ALGICIDAL, ALGISTATIC, HERBICIDAL AND HERBISTATIC TREATMENT OF WATER

Abstract

A use of a composition comprising gallic acid as an active ingredient for an algicidal, algistatic, herbicidal or herbistatic treatment of an aquatic bottom stratum of water by the controlled release of the active ingredient. The invention also concerns the processes for manufacturing this composition. Another object concerns a method for treating an aquatic bottom stratum.

Claims

1. A use of a composition comprising gallic acid as an active ingredient wherein gallic acid is associated with one or more excipients selected from the following groups: (1) a binder product selected from the group consisting of wheat flour, soluble starch or rosin, (2) a gelling product selected from the group consisting of agar-agar, alginates, carrageenan, pectin, chitosan, cellulose or gelatin, (3) a thickening product selected from the group consisting of gum arabic, guar gum or xanthan gum, (4) a swelling and disintegrating product selected from the group consisting of bentonite or smectite, and (5) an effervescent product selected from the group consisting of bicarbonates, wherein gallic acid is in encapsulated or compacted form, and wherein the content of excipients is comprised between 50% and 5% of the total weight of the composition, for an algicidal or algistatic, treatment of akinetes at an aquatic bottom stratum of water by the controlled release of the active ingredient, wherein the use comprises contacting the composition with the aquatic environment to be treated, the composition being deposited on the aquatic bottom, being gradually dissolved by releasing gallic acid for a few days to a few weeks preferably in an aquatic bottom stratum of water having a height of at most 30 cm, more preferably at most 20 cm, in particular at most 15 cm.

2. The use of a composition according to claim 1 wherein gallic acid is associated with at least one phenolic acid or polyphenol selected from the group consisting of pyrogallic acid, ellagic acid, tannic acid, gallotanic acid, caffeic acid, quercetin, resveratrol, resorcinol, catechol, scopoletin or at least one alkaloid selected from gramine and hordenine.

3. The use of the composition according to claim 1, wherein the density of the composition is greater than 1 kg/dm3, preferably greater than 1.05 kg/dm3 and more preferably greater than 1.1 kg/dm3.

4. The use of the composition according to claim 3, wherein the excipients are preferably selected from two excipients belonging to two distinct groups, and preferably the excipients are chosen from the groups (1) and (3).

5. The use of the composition according to claim 1, being in the form of granules, balls or capsules of an average mass between 1 and 100 g, preferably between 2 and 50 g, more preferably between 10 and 30 g for the balls and between 2 and 5 g for the granules and the capsules.

6. The use of the composition according to claim 1, wherein gallic acid content is comprised between 50% and 95% of the total weight of the composition, preferably between 70% and 90% of the total weight of the composition, and more preferably between 75% and 85% of the total weight of the composition.

7. The use of the composition according to claim 1, wherein the content of excipients is comprised between 30% and 10% of the total weight of the composition, and more preferably between 25% and 15% of the total weight of the composition.

8. The use of the composition according to claim 1, wherein the concentration of total gallic acid in the aquatic bottom stratum of water is controlled to values ranging from 0.05 mg/L to 500 mg/L, in particular to chronic toxic concentrations, such as concentrations ranging from 0.1 mg/L to 10 mg/L, preferably ranging from 0.2 mg/L to 5 mg/L, or in particular to acute toxic concentrations, such as concentrations ranging from 60 mg/L to 500 mg/L.

9. The use of the composition according to claim 8, of which at least one part of the algicidal or algistatic effect is obtained by coloration in an aquatic bottom stratum of water due to the formation of gallates of iron or other metals that shield against light rays.

10. A composition having an algicidal or algistatic effect on akinetes at an aquatic bottom stratum of water, the composition comprising, as an active ingredient, gallic acid associated with one or more excipients selected from the following groups: (1) a binder product selected from the group consisting of wheat flour, soluble starch or rosin, (2) a gelling product selected from the group consisting of agar-agar, carrageenan, pectin, chitosan, cellulose or gelatin, (3) a thickening product selected from the group consisting of gum arabic, guar gum or xanthan gum, (4) a swelling product selected from the group consisting of bentonite or smectite, and (5) an effervescent product selected from the group consisting of bicarbonates, wherein gallic acid is in encapsulated or compacted form, wherein the content of excipients is comprised between 50% and 5% of the total weight of the composition and whose density is greater than 1 kg/dm3, preferably greater than 1.05 kg/dm3 and more preferably greater than 1.1 kg/dm3.

11. The composition according to claim 10, wherein gallic acid is associated with at least one phenolic acid or polyphenol selected from the group consisting of pyrogallic acid, ellagic acid, tannic acid, gallotanic acid, caffeic acid, quercetin, resveratrol, resorcinol, catechol, scopoletine or at least one alkaloid selected from gramine and hordenine.

12. The composition according to claim 11, wherein the excipients are chosen from two excipients belonging to two distinct groups, and preferably the excipients are selected from the groups (1) and (3).

13. The composition according to claim 10, being in the form of granules, balls or capsules of an average mass between 1 and 100 g, preferably between 2 and 50 g, more preferably between 5 and 30 g for the balls and between 2 and 5 g for the granules and the capsules.

14. The composition according to claim 10, wherein the content of gallic acid associated with at least one phenolic acid or polyphenol or alkaloid is comprised between 50% and 95% of the total weight of the composition, preferably between 70% and 90% of the total weight of the composition, and more preferably between 75% and 85% of the total weight of the composition.

15. The composition according to claim 10, wherein the content of excipient(s) is comprised between 30% and 10% of the total weight of the composition, and more preferably between 25% and 15% of the total weight of the composition.

16. A process for manufacturing a composition having an algicidal or algistatic effect on akinetes according to claim 10 in encapsulated form, comprising the step of conditioning gallic acid in a water-degradable hard-shell capsule selected from gelatin or starch.

17. The process for manufacturing a composition having an algicidal or algistatic effect on akinetes in compacted form according to claim 10, preferably in the form of granules or balls, comprising the steps of: mixing the at least one phenolic acid or polyphenol or alkaloid with one or more excipients selected from the following groups: (1) a binder product selected from the group consisting of wheat flour, soluble starch, or rosin, (2) a gelling product selected from the group consisting of agar-agar, alginates, carrageenan, pectin, chitosan, cellulose or gelatin, (3) a thickening product selected from the group consisting of gum arabic, guar gum or xanthan gum, (4) a swelling and disintegrating product selected from the group consisting of bentonite or smectite, and (5) an effervescent product selected from the group consisting of bicarbonates, and compressing the mixture with the excipients(s) to form compacted granules or balls.

18. The process according to claim 17 comprising the additional step of adjusting the particle size of the granules by grating the balls in a grater granulator then screening.

19. A method of algicidal or algistatic treatment of akinetes of an aquatic bottom stratum comprising contacting the composition according to claim 10 with the aquatic environment to be treated, the composition being deposited on the aquatic bottom, being gradually dissolved by releasing gallic acid for a few days to a few weeks preferably in an aquatic bottom stratum of water having a height of at most 30 cm, more preferably at most 20 cm, in particular at most 15 cm.

20. The method of algicidal or algistatic treatment according to claim 19, wherein gallic acid forms a coloration in an aquatic bottom stratum of water in the form of gallates of iron or other metals that shield against light rays.

Description

DESCRIPTION OF THE FIGURES

[0149] Other particularities and features of the invention will emerge from the detailed description of some advantageous embodiments presented below, by way of illustration, with reference to the appended figures. These show:

[0150] FIG. 1: is a photo of balls, granules (a) and a capsule (b) comprising 79.4% gallic acid, 13.9% guar gum and 6.7% starch.

[0151] FIG. 2: are photos showing the herbicidal effect of gallic acid compacted with guar gum and starch on Nuttall's waterweed in comparison with an untreated control Nuttall's waterweed.

[0152] FIG. 2a represents the control foot with, in the center, the main stem, its terminal bud and an axillary bud. On either side of the main stem, two secondary stems formed by the growth of two axillary buds can be seen.

[0153] FIG. 2b represents necrotic waterweed stems with deposits of gallate of iron on the surface of the plant and inside the cells.

[0154] FIG. 2c represents a detail of a control stem apex.

[0155] FIG. 2d represents the apex of the necrotic stem.

[0156] FIG. 3: shows the biocidal effect on Eurasian Watermilfoil (Myriophyllum spicatum); on the left, control individual; on the right, individual treated.

EXAMPLES

[0157] Preparation of the Gallic Acid Composition and Preparation of the Balls or Granules

[0158] For example, for the treatment of rooted hydrophytes, the active substance comprising gallic acid is conditioned in the form of balls (average weight of 15 g) obtained by compression (slugging) of a mixture with various excipients allowing release kinetics of the active substance. The granules can be obtained by grating the balls according to a desired particle size and the capsules are obtained by encapsulating the active substance in a hydrodegradable hard-shell capsule (FIG. 1).

[0159] The immersion of the balls, granules or capsules takes place during the period of resumption of activity of the aquatic plants, in spring, during budding from rooted and perennial parts. Another application may be performed in case of incomplete water weed cutting or lifting with the effect of blocking a regrowth from the buds remaining on the stems below the cutting height of about 30 cm and from the remaining rhizomes. The treatment is effective within a bottom stratum created by one of the excipients. This protocol allows an early attack of the hydrophyte with a treatment restricted to a volume of bottom water limited to a thickness of 10 to 20 cm whereas at the maximum of the growth, the stems can reach the surface and exceed, according to the target species, the 4 m long with many buds attached along the length of the main stem.

[0160] The choice of excipient is made among the excipients allowing the release then the more or less rapid dissolution of the active substance in the aquatic environment. The main excipients that have been tested are starch, bentonite and guar gum:

[0161] Soluble starch allows disintegration of the granule or ball with contacting the gallic acid powder with water.

[0162] Bentonite allows swelling of the entire ball at the same time as cracking to its core which increases the exchange surface between water and the active substance.

[0163] The guar gum allows a progressive swelling of the ball from the surface to the core with a formation of a hydrogel sticking the ball to the substrate.

[0164] The quantity of balls, with an average weight of 15 g, to be immersed per m.sup.2 is a function of the density of the population of hydrophytes to be treated. It is necessary to achieve, for a chronic toxicity effect, a concentration of gallic acid and its gallates of at least a few mg/L over a period of 4 to 6 weeks. This contact time between the active substance and the plant corresponds to the time taken by the buds to reach a length of 20 cm. This protocol allows to take place in chronic toxicity and not in acute toxicity. An on-site prospection at the beginning of spring growth allows to choose the most appropriate formulation for the site to be treated.

[0165] The number of 15 g balls to be immersed varies from 1 to 3 per m.sup.2 depending on the concentration of gallic acid relative to those of the different excipients.

[0166] In order to monitor the evolution of active substance concentrations in bottom, two different methods of analysis were used: HPLC-UV for the analysis of non-chelated gallic acid and UV-visible spectrophotometry for the analysis of gallates of iron (III). The results provided are those obtained by HPLC in the laboratory and those obtained by spectrophotometry in the laboratory and in the field.

[0167] Protocol of Analysis of Gallic Acid from Gallates of Iron.

[0168] The knowledge, on-treated site, of gallic acid concentrations is obtained by an indirect method by causing, by addition of a ferric chloride solution in a water sample of the treated site, the quick formation in few minutes of the gallates of iron (III). The respect of the ratio gallic acid/FeCl3 of 3:2 allows obtaining the maximum absorbance at 625 nm. Obtaining, from reference scale, the equations of the regression lines allows deducing, in the field, the concentration of gallic acid at the source of the formation of gallates. These regression lines are obtained as a function of the salting-out time of gallic acid and the temperature.

[0169] Results on Natural Site.

[0170] The pond of the municipality of Bousse (France) is a former sandpit of 2 hectares in North/South orientation water, of an average depth of 2.50 m with a maximum of 3.50 m; distant from the course of the Moselle of about 15 m with episodes of flood which brought in the gravelpit in addition to the conventional species of a water classified in 2nd category, three species of fish in course of colonization: the catfish, the goby and the catfish. Since 2010, the Fishing Society La Sander has been observing an invasion of hydrophytes and has practiced water weed cutting and grubbing in 2014 and 2015 with the known harmful consequence of an intense propagation by cutting. The treated surface is 1000 m.sup.2 namely 50 m of bank (pseudo-dyke) on 20 m distance to this bank. This surface is actually a rectangular surface with 2 sides on the bank.

[0171] Four successive sectors (SA1 to SA4) were marked by laying buoys on the open water side and by stakes on the 20 m bank. Two formulations were tested namely granules (SA2, SA4) or balls (SA1, SA3) with the active substance associated with two excipients, namely guar gum or soluble starch.

[0172] The quantity of granules or balls to be used per area of 1 m.sup.2 was calculated to obtain a theoretical maximum active substance concentration of 200 mg/L in a bottom stratum of water of 10 cm thick and in a short time. A control of concentrations was carried out. This control showed that the use of excipients allowed a delayed and slow salting-out of the active substance which caused the maintenance for several weeks of low concentrations. The toxicity generated is therefore a chronic toxicity and not an acute toxicity.

[0173] Result of Genic Acid Concentrations in Bousse Water Samples Taken at 30 Cm from the Bottom and at Different Time Periods (4 h, 6 h and 48 h).

TABLE-US-00001 TABLE 1 Sector 4 h 6 h T48 h SA1 <0.05 mg/L <0.05 mg/L <0.05 mg/L SA2 <0.05 mg/L <0.05 mg/L <0.05 mg/L SA3 <0.05 mg/L <0.05 mg/L 0.172 mg/L SA4 <0.05 mg/L <0.05 mg/L 0.213 mg/L

[0174] The gallic acid concentrations released from the balls and granules, solubilized in the water of the site and not chelated are, at the bottom and during the 48 hours following the treatment, mainly below the threshold of detection by HPLC-UV which is 0.050 mg/L. This threshold is only exceeded, 48 hours after the treatment, in sector SA3 and SA4 in the samples of bottom water. These gallic acid concentrations are referred to as residual. Gallic acid concentrations at the surface are always below the threshold of detection by HPLC-UV.

[0175] Result of Total Gallic Acid Concentrations in Bousse Water Samples Taken at 30 cm from the Bottom and at Different Time Periods (4 h and 48 h).

[0176] The term total gallic acid refers to the sum of residual gallic acid concentrations with those of chelate gallic acid (gallates of iron).

TABLE-US-00002 TABLE 2 Sector SA4 - Granules 4 h 48 h Gallates 2.837 mg/L 4.605 mg/L Residual Gallic Acid <0.050 mg/L 0.213 mg/L Total Gallic Acid 2.837 mg/L 4.818 mg/

[0177] The release of the active substance from balls (SA3) or granules (SA4) is therefore slow and allows exerting an algicidal, algistatic, herbicidal or herbistatic action on chronic exposure over several weeks with an impact limited to the bottom stratum of water. These low but effective concentrations allow limiting the algicidal, algistatic, herbicidal or herbistatic action to the target organisms (hydrophytes) and respecting non-target organisms.

[0178] Evaluation of the Algicidal, Algistatic, Herbicidal or Herbistatic Effect of the Treatment on Hydrophytes.

[0179] The aim of the treatment being a slowing down of the growth (preventive effect) or a destruction of hydrophytes during the spring period of recovery of growth (curative effect).

[0180] The evaluation of the effects of the active substance on the hydrophytes as a function of the treated sectors and the nature of the excipient used successively concerns:

[0181] The effect of the active substance on the stems, the terminal and axillary buds of waterweed (Elodea Nuttallii) at 48 h and at 3 weeks depending on the excipient used (FIG. 2).

[0182] The effect of the active substance on the other hydrophytes since the waterweed represents 91% of the stand of hydrophytes, Eurasian watermilfoil (Myriophyllum spicatum) 5% and Ceratophyll (Ceratophyllum cornutum=C. demersum) 4%.

[0183] The theoretical quantity of active substance that can be released from balls or granules is the same in all cases, the excipient used does not have an algicidal, algistatic, herbicidal or herbistatic effect and is of food grade.

[0184] Evaluation of the Algicidal, Algistatic, Herbicidal or Herbistatic Effect on the Stems and their Terminal Bud at 48 h and at 3 Weeks According to the Formulation Used.

[0185] A control sector and each treated sector are subject to sampling from a batch of hydrophytes with a 4 m telescopic rake. After gentle washing in the water of the site, 21 to 25 feet of waterweed with their root, the main stem, the secondary stems and the axillary buds are randomly taken and are subject to measurements and observations concerning the existence, location and importance of necrosis.

[0186] Results after 48 Hours of Treatment:

TABLE-US-00003 TABLE 3 Site: Bousse Duration of treatment: 48 h Terminal Main stem with terminal bud bud Necrosis Necrosis Station Excipient N1 L1 N1 Ln1 % n1/N1 % necrotic L N2 % n2/N1 StREF 0 25 695 11 147 44.00% 21.15% 0 0.00% SA1 Boul 25 686 14 104 56.00% 15.16% 4 16.00% Exc1 SA2 GR Exc2 25 553 8 36 32.00% 6.51% 2 8.00% SA3 Boul 25 625 13 178 52.00% 28.48% 6 24.00% Exc2 SA4 GR Exc1 25 580 20 391 80.00% 67.41% 19 76.00% Legend of abbreviations: Ni: Number of feet studied. L1: Total length of stems of N1 feet including their terminal bud (in cm). n1: number of feet with necrosis. Ln1: Total length of stem with necrosis (in cm). % n1/N1: % of feet with necrosis among the N1 number of feet studied. % necrotic L: % necrotic stem length (Ln1/L1) 100. n2: Number of feet with necrotic terminal bud. % n2/Ni: % of feet with one necrotic terminal bud among all the terminal buds. These are as numerous as the stems studied.

[0187] Result after 3 Weeks of Treatment:

TABLE-US-00004 TABLE 4 Site: Bousse Duration of treatment: 3 weeks Main stem with terminal bud Terminal bud Necrosis Necrosis Station Excipient N1 L1 N1 Ln1 % n1/N1 % necrotic L N2 % n2/N1 StREF 0 25 700 0 0 0.00% 0.00% 0 0.00% SA1 Boul 21 460 21 406 100.00% 88.26% 21 100.00% Exc1 SA2 GR Exc2 24 735 24 649 100.00% 88.30% 24 100.00% SA3 Boul 21 530 21 462 100.00% 87.17% 21 100.00% Exc2 SA4 GR Exc1 23 540 23 424 100.00% 78.52% 23 100.00%

[0188] The effectiveness of the treatment for % of feet having a necrosis relative to the number of feet studied at 3 weeks is identical and of 100% regardless of the formulation used. No necrosis was observed in individuals of the control group.

[0189] The effectiveness of the treatment concerning the % of necrosis of the terminal bud at 3 weeks is identical and 100% regardless of the formulation used.

[0190] The effectiveness of the 100% treatment, identical to 3 weeks, on the number of necrotic feet and on that of the necrotic terminal buds indicates that after this time of presence the necrosis affects the entire plant.

[0191] Partial Conclusions of the Algicidal, Algistatic, Herbicidal or Herbistatic Effect of the Treatment on the Stems and their Terminal Bud at 48 h and at 3 Weeks.

[0192] After 48 hours of treatment the use of the composition SA4 is most effective with 80% of the stems having a necrosis affecting 67.4% of their length. After 3 weeks the number of feet with necrosis is 100% regardless of the formulation but the % of necrotic stem length is significantly lower with the composition SA4 than for the other formulations (78.5% against an average of 87.9% for the groups SA1 to SA3). The explanation proposed is a too rapid dilution of the active substance delivered in the form of granules containing the excipient 1. Ball compression with the same excipient (starch) allows a slow dissolution and it is the same with the balls or granules associated with the excipient 2 (starch and guar gum). These three formulations provide the same results after 3 weeks with 100% of the stems having a necrosis on an average of 87.9% of their length.

[0193] At 48 h and in the presence of the composition SA4, the terminal bud affected concerns 76% of the feet; the other formulations have a significantly lower efficiency with an average of 16% of necrotic terminal buds. After 3 weeks, necrosis of the terminal bud affects 100% of the feet regardless of the formulation.

[0194] In order to refine the choice of the best formulation, the algicidal, algistatic, herbicidal or herbistatic effect on the axillary buds, which are the source of the multiplication of secondary branches carried by the main stem of waterweed, should be studied in parallel.

[0195] Evaluation of the Algicidal, Algistatic, Herbicidal or Herbistatic Effect on the Other Hydrophytes: Eurasian Watermilfoil (Myriophyllum spicatum) and Ceratophyll (Ceratophyllum cornutum).

[0196] Two other hydrophytes are associated with Nuttall's Waterweed, Eurasian watermilfoil (Myriophyllum spicatum), and Ceratophyllum (Ceratophyllum cornutum), which represent respectively 5% and 4%, of the stand.

[0197] Given the low presence of these two species relative to the Waterweed dominance, the evaluation of the effectiveness of the treatment was done by grouping the data of all individuals harvested on all the treated sectors and regardless of the formulation used.

[0198] The Watermilfoil stems can reach 1.50 m in length with an average of 0.87 m for the studied stems. The average biocidal effectiveness is 97.3% for the stems including the terminal bud. The average number of axillary bud is 1 per stem with 100% biocidal effectiveness. The biocidal effect on the Eurasian Watermilfoil (Myriophyllum spicatum) is shown in FIG. 3; on the left, control individual; on the right, treated individual.

[0199] Hornwort stems can reach 1.10 m in length with an average of 0.69 m for the studied stems. The algicidal, algistatic, herbicidal or herbistatic effectiveness is on average 52.8% for the stems including the terminal bud. The average number of axillary buds is 2.2 per stem with 47.3% algicidal, algistatic, herbicidal or herbistatic effectiveness.

[0200] The treatment is therefore active on the two species of hydrophytes associated with Waterweed with a higher effectiveness for Watermilfoil compared to Hornwort.

[0201] General Conclusion on the Evaluation of Algicidal, Algistatic, Herbicidal or Herbistatic Effect of the Treatment.

[0202] Regardless of the formulation used, the algicidal, algistatic, herbicidal or herbistatic effectiveness of the treatment can be evaluated after three weeks of effect.

[0203] Concerning the feet with their terminal bud, the consideration of the criteria of % of feet and % of necrotic terminal buds does not allow promoting a formulation over the others because the algicidal, algistatic, herbicide or herbistatic effectiveness is identical and 100%. The consideration of the criterion of the necrotic stem length allows distinguishing the formulation in granules containing the excipient of the composition SA4 from the other three because of its lower effectiveness (78.5% against an average of 87.9%).

[0204] Concerning axillary buds, which play a major role in biomass increment capacity and propagation by cutting, the consideration of the criterion of % of necrotic buds allows distinguishing the granules (composition SA2 and SA4) from the balls (composition SA1 and SA3) because of their lower effectiveness, namely on average 31.8% against 42.3%.

[0205] Considering in last criterion the % of feet bearing necrotic axillary buds the treatment with balls containing the excipient of the composition SA1 differs from that with balls containing the excipient of the composition SA3 because of its reduced effectiveness namely 33.3% against 42.86%.

[0206] Independently of the formulation used, the treatment is of an overall efficiency (stem and buds) of 100% on Watermilfoil and of an overall efficiency (stem and buds) of 50% on the Hornwort.