FR2775869A1 - Cauterization of vine pruning wounds, also applicable to trees, shrubs, or woody plants - Google Patents

Abstract

Method for treating wounds on trees, shrubs or woody perennial plants using cauterization, is new. The method consists of the following steps: (a) The wound is surface-disinfected by an intense optical source (3), until such a temperature (T) is reached that bacteria, fungi and molds are destroyed. (b) The wound is then sealed using the same source on a surface layer. (c) Its physical (and chemical) state is changed, isolating the wound from the exterior. An Independent claim is also included for a portable device used to carry out the process, comprises an energy source (1) to power the intense optical source (3), which has a light pipe or optical fibers (4) directing energy onto the surface to be treated, under the direction of a regulating control system (5).

Description

METHOD FOR TREATING A WAIST WOUND OF A

  TREE, BUSH OR PERENARY PLANT

  LAMINATOR, APPLICATION OF THIS PROCESS TO A SORTING

  PRUNED VINE AND DEVICE FOR IMPLEMENTING

OF THE PROCESS

  The present invention relates to a method of treating a pruning wound of a tree, shrub or woody perennial, the application of this method to the treatment of a vine shoot.

  pruned vine, and a device for implementing this process.

  In the following, we will refer more particularly to the treatment of vine shoots, but the invention applies equally well to

  other forms of living cut wood.

  When the vines are pruned, the cutting tool, for example pruning shears, can deposit bacteria or microorganisms on the wound surface of the pruned vine shoot. Fungi and mold can also form on this wound. To prevent these infectious elements from entering the vineyard intimately

  by these wounds, it is necessary to disinfect them.

  However, this simple disinfection is not in itself sufficient, because later, bacteria or microorganisms can be entrained by the water which comes into contact with the wound and aerosols or spores can be deposited on the wound, thus penetrating into the exposed "pores" of the wound which communicate with the channels intended to convey the sap in the branch. It is therefore necessary to seal this wound. Within the meaning of the invention, sealing means sealing against water, aerosols, bacteria, spores and microorganisms. The object of the invention is therefore to eliminate the aforementioned drawbacks and to propose a treatment for a pruning wound of a tree, a shrub or a woody perennial plant, which allows disinfecting and

to seal this wound.

  To this end, the subject of the invention is a method for treating a pruning wound of a tree, a shrub or a woody perennial plant, characterized in that it consists in: - disinfecting the wound , by applying directly or indirectly a radiation produced by an intense optical source on the surface of the wound in order to generate a heating of said surface up to a sufficient temperature preferably higher than C to destroy bacteria, fungi and molds, and - to make said wound watertight, by applying radiation produced by the same source on a layer of material at or near the surface of the wound in order to cause a change

  physical state of said layer which then isolates the wound from the outside.

  In a first embodiment, the radiation is applied continuously and directly to the surface of the wound to successively cause the destruction of bacteria, fungi and other molds and the carbonization of a surface layer of the wood.

  to seal the exposed pores of the wound surface.

  Advantageously, the time of exposure to radiation and the power density of the optical source are determined so as to reach a temperature above 500 C at the surface of the wound and

  a depth of the order of a millimeter.

  In another embodiment, the sealing operation of the wound consists in depositing a material capable of forming a thin waterproof layer over the entire surface of the wound and then applying radiation on said layer to harden it and thus isolate pores

  exposed from the outside.

  In a first variant, the disinfection operation consists in applying radiation directly to the surface of the wound so as to reach a temperature sufficient to destroy bacteria, fungi and other molds and then to carry out the operation

  of the aforementioned seal on the wound thus disinfected.

  In another variant, the radiation is applied to the layer of material previously deposited so that the heat transmitted at the interface between the surface of the wound and the said layer causes heating to a temperature sufficient to destroy bacteria, fungi and other molds in order to

  disinfect the wound during the sealing operation.

  Advantageously, the layer of material is a hot-polymerizable product chosen from the group consisting of a silicone-based solution, an acrylic adhesive paste and a resin.

  epoxy or any other product suitable for different applications.

  According to another characteristic, the time of exposure to radiation and the power density of the optical source are determined so that the hot-polymerizable layer reaches a temperature between 60 C and 300 C, preferably of the order of

200 C.

  Advantageously, the optical source is a laser source, chosen for example from the assembly consisting of a CO2 laser source, a

  source with ultraviolet radiation, from a source with infrared radiation

red, and a laser diode.

  The invention also relates to the application of the aforementioned method to the treatment of a pruned vine shoot, the diameter of the cut of which is

between 5 and 30 mm.

  The subject of the invention is also a portable device for implementing the aforementioned method, characterized in that it comprises an energy source for supplying an intense optical source which is arranged to produce radiation directed through a guide waves or an optical fiber towards the surface of the wound to be treated, under the action of a control and regulation system of the

  power density of the optical source.

  In a particular embodiment, the device may further comprise a tank of hot-polymerizable and waterproof product, associated with a spray head or of application of this product on the surface of the

wound to be treated.

  This device could also be mounted on a mechanical pruner, to treat the wound immediately after cutting the

vine shoot.

  Advantageously, the optical source has a power density of between approximately 25 and 50 W / cm2 and the radiation is applied for a period of a few seconds, preferably between 1 and 4

seconds.

  To better understand the object of the invention, we will now describe it by way of purely illustrative example and not

  limiting, an embodiment shown in the accompanying drawing.

  In this drawing: FIG. 1 is a functional block diagram of the device of the invention; - Figure 2 is a graph showing the evolution of the temperature as a function of the duration of exposure to a laser beam, for different depths from the wound surface of a strain treated by the method of the invention ; - Figure 3 is a graph showing the change in temperature as a function of the duration of exposure to a laser beam, for different intensities of the laser source of the device of the invention; and - Figures 4 to 6 are photographic views partially representing the wound of a strain respectively before laser disinfection, after disinfection, and after polymerization of a layer

  polymer, according to an alternative embodiment of the process of the invention.

  The invention consists in treating the wound of a vine stump using laser radiation which is a means for spatially depositing localized energy on a surface. The lateral extension of this energy deposit can be controlled by acting on the convergence or divergence of the laser beam thanks to an appropriate optical system. The depth of deposition can also be controlled as a function of the wavelength of the radiation. Light incident on a surface can be absorbed, reflected or transmitted. When light is absorbed by the surface of an object, a rise in temperature and a diffusion of heat through the body of the object occur. For significant absorption and heating, the boiling point can

  be reached on the surface and a liquid or gaseous film is formed there.

  On the other hand, the molecular dissociation temperature can be reached, the chemical composition can then change and certain components can then escape in the form of vapor. More intense absorption of energy produces vaporization and / or sublimation. The resolution of the heat equation generated by the laser beam makes it possible to determine the ranges of laser power necessary to decontaminate the section of the vine shoots and to make them impervious to water and to microorganisms which are

  likely to harm the health of the plant.

  CO2 laser sources are interesting because the lengths

  waves produced are completely absorbed by organic matter.

  In other words, the power absorbed is practically identical to the incident power. The incident laser radiation, which is not reflected by the surface of the wood, crosses this surface and is transformed into heat within the material over a depth called skin thickness. A volume heat absorption is thus obtained. From the thermodynamic parameters of the wood, we have drawn, in Figure 2, three temperature curves corresponding to different depths from the surface of the section of a vine shoot, as a function of the time of exposure to laser radiation , and in FIG. 3, four temperature curves on the surface of the vine shoot section as a function of the power density of the laser and the time of exposure to radiation. Power density is the ratio of laser power (in Watts) to the opening area

  diaphragm (in cm2) of the laser beam.

  In FIG. 2, it can be seen that for a power density of the laser source of the order of 100 W / cm2 and an exposure duration of the order of 0.1 seconds, a surface temperature greater than 500 C, a temperature of the order of 300 C for a depth z of approximately 0.15 mm and a temperature of the order of 100 C for a depth z of approximately 0.3 mm. The temperature values, given for different depths from the surface of the vine shoot section, were measured along

the axis of the laser beam.

  In FIG. 3, it can be seen that for an exposure time of approximately 0.6 seconds, the surface temperature at all points of the vine shoot section is greater than 700 C for a power density I of the around 280 W / cm2, while for a period of approximately 1 second, the temperature is approximately 700 C for a power density I of the order of 190 W / cm2, approximately 400 C for a density power I of the order of 100 W / cm2 and around 100 C

  for a power density I of the order of 10 W / cm2.

  Experimental tests have shown that to obtain carbonization of the vine shoot section, in order to reduce the conditions favoring the development of microorganisms, a surface temperature above 500 C is necessary. From the curves of Figures 2 and 3, we can deduce that to cauterize a depth of the order of a millimeter, an exposure time of one to

  two seconds is sufficient with a power of approximately 100 W / cm2.

  The tests were carried out to verify experimentally that the carbonization by continuous radiation on the surface of the cut branches, ensures well the plugging of the channels as well as a disinfection of the surface at the time of the treatment. Samples with a diameter between 5 and 20 mm were used. The tests were conducted with a power density of up to 10 W / cm2 for an exposure time of 5 seconds. Analysis by optical microscopy of the samples treated with laser, shows changes in the appearance of the surface. Carbonization of the surface layer of the samples was observed from a power density of the order of 150 W / cm2 and obturation of the channels was obtained for a power density of the order of 300 W / cm2 for an exposure time of less than 0.3 seconds. Under these conditions, the

  depth of carbonization becomes substantial.

  However, for some samples with a diameter greater than 10 mm, the carbonization of the surface layer of the vine shoot has caused the appearance of cracks along the branch below the surface, which allows water and micro -organisms to penetrate

  in the stump, despite the obstruction on the surface of the canals.

  To solve this problem, in an alternative embodiment, a layer of tight material is deposited on the surface of the stump in order to prevent the laser radiation causing the appearance of cracks.

  in the branch by charring of the wound surface.

  In FIG. 4, a photograph of

  the wound 10 of a strain 11, whose tender heart 12 is visible.

  This wound 10 is first subjected to laser radiation with a power density of the order of 40 W / cm 2 for approximately one second, in order to carry out local preliminary disinfection of the surface. In the figure, a partial photographic view is shown of the wound 110 disinfected by laser, the heart 112 of which is charred slightly in

surface because it is softer.

  Then, a layer of waterproof product is applied to the surface thus disinfected 110, for example a layer of pasty product having a thickness of between 0.5 and 1 mm, or a fluid product.

  sprayed to a thickness of about 0.1 mm.

  The products which were used in the tests are - a silicone-based solution resistant to a temperature of 300 ° C. and packaged in the form of an aerosol, such a solution being commercially available under the name "Electrolube" DCA H, an acrylic adhesive having a pasty consistency and rapidly polymerizing under ultraviolet or infrared radiation, this adhesive preferably being red in color to facilitate the control of its application; an epoxy resin which polymerizes rapidly on contact with heat, such a resin being commercially available under the

denomination "Loc 360".

  The aerosol product was applied in one to three sprays.

  After application of the layer of waterproof material, laser radiation is directed onto the wound thus covered to cause polymerization of the layer of material. Solidification of the layer of material is thus obtained from a power density of the order of 5 W / cm2 for an exposure time of 2 to 4 seconds. If a silicone-based product known as DCA / 200 M is used, the power density of the laser source must be less than 100 W / cm2 to avoid decomposition of the product,

  because this product withstands a maximum temperature of 373 C.

  After this last laser treatment, a completely sealed wound surface 210 is obtained, as shown in the partial photographic view of FIG. 6. This treatment thus ensures prior surface disinfection, with the pores closed and

  sealing of the wound with the polymerized product.

  In another alternative embodiment, the preliminary step of

  disinfection of the wound by direct laser radiation is removed.

  This simplifies the treatment of the vine shoot and reduces the weight of the portable device, using batteries

  smaller power supplies.

  In this case, the aerosol product is deposited directly on the section without laser pre-treatment. The conditions for polymerization or solidification of the sprayed product have been

determined experimentally.

  The silicone solution requires thermal curing for it to solidify. The laser radiation must provide heat within the liquid layer deposited on the section of the branch. To determine the ideal heating temperature as well as the optimal power density, some preliminary tests were carried out. The major result of these tests is that below 50 C in the silicone layer, the curing is very slow and requires more than 3 minutes. On the other hand, the maximum temperature that this solution supports is, according to the manufacturer, 200 C, which limits the acceptable temperature range between about 60 and 200 C. Indeed, vaporization of the silicone layer on the surface of the sample is

  observed from a power density of the order of 200 W / cm2.

  To obtain such a temperature, laser radiation must be used with a power density between 5 and 100 W / cm2 for an exposure time of a few seconds. Of course, the higher the power density, the more the exposure time can be shortened. In addition, the heat transmitted to the layer of polymers must be sufficient to cause heating at the interface between said layer and the surface of the wound, so as to disinfect it. For this purpose, a surface temperature of around 230 C must be reached, which requires for example a power density of the order of 20

W / cm2.

  Tables 1 and 2 below summarize the experimental conditions and the results obtained on 32 samples covered with a sprayed silicone solution, without prior laser treatment of the wound surface. For all the samples, a layer of about 0.1 mm was deposited on the surface

  of the wound by performing three sprays.

Table 1

  N of Tnrico- Trico- Trico- Density Duration Number Number Energy echanderma derma derma of exposure- of repetition in J / cm2

  tillon à la à environ à more power tion in s tions spraying-

  surface 2 mm of 4 mm in-depth consumption deep in W-cm2 Laser C02 1 absence absence absence absence 2,04 5 I 3 10,2 2 presence presence presence 2,04 5 I 3 10, 2 3 absence absence absence 2.04 5 1 3 10.2 4 absence absence absence 2.04 5 1 3 10.2 absence absence absence 2.04 5 I 3 10.2 6 absence absence absence 2.04 10 1 3 204 7 absence absence absence 2, 04 10 I 3 20.4 8 absence absence absence 2.04 10 I 3 20.4 9 absence absence absence 2.04 10 1 3 20.4 absence absence absence 2.04 10 I 3 20, 4 11 presence presence presence 2,04 10 2 3 40,8 12 absence absence absence 2,04 10 2 3 40,8 13 absence absence absence 2,04 10 2 3 40,8 14 absence absence absence 2,04 10 23 40,8 absence absence absence 2, 04 10 2 3 40.8 Diode Laser 16 absence absence absence 15 5 1 3 75 17 absence absence absence 1 5 '5I 3 75 18 absence absence absence 15 5 1 3 75 19 absence absence absence 15 5, I 3 75

Table2

  N 'of Trico- Trico- Trico- Puissunco Duration Number Number Energy the echandema derma dewma total of repeti- of repetition of total tillobn la at about more than enW tion ens l tions pulveri- in J surface 2 mmn of 4mmde sations

deep- deep-

  deur deur | 12 V lOA lamp absence absence absence 60 5 1 3 300 21 absence absence absence 60 5 I 3 300 22 absence absence absence 60 5 1 3 300 23 absence absence absence 60 5 2 3 600 24 absence absence absence 60 1 5 2 3 600 absence absence absence 60 10 2 3 1200 26 presence presence presence 60 10 2 3 1200 27 absence absence absence 60 10 2 3 1200 28 absence absence absence 60 10 2 3 1200 29 absence absence absence 60 10 2 3 1200 absence absence absence 60 10 2 3 1200 31 absence absence absence 60 10 2 3 1200 The first fifteen samples were processed by a CO2 laser source, the beam opening of which has a diameter of approximately mm and is approximately 21 cm from the surface to be treated. It is found that only samples no 2 and 11 revealed the presence of a Tricoderma bacterium on the surface of the wound as at 2 mm or more than 4 mm deep. These two positive results can be explained by samples more seriously infected than normal. We can deduce from the experimental conditions on these samples that, for the same power density of 2.4 W / cm2, an exposure time of 5 seconds is sufficient, because with an exposure time of 10 seconds, the results are substantially identical. In addition, exposing the wound to laser radiation in one or two passes

  does not affect the quality of the results.

  Samples 16 to 19 were subjected to radiation produced by a laser diode having a power density of about 15 W / cm2. None of the samples tested revealed the

presence of bacteria.

  Finally, samples n 20 to 31 were subjected to an infrared radiation source having an intensity of 10A and a supply voltage of 12V. Here, only sample n 32 presents a result

  positive for the presence of Tricoderma bacteria, which is negligible.

  We also note that for the same power of the order of W, the increase in the exposure time beyond 5 seconds

does not improve results.

  Since the vine shoots are naturally exposed to climatic conditions, with an external temperature generally varying between - 10 C and + 40 C in extreme cases, to test the rigidity and the resistance of the layer of silicone polymerized by laser radiation, some samples were placed in a freezer at -15 ° C and in an oven at + 45 ° C. A microscopic inspection revealed the persistent presence of a thin transparent layer covering the open canals of the wound with the vine shoot. Thus, the vine shoot treated according to the invention is not only waterproof, but also resists variations in

temperature.

  Referring now to Figure 1, we will describe a particular embodiment of the device of the invention. This device comprises a power supply battery 1 coupled to an adapter 2 which is connected to an optical source 3, for example having a power density between 25 and 50 W / cm2. At the output of the optical source 3, there is provided a waveguide or an optical fiber 4 having a head 9 for shaping the radiating beam. A control and / or trigger system 5 is provided between the adapter 2 and the head 9. This system 5 can also make it possible to adjust the temperature to be applied at the level of the wound to be treated. We can also provide a security system to avoid

  any incident while handling the device.

  This device may further comprise a reserve 6 containing the product to be applied to the surface of the wound, the reserve 6 being connected by a flexible connection 7 to an application head 8 for a product.

  pasty or spray head for an aerosol product.

  Although the invention has been described in connection with particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these are within the scope of the invention.

Claims (12)

  1. A method of treating a pruning wound (10) of a tree, shrub or woody perennial plant (11), characterized in that it consists of - disinfecting the wound, by applying directly or indirectly radiation produced by an intense optical source (3) on the surface of the wound in order to generate a heating of said surface to a temperature (T) sufficient to destroy bacteria, fungi and molds, and - to render said sealed wound, by applying radiation produced by the same source (3) to a layer of material at or near the surface of the wound in order to cause a change   physical state of said layer which then isolates the wound from the outside.   2. Method according to claim 1, characterized in that the radiation is applied continuously and directly to the surface of the wound (10) to successively cause the destruction of bacteria, fungi and molds and the carbonization of a layer surface of the wood to seal the exposed pores of the wound surface. 3. Method according to claim 2, characterized in that the time (t) of exposure to radiation and the power density (I) of the optical source (3) are determined so as to reach a temperature (T) greater than 500 C at the wound surface and a   depth (z) of carbonization on the order of a millimeter.   4. Method according to claim 1, characterized in that the sealing operation of the wound consists in depositing a material capable of forming a thin waterproof layer over the entire surface of the wound and then applying radiation on said layer (210) to harden it and thus isolate the exposed pores of the wound from outside.   5. Method according to claim 4, characterized in that the disinfection operation consists in applying radiation directly to the surface of the wound (10) so as to reach a temperature (T) sufficient to destroy the bacteria, fungi and molds and then to implement the aforementioned sealing operation   on the wound thus disinfected (110).   6. Method according to claim 4, characterized in that the radiation is applied to the layer of material previously deposited so that the heat transmitted at the interface between the surface of the wound and said layer causes heating up to a temperature (T) sufficient to destroy bacteria, fungi and molds, in order to disinfect the wound during the operation sealing.   7. Method according to one of claims 4 to 6, characterized by the   the fact that the layer of material is a hot-polymerizable product chosen from the group consisting of a silicone-based solution,   an acrylic adhesive paste and an epoxy resin.   8. Method according to one of claims 4 to 7, characterized by the   fact that the time of exposure to radiation and the power density (I) of the optical source (3) are determined so that the heat-polymerizable layer reaches a temperature (T) between    C and 300 C, preferably around 200 C.   9. Method according to one of claims 1 to 8, characterized by the   fact that the optical source (3) is a laser source, chosen for example from the assembly consisting of a CO2 laser source, a source with ultraviolet radiation, a source with infrared radiation, and of a laser diode.   10. Application of the method according to one of claims 1 to 9,   to the treatment of a pruned vine branch (11), the diameter of the cutting is between 5 and 30 mm.   11. Portable device for implementing the method according to   one of claims 1 to 9, characterized in that it comprises a   energy source (1) for supplying an intense optical source (3) which is arranged to produce radiation directed through a waveguide or an optical fiber (4) towards the surface of the wound to be treated (10), under the action of a control and adjustment system (5) of the   power density (I) of the optical source (3).   12. Device according to claim 11, characterized in that it further comprises a reservoir (6) of hot-polymerizable and waterproof product, associated with a spray or application head   (8) of this product on the surface of the wound to be treated (10).