WO1999027785A1

WO1999027785A1 - Composition and method for combating plagues caused by phyllocnistis citrella

Info

Publication number: WO1999027785A1
Application number: PCT/ES1997/000293
Authority: WO
Inventors: José Alfredo PIERA PELLICER
Original assignee: Coarval Coop. V.
Priority date: 1997-11-28
Filing date: 1997-11-28
Publication date: 1999-06-10
Also published as: AU5122198A

Abstract

The fumigation composition contains camphor as a butterfly repellent as well as disinfecting/antiseptic products in a quantity which is sufficient to exterminate the larvae of third age (L3) without producing important damages to the fumigated plant. The preferred disinfecting/antiseptic products are glutaraldehyde, glyoxal, formaldehyde, dialkyldimethylammonium chloride, alkylbenzyldimethylammonium chloride and mixtures thereof. Optionally it also contains surfactants and mineral or plant oil. The treatment method comprises the preparation of the composition which has been diluted from a concentrate of the same, and fumigating the plants preferably in the afternoon. The larvae are exterminated and the butterflies are repelled and do not lay anymore eggs. The method which goes against the present tendency to combat said plagues by means of biological methods is very efficient and has a persistent effect with the advantage of being less harmful for human kind and the environment.

Description

D E S C R I P C I Ó N

COMPOSITION AND METHOD TO COMBAT PHYLT PESTS. CNTSTTS CTTPE LA.

The present invention relates to compositions for the treatment of pests caused by Phyllo nistis citrell. a microlepidopter commonly known as a citrus miner, as well as a method for treating plants against such pests.

STATE OF THE PREVIOUS TECHNIQUE

Phyllocnistis cA trella (or Phyllocnistis l trella

Stainton) is a microlepidoptera belonging to the family Gracillariidae, subfamily Phyllocnistidae, which is currently considered one of the most important citrus pests worldwide and economic impact, due to the severity and importance of the damage caused by These trees on five continents.

The biological cycle of Phyllo nistis el rella is divided into the following stages: adult (butterfly), egg, larva from I ^to age (Ll), larva from 2 ^to age (L2), larva from 3 ^to age (L3), precrisálida and chrysalis

The larvae of Phyllocnistis citrella in their different stages escape galleries or subepithelial mines, developing a food activity that affects the leaves (mainly the young ones), the growing shoots and, sometimes, the tender stems and The small fresh fruit set. The action of the miner entails a loss of foliar mass and a loss of the photosynthetic capacity of the tree, so that it loses its vigor and reduces its productivity.

The adult of Phyllocnistis citrella is a small butterfly of twilight flight, whose life is between 1 and 12 days, although it can reach 20 days. A female can deposit a variable amount of eggs, which ranges between 36 and 76 units. The larva penetrates directly into the leaf, piercing its epidermis and beginning its nutritional activity. To do this, he excavates a gallery that during its first larval stage (Ll) is parallel to the central nerve of the leaf. In the following larval states (L2, L3) the galleries increase in section, evolving with sinuous paths.

Because the larvae develop under the epidermis, only a small number of pesticides are effective for their control. Among these are the following: abamectin, benfuracarb, carbosulfan, hexitiazox, lufernuron, methyl pyrimiphos, diflubenzuron, flufenoxuron and hexaflumuron. The last three, belonging to the acylureas group, should only be applied once throughout the year. All these products are applied by spraying aqueous compositions with recommended concentrations between 0.02 and 0.15% in active matter. Generally the fumigation composition also contains icrofiltered, mineral or vegetable oils, in a proportion of approximately 0.5%. Apart from its considerable economic cost, one of the problems of chemical treatments known in the art is that its effectiveness (expressed inversely as a degree of survival) is quite limited. For example, it is known that survival after fumigation with commonly used active substances ranges from 38 to 48%, the most effective being abamectin or Epimek ^® , with a survival of 8%, and imidacloprid or Confidor ^® , with a survival of 11% (cf. JM Llorens-Climent et al., "Test to determine the effectiveness of various insecticide products applied in helicopter aerial treatment, using ULV against the citrus leaf miner", Levante Agricola 1996 , vol. 3, pp. 247-256).

One of the problems of known chemical treatment methods is that the pesticides used are quite toxic to humans and the environment, which means a high danger in their handling. In addition, some of the pesticides used have adverse effects on beneficial species. Thus, for example, fumigation with imidacloprid also kills the predatory insect of the red spider, thereby greatly increasing the population of red spider.

The fact that the attack of the Phyllocnistis citrella on the citrus tree takes place over extended periods of time, constitutes an additional difficulty for the chemical fight, since it forces to multiply the number of treatments. Thus, all specialists agree that the control of this pest, medium and long term, must be based on biological control, as stated in the book "The citrus leaf miner, Phyllocnistis citrella Stainton", published in 1996 by the agricultural health authorities of the Valencian Community (Plant Health and Certification Service ; Directorate General for Research, Health and Technology; Ministry of Agriculture and Environment; Generalitat Valenciana; Valencia; Spain). In fact, these authorities recommend fighting the plague of Phyllocnistis citrella in the Valencian Community (Spain) with the parasite Agenisapis citricola Long. and, in the future, also with other parasites such as Cirrospilus quadristriatus, citrostichus phyllQcnistQides, Quadrastrichus a_ _^ , Semialacher petiolatus or Zaommomentedon breviapetiolatus. These health authorities also recommend that chemical treatment only be carried out under very restrictive conditions, and never for preventive purposes when there is little damage, because then it is useless.

For all this, it is clear that fighting pests of

Phyllocnistis citrella by chemical treatment, is still a problem not satisfactorily solved.

EXPLANATION OF THE INVENTION

The present invention solves the aforementioned problem by providing new dilute aqueous compositions for fumigation, comprising camphor in an amount sufficient to substantially repel adult individuals of the Phyl 1 or is is citrella microlepidoptera, and one or more disinfectant / antiseptic products, not volatile or metallic, in an amount sufficient to substantially kill the 3 ^-year- old larvae (L3) of said microlepidoptera, but not so large as to cause significant damage to the fumigated plant. It is convenient that the camphor is well solubilized, so that in the preparation of these compositions it is convenient to use some organic solvents to crush and solubilize the solid camphor. Preferably these solvents are alcohols, such as ethanol, or polyalcohols, such as ethylene glycol or propylene glycol.

In the context of the present invention, the term "disinfectant" is used in its normal sense, that is, to designate any chemical substance that releases from an infection and that in practice is used on inanimate objects. The term "antiseptic" is also used in its normal sense, to designate any chemical substance that prevents or inhibits the action or growth of microorganisms (although not necessarily kill them), and that is used topically on living tissue. Some of the active substances that accompany camphor in the compositions object of the present invention (eg formaldehyde, glutaraldehyde and glyoxal) are normally considered disinfectants, while others (eg benzalkonium chlorides and dimethyldialkylammonium) are normally considered antiseptics. Therefore, in the context of this invention these active substances are jointly designated as disinfectants / antiseptics. Some of the disinfectants / antiseptics of the compositions of the present invention (eg, benzalkonium and dimethyldialkylammonium chlorides), simultaneously perform the surfactant paper, so that the addition of other surfactants may be unnecessary.

The disinfectant / antiseptic products of the compositions object of the invention can be selected from the different products used in the art, such as aldehydes, phenolic derivatives, carboxylic acids, quaternary ammonium salts, nitrogen compounds, etc. (see a summary in "Disinfectants and antiseptics", Kirk-Othmer "Encyclopedia of Chemical Technology", 4th edition, 1993, Vol. 8, pp. 237-292). However, disinfectants / antiseptics that are unsuitable for fumigation are excluded from the compositions of the invention because they are volatile, such as chlorine, iodine, ozone, ethylene oxide, propylene oxide, hydrogen peroxide and sulfur dioxide. Disinfectants / antiseptics that are metal compounds, such as mercurochrome or copper sulfate, are also excluded because of their toxicity.

As disinfectant / antiseptic components of the compositions of the present invention, glutaraldehyde, glyoxal, formaldehyde (formaldehyde or a substance that releases formaldehyde, such as hexamine), dialkyl dimethylammonium halides (such as didec chloride) are preferred. tell me 1 ammonium), alkylbenzyl dimethyl ammonium halides (such as benzalkonium chloride), and mixtures of any of them, where the alkyl groups are linear and have between 8 and 18 carbon atoms. Especially preferred are the glutaraldehyde, glyoxal and formaldehyde, as well as mixtures thereof; and formaldehyde is even more preferred.

In a particular embodiment, the diluted aqueous composition should contain one or more surfactant products in sufficient quantity for uniform spraying on the surface of the plants. Surfactants can be selected from those employed in the art (see a summary in "Surfactants", Kirk-Othmer "Encyclopedia of Chemical Technology", 4th edition, 1997, Vol. 23, pp. 478-541), but with the caution of avoid incompatibilities with the other components of the composition. Thus, eg, to a composition containing disinfectants / antiseptics of the quaternary ammonium salt type, an anionic surfactant, such as a soap, cannot be added, as a precipitate would form. Especially preferred for the compositions of the invention are cationic surfactants, especially those of the quaternary ammonium salts type. Surfactants play an important role in the homogenization of the aqueous composition to be fumigated, and aid in impregnating the leaves during fumigation. Their role may be played, in whole or in part, by any of the disinfectants / antiseptics used, as in the case of some quaternary ammonium halides.

Generally diluted compositions for fumigation are prepared by dilution in situ, from concentrated aqueous compositions containing the active substances. These concentrated aqueous compositions are generally distributed. commercially and it is of interest that, being stable and homogeneous, they contain the minimum amount of water possible, in order to simplify their storage and transport. Thus, the concentrated aqueous compositions used to prepare any of the aforementioned diluted compositions are also the subject of the present invention. Especially preferred are concentrated compositions whose proportion of water is less than about 50%; and even more preferred are those in which the proportion of water is less than about 25%.

The use of oil, both mineral and vegetable, is common in the fumigation of pesticides already used against Phyllocni stis citrella. Apparently, the oil forms a superficial lipophilic film that hinders the oxygenation of the eggs and, consequently, their evolution to larvae. On the other hand, the oil helps to fix the pesticide on the leaves, avoiding the elimination of said pesticide by atmospheric agents (sun, wind, rain, etc.). Thus, in a preferred embodiment of the present invention, the aqueous compositions used for fumigation also contain oil in an amount sufficient for the film coating of the sheets. Said oil is selected from the known microfiltrated mineral oils and vegetable oils (eg sunflower). It is recommended that the proportion of oil in the diluted fumigation composition be approximately 0.5% to 1%. The oil can be added at the end, during the preparation of the diluted composition to fumigate, as usual among farmers. Alternatively, the oil can be added previously, during the preparation of the concentrated composition containing the active substances, as illustrated in the examples.

The compositions of the present invention are prepared by dissolving their components in the form and order that are suitable by their nature. Thus, for example, camphor, of natural or synthetic origin, is crushed with the help of an organic solvent (eg ethyl alcohol) until a very fine paste is obtained. It is convenient to dilute the paste somewhat with an organic co-solvent (eg ethylene glycol or propylene glycol) to favor homogenization of camphor in the concentrated composition. The oil can either be included in the concentrated composition, or added to the diluted composition for fumigation.

Another aspect of the present invention is to provide a new method of treating pests caused by Phyllocnistis citrella comprising the fumigation of the affected plants with the diluted fumigation compositions described. This method is especially useful for the treatment of citrus trees. Preferably, the spraying is done at dusk so as to also attack the butterflies, which are of twilight flight. After spraying the larvae die quickly, especially the youngest (Ll and

L2), giving very low survival rates

(typically less than 2%). If new butterflies reappear (which will surely lay eggs), it is advisable to spray again, preferably three days after the appearance, to kill the new larvae in their younger stages. The proportion in disinfectants / antiseptics of the diluted fumigation composition is optimized by common experimental tests, and is a function of the planting to be treated and the chemical nature of said disinfectants / antiseptics. When the proportion is substantially less than optimal, the activity will be low. But if the proportion is much greater than the optimum, then the tree can be damaged, which usually manifests itself because the most tender shoots are dried. The optimal proportion that appears in the examples can serve as a guide.

The mechanism of action of the compositions object of the present invention is not yet well known. Thus, for example, it is not known which is the exact mechanism by which the disinfectant / antiseptic exterminates the larvae L3 (and the Ll and L2, even more easily). It is probably due to an effect on the protective membrane of the epithelium of the plant, since it is known that the larvae of Phyllocnistis citrella are very vulnerable when they leave their gallery. The mechanism of action of camphor seems clearer, as this is a product used to repel moths, as well as to kill them in closed environments (trunks, cabinets, etc). Everything suggests that camphor repels the female of

Phyllocnistis citrella, moving it away from the treated leaves and, consequently, prevents it from laying eggs on them.

The method of treating Phyllocnistis citrella pests of the present invention, as well as the concentrated or diluted aqueous compositions involved, represents several technical advantages over to the known chemical treatment methods. An advantage is that it is much less dangerous, both for the farmer and for the environment, since it involves the use of much less toxic products. In addition, it is a more efficient method than those known, since the corresponding insect survival rate after fumigation is substantially lower. And it is also of more persistent effect, since it does not require repeating the spraying so frequently.

The present invention represents a considerable technical advance in the field of citrus farming, as it provides a new and effective solution to the pests of Phyllocnistis citrella in citrus fruits. In addition, the solution is surprising and goes against the current tendency to abandon chemical methods and adopt biological methods. To date, in the case of citrus fruits, biological methods are of limited efficacy and are complex and slow.

DETAILED EXHIBITION OF AN EMBODIMENT

Example 1: Preparation of a composition concentrated in active substances

About 15 grams of synthetic camphor were crushed with a similar amount of ethyl alcohol, obtaining a very fine paste, which was subsequently diluted with an amount of propylene glycol approximately double that of alcohol. With stirring, sunflower oil was added to a volume of 100 mL of mixture. This mixture was combined with 100 mL of a disinfectant composition whose - In quantitative composition by weight was:

Formol of 40% 10%

50% Glutaraldehyde 4% Glioxal 40% 24%

50% Didecyldimethylammonium Chloride .. 16%

Water (100% c.s.p.)

In some cases, microfiltered mineral oil was used instead of vegetable oil, with similar results. Similarly, in other cases the oil was not incorporated into the concentrated composition, but was subsequently added, when preparing the diluted composition for fumigation.

Example 2: Preparation of a diluted composition for fumigation

About 200 mL of the concentrated composition of active ingredients prepared according to Example 1, were placed in a conventional fumigation backpack, equipped with a stirring / mixing system, and filled with water to about 15 L, thus obtaining the aqueous fumigation composition used in the field tests of Example 3. In other cases, vegetable or mineral oil was added directly to the fumigation backpack.

Example 3: Phytosanitary Activity Tests

The tests were carried out in a test field in the area called Liorna de la Verge (Picassent, Valencia, Spain) with 36 citrus-type fruit trees (2 lemon and 34 orange trees of the Navelina, Navel Late, Tangerine and Oroval varieties), all of which were heavily infected with larvae and butterflies of Phyllocnistis citrella. During the trial the field was not subject to the water stress that is advised to combat the pests of Phyllocnistis citrella, but was irrigated every 8 days, which formed quite a few trunk buds (the so-called "mamones").

At dusk the trees were fumigated, using four full backpacks (60 L in total) of the diluted composition of Example 2. That same night the total absence of butterflies was observed.

The next morning it was observed through a magnifying glass that the larvae, especially the L3, continued in their subepithelial galleries, but had ceased their food activity. Microscopically, it was observed that the digestive tract of the L3 larvae, opaque when they were alive and eating, gradually became transparent. Later the larvae turned dark brown, indicating that they had died. The younger larvae (Ll and L2) died long before the L3, and their bodies were absorbed by the epithelium of the leaf. After 48 h from fumigation, a degree of larval survival of less than 2% was determined.

After a few days, the crepuscular presence of new butterflies (probably from neighboring fields) was observed. Three days after the first observations of butterflies, the field was fumigated again with the same amount of the same composition. After this second fumigation no L2 larvae, L3 larvae, or butterflies were observed.

In other tests compositions with different proportions of disinfectant / surfactant products were used. When the proportion of these products was half that of the test described above, the insecticidal activity against Phyllocnistis citrella was practically nil. When the proportion was double that, the pesticide activity was very large, but some damage was observed in the most tender shoots (its leaves dried). These results showed that, for a given composition in active substances and for a given plantation, the proportion of active substances in the diluted fumigation composition can be easily optimized.

Claims

1. Diluted aqueous composition for fumigation of the pests of the Phyllocnistis citrella microlepidoptera, comprising camphor in sufficient quantity to substantially repel adult individuals of said microlepidoptera, and one or more disinfectant / antiseptic, non-volatile or metallic products, in sufficient quantity large to substantially exterminate the 3-year ^- old larvae (L3) of said microlepidoptera, but not so large as to cause significant damage to the fumigated plant.

2. Composition according to claim 1, further containing organic solvents in sufficient quantity to crush and solubilize the camphor.

3. Composition according to claim 2, wherein the solvent is selected from ethyl alcohol, ethylene glycol, propylene glycol and mixtures thereof.

4. Composition according to any of claims 1-3, wherein the disinfectant / antiseptic products are selected from glutaraldehyde, glyoxal, formaldehyde (formol or other substance that releases formaldehyde), dialkyl dimethylammonium halides, alkylbenzyl dimethyl ammonium halides and mixtures thereof, wherein the groups alkyl are linear, between 8 and 18 carbon atoms.

5. Composition according to claim 4, wherein the disinfectant / antiseptic products are selected from glutaraldehyde, formaldehyde, glyoxal and their mixtures

6. Composition according to claim 5, wherein the disinfectant / antiseptic product is formaldehyde (formaldehyde or other substance that releases formaldehyde).

7. Composition according to any of the preceding claims, which also contains one or more surfactant products, in an amount sufficient for uniform application on the surface of the plants.

8. Composition according to claim 7, wherein the surfactant products are quaternary ammonium salts.

9. Concentrated aqueous composition for preparing any of the diluted compositions of claims 1-8, which contains the same active substances and in the same relative proportion as said diluted compositions, but where the water is in a substantially smaller proportion.

10. Composition according to claim 9, wherein the proportion of water is less than about 50%.

11. Composition according to claim 10, wherein the proportion of water is less than about 25%.

12. Composition according to any of the preceding claims, which also contains a mineral or vegetable oil, in an amount suitable for film coating of the leaves.

13. Composition according to claim 12, wherein the Oil is microfiltered mineral oil.

14. Composition according to any of claims 1-8, which also contains an oil ratio of approximately 0.5% to 1%.

15. Method of treatment of plants against pests caused by Phyllocnistis citrella, characterized in that said plants are fumigated with a dilute aqueous composition whose content is defined in any of claims 1-8.