization by corona discharge It is considered that the region where the effect has been confirmed and the region where the brush corona discharge occurs substantially correspond.
As described above, the range of the distance at which the corona discharge having the bactericidal effect is generated has a considerably large width (for example, 3 mm width in the case of 10 kV). If the distance to which the value is added is set, it is possible to treat a disease using corona discharge effectively without fear of damage to the plant body due to spark discharge.

In addition, it is considered that the distance at which corona discharge and spark discharge occur when the applied voltage is constant varies depending on the humidity, the type of plant body, or the shape of the disease-infected site of the plant body. However, as described above, the range of distance that can be expected to treat disease by corona discharge has a considerably large range, and the variation due to the above factors is considered to be small compared to this range.
Regarding the effects of changes in humidity and the type of plant, if you set a distance that adds a certain value from the distance at which spark discharge occurs as described above, there is a risk of spark discharge due to changes in humidity or changes in the type of plant. And corona discharge can be used effectively. Similarly, the shape of the disease-infected site of the plant body is considered to be planar or cylindrical, and the difference is considered to be small compared to whether or not it has sharp parts, and is constant from the distance at which spark discharge occurs. If the distance to which the value is added is set, there is no fear of spark discharge due to the shape change of the plant body, and corona discharge can be used effectively. It is also possible to take test data for each shape of the disease-infected part of the plant body, and to set an optimum distance for each shape of the disease-infected part of the plant body based on the data.

(Description of other embodiments of the distance changing mechanism according to the present invention)
In the above embodiment, the distance changing means composed of screw screws is described, but the distance changing means according to the present invention is not limited to this, and the tip of the electrode and the tip of the shielding member Any member, mechanism, or device can be used as long as the relative distance can be changed. For example, as shown in FIG. 5, a plurality of space blocks 20 for securing distances corresponding to different voltage values are created and rearranged into the blocks 20 according to the set voltage to shield the tip 7 a of the electrode 7. It is also conceivable to change the distance between the tip 6a of the member 6 to a value corresponding to the set voltage. FIG. 5A shows a space block 20 corresponding to minus 10 KV incorporated in the cylindrical shielding member 6, and FIG. 5B shows a space block 20 corresponding to minus 20 KV. It shows the place where it is incorporated in the shield member 6. When the space block 20 is replaced, the pressing piece 21 attached to the tip of the shielding member 6 is attached and detached. The holding piece 21 can be attached to the tip of the shielding member 6 using an attaching screw, a snap fastener or the like.

As another embodiment of the distance changing means according to the present invention, a distance changing means for moving an electrode using an actuator as shown in FIG. 6 is also conceivable. The distance changing means 9 includes a mechanism for changing the distance between the tip 7 a of the electrode 7 and the tip 6 a of the shielding member 6 by moving the case 10 in which the electrode 7 is inserted using the actuator 22. As the actuator 22, a solenoid, electric, pneumatic, or hydraulic cylinder as shown in the figure can be used, and various electric motors such as a servo motor can be used. A control device 23 for controlling the actuator 22 is further provided. For example, the operator sets an applied voltage, and inputs conditions such as the shape of a disease-infected site as necessary, so that the control device 23 performs an operation. Thus, a control signal can be sent to the actuator 22 to automatically change the distance between the tip 7a of the electrode 7 and the tip 6a of the shielding member 6 to an optimum value corresponding to the applied voltage. As an arithmetic expression performed by the control device 23, for example, the calculation expression shown in Table 1 can be used. In addition, it is also possible to perform control to change the applied voltage to an optimum value by making the distance between the tip 7a of the electrode 7 and the tip 6a of the shielding member 6 constant by using a similar arithmetic expression.
Moreover, the electric potential difference between the electrode 7 and the plant body 1 is measured with a sensor, and based on the detection data, the tip end portion of the electrode 7 so that corona discharge having the highest energy occurs in a range where no spark discharge occurs. It is also conceivable to automatically control the distance between 7a and the tip 6a of the shielding member 6.

(Description of treatment device using linear electrodes)
In the above-described embodiment of the treatment apparatus, the treatment apparatus using the needle-like electrode is shown. However, as another embodiment of the treatment apparatus of the present invention, the treatment using the linear electrode 7 as shown in FIG. A device 5 is also conceivable. In this treatment device 5, a large number of openings 6 b are provided on the side surface of the cylindrical shielding member 6, and the distal end portion 6 a is closed with a plate. Further, the rear end portion of the shielding member 6 is inserted into the grip portion 14.
Examples of the material of the linear electrode 7 include copper, stainless steel, iron, and tungsten, and it is preferable to use a tungsten wire. The linear electrode 7 is disposed at the center of the cylindrical shielding member 6 along the longitudinal direction thereof. One end of the linear electrode 7 is attached to the plate of the front end portion 6 a of the shielding member 6, and the other end is attached to the rear end portion of the shielding member 6. The linear electrode 7 is electrically connected to the high voltage electricity generator 8 through the cable 11. Therefore, in this embodiment, the plant body to be treated is grounded.

In order to perform treatment using the treatment device 5, first, the electrode 7 is charged by the high-voltage electricity generation device 8, and the side surface of the cylindrical shielding member 6 is brought into contact with the disease occurrence site of the plant body. As a result, corona discharge occurs between the linear electrode 7 and the plant disease occurrence site through the opening 6b of the shielding member 6, thereby killing the plant disease bacteria and performing treatment. .
Moreover, as a dimension of the main member of this treatment apparatus 5, the thickness of the linear electrode 7 is 20-1000 micrometers, Preferably it is 40-800 micrometers, More preferably, it is 50-100 micrometers. Corona discharge easily occurs when the dimensions are within this range. About the diameter of the cylindrical shielding member 6, it is necessary to set to an appropriate value so that the distance between the electrode 7 and the disease occurrence part of a plant body may become an appropriate value according to the applied voltage. For example, if the applied voltage is minus 10 kV, the diameter may be set around 12 mm, and if the applied voltage is minus 20 kV, the diameter may be set around 30 mm. In addition, the size of the opening 6b provided in the shielding member 6 is appropriate such that the leaves of the plant body do not enter the inside, and may be about 2 to 4 mm, for example.

  The length of the shielding member 6 can be set to a desired length depending on the use situation. For example, by replacing the shielding member 6, the length can be changed to a length suitable for the use situation. For example, 50 cm, 30 cm, or 15 cm can be exemplified as the length of the shielding member 6.

In the present treatment apparatus 5, the operator can easily treat the disease of the plant body by holding the grip portion 14 and making the shielding member 6 contact or slide the diseased site of the plant body. be able to. Moreover, it can also be made to have the simple attachment or detachment mechanism of the shielding member 6 which can be easily replaced | exchanged for the shielding member 6 from which a diameter and length differ according to the kind, size, and position of a plant body or a diseased part. .
In this embodiment, when the shielding member 6 having the same diameter is used, since the distance between the electrode 7 and the diseased part of the plant body is constant, the applied voltage between the electrode 7 and the plant body is changed. It is preferable to perform control to change to an optimum value.
(Description of Examples of Treatment Method and Treatment Device of the Present Invention)
Next, an embodiment of the treatment method of the present invention in which corona discharge is applied to a disease-infected site of a plant body using the treatment apparatus shown in FIG. 1 will be described.

  In Example 1, the therapeutic effect of barley powdery mildew by the treatment apparatus 5 shown in FIG. 1 was examined. The detailed dimensions of the electrode 7 and the shielding member 6 of the treatment apparatus 5 are shown as follows. The electrode 7 has a needle-like tip of a copper rod having an outer diameter of 1.2 mm and a length of 30 cm. Is made of acrylic resin and has a cylindrical shape with an inner diameter of 4 mm, a thickness of 6 mm, and a length of 35 cm. The electrode 7 is inserted so as to pass through substantially the center of the shielding member 6, and the distance changing means 9 is adjusted so that the tip 7 a of the electrode 7 is 16 mm before the tip 6 a of the shielding member 6. . A ground wire 12 is connected to the rear end of the electrode 7 and grounded.

  In addition, a plant 1 infected with barley powdery mildew is planted in a prop 4 pot 12 cm in diameter and without a bottom hole, and a clip attached to the tip of a cable 11 b connected to a high voltage electricity generator 8 The mold terminal 11a was connected to the stem of the plant body 1 and charged to minus 20 kV. In this state, the shielding member 6 of the treatment device 5 was brought close to a vertical position on the powdery mildew spot formed on the leaf of the plant body 1, the tip portion 6a was brought into contact therewith, and discharged for 10 seconds.

As shown in the data of FIG. 4 (c) above, when the distance between the distal end portion 7a of the electrode 7 and the disease-infected site of the plant body 1 is set to 16 mm while being charged to a pressure of minus 20 kV. Corona discharge having a relatively large energy without causing a spark discharge and having a large effect of killing pathogenic bacteria can be used.
The test results of Example 1 showed that the spore pattern on the lesions subjected to corona discharge was completely atrophied and laid down, but the surrounding healthy leaves were not affected. Therefore, it can be said that the effect of the treatment method and treatment apparatus of the present invention was confirmed by this test.

  Next, in Example 2, using the treatment device shown in FIG. 1, treatment of lesions formed on an open-planted cucumber seedling 1 (variety: Sharp 1, 1.2 leaf stage) suffering from powdery mildew. The test was conducted. The distance changing means 9 was adjusted so that the tip 7 a of the electrode 7 was 8 mm before the tip 6 a of the shielding member 6, and the high voltage electricity generator 8 was charged to minus 10 kV. In this state, the shielding member 6 of the treatment apparatus 5 was brought close to the vertical to all the lesions formed on the leaves, and the distal end portion 6a was brought into contact with the lesioned portion for 10 seconds.

As shown in the data of FIG. 4 (b) described above, when the distance between the tip 7a of the electrode 7 and the disease-infected site of the plant body 1 is set to 8 mm while being charged to a pressure of minus 10 kV. Corona discharge having a relatively large energy without causing a spark discharge and having a large effect of killing pathogenic bacteria can be used.
As a result of the test of Example 2, when the therapeutic effect was observed 10 days later, in the seedling discharged to the lesion, both the disease incidence and the disease severity were suppressed as compared with the untreated seedling. Therefore, it can be said that the effect of the treatment method and treatment apparatus of the present invention was confirmed by this test.

  The method for treating plant diseases by killing the mycelium, spores and / or spore pattern of the plant pathogenic fungi of the present invention by discharge, using only the site where the disease occurs as a target, and healthy sites of surrounding plants Plant diseases can be treated without causing damage to the environment and without damaging the environment.

The figure which showed one Embodiment of the treatment apparatus of this invention notionally. The figure which showed notionally other embodiment of the shielding member which accommodated the electrode inside. The graph which shows an example of the test result which showed the conditions which a corona discharge and a spark discharge generate | occur | produce at the time of using a needle electrode and a flat electrode. The graph which shows the effect on pathogenic microbe, the conditions which corona discharge in the treatment apparatus of this invention, and spark discharge generate. The figure which shows notionally other embodiment of the distance change mechanism of the treatment apparatus of this invention. The figure which shows notionally other embodiment of the distance change mechanism of the treatment apparatus of this invention. The figure which shows other embodiment of the treatment apparatus of this invention using a linear electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plant 2 Spore pattern 3 Spore 4 Pot 5 Treatment apparatus 6 Shielding member 6a Shielding member tip 7 Electrode 7a Electrode tip 7a
8 High Voltage Electric Generator 9 Distance Change Mechanism 10 Case 11 Connection Member 11a Terminal 11b Cable 12 Ground Wire 14 Grip 20 Space Block 21 Pressing Piece 22 Actuator 23 Control Device

Claims (8)

  By applying a high direct current voltage to the electrode and the plant body and charging the electrode and / or the plant body with static electricity, a corona discharge is generated between the electrode and the plant body, A method for treating plant diseases characterized by killing attached or generated plant pathogens.   The distance between the electrode and the plant body kills the phytopathogenic fungus based on the voltage applied to the electrode and the plant body, but kills the area of the plant body that is affected by the corona discharge. The method for treating plant diseases according to claim 1, wherein the method is determined within a range that does not occur.   The said electrode is accommodated in the inside of the shielding member which consists of a nonconductor which has an opening part, A corona discharge is produced between the said electrode and the said plant body through the said opening part. The treatment method of the plant disease of description.   The method for treating a plant disease according to claim 3, wherein the opening has a size and a shape corresponding to a disease-infected site of the plant body.   The plant disease treatment method according to any one of claims 1 to 4, wherein the corona discharge is a brush corona discharge. A shielding member made of a non-conductor having an opening;
An electrode housed inside the shielding member;
High voltage applying means for applying a predetermined high voltage to the electrode and the plant;
With
An apparatus for treating plant diseases, wherein corona discharge is caused between the electrode and the plant body through the opening to kill plant pathogens attached to or generated in the plant body.   The plant disease treatment apparatus according to claim 6, further comprising distance changing means for changing a distance between the electrode and the plant body.   The plant disease treatment apparatus according to claim 6 or 7, further comprising voltage changing means for changing a voltage applied to the electrode and the plant body.

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