Disease control methods

Abstract

Provided is a novel method for controlling plant diseases that efficiently utilizes light energy and enables further downsizing of an irradiation device.　The disease control method of the present invention is characterized by comprising irradiating the shoot apex part of a plant with near-infrared light. The irradiation area may, for example, be the vicinity of the shoot apex part including the shoot apex part.

Description

[Technical Field]

[0001] The present invention relates to a method for controlling plant diseases. [Background technology]

[0002] In the cultivation process of plants, it is known that plants are irradiated with near-infrared light to control diseases (Patent Document 1). However, this method requires continuous irradiation throughout the day, so irradiating the entire cultivation area requires a large irradiation device with multiple light sources, which presents cost problems. Therefore, by optimizing the irradiation conditions of near-infrared light, it is possible to reduce costs by efficiently utilizing light energy. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6061124 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, since near-infrared light irradiation is intended to irradiate the entire plant, the need for large irradiation equipment remains a problem.

[0005] Therefore, the present invention aims to provide a new method for controlling plant diseases that further efficiently utilizes light energy and enables further miniaturization of the irradiation device. [Means for solving the problem]

[0006] To achieve the aforementioned objective, the disease control method of the present invention is characterized by irradiating the apex of a plant stem with near-infrared light. [Effects of the Invention]

[0007] According to the present invention, for example, even without irradiating the entire plant with near-infrared light, by irradiating the apical part of the plant stem, it is possible to effectively control diseases of the plants during cultivation. Therefore, according to the present invention, for example, it becomes possible to miniaturize the irradiation device used for near-infrared light irradiation and further reduce the light energy consumed, and cost reduction and labor saving of the irradiation work can be realized.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a diagram showing an outline of a method for growing plants. (A) shows a fence arrangement, and (B) shows a shelf arrangement. [Figure 2] FIG. 2 is a photograph of a handy-type irradiation device used in the examples. [Figure 3] FIG. 3 is a diagram showing an outline of the irradiation position of near-infrared light on cherry tomatoes in Example 1. [Figure 4] FIG. 4 is a photograph of the leaves of the lowest branch of cherry tomatoes in Example 1. (A) is a control group without near-infrared light irradiation, (B) is a test group irradiated with near-infrared light near the apical part of the stem, and (C) is the result of a reference group irradiated with near-infrared light throughout. [Figure 5] FIG. 5 is a diagram showing an outline of the leaf collection sites from grapes in Example 2(1). (A) shows a fence arrangement, and (B) shows a shelf arrangement. [Figure 6] FIG. 6 is a graph confirming an increase in gene expression for leaves at multiple sites recovered from grapes irradiated with near-infrared light near the apical part of the stem in Example 2(1). (A) shows a fence arrangement, and (B) shows a shelf arrangement. [Figure 7] FIG. 7 is a graph showing the relationship between the irradiance of near-infrared light and the irradiation time. [Figure 8] FIG. 8 is a diagram showing an outline of the irradiation site and observation site of near-infrared light on grapes in Example 2(2). [Figure 9] FIG. 9 is a schematic diagram illustrating the vicinity of the apical part of the stem of a strawberry seedling. [Figure 10] FIG. 10 is a schematic diagram illustrating the vicinity of the growth point of a lettuce seedling.

Mode for Carrying Out the Invention

[0009] The present invention includes the following aspects. [1] A disease control method characterized by irradiating near-infrared light to the apical part of a plant stem. [2] The disease control method according to [1], wherein the irradiation range of the near-infrared light is near the apical part of the stem including the apical part. [3] The disease control method according to [2], wherein the vicinity of the apical part of the stem is a range of a distance of 1 / 3 or less from the tip of the stem when the full length is from the tip of the stem to the position of the branch at the other end of the stem in the growth direction of the stem. [4] The disease control method according to any one of [1] to [3], wherein the irradiation conditions for the apical part of the stem or the vicinity of the apical part of the stem satisfy Formula 1, Formula 2, and Formula 3. Formula 1: 644893X -1.873 ≧Y≧5901.9X -1.856 Formula 2: X≧1 Formula 3: Y≧0.01 In each of the above formulas, X is the irradiance (W / m 2 ), and Y is the irradiation time (seconds). [5] The disease control method according to any one of [1] to [4], wherein the near-infrared light includes wavelengths set within the wavelength range of 800 to 1000 nm. [6] The disease control method according to any one of [1] to [5], wherein the irradiation frequency for the apical part of the stem or the vicinity of the apical part of the stem is once a day to once a month. [7] The disease control method according to any one of [1] to [6], wherein the disease of the plant is a disease derived from fungi. [8] The disease control method according to [7], wherein the fungi are at least one selected from the group consisting of ascomycetes, basidiomycetes, mastigomycetes, oomycetes, and imperfect fungi. [9] The disease control method according to any one of [1] to [8], wherein the disease of the plant is at least one selected from the group consisting of powdery mildew, gray mold, leaf mold, anthracnose, and blight.

[10] The disease control method according to any one of [1] to [9], wherein the plant is at least one selected from the group consisting of strawberries, tomatoes, cherry tomatoes, shishito peppers, bell peppers, paprika, eggplants, cucumbers, pumpkins, melons, watermelons, okra, cabbage, broccoli, cauliflower, Chinese cabbage, komatsuna, rapeseed, leeks, onions, asparagus, grapes, citrus fruits, peaches, pears, persimmons, cherries, chrysanthemums, roses, carnations, and lisianthus.

[0010] Embodiments of the present invention are described below. However, the present invention is not limited to the embodiments described below.

[0011] As described above, the disease control method of the present invention is characterized by irradiating the apex of a plant stem with near-infrared light, and other steps and other conditions are not particularly limited.

[0012] In this invention, disease control means, for example, preventing disease or eliminating disease, and may mean either one or both. Furthermore, specific examples of disease control include suppressing (preventing) the occurrence of disease, suppressing the progression of disease, etc., and can also be called disease suppression.

[0013] In this specification, "area irradiated with near-infrared light" means, for example, the area of ​​a plant that is exposed to near-infrared light, and is hereinafter also referred to as the irradiated area or irradiated region. In this specification, "target area for near-infrared light irradiation" means, for example, the area of ​​a plant that is set as the irradiation target when irradiating a plant with near-infrared light, and is also referred to as the irradiation target region. That is, in this specification, the irradiation target area is, for example, the area set by the irradiation device or the area set by the operator of the irradiation device.

[0014] In this invention, the part of a plant irradiated with near-infrared light may be, for example, only the stem apex, or it may include the area near the stem apex. In this specification, unless otherwise specified, the area near the stem apex includes both the stem apex and the area surrounding it.

[0015] In the present invention, it is preferable, for example, to set the irradiation target area for near-infrared light to either the apex of the stem or the area near the apex including the apex. In the present invention, for example, when the apex or the area near the apex is set as the irradiation target area, the present invention does not exclude the possibility that the vicinity of the irradiation target area will consequently be irradiated during irradiation of the said irradiation target area.

[0016] In the present invention, when irradiating with near-infrared light, for example, the apex of the stem may be set as the target irradiation area with pinpoint accuracy. In this case, for example, the apex of the stem may be set as the irradiation point (also called the focal point) within the vicinity of the apex. Furthermore, in the present invention, when irradiating with near-infrared light, a wider area near the apex of the stem may be set as the target irradiation area. In this case, for example, the apex of the stem may be set as the irradiation point (also called the focal point) within the vicinity of the apex of the stem. Furthermore, since the present invention only requires that near-infrared light be irradiated to at least the apex of the stem, for example, when the vicinity of the apex of the stem is set as the target irradiation area, the irradiation point may be set in a region other than the apex of the stem within the range in which near-infrared light is irradiated to the apex of the stem.

[0017] In the present invention, it is preferable to irradiate the target area (shoot apex or near the shoot apex) in such a way that the set irradiation conditions are met, for example, when the irradiation conditions are set as described later. Specifically, it is preferable to set the target area for near-infrared light irradiation to the shoot apex or near the shoot apex, and to irradiate the target area with the set irradiation conditions. As mentioned above, the present invention does not exclude the irradiation of the vicinity of the target area, but for example, it is not necessary to satisfy the set irradiation conditions in the vicinity of areas other than the target area. Therefore, according to the present invention, it is unnecessary to use a large irradiation device capable of irradiating the entire length of a plant in one pass in order to irradiate the entire plant in a way that satisfies the set irradiation conditions, or to move the irradiation device from the bottom to the top of the plant.

[0018] In plants, the stem apex is the tip of the stem (main trunk), also known as the growth point. In this invention, the area near the stem apex, including the stem apex, does not refer to the entire plant including the stem apex, but rather, for example, the region on the tip side of the stem in the direction of stem growth.

[0019] The area near the stem apex can also be defined, for example, by the ratio of the length of the stem relative to the length of the stem in the direction of stem growth (e.g., total stem length), with respect to the tip of the stem. The direction of stem growth can be appropriately determined, for example, depending on the growth method. The direction of stem growth may be, for example, the height perpendicular to the ground, the length horizontal to the ground, or both. Specific examples of plant growth methods include, for example, (A) hedge training and (B) trellis training, as shown in Figure 1.

[0020] In the case of the hedge arrangement shown in Figure 1(A), stakes are erected vertically to the ground, and wires or the like are stretched parallel to the ground from the stakes to create the hedge. The stems of the plants grow upward from the ground along the vertical stakes. In this case, the direction of growth of the plant stems in this invention is, for example, the direction perpendicular to the ground (direction A). The length of the stem in the direction of growth is not, for example, the length of the stem itself when artificially pulled and stretched vertically, but the length in the vertical direction in its natural state during growth. As a specific example, in the direction of growth of the stem (direction A), the length (X) from the tip of the stem (for example, the stem apex) to the position of the leaves on the branch at the other end of the stem can be defined as the length of the stem. The branch at the other end of the stem is, for example, the branch furthest away from the tip of the stem in the direction of growth, and in the case of Figure 1(A), for example, the branch closest to the root (for convenience, also called the lowest branch). Furthermore, the area near the apex of the plant stem is, for example, the region in Figure 1(A) with respect to the tip, and in the direction of stem growth (direction A), the length near the apex is the distance (Y) with respect to the tip, that is, the distance from the tip. When the length of the stem (X) in the direction of growth is set to a relative value of 1, the ratio of the distance (Y) near the apex is, for example, 1 / 3 or less, 1 / 5 or less, 1 / 10 or less, 1 / 50 or less, 1 / 100 or less, 1 / 200 or less, 1 / 400 or less, 1 / 1000 or less, 1 / 1500 or less, and 1 / 2000 or less. The length of the stem (X) in the direction of growth can be set, for example, to the length from the tip of the stem (for example, the apex) to the position of the branch at the other end of the stem, and this will hereafter be referred to as the total length of the stem.

[0021] In the trellis arrangement shown in Figure 1(B), a straight support post is erected perpendicular to the ground at the desired height, and a trellis parallel to the ground is installed at the same height. The plant stem grows along the vertical support post to the desired height, and then creeps along the trellis parallel to the ground. In this case, the direction of stem growth in the present invention is, for example, the direction parallel to the ground (direction B). The length of the stem in the direction of growth is not, for example, the length of the stem itself when artificially pulled and stretched in the parallel direction, but the length in the parallel direction in its natural state during growth. As a specific example, in the direction of stem growth (B), the length of the stem can be defined as the length (X) from the tip of the stem (for example, the stem apex) to the position of the leaves on the branch at the other end of the stem. The branch at the other end of the stem is, for example, the branch furthest from the tip of the stem in the direction of growth, that is, the branch closest to the support post (for convenience, it is also called the lowest branch, as in Figure 1(A)). Furthermore, the area near the apex of the plant stem is, for example, the region in Figure 1(B) with respect to the tip, and in the direction of stem growth (direction B), the length near the apex is the distance (Y) with respect to the tip, that is, the distance from the tip. When the length of the stem (X) in the direction of growth is set to a relative value of 1, the ratio of the distance (Y) near the apex is, for example, 1 / 3 or less, 1 / 5 or less, 1 / 10 or less, 1 / 50 or less, 1 / 100 or less, 1 / 200 or less, 1 / 400 or less, 1 / 1000 or less, 1 / 1500 or less, and 1 / 2000 or less. The length of the stem (X) in the direction of growth can be set, for example, to the length from the tip of the stem (for example, the apex) to the position of the branch at the other end of the stem, and this will hereafter be referred to as the total length of the stem.

[0022] If the target of irradiation is a plant in which multiple flower clusters appear sequentially as it grows, irradiation of the stem apex or the area near the stem apex can be set as follows, for example. That is, in a plant, the area closer to the stem apex than the flower cluster closest to the stem apex may be used as the area near the stem apex for irradiation, or the area near the stem apex may be set as the irradiation target area. The area may include the stem apex, and may or may not include, for example, the flower cluster closest to the stem apex.

[0023] In the present invention, for example, near-infrared light irradiation of the same plant individual is performed once or more times during the plant's cultivation period, preferably two or more times (multiple times) with an arbitrary time interval between them. In the present invention, one irradiation is, for example, irradiation that reaches a set arbitrary cumulative light amount, which may be achieved by continuous irradiation or by intermittent irradiation. In the present invention, the interval between one irradiation and the next irradiation, i.e., the irradiation interval, is not particularly limited, and may be, for example, one day, two days or more, and specific examples will be described later.

[0024] Intermittent irradiation is, for example, irradiation that repeatedly flashes at short time intervals, and is also called pulsed irradiation, which is repeated in sets of pulse ON (irradiation) and pulse OFF (irradiation). The width of the pulse ON (pulse width) and the width of the pulse OFF are both in units of tens of seconds (for example, less than 1 minute, 30 seconds or less, 10 seconds or less, 5 seconds or less, 1 second or less), milliseconds, or microseconds. In this invention, for example, when one irradiation is performed by intermittent irradiation, the entire repetition of the above multiple sets is referred to as one intermittent irradiation.

[0025] In the present invention, the area irradiated by a single near-infrared light irradiation of the irradiated object is not particularly limited, for example, 5 to 20 mm². 2 , 4900~10000mm 2 The area is, for example, 5 to 100 mm in length and 5 to 100 mm in width. To irradiate the area with near-infrared light, for example, an irradiation device having a light source whose effective irradiation range is the area can be used. Furthermore, in the present invention, it is preferable that the area within the range of the area, including the stem apex of the plant to be irradiated, receives near-infrared light that satisfies, for example, formulas 1, 2, and 3 as described later.

[0026] The near-infrared light is not particularly limited, and its wavelength is, for example, in the range (region) of 800 to 1000 nm. The irradiated near-infrared light may include all of the light within the wavelength region, or it may include only a portion of the light within the wavelength region. When irradiating with near-infrared light, for example, the wavelength can be arbitrarily set within the wavelength region. Specifically, it is preferable that the central wavelength or peak wavelength of the irradiated near-infrared light is, for example, within the wavelength region of 800 to 1000 nm. The near-infrared light may be, for example, a single-wavelength light such as a laser, or it may have a wavelength distribution such as a fluorescent lamp or LED. Furthermore, the near-infrared light may have, for example, one peak wavelength, or two or more different peak wavelengths, and it is preferable that the central wavelength of the irradiated near-infrared light is, as mentioned above, within the wavelength region of 800 to 1000 nm.

[0027] In this invention, "irradiation with near-infrared light" refers to artificial irradiation, not non-artificial irradiation. Non-artificial irradiation means, for example, simply placing plants in an environment that receives natural light such as sunlight, so that the plants receive natural light including near-infrared light non-artificially. On the other hand, artificial irradiation means, for example, artificially irradiating plants with near-infrared light by adjusting the wavelength of light, or irradiating separated near-infrared light. For adjusting the wavelength of light, for example, an irradiation device that irradiates near-infrared light can be used. Examples of such irradiation devices include a light irradiation device having a light source, a light adjustment device that extracts the desired light, and so on. The light adjustment device may, for example, extract the desired light from an external light source or natural light, or the device may further have a light source and extract the desired light from the light emitted from that light source.

[0028] For irradiating plants with near-infrared light, for example, an irradiation device with a light source can be used, as described above. According to the present invention, as described above, for example, it is not necessary to irradiate the entire plant, and it is sufficient to set the stem apex or the area near the stem apex as the irradiation target area. Therefore, a small irradiation device with a light source is sufficient, rather than a large irradiation device that irradiates the entire plant. Examples of such small irradiation devices include, as will be described later, a handheld type that can be easily carried by an operator, a cart for moving around a field, and an attachment type that can be attached to or detached from a mobile body such as a drone.

[0029] Examples of light sources that emit near-infrared light include light-emitting diodes (LEDs), fluorescent tubes, metal halide lamps, sodium lamps, halogen lamps, xenon lamps, neon tubes, inorganic electroluminescence, organic electroluminescence, chemiluminescence, lasers, etc. It is preferable to irradiate the light source with near-infrared light set to the wavelength range.

[0030] Furthermore, when irradiating with near-infrared light, for example, a spectrometer (spectroscopic component) that extracts the desired light may be used as the light irradiation adjustment device. The spectrometer may include, for example, a spectral filter that transmits only the near-infrared light, and as a specific example, a spectral filter that transmits only wavelengths set within the wavelength range may be used. When using the spectral filter, for example, a light source that emits not only near-infrared light but also other light, or natural light such as sunlight, can be used. By transmitting the light emitted from the light source or natural light through the spectral filter, for example, the wavelength can be artificially adjusted (near-infrared light can be separated) and near-infrared light can be irradiated onto the plant.

[0031] The irradiation conditions in the present invention are not particularly limited, and examples thereof include the following conditions. In the present invention, it is preferable to set the irradiation conditions for the shoot tip or near the shoot tip as follows, and particularly, it is preferable to set at least the irradiation conditions for the shoot tip as follows. Regarding the irradiation conditions, for example, WO2021 / 049640 etc. can be referred to. Further, in the present invention, for example, the relationship between the irradiance of near-infrared light and the irradiation time, the suitable conditions for irradiation in disease control, etc. can be applied regardless of the type of plant. Note that the present invention is not limited to the following specific examples.

[0032] The irradiation conditions preferably satisfy, for example, Formula 1, Formula 2, and Formula 3. Specifically, it is the wavelength region and preferably satisfies each of the formulas. Formula 1: 644893X -1.873 ≧Y≧5901.9X -1.856 Formula 2: X≧1 Formula 3: Y≧0.01 In each of the above formulas, X is the irradiance (W / m 2 ), and Y is the irradiation time (seconds).

[0033] Formula 1, Formula 2, and Formula 3 are an example of the relationship between the irradiance X of near-infrared light and the irradiation time Y that effectively exhibits a disease control effect in plants. Formula 1, Formula 2, and Formula 3 are preferably conditions regarding the irradiation of near-infrared light in the wavelength region among near-infrared light, for example.

[0034] The regression formula "Y = 644893X -1.873 " in Formula 1 is represented by the regression line LA in the double logarithmic graph of FIG. 7. Here, when the coordinates indicated by the irradiance X and the irradiation time Y are above the regression line LA, it corresponds to excessive irradiation of near-infrared light to the plant. If the coordinates are below the regression line LA, for example, the irradiance or the irradiation time satisfies the required amount, and a sufficient disease control effect can also be obtained. Therefore, the power for generating near-infrared light can be further energy-saving, and the lifespan of the light source can be further prolonged.

[0035] Furthermore, the regression equation in Equation 1 above, "Y = 5901.9X -1.856 This is represented by the regression line LC in the log-log graph of Figure 7. Here, if the coordinates represented by irradiance X and irradiation time Y are below the regression line LC, it corresponds to insufficient near-infrared light irradiation of plants. If the coordinates are above the regression line LC, for example, the required amount of irradiance or irradiation time can be met, and sufficient disease control effects can also be obtained.

[0036] Furthermore, the regression line LB shown in Figure 7 is given by the regression equation "Y=41491X -1.848 This regression line LB represents, for example, the relationship between irradiance and irradiation time that provides the highest effectiveness in controlling plant diseases.

[0037] Furthermore, when irradiating plants with near-infrared light, for example, the lower the irradiance, the longer the irradiation time is set, and conversely, the shorter the irradiation time, the higher the irradiance is set. Therefore, considering the irradiation time and irradiance from the standpoint of work efficiency and energy saving, for example, the irradiance should be 1 W / m 2 The above is preferable, and the irradiation time is preferably 0.01 seconds or longer.

[0038] Based on the above, in the present invention, for example, it is particularly preferable to set the irradiance and irradiation time such that the coordinates lie within the range enclosed by the four lines LA, LC, X=1, and Y=0.01 in Figure 7. These irradiation conditions can be expressed by equations as satisfying all of equations 1, 2, and 3. By irradiating the stem apex or vicinity of the stem apex of a plant with near-infrared light under such setting conditions, it is possible to further improve work efficiency and energy saving, for example, in addition to a more effective disease control effect.

[0039] According to Equations 1, 2, and 3, the relationship between the irradiance of near-infrared light and the irradiation time is clearly defined. Therefore, in the present invention, by utilizing Equations 1, 2, and 3, it is possible to more easily set either or both of the irradiance of near-infrared light and the irradiation time as irradiation conditions that can effectively control plant diseases. That is, for example, if the distance between the near-infrared light source and the stem apex of the plant being irradiated increases, the irradiance at the stem apex will be lower compared to when the distance is closer, and the irradiation energy received by the stem apex will be smaller even with the same irradiation time. In such cases, for example, based on Equations 1, 2, and 3, the irradiation time can be easily adjusted to be relatively longer so that a sufficient disease control effect can be obtained even with low irradiance. Furthermore, when irradiating the stem apex of each individual plant with near-infrared light while moving the light source, for example, if the time the light source passes near each individual is short, the irradiation energy received by the stem apex will be smaller compared to when the time the light source passes is long. In such cases, based on equations 1, 2, and 3, the irradiance can be easily adjusted to a relatively high level so that a sufficient disease control effect can be obtained even with a short irradiation time.

[0040] Specific examples of adjusting irradiation conditions using the above-mentioned Equations 1, 2, and 3 are given below. Note that these are illustrative examples, and the present invention is not limited to these examples. For example, near-infrared light containing wavelengths set within the wavelength range of 800-1000 nm is applied to the stem apex or vicinity of the stem apex of a plant under cultivation, with irradiance (W / m²). 2 When X is the value of the pulse and Y is the irradiation time (seconds), all of the above equations 1, 2, and 3 are satisfied, and Y = 41491X -1.848 One embodiment involves irradiating with near-infrared light by adjusting at least one of the irradiance and irradiation time based on a function represented by the equation "Y=41491X -1.848 As mentioned above, this is the regression equation (function) that represents the regression line LB shown in Figure 7.

[0041] In another embodiment, near-infrared light containing wavelengths set within the 800-1000 nm wavelength range is applied to the stem apex or vicinity of the stem apex of a plant being cultivated, with an irradiance (W / m²). 2 When X is the value of the pulse and Y is the irradiation time (seconds), all of the above equations 1, 2, and 3 are satisfied, and Y = 644893X -1.873 One embodiment involves irradiating with near-infrared light by adjusting at least one of the irradiance and irradiation time based on a function represented by the equation "Y=644893X -1.873 As mentioned above, this is the regression equation (function) that represents the regression line LA shown in Figure 7.

[0042] Furthermore, in another embodiment, near-infrared light containing wavelengths set within the wavelength range of 800-1000 nm is applied to the stem apex or vicinity of the stem apex of a plant being cultivated, with an irradiance (W / m²). 2 When X is the value of the time and Y is the irradiation time (seconds), all of the above equations 1, 2, and 3 are satisfied, and Y = 5901.9X -1.856 One embodiment involves irradiating with near-infrared light by adjusting at least one of the irradiance and irradiation time based on a function represented by the formula "Y=5901.9X -1.856 As mentioned above, this is the regression equation (function) that represents the regression line LC shown in Figure 7.

[0043] In the present invention, each irradiation with near-infrared light may be continuous or intermittent, for example, to a single location, as described above. Continuous irradiation means, for example, irradiating with near-infrared light continuously for a predetermined time (for example, 5 minutes). Intermittent irradiation is pulse irradiation in which multiple sets are repeated, for example, with a predetermined time of irradiation (ON) and a predetermined time of non-irradiation (OFF) as one set. In one intermittent irradiation, for example, the ON time and OFF time of each set may be the same or different. Continuous irradiation and intermittent irradiation can be made similar by, for example, making the total irradiation time of one intermittent irradiation (for example, the ON time of one set × the number of sets) the same as the continuous irradiation time of one continuous irradiation. As a specific example, when performing one intermittent irradiation that is the same as one continuous irradiation (5 minutes), for example, one set may consist of an ON time of 10 seconds and an OFF time of 10 seconds, and this may be repeated 30 times so that the total ON time is 5 minutes. For the continuous irradiation time per continuous irradiation and the total irradiation time per intermittent irradiation, it is preferable to set the upper limit to 5 minutes or less, 1 minute or less, 30 seconds or less, 10 seconds or less, 1 second or less, etc., from the viewpoint of work efficiency, and the lower limit to 0.1 seconds or more, 0.5 seconds or more, 1 second or more, 3 seconds or more, 5 seconds or more, etc., and the range to 0.1 seconds to 5 minutes, 0.1 seconds to 1 minute, 0.1 seconds to 30 seconds, 0.1 seconds to 10 seconds, 0.5 seconds to 5 minutes, 0.5 seconds to 1 minute, 0.5 seconds to 30 seconds, 0.5 seconds to 10 seconds, 1 second to 5 minutes, 1 second to 1 minute, 1 second to 30 seconds, 1 second to 10 seconds, etc. Furthermore, it is preferable to set the irradiance such that it satisfies each of the relationship formulas exemplified above.

[0044] The frequency of near-infrared light irradiation to the same plant individual (also referred to as the irradiation interval mentioned above) is not particularly limited. For example, any period between 1 day and 1 month, any period between 1 day and 30 days, or any period between 1 day and 14 days can be cited. In other words, specific examples of irradiation frequencies include once every 1 day to 1 month, once every 1 day to 30 days, or once every 1 day to 14 days. When near-infrared light irradiation is performed regularly during the plant cultivation period, the period between irradiations (non-irradiation periods) may be a fixed number of days or a different number of days. The effect of disease control by near-infrared light irradiation can be particularly effective and can be sustained for about 14 days with a single irradiation. For this reason, it is preferable to irradiate with near-infrared light once every 1 to 14 days.

[0045] According to the present invention, during the plant cultivation period, the effect of disease control can be continuously maintained by repeatedly performing periodic near-infrared light irradiation at the example irradiation intervals described above, preferably 1 to 14 days (irradiation frequency). During the cultivation period, there are no particular limitations on the number of times the stem apex or the area near the stem apex is irradiated at the irradiation intervals.

[0046] In the present invention, when irradiating plants with near-infrared light, the light environment surrounding the plants to be irradiated may be, for example, dark or bright, and the plants can be artificially irradiated with near-infrared light using the irradiation device described above. When the plants to be irradiated are in a dark state, for example, the plants may be irradiated with near-infrared light using the light irradiation device having the light source, or the plants may be artificially irradiated with adjusted near-infrared light by extracting near-infrared light from light of a wide wavelength using the light irradiation adjustment device. On the other hand, the latter bright state includes, for example, a state in which the plants to be irradiated are under artificial lighting such as fluorescent lamps or LEDs, or under natural light such as sunlight. In this case, for example, the plants may be irradiated with near-infrared light using the light irradiation device, or the plants may be artificially irradiated with adjusted near-infrared light by extracting near-infrared light from the light of the illumination or natural light using the light irradiation adjustment device. In a light-filled environment, for example, it is preferable that the irradiance of light other than near-infrared light is weaker than the irradiance of near-infrared light artificially irradiated onto the plants.

[0047] In the present invention, there are no particular limitations on the specific method of irradiating plants with near-infrared light. If the plant is grown in a building, such as a greenhouse or hydroponic room, near-infrared light may be irradiated to the stem apex or near the stem apex of the plant using an irradiation device installed on the ceiling or walls of the building. If the plant is grown in an open field, for example, a mobile irradiation device equipped with a near-infrared light source can be used. The mobile irradiation device may be, for example, a mobile irradiation device with a light source installed on a cart that moves automatically or manually, a device with a light source installed on a drone, or a handheld device with a light source installed.

[0048] In the present invention, the plants to be irradiated are not particularly limited. The irradiated plants include, for example, all plants cultivated by agricultural methods, and the disease control method of the present invention can be broadly applied to cultivated plants, for example. Specific examples include, for example, fruit vegetables (eggplant, pepino, tomato, cherry tomato, tamarillo, chili pepper, shishito pepper, habanero, bell pepper, paprika, colored bell pepper, pumpkin, zucchini, cucumber, bitter melon, white melon, bitter gourd, winter melon, chayote, loofah, bottle gourd, okra, strawberry, watermelon, melon, cantaloupe, etc.); grains such as corn; and (including beans such as green beans, peas, edamame, cowpeas, winged beans, broad beans, soybeans, sword beans, peanuts, lentils, sesame, etc.), leafy and stem vegetables (ice plant, angelica tree, mustard greens, cabbage, watercress, kale, komatsuna, salad greens, sunny lettuce, saisin, sanchu, shandong cabbage, shiso, garland chrysanthemum, water shield, white greens, celery, tatsoi, radish, etc.) Leafy vegetables such as radish, mustard greens, lettuce, bok choy, pickled mustard greens, rapeseed blossoms, Nozawana, Chinese cabbage, parsley, spring greens, Swiss chard, spinach, henbit, mizuna, green chickweed, small chickweed, cow chickweed, Mibuna, Mitsuba, Brussels sprouts, molokhia, leaf lettuce, arugula, lettuce, wasabi greens, etc.; green onions, scallions, chives, leeks, asparagus, udo, kohlrabi, zha cai, bamboo shoots , stem vegetables such as garlic, water cabbage, green onions, scallions, and onions; flower vegetables such as artichokes, broccoli, cauliflower, edible chrysanthemums, rapeseed blossoms, butterbur sprouts, and myoga ginger; including sprouted vegetables such as sprouts, bean sprouts, and radish sprouts), root vegetables (turnips, radishes, daikon radish, wasabi, horseradish, burdock, Chinese artichoke, ginger, carrots, shallots, lotus root, lily bulbs, etc.);Sweet potatoes, taro, potatoes, Chinese yams (including Japanese yam, wild yam, and other root vegetables), various citrus fruits such as mandarins, apples, peaches, pears, European pears, bananas, grapes, cherries, gooseberries, raspberries, blueberries, raspberries, blackberries, mulberries, loquats, figs, persimmons, akebi, mangoes, avocados, jujubes, pomegranates, passion fruit, pineapples, bananas, papayas, apricots, Japanese apricot, Japanese plum, peach, kiwi fruit, quince, Japanese bayberry, chestnut, miracle fruit, guava, star fruit, acerola, hollyhock, bouvardia, godetia, evening primrose, stock, ornamental cabbage, lunaria, acidanthera, iris, gladiolus, California poppy, peperomia, calceolaria, snapdragon, torenia, primrose, cyclamen, ice plant, anthurium, calla lily, caladium, sweet flag Syngonium, Spathiphyllum, Diefenbachia, Philodendron, Cacti, Ajuga, Physostegia virginiana, Salvia, Begonia, Curcuma, Water lily, Portulaca, Violet, White Lace Flower, Setcreasea, Limonium monticola, Tradescantia virginiana, Impatiens, Eggplant, Petunia, Chinese Lantern Plant, Carnation, Dianthus, Dianthus, Gypsophila, Perennial Gypsophila, Catchfly, G Zummania, Strelitzia, Phlox, Oiran, Kyokanoko, Amaryllis, Chrysanthemum, Marguerite, Clivia, Cyrtanthus, Daffodil, Snowflake, Zephyranthes, Nerine, Crinum asiaticum, Eucharis, Lycoris, Agave, Celosia, Gomphrena, Morning Glory, Evolvulus, Cleome, Geranium, Kalanchoe, Scabiosa, Sweet Pea, Lupine, Borage; saForget-me-not, astilbe, saxifrage, agapanthus, Polygonatum odoratum, aloe, ornithogalum, Rohdea japonica, spider plant, hosta, black lily, gloriosa, colchicum, sansevieria, sandersonia, oyster beard, tulip, tulbaghia, German lily, dracaena, triteleia, Solomon's seal, New Zealand flax, fritillary, hyacinth, toad lily, daylily, lily, lily, alstroemeria, ruscus, Cypripedium macranthos, Calanthe, oncidium, cattleya, Examples of plants grown for their foliage include Colmanara, Bletilla striata, Cymbidium, Coelogyne, Dendrivium, Doritaenopsis, Nagoran, Paphiopedilum, Vanda, Birstechera, Phalaenopsis, Braunau, Miltonia, Exacum, Lisianthus, Gentian, Lantana, Rose, Cherry, Gerbera, etc.; and plants grown for their foliage include Sakaki, Cycad, Fern, Dracaena, Aspidistra, Monstera, Pothos, Compacta, Polyscias, Jungle Bush, Ligustrum, Beargrass, Pittosporum, etc.

[0049] The plant diseases that can be controlled by the present invention are not particularly limited, and include, for example, those mainly caused by fungi. Examples of pathogenic fungi include ascomycetes, basidiomycetes, flagellated fungi, oomycetes, and imperfect fungi. Examples of ascomycetes include powdery mildew fungi, with specific examples being strawberry powdery mildew fungi (Sphaerotheca aphanis) and tomato powdery mildew fungi (Oidium and Oidiopsis species). Examples of oomycetes include downy mildew fungi, with specific examples being cucumber downy mildew fungi (Pseudoperonospora cubensis). Examples of imperfect fungi include leaf mold fungi and gray mold fungi, with specific examples being tomato leaf mold fungi (Fulvia fulva) and tomato gray mold fungi (Botrytis cinerea). These are merely examples, and the present invention is not limited to these. [Examples]

[0050] [Example 1] We confirmed the disease control effect by irradiating only the area near the top of the stems of mini tomatoes with near-infrared light.

[0051] The near-infrared light irradiation device used was a handheld type, as shown in the photograph in Figure 2, with a light source unit 10 at the tip of a rod 11. The light source unit 10 has 10x10 LEDs mounted in an area of ​​70mm x 70mm, and its effective irradiation range is 70mm x 70mm. Here, the effective irradiation range is the range of the area on the irradiated object that receives near-infrared light when the irradiated object is irradiated with near-infrared light using the light source unit 10. The wavelength of the near-infrared light irradiated from the irradiation device was set to 800-900nm (peak 850nm).

[0052] Healthy mini-tomato plants were planted in a trellis-style arrangement in the soil of a greenhouse with sunlight (August 4, 2021, Japan), and near-infrared light irradiation was applied to three groups (control group, example test group, reference group, with n=10 plants in each group). Specifically, mini-tomato plants that had not yet budded or flowered were planted, and near-infrared light irradiation was applied from the time of planting. The conditions for near-infrared light irradiation are shown in Table 1 below. As shown in Table 1 below, the irradiance was 300 W / m². 2 The irradiation time per location (70 mm x 70 mm) was set to 1 second, which satisfies the conditions of equations 1, 2, and 3 in Figure 7. Irradiation was performed at a frequency of every two weeks, with the first irradiation occurring on the day of planting (a total of 7 times). The positions (P) of near-infrared light irradiation for each section are shown in the schematic diagram of Figure 3. In the example described above, irradiation was performed only near the stem apex (growing point). In the reference section, in addition to the area near the stem apex, irradiation was also performed on the leaves directly above the inflorescence (compound leaves just above the fruit). That is, when the first inflorescence (i.e., the first inflorescence) appeared after planting, irradiation was performed at two locations: the stem apex and the leaves directly above the first inflorescence. When the second inflorescence appeared, irradiation was performed at three locations: the stem apex and the leaves directly above both the first and second inflorescences. The number of irradiation sites was increased to five in accordance with growth. Since mini tomato flower clusters typically appear every three leaves, this method was used to evenly irradiate the entire plant in the reference section. Compound leaves refer to a condition where many small leaves are clustered together to form a single leaf, such as the leaves of a tomato plant.

[0053] [Table 1]

[0054] Then, on October 28, 2021, 15 days after the final 7th irradiation, for each test plot, the compound leaves on the lowest branch (the branch closest to the roots) of each plant were collected as one sample, and the degree of disease incidence of leaf spot was evaluated by visual observation based on the following evaluation criteria (10 samples per test plot). From the obtained evaluation index, the degree of disease incidence was calculated using the following formula, and from the obtained degree of disease incidence, the control value was calculated using the following formula (n=10). The control value is an indicator that represents the control effect of pesticides and other control materials. Generally, a value of 10 or higher is considered to indicate a control effect, and a value of 50 or higher is considered to indicate a strong control effect equivalent to that of chemical pesticides.

[0055] (Criteria for evaluating the severity of the disease) Disease incidence index 0: No lesions are observed on the surface of compound leaves. Disease incidence index 1: Lesion area percentage on the entire surface of compound leaves is less than 5%. Disease incidence index 2: The percentage of lesion area on the entire surface of the compound leaf is 5% or more and less than 25%. Disease incidence index 3: The percentage of lesion area on the entire surface of the compound leaf is 25% or more but less than 50%. Disease incidence index 4: Lesion area percentage of the entire surface of compound leaves is 50% or more.

[0056] (Formula for calculating the severity of the disease) Disease severity = [Σ(number of samples per disease severity × disease severity index) ÷ (number of samples × 4)] × 100 (Formula for calculating control effectiveness) Control value = 100 - [(Disease severity in test plot or reference plot / Disease severity in control plot) × 100]

[0057] These results are shown in Figure 4 and Table 2. In Figure 4, (A) is a photograph of the lowest branch leaves of the mini-tomato plants in the control group, (B) is a photograph of the test group of the example, and (C) is a photograph of the lowest branch leaves of the reference group. As shown in Figure 4 and Table 2, in the control group (comparative example) which was not irradiated with near-infrared light, lesions were observed on many of the leaves of the lowest branches, which are prone to disease. In the reference group (reference example) in which near-infrared light was irradiated over the entire length of the mini-tomato plant, i.e., the entire plant, the occurrence of lesions on the leaves of the lowest branches, which are prone to disease, was controlled, and the disease severity was reduced compared to the control group. In contrast, in the test group (example), even though the irradiation of near-infrared light was limited to P1 near the stem apex, the occurrence of lesions was controlled, unlike in the control group. Furthermore, in the test group (example), the disease severity and control value, which indicate the degree of control, were better than those of the reference group (reference example) in which the entire plant was irradiated.

[0058] [Table 2]

[0059] In plants, disease lesions generally tend to occur in the lower parts of the plant, particularly on the first leaves to grow near the roots (leaves on the lowest branches). Therefore, as shown in the reference conditions, when controlling plant diseases, the entire plant, including the leaves on the lowest branches, is irradiated with near-infrared light. In contrast, in this invention, excellent results were obtained despite irradiating only the area near the stem apex, where the risk of disease lesions is considered low, with near-infrared light. These irradiation conditions are a discovery made by the inventors for the first time.

[0060] Furthermore, the control group, test group (example), and reference group were all cultivated simultaneously in the same greenhouse with sunlight. However, as mentioned above, the test group that was artificially irradiated with near-infrared light showed superior results. Although sunlight contains near-infrared light, the difference in results indicates that the effect in the test group was not obtained simply by non-artificial sunlight irradiation, but rather by selectively irradiating the shoot apex with near-infrared light.

[0061] [Example 2] Grapes were irradiated with near-infrared light to confirm the expression of disease resistance-related genes and the disease control effect. The same handheld irradiation device as in Example 1 was used for near-infrared light irradiation, and the irradiation conditions for the irradiated parts of the grapes were also the same as in Example 1.

[0062] (1) Expression of disease resistance-related genes In a vineyard, white grape varieties (Chardonnay) were grown using the trellis system shown in Figure 1, and black grape varieties (Eightgold) were grown using the cordon system (Japan, July). A control group (no irradiation, comparative example, 1 individual) and a test group (irradiated, example, 1 individual) were prepared for each. Near-infrared light was then irradiated to the area P1 near the apex (growth point) of the main stem of the grape individual in the test group (irradiation intensity 300 W / m²). 2 (Irradiation time 1 second, 1 time) On the other hand, no near-infrared light irradiation was performed on any part of the grape plants in the control group. One hour after near-infrared light irradiation, three leaves were collected from predetermined locations on both the test group and the control group grape plants. Figure 5 shows a schematic representation of the locations of the leaves collected from the grapes. As shown in Figure 5(A), for the trellis-trained plants, healthy leaves (lower leaves) were collected at a position approximately 1.5 m downward from the stem apex, i.e., near the lowest leaves. As shown in Figure 5(B), for the trellis-trained plants, healthy intermediate leaves were collected in the middle of the main branch, i.e., at a position approximately 2 m from the tip of the main branch (stem apex).

[0063] After freezing the collected leaves with dry ice, RNA was extracted, and the expression of the following disease resistance-related genes was analyzed using real-time PCR. The relative value (E1 / E0) of the gene expression level (E1) in the irradiated test group to the gene expression level (E0) in the unirradiated control group was calculated, and the increase in gene expression due to near-infrared light irradiation was evaluated accordingly.

[0064] (Disease resistance-related genes) • PAL (phenylalanine ammonia lyase) gene: A key enzyme gene in the biosynthesis pathway of phenylpropanoid compounds such as lignin. • PR5 (Pathogenesis-related protein) gene: A gene for an antimicrobial protein produced within a plant when it is infected with a pathogen.

[0065] These results are shown in Figure 6. Figure 6 is a graph showing the relative value (E1 / E0) of the gene expression level (E1) of the irradiated test group to the gene expression level (E0) of the unirradiated control group, indicating the degree of increase in gene expression due to near-infrared light irradiation. In Figure 6, (A) is the result for the trellis cultivation method, and (B) is the result for the shelf cultivation method.

[0066] First, as shown in Figures 6(A) and 6(B), when near-infrared light was irradiated only near the stem apex, all genes showed a significant increase in gene expression in the lower leaves, which are located far from the stem apex and are generally prone to disease. The inventors have discovered for the first time that by irradiating the area near the stem apex, which is located far from the lower leaves, rather than the lower leaves themselves, it is possible to increase the expression of various genes involved in disease control in the lower leaves. Furthermore, it has already been confirmed in Example 1 that irradiating the area near the stem apex with near-infrared light can prevent disease in the lower leaves on the opposite side.

[0067] (2) Disease control effect White grape varieties (Chardonnay) used for wine were grown in a vineyard using the trellis system shown in Figure 1(B) (July, Japan). Two groups were prepared: a control group (no irradiation, comparative example, 6 individuals) and an experimental group (irradiated, example, 6 individuals). The grape individuals in the experimental group were then irradiated with near-infrared light near the apex (growth point) of the lateral branches (side buds) that emerged from the tip of the main stem, as shown in Figure 8. The same irradiation device as in (1) above was used, and the irradiation conditions were once every two weeks with an irradiance of 300 W / m². 2 The irradiation time was 1 second, and the wavelength was 800-900 nm (peak 850 nm). On the other hand, the grape plants in the control group were not irradiated with near-infrared light at any point.

[0068] Then, after irradiating with near-infrared light under the above conditions for two months from the start of irradiation, the degree of downy mildew disease was evaluated by visual observation of the grapes in the test plot and the control plot. Specifically, as shown in Figure 8, all the leaves of the lateral branches that grew in the middle of the main branch (approximately 2 m from the tip of the main branch) when the main branch had grown to about 4 m were collected as one sample, and the degree of downy mildew disease was evaluated by visually observing the surface of the leaves based on the following evaluation criteria (6 samples per test plot). Then, the degree of disease was calculated from the obtained evaluation index using the following formula, and furthermore, the control value was calculated from the obtained degree of disease using the following formula (n=6). Note that the control value is an index that represents the control effect of pesticides and other control materials, and generally, a value of 10 or more is considered to indicate a control effect, and a value of 50 or more is considered to indicate a strong control effect equivalent to that of chemical pesticides.

[0069] (Criteria for evaluating the severity of the disease) Disease index 0: No lesions are observed on the surface of any of the leaves. Disease incidence index 1: Leaves with scattered lesions on the surface were observed, but no leaves with lesions covering more than half of the surface area were observed. Disease Index 2: One or two leaves are observed with lesions covering more than half of the plant's surface area. Disease Index 3: Three or more leaves are observed with lesions covering more than half of the plant's surface area. Disease index 4: Lesion covers more than half of the area of ​​all leaves.

[0070] (Formula for calculating the severity of the disease) Disease severity = [Σ(number of samples per disease severity × disease severity index) ÷ (number of samples × 4)] × 100 (Formula for calculating control effectiveness) Control value = 100 - [(Disease severity in test plot or reference plot / Disease severity in control plot) × 100]

[0071] These results are shown in Table 3. As shown in Table 3, a high disease incidence was observed in the control group (comparative example) that was not irradiated with near-infrared light. In contrast, in the test group (example), even though near-infrared light was only irradiated near the apex of the lateral branches at the tip of the main branch, the disease incidence was suppressed on the leaves of the lateral branches in the central part away from the tip of the main branch, demonstrating excellent control efficacy. In this example, the disease incidence and control efficacy were calculated as described above for the leaves of the lateral branches in the central part of the main branch, but it was visually confirmed that sufficient control effect was also observed on the leaves of other lateral branches.

[0072] [Table 3]

[0073] In both the (1) and (2) tests described above, cultivation was carried out outdoors under sunlight, but as mentioned above, the test plots that were artificially irradiated with near-infrared light showed superior results. Therefore, similar to Example 1, it was confirmed that the effect in the test plots was not obtained simply by non-artificial sunlight irradiation, but rather by selectively irradiating the shoot apex with near-infrared light.

[0074] [Example 3] We irradiated strawberries with near-infrared light to confirm the expression of disease resistance-related genes and the disease control effect.

[0075] (1) Expression of disease resistance-related genes We confirmed the expression of disease resistance-related genes by irradiating strawberry seedlings (variety name: Nyoho) with near-infrared light. Specifically, for strawberry seedlings (n=3) that had developed up to the 5th leaf in a greenhouse with sunlight, we irradiated the area near the stem apex with 850 nm near-infrared light once at an irradiance of 300 W / m², as shown in Figure 9. 2The plants were irradiated for 1 second (June, Japan). Figure 9 is a schematic diagram showing the area near the stem apex of a strawberry seedling. Thirty minutes after irradiation, the third leaf, which is a representative leaf for growth measurement and has not yet begun to age, was collected from the seedling, and the expression of the PAL gene was analyzed in the same manner as in Example 2(1). The collected third leaf is a leaf that has not yet begun to age, with the petiole and leaf area having reached their full growth stage. It is the third leaf counted in order of newness, with the most recent leaf that unfolded near the stem apex being considered the first leaf (newly grown first leaf). On the other hand, the third leaf was also collected from strawberry seedlings (variety name: Nyoho) (n=3) that were not irradiated with near-infrared light, and the expression of the PAL gene was analyzed in the same manner as in Example 2(1). Then, the relative value (E1 / E0) of the gene expression level (E1) of irradiated seedlings to the gene expression level (E0) of unirradiated seedlings was calculated, and the increase in gene expression due to near-infrared light irradiation was evaluated accordingly.

[0076] As a result, the relative value (E1 / E0) of the gene expression level (E1) in the irradiated seedlings was 3.5. Thus, a significant increase in PAL gene expression was confirmed even though near-infrared light was only irradiated near the stem apex and not the third leaf.

[0077] (2) Disease control effect Strawberry seedlings (variety name: Nyoho) were divided into two test plots and cultivated in a greenhouse using a Kagawa-type strawberry peat bag hydroponic cultivation system (started October 1, 2021). During this cultivation period, one of the irradiation plots (100 seedlings) received near-infrared light irradiation to the stem apex of each plant once every two weeks. The near-infrared light irradiation conditions were a wavelength of 850 nm and an irradiance of 300 W / m². 2 The irradiation time was 1 second, once per treatment. The other unirradiated group (100 seedlings) was cultivated similarly, except that near-infrared light irradiation was not performed. During the cultivation period, plants that died from anthracnose were removed. Irradiation was then carried out under the above conditions until 253 days after the start of cultivation (June 10, 2022), and the final fruit was harvested to end the cultivation. At the end of cultivation, the number of plants missing due to disease was counted for each test group, and the percentage of missing plants per 100 plants was calculated. These results are shown in Table 4.

[0078] [Table 4]

[0079] As shown in Table 4, irradiating the stem tips of strawberry seedlings with near-infrared light significantly reduced the rate of missing plants.

[0080] In both the (1) and (2) tests described above, cultivation was carried out indoors where sunlight entered the plants. However, as mentioned above, the test plot (Example) in which near-infrared light was artificially irradiated showed superior results. Therefore, similar to Example 1, it was confirmed that the effect in the test plot (Example) was not obtained simply by non-artificial sunlight irradiation, but rather by selectively irradiating the stem apex with near-infrared light.

[0081] [Example 4] We irradiated shishito peppers with near-infrared light to confirm the expression of disease resistance-related genes.

[0082] We irradiated three seedlings (n=3) of Shishito peppers (variety name: Aoi Shishito) with near-infrared light to confirm the expression of disease resistance-related genes. Specifically, as shown in Figure 10, we irradiated the area near the stem apex (growth point) of one of the two branches that branched off from the main stem of seedlings grown in a greenhouse with sunlight (Japan, November) with 850 nm near-infrared light at an irradiance of 300 W / m². 2 The plants were irradiated for 1 second, once. Figure 10 is a schematic diagram showing the area near the apex of a shishito pepper seedling. 60 minutes after irradiation, one fully developed leaf (X) was collected from the apex of the other branch (unirradiated), and one fully developed leaf (lowest leaf, Y) was collected from just below the branching point on the main stem. The expression of the PAL gene was analyzed in the same manner as in Example 2(1). On the other hand, the expression of the PAL gene was similarly analyzed for seedlings of the same species that had not been irradiated with near-infrared light in any part as described above. The relative value (E1 / E0) of the gene expression level (E1) of the irradiated seedlings to the gene expression level (E0) of the unirradiated seedlings was calculated to evaluate the increase in gene expression due to near-infrared light irradiation.

[0083] As a result, the relative gene expression level (E1 / E0) of the leaves near the apex of the unirradiated branch (X) in the irradiated seedlings was 17.0, and the relative gene expression level (E1 / E0) of the lowest leaf of the main stem (Y) in the irradiated seedlings was 4.1. Thus, by irradiating only the apex of one branch with near-infrared light, it was possible to increase the expression of disease resistance-related genes widely, even to the other unirradiated branch and further to the lowest leaf of the main stem.

[0084] This experiment was conducted in a greenhouse where sunlight entered, but as mentioned above, seedlings irradiated with near-infrared light showed superior results compared to unirradiated seedlings. Therefore, similar to Example 1, it was confirmed that the effect in the test plot was not obtained simply by non-artificial sunlight irradiation, but rather by artificially irradiating the shoot apex with near-infrared light.

[0085] Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples. Various modifications to the structure and details of the present invention can be made within the scope of the present invention as can be understood by those skilled in the art.

[0086] This application claims priority based on Japanese Patent Application No. 2022-45376, filed on 22 March 2022, and incorporates all of its disclosures herein. [Industrial applicability]

[0087] According to the present invention, for example, by irradiating the apex of the stem of a plant with near-infrared light, it is possible to effectively control diseases in cultivated plants without irradiating the entire plant. Therefore, according to the present invention, for example, it is possible to miniaturize the irradiation device used for near-infrared light irradiation and further reduce the amount of light energy consumed, thereby achieving cost reduction and labor savings in irradiation work.

Claims

1. The target area for irradiation with near-infrared light is set to the vicinity of the stem apex, including the stem apex of the plant, and near-infrared light is irradiated onto the stem apex of the plant. A method for controlling diseases, characterized in that the irradiation range of the near-infrared light is near the stem apex, including the stem apex.

2. The disease control method according to claim 1, wherein the area near the stem apex is within a distance of 1 / 3 or less of the total length from the tip of the stem to the position of the branch at the other end of the stem, in the direction of stem growth.

3. The disease control method according to claim 1 or 2, wherein the irradiation conditions for the stem apex or the vicinity of the stem apex satisfy formulas 1, 2, and 3. Formula 1: 644893X －１．８７３ ≧Y≧5901.9X －１．８５６ Formula 2: X≧1 Formula 3: Y≧0.01 In the above equations, X is the irradiance (W / m²). ２ ) where Y is the irradiation time (seconds).

4. The disease control method according to claim 1 or 2, wherein the wavelength of the near-infrared light is in the range of 800 to 1000 nm.

5. The disease control method according to claim 1 or 2, wherein the irradiation frequency to the shoot apex or the vicinity of the shoot apex is once a day to once a month.

6. A method for controlling plant diseases according to claim 1 or 2, wherein the plant disease is a fungal disease.

7. The disease control method according to claim 6, wherein the fungus is at least one selected from the group consisting of ascomycetes, basidiomycetes, flagellates, oomycetes, and imperfect fungi.

8. The method for controlling plant diseases according to claim 1 or 2, wherein the plant disease is at least one selected from the group consisting of powdery mildew, gray mold, leaf mold, anthracnose, and downy mildew.

9. The disease control method according to claim 1 or 2, wherein the plant is at least one selected from the group consisting of strawberries, tomatoes, cherry tomatoes, shishito peppers, bell peppers, paprika, eggplants, cucumbers, pumpkins, melons, watermelons, okra, cabbage, broccoli, cauliflower, Chinese cabbage, komatsuna, rapeseed, leeks, onions, asparagus, grapes, citrus fruits, peaches, pears, persimmons, cherries, chrysanthemums, roses, carnations, and lisianthus.

10. The disease control method according to claim 1, wherein the area near the stem apex is, with reference to the flower cluster closest to the stem apex, the region closer to the stem apex than the flower cluster closest to the stem apex, or the region closer to the stem apex that includes the flower cluster.

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