OA18998A - Utilisation d'un acide dicarboxylique pour lutter contre la croissance de plantes holoparasites ou hémiparasites - Google Patents

Abstract

L'Invention concerne l'utilisation d'un acide dicarboxylique comportant de 2 à 5 atomes de carbone pour lutter contre la croissance de plantes holo ou hémiparasites, ainsi que la souche Azospirillum brasiliense L4, déposée, sous le numéro 1-4830 auprès de la CNCM (Collection Nationale de Cultures de MicrOorganismes, France) capable de produire un acide dicarboxylique ayant une activité bioherbicide vis-à-vis du Striga et de l'orobanche.

Description

Use of a dicarboxylic acid to combat the growth of holoparasitic or hemiparasitic plants

The present invention relates to the technical field of the protection of agricultural crops (poaceae, solanaceae, brassicaceae, asteraceaë) vis-à-vis holoparasitic and hemiparasitic plants (that is to say which develop on the roots of their host plant) , of the order of Scrophulariales, and in particular of Striga and Orobanche. More specifically, the invention relates to the use of a dicarboxyic acid comprising from 2 to 5 carbon atoms or to a strain Azospiriiïum brasiiense L4, registered under the number 1-4830 with the CNCM to combat the growth of holo plants or hemiparasites.

Holoparasitic plants are non-chlorophyllous parasitic plants by nature and which must therefore take their organic matter from a host plant. Hemiparasitic plants are chlorophyll parasitic plants which only provide part of the synthesis of carbonaceous substances necessary for their development. These parasitic plants develop at the expense of their host by attaching to their roots via the formation of a haustorium (sucker) which leads to the establishment of a connection between the xylem conducting vessels of the host plant and the parasitic plant (Bouwmeester et al., 2003, Curr. Opin. Plant Biol. 6: 358-364). Once connected, the parasitic plants will pump the sap of the host plant, slow down the development of the aerial parts, induce chlorosis and reduce photosynthesis (Ejeta and Butler, 2000. Parasitic plants. Int RA Frederiksen and GN Odvody (eds). Compendium of Sorghum Diseases, 2nd edition. APS Press, The American Phytopathological Society, pp. 53-56). To survive, these parasitic plants must produce a large quantity of seeds. Thus, from the emergence of the aerial parts, the parasitic plant flowers and produces enormous quantities of seeds which can remain viable in the soil for several years (Haussmann et al., 2000, Field Crop Res. 66: 195-211) . Plants of the genera Striga and Orobanche belong to the same order, that of the Scrophulariales, but do not belong to the same family (the piantes of the genus Striga belong to the family of Scropfwfariaceae and are hemiparasites, while the plants of the genus Orobanche belong to the family of Orobanchaceae and are holoparasites). These plants have many points in common: small seeds facilitating their dissemination, 5 germination dependent on the presence of strigolactone-type elicitors, trophic spoliation of the host plant via the development of a haustorium. On the other hand, their distribution areas are different: Striga in all your tropical and subtropical regions of the world and in particular in sub-Saharan Africa and Orobanche mainly in the temperate countries of Asia and 10 of Central Europe and in particular around the Mediterranean. They affect the growth of a very wide variety of plants of agronomic interest (corn, rice, sorghum, millet, sunflower, rapeseed, tobacco, tomato, etc.), whether in temperate zones (Orobanche), or tropical (Strlga ). They cause significant yield losses on a large number of crops. On the African continent: around 50 million hectares are infested with Striga, resulting in the loss of more than 10 million tonnes of cereals (Gressel et al., 2004, Crop Prot. 23: 661-689). Grain yield losses, due to Striga infestation, can vary from 5 to 100%, depending on the agrodimatic conditions, the level of infestation of the plot and the vulnerability of the cereal (Haussmann and aL , 2000, Held Crop Res. 66: 195211). In Europe, especially in the Mediterranean basin, 16 million hectares are infested with Orobanche, with annual losses estimated at 50 million euros for sunflower, 175 million euros for tobacco, and 200 million euros for tomatoes (Bülbül et al., 2009, Helia 32: 141-152).

The seeds of these parasitic plants are very small which favors their propagation over long distances by the wind, your animals, or by contaminated agricultural machinery. Transport of seeds from contaminated host plants is also a source of spread. Since the production of seeds by a parasitic plant is enormous (up to 100,000 seeds per plant), your infested land must generally be abandoned.

Until now, the protection of crops against Orobanche or Striga plants involves the use of non-selective herbicides, coupled with the use of cereal varieties resistant to these herbicides (De Groote et al., 2008, Agric. Syst. 97: 83-94). These chemical control means, in addition to their toxicity for the environment, have a high cost. In addition, as part of the Ecophyto 2018 plan, the use of plant protection products including herbicides will be greatly reduced.

It is also possible to stimulate the germination of Striga seeds in the absence of the host plant. As 5. hermonthica is a hemiparasite, this stimulation in the absence of the host plant can lead to the death of the parasite in 2-3 days and ultimately to the reduction of seed reserves of the epirhize parasite in the soil. This can be achieved through the use of ethylene (Logan and Stewart, 1991, Plant Physiol. 97: 1435-1438). Ethylene is a phytohormone which can induce the germination of Striga seeds, but the application of ethylene on the soil presents a prohibitive cost, not allowing the use of this technology in agriculture (Berner et al., 1999, Bioiogical Control 15: 274-282).

Other control methods exist such as manual uprooting or the use of rotations with non-host plants, but their effectiveness is reduced. Variety selection of cereal lines resistant to phytoparasitic plants is also an alternative, but the costs are high.

There is currently no alternative control product, such as the use of molecules of natural origin, against Striga or Orobanche available on the market.

In the literature, various studies have revealed the capacity of different biological agents to limit the growth of the Striga or Orobanche parasitic plants. This includes larvae of monophagous herbivorous insects like Phytomyza orpbanchia, Eulocastra argentisparsa, fungi like Fusarium oxysporwn f. sp. Orthoceras, F. oxysporum f. sp. Strigae, or Fusarium artbrosporioides which produce mycotoxins (ie fusaric acid, fumonisins, and deoxynivalenol (DON)) (Amseiîem et al., 2001, BioControl 46: 211-228; Abueigasim and Kroschel, 2003, FAO plant production and protection. Paper No. 120. Addendum 1, 109-144; Lendzemo et al. 2004 Field Crop Res, 91: 51-61; Venne et al., 2009, Pest. Manag. Sci. 65: 572-580). Mycotoxins (especially DON) are able to inhibit the germination of Striga and Orobanche seeds, but they can trigger health problems in mammals. In particular, they represent a risk for animal and human nutrition and therefore cannot be considered as completely harmless substances.

We can also cite the work of Dadon et al., 2004 (Isr. J. Plant 10 Sci. 52: 83-86) entitled "A factor from Azospiriiïum brasitense inhibits germination and radicle growth of Orobanche aegyptiaca Tikva", describing the activity antagonist of a metabolite produced by a strain z'AzospiriÎlum brasi / taught on the Orobanche, In this publication, the active molecule produced by this strain (whose name is not mentioned) has been identified as being an oligopeptide present in an ethanolic fraction of the supernatant.

In addition, only an activity inhibiting the germination of Orobanche seeds has been demonstrated for this strain. Furthermore, it has been reported by Bouillant and ak, 1997 (CR Acad. ΠΪ Sci, Vie 320: 159-162) that not all strains of Azospiriitum brasiïense exhibit such an inhibitory activity on germination and growth. parasitic plants.

In this last publication, it is also reported that on two strains of Azospiriflum brasilense which have such an inhibitory activity on germination and the growth of Striga in microcosms, only one of these strains, Azospiriïum brasi / ens L4, has an effect phytostimulator 25 on sorghum.

It is therefore urgent, given the rapid multiplication of these parasitic plants worldwide, to develop new sustainable solutions, respectful of the environment, to combat holo or hemiparasitic plants, of the order Scrophulariales, which generate 30 significant havoc on agricultural crops and plants of agronomic interest.

In this context, the present invention proposes to use a dtcarboxylic acid, comprising from 2 to 5 carbon atoms, to combat the growth of holo or hemiparasitic plants, and in particular to combat the growth of plants of the genus Striga and / or plants of the genus Orobanche. It is also possible to use combinations of several dicarboxylic acids, comprising from 2 to 5 carbon atoms, to combat the growth of holo or hemiparasitic plants, to obtain the desired effect.

In the context of the invention, the active agents proposed for inhibiting the development of holo or hemiparasitic plants, such as Striga or Orobanche plants, are chosen from dicarboxylic acids (hereinafter also called diacids) comprising from 2 to 5 atoms of carbon. Such diacids comprise two carboxyic acid functions either directly linked to one another, in the case of oxalic acid, or linked by a saturated or unsaturated carbon chain comprising 1, 2 or 3 carbon atoms. This carbon chain is preferably linear and may be unsubstituted or substituted by one or more substituents, in particular of the OH, OCHs and CH2OCH3 type. By way of example of such diacids, mention may be made of oxalic acid, malonic acid, maleic acid, malic acid, glutaric acid, and acetylene dicarboxylic acid. The use of malic acid in L form, which has been shown to be particularly active in inhibiting the growth of Striga or Orobanche plants, is preferred.

Malic acid in L form could be isolated, by the inventors, from culture supernatant of a bacterial strain, Azospiriium brasilense L4, deposited, in accordance with the Budapest Treaty of 1977, under number 1-4830, December 18, 2013, at the CNCM, National Collection of Cultures of Microorganisms, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, FRANCE. This strain was isolated in 1995 from a field of sorghum infested by a Striga parasitic plant in Mali. The AzospirïHum brasilense L4 strain which has been reported to have the ability to inhibit, in vitro, the growth of Striga hermontica and Orobanche ramosa and, in soil microcosms, to protect sorghum from Striga and to stimulate the growth of the cereal (Bouillant et al., 1997, CR Acad. III Sci. Vie 320: 159-162; Miche et al., 2000, Eur. J. Plant Pathol.

106: 347-351) has now been the subject of a deposit, under the number 1-4830, with the CNCM (National Collection of Cultures of Microorganisms, France). This strain produces very specific metabolites in culture, compared to other strains ü'Azospiriiïum brasiïense (and in particular compared to that reported by Dadon et al., 2004: ïsr. J. Plant Sel. 52: 83-86) . In fact, in view of the activity observed, the inventors analyzed the culture supernatant of the Azospîriiïum brasiïense L4 strain, deposited under the number 1-4830, with the CNCM (National Collection of Cultures of Microorganisms, France) and have was able to demonstrate that malic acid in L form is responsible for the herbicidal activity observed with respect to holo or hemiparasitic plants. However, it turns out that malic acid in L form is not the majority component present in the culture supernatant of the bacterial strain, Azospîriiïum brasiïense L4, deposited under the number I-483Û at the CNCM (National Collection of Cultures of Microorganisms, France). The inventors have also demonstrated that this herbicidal activity observed with respect to holo or hemiparasitic plants was generalizable to the chemical class of dicarboxylic acids comprising from 2 to 5 carbon atoms.

The invention therefore proposes to use active agents of natural origin, with low environmental impact, to limit, inhibit the growth of parasitic plants. Unlike other biological agents which act mainly by inhibiting the germination of seeds of Orobanche and Striga, dicarboxylic acids comprising from 2 to 5 carbon atoms are, moreover, capable of inhibiting the lengthening of procauiomas or radicles from germinated seeds of the parasitic plant, and therefore to block the growth of the parasitic plant, as can be seen in particular from the data presented in Table 1 below. This should make it possible to significantly reduce your stocks of viable holo or hemiparasitic seeds in infested soils, an effect which cannot be completely obtained by inhibiting the germination stage alone. Indeed, in the absence of conditions favorable to the germination of parasitic plants (in particular, in the absence of strigolactones), the seeds can remain viable in the soil for several years.

In the context of the invention, the dicarboxyic acid may be brought into contact with at least one seed of a holo or hemiparasite plant to be eradicated. The dicarboxyic acid will be used in sufficient quantity to obtain the desired effect, and in particular to block the germination of seeds and / or to inhibit lengthening of procautomes or radicles from germinated seeds of holo plants or hemiparasites, of the order Scrophulariales, and in particular Striga and / or Orobanche. Preferably, 30 to 300 kg of dicarboxyic acid can be used per hectare of treated soil. In the case where the dicarboxyic acid is applied in the form of an aqueous solution, a solution comprising from 1 to 20 g of dicarboxyic acid per liter of solution may be used.

Dicarboxyic acid can be applied to seeds and / or plants of plants or crops to be protected. The herbicidal compositions containing a dicarboxyic acid in accordance with the invention may in particular be in the form of aqueous solutions or of granules. These compositions may contain, in addition to the active dicarboxyic acid, ions from KzHPCL or KH ^ PO ^, one or more fillers such as silica, clay, kaolin or talc and one or more surfactants such as dodecylbenzene or calcium lignosulfonate. In the case of malic acid in L form, the latter can be produced by chemical synthesis or directly by the bacterial strain, Azospiriïlum brasitense L4, deposited, under the number ï-4830 with the CNCM (National Collection of Cultures of Microorganisms , France). In this case, the acid may be isolated or the herbicidal composition may directly contain the culture supernatant of the bacteria. The culture supernatant can be obtained by placing the bacteria in any suitable culture medium. The conditions for growth of AzospiriHum brasitense bacteria known to those skilled in the art and in particular described in (Nelson and Knowles, 1978, Can J. Microbiol24: 1395-1403) may be used. In particular, growth will be carried out at a temperature of 26 to 32 ° C, typically at 28 ^C C, in a buffered aqueous medium containing sets, nutrients and a carbon source for the growth of bacteria ia. Examples of salts that may be mentioned include NaCi, K ₂ HPO ₄ , KH ₂ PO ₄ , MgSCb, NaCi, CaCh, NH ₄ CL. Examples of nutrients that may be mentioned are Na ₂ MoO ₄ , MnSO _{4 /} Η ₃ δΟ ₃ , CuSO ₄ , ZnSO ₄ , FeEDTA, yeast extract, biotin. By way of examples of carbon sources, mention may be made of glucose, malate and fructose in particular. As examples of such media, mention may be made of Nfb and Nfb * media, especially described in Nelson and Knowles, 1978, Can. J. Microbiol, 24: 1395-1403 and Vial et ak, 2006, J. Bacteriol. 188: 5364-5373.

It is also possible to apply bacteria of the Azospîriiïum brasiïense L4 strain, deposited under the number 1-4830 with the CNCM (National Collection of Cultures of Microorganisms, France) and producing one of the active dicarboxylic acids, directly on the seeds or crops of the plant to be protected or on soils to be protected against the growth of holo and hemiparasitic plants, and thus directly produce in situ dicarboxylic acid. In addition, the Azospîriiïum brasiïense strain, deposited under the number 1-4830, from ia CNCM (National Collection of Cultures of Microorganisms, France) and used in the context of the invention to inhibit the growth of holo or hemiparasitic plants, the order of Scrophuiariaîes, and in particular of Striga and / or Orobanche, presents another advantage for crop improvement, since it is also capable of stimulating plant growth, and is capable of producing a phytostimulatory agent vis- with respect to plants of agronomic interest (Bouillant et aL, 1997, CR Acad. Sel. 320: 159-162). Consequently, the invention proposes to use bacteria of the Azospîriiïum brasiïense L4 strain, deposited under the number 1-4830, with the CNCM (National Collection of Cultures of Microorganisms, France) also to produce a phytostimulatory agent vis-à-vis -vis agricultural crops or plants of agronomic interest to protect against ia growth of holo plants or hemiparasites. By "phytostimulatory agent" means an agent promoting the growth of plants of interest. Such an effect of the Azospîriiïum brasiïense 14 strain, deposited under the number ï-4830, with the

CNCM (National Collection of Cultures of Microorganisms, France) was highlighted by the modification of the architecture of the root system of the plant of interest, and is described in the publication Bouillant et al., 1997, C. R. Acad. Sci. 320: 159-162. In particular, the phytostimulatory effect can be obtained with respect to agricultural crops or plants of agronomic interest chosen in particular from corn, rice, wheat, sorghum, cowpea, tobacco, sunflower, rapeseed, cabbage, tomato, eggplant, potato, chili, celery, bean ...

In particular, bacteria of the Azospirilium bras / '/ Ens strain, deposited under the number 1-4830, with the CNCM (National Collection of Cultures of Microorganisms, France) could be used to coat seeds of such agricultural crops or plants of agronomic interest. In such a case, the bacteria are incorporated into a matrix constituting a coating of the seeds of agricultural crops or plants of agronomic interest. This coating may contain one or more constituents such as peat, perlite, gum arabic, carboxymethyl cellulose, polyvinylpyrrolidone, ie chitosan or Laiginate. The bacteria will be used in sufficient quantity to obtain the desired effect, and in particular to block the germination of seeds of holo plants or hemiparasites, of the order of Scrophuiariaies, and in particular of Striga and / or Orobanche, and / or for inhibit the lengthening of procauiomas or radicles from germinated seeds of holo or hemiparasitic plants, of the order Scrophuiariaies, and in particular Striga and / or Orobanche, and / or to stimulate the growth of agricultural crops or plants agronomic interest. Use preferably 3.10 ⁷ bacterial cells per gram of seeds of agricultural crops or plants of agronomic interest to protect and / or phytostimulate.

The dicarboxylic acids comprising from 2 to 5 carbon atoms proposed in the context of the invention for combating the growth of holo or hemiparasitic plants, of the order of Scrophuiariaies, and in particular of Striga and / or Orobanche can be used , by seed companies, to coat their seeds, but also for plant protection companies, both in the field of conventional agriculture (synthesis of dicarboxylic acids comprising from 2 to 5 carbon atoms by chemical processes) as in the field of organic farming (production of active agents by living organisms, in the case of acid lacking in L form, in particular).

The preparation and application examples mentioned below, with reference to the appended Figures, make it possible to illustrate the invention, but are not in any way limiting.

Figure 1 presents photographs representative of the effect obtained on the growth of Striga hermontica _f in a microtiter dish, in the presence of the supernatant of the strain A. brasilense L4 cultivated in Nfb * medium and of L-malic acid at 2mg / mL in 50mM phosphate buffer.

FIG. 2 shows the effect of the supernatant of the strain A. brasilense L4 on the percentage of germination of the seeds of Striga hermontica and Orobanche ramosa (A) and on the length of the procaulome of the seeds of Striga hermontica and Orobanche ramosa (B).

The activity of the diacids and of the culture supernatant of the bacterial strain, Azospirilium brasilense, deposited, under the number 1-4830 with the CNCM (National Collection of Cultures of Microorganisms, France), named L4 in the Figures, has been demonstrated in vitro and / or in soil microcosms on the parasitic plants Striga and Orobanche.

• Preparation of products:

For the culture supernatant: culture of the AzospiriHum brasilense L4 strain, deposited, under the number 1-4830 with the CNCM (National Collection of Cultures of Microorganisms, France) in the culture medium Nfo * (MgSO ", 7H ₂ O 100 mg / L, CaCb, 2H ₂ O 13 mg / L, NaCI 175 mg / L, Na ₂ MoO ₄ , 2H ₂ O 1 mg / L, MnCI ₂ , 4H ₂ O 3.5 mg / L, KH ₂ PO ₄₆₀₀ mg / L, K ₂ HPO ₄ 900 mg / L, biotin 1 mg / L Fe-EDTA 65.6 mg / L, tryptone 250 mg / L, yeast extract 125 mg / L) (Nelson et Knowies, 1978, Can J. Microbiol24: 1395-1403, Vial et al., 2006, J. BacterioL 188: 5364-5373) for 16 hours at 28 ° C; centrifugation of the culture, recovery of the supernatant and sterilization by filtration on a filter at,, 2 pm. A bioguided purification (fractionation by chromatography coupled to a biological test of the herbicidal activity of the fractions vis-à-vis Striga) of the supernatant of the strain A brasiïense L4 was carried out. Within the fraction showing herbicidal activity, a C4 dicarboxylic acid was identified by mass spectrometry in comparison to a chemical standard. The identity of the mass spectra of the purified compound and of the maiic acid (chemical standard) made it possible to identify that the active molecule is malic acid. A circular dichroism detector revealed the presence of L-malic acid.

The activity of the diacids on the parasitic plants Striga and Orobanche was tested by preparing solutions of the selected diacid in water or in a 50 mM phosphate buffer pH 7 at concentrations of 1 to 20 mg / ml • Herbicidal effect tested on hoio or hemioasitaria plants Striga hermonb'ca and Orobanche ramosa ·.

1. In a 12-well microtiter dish, filter papers (Whatmann 3) are placed at the bottom of the wells and are soaked with sterile water. About thirty sterilized seeds (rinsing with 70% ethanol, then 1% CafCIOh (m / v) and tween® 20, then abundantly with water) hoio plants or hemipasites are placed in each well, on the surface of the filter papers. After 10 days of incubation at 30 ° C and in the dark, increasing doses of a diacid or of culture supernatant are added, in the presence of a germination inducer, GR24. After 3 days of incubation at 30 ^c C, the development of plant pests in the presence of a diacid or the culture supernatant compared to the negative control (water, phosphate buffer or medium of sterile culture), with a macroscope coupled to a camera. The length of the procaulomas (radicles) of hoio or hemipasite plants is measured in order to express the phytotoxic power of the products tested. All the results are presented in Table 1 below.

Table 1: Impact of different dicarboxylic acids on the growth of Strigs herîTicntica in microtitradon dish

Compound and formula

Concentration (mg / ml buffer) inhibition of Striga ¹

Buffer

Oxalic acid

Maionic acid

Acetylene dicaborxylic acid

Maleic acid

DL-malic acid

2mg / ml

2mg / ml

Zmg / ml

2mg / mi

2mg / mi

L-maftque acid

Glutaric acid

2mg / mt

2mg / ml ¹ -: no inhibition (size of prccaulôme> 0.8 mm); +: weak inhibition (size of the procauiôme between 0.2 and 0.8 mm); + -5-: strong inhibition (size of procauiôme <0.2 mm)

Figure 1 presents the photographs representative of the effects obtained on the growth of Striga hermonb'ca in a microtiter dish in the presence of the supernatant of the strain A. brasiïense L4 cultivated in Nfb * and of L-malic acid at 2 mg / ml in phosphate buffer and highlights their inhibitory effect on the growth of procauiomas of holo or hemiparasitic plants.

Figure 2 highlights the impact of the supernatant of the strain 4, brasilense L4 on the percentage of germination of the seeds of Striga hermontica and Orobanche ramosa (A) and on the length of the procauloma of the seeds of Striga hermontica and Orobanche ramosa (B ),

Conclusion: The capacity of the culture supernatant of the bacterial strain, AzQSpiriium brasilense L4, deposited, under the number ï-4830 with the CNCM (National Collection of Cultures of Microorganisms, France), to stop the elongation of the procaulomas of holoparasite plants Striga and Orobanche in vitro (bioassays in microtiter boxes, Figures 1 and 2) and to inhibit the growth of Striga in sorghum cultures in microcosms under controlled conditions (Bouillant et al., 1997, CR Acad. Sci. 320: 159-162) has been observed. The molecules involved in this effect were isolated, by an appropriate chromatographic method, then identified by mass spectrometry by comparison with chemical standards. It has also been shown that different dicarboxylic acids are effective in combating the growth of holo or hemiparasitic plants, of the order Scrophulariales, and in particular Striga and / or Orobanche (Table 1).

2. Seeds of Striga hermontica (about 100 seeds / pot) and sorghum (1 seed / pot) were introduced simultaneously into soil mesocosms, in the presence of increasing doses of malic acid (2 and 20 g / L) or culture supernatant, then cultured in a greenhouse or on a plot.

The emergence of Striga plants is estimated visually, after 2 months of incubation. The phytotoxic power is estimated by comparison with a control without addition of malic acid or culture supernatant. A reduction of 22% in the number of Striga plants that emerged compared to the control condition is observed in the presence of malic acid 2 g / L and by 90% in the presence of malic acid 20 g / L. In the presence of the bacterial supernatant, a 58% decrease in the number of Striga compared to the control condition was observed.

3. RESULTS ON THE PHYTOSTIMULATING EFFECT

The phytostimulatory effect of the bacterial strain, Azospiriilum brasitense L4, filed under number 1-4830 with the CNCM (National Collection of Cultures of Microorganisms, France) is presented in Souillant et al., 1997 C. R. Acad. ΙΠ ScL Vie 320: 159-162.

Claims (5)

1 - Use of one or more dicarboxylic acids comprising from 2 to 5 carbon atoms to combat the growth of holo or hemiparasitic plants, 2 - Use according to claim 1 characterized in that the dicarboxylic acid is chosen from oxalic acid, malonic acid, malic acid, glutaric acid, maleic acid and acetylene dicarboxilic acid. 3 - Use according to claim 1 characterized in that the dicarboxylic acid is malic acid in L form. 4 - Use according to any one of claims 1 to 3 characterized in that the dicarboxylic acid is brought into contact with at least one seed of holo or hemiparasite plant. 5 - Use according to any one of claims 1 to 4 for combating the growth of plants of the genus Striga or Orobranch. 6 - Use according to any one of claims 1 to 5 characterized in that the dicarboxylic acid is applied to seeds and / or plant of agronomic plants to be protected, in particular chosen from corn, rice, wheat, sorghum , cowpea, tobacco, sunflower, rapeseed, cabbage, tomato, eggplant, potato, chilli, celery and bean. 7 - Use according to any one of claims 1 to 6 characterized in that the dicarboxylic acid used is produced by the strain AzospiriHum brasüense L4, filed under number 1-4830 with the CNCM (National Collection of Cultures of Microorganisms , France). 8 - Herbicidal compositions for combating the growth of holo or hemiparasitic plants containing a dicarboxylic acid containing from 2 to 5 carbon atoms, and ions from K ₂ HPO ₄ or KH ₂ PO ₄ , one or more fillers such as silica , clay, kaolin or talc and one or more surfactants such as dodecylbenzene or calcium lignosulfonate. 9 - Compositions according to claim 8 characterized in that the dicarboxylic acid is chosen from oxalic acid, malonic acid, malic acid, glutaric acid, maleic acid and acetylene dicarboxilic acid. 5 10 - Compositions according to claim 8 or 9 characterized in that they are in the form of a solution comprising from 1 to 20 g of dicarboxylic acid per liter of solution.