WO2019021235A1

WO2019021235A1 - Calcium and nitrogen based fungicidal compositions for plant protection

Info

Publication number: WO2019021235A1
Application number: PCT/IB2018/055597
Authority: WO
Inventors: Giovanni Miglio
Original assignee: Altinco S.L.
Priority date: 2017-07-28
Filing date: 2018-07-26
Publication date: 2019-01-31
Also published as: IT201700086728A1

Abstract

The present invention relates to a method for protecting arboreal and shrubby plants against fungal infections by treating the areal part with an aqueous solution comprising ammonium nitrate and/or calcium nitrate.

Description

CALCIUM AND NITROGEN BASED FUNGICIDAL COMPOSITIONS

FOR PLANT PROTECTION

DESCRIPTION

FIELD OF THE INVENTION

The present invention relates to a method for protecting arboreal and shrubby plants against fungal infections by treating the areal part with an aqueous solution comprising ammonium nitrate and/or calcium nitrate. PRIOR ART

In the agronomic field, the role played by certain diseases in reducing general crop harvests is well known and recognized. Although the possible biotic causes of disease are generally the same as for all living organisms, i.e. the diseases are caused by bacteria, viruses and/or other ultramicroscopic organisms as well as fungi, which undoubtedly play a primary role in causing disease in spontaneous and cultivated plants.

It has been estimated that 15-18% of the world's main crops are lost to phytopathogenic fungi each year (Oerke, E.C.; Dehne, H.W., Crop Protection, 23 (2004) 275-285).

Synthetic or natural substances known as "fungicides" that are capable of preventing or reducing damage by fungi play an essential part in producing food for people and livestock.

In the last 20 years, at least inside the European Union, over 300 different active substances have been registered, used and classified as fungicides for agricultural use. Nevertheless, in the prior art, most of them have been banned or restricted for toxicological reasons or for other regulatory reasons and only about a third of this amount is currently authorized and usable legally to protect plants.

It is thus clear that although using chemical fungicides is crucial and indispensable, such use is not entirely free of problems, which sometimes have a particularly great impact. A first drawback that is still largely unresolved is the fact that as most fungicides are synthetic in origin, they are intended to leave chemical residues on sprayed crops and these residues can be considered to be pollutants to all effects and purposes.

A second problem that is still unsolved consists of the fact that the biological activity of known fungicides is not always sufficient for satisfactory control of certain diseases and developing new more effective substances becomes necessary in all cases.

In addition, a problem that is just as important linked to the toxicity of fungicides in the broad sense of the term consists of the aforesaid ban and the resulting reduction in available active substances.

Following this, not only have certain fungal diseases become difficult to control but even more importantly resorting intensively to the use of compounds belonging to a small number of chemical families has led to widespread problems of resistance, i.e. reduced sensitivity of target parasites to more widely used active substances.

Lastly, it is of enormous practical importance that chemical fungicides require regulatory processes that are extremely long and costly in order to be registered and used legally in accordance with the laws of the vast majority of the countries of the world, which can use up enormous financial resources over a period of 5-10 years.

In this context, a first object of the present invention is to provide a method for protecting plants against fungal infections, in particular to protect fruit- bearing plants, comprising using active substances that do not leave hazardous residues on the edible parts of the crops to which they are applied.

A further, no less important, object of the present invention is to make available compositions that are effective against plant diseases of fungal origin, especially those in which a decline in the efficacy of known fungicides has been observed. Further, a highly desirable requirement is for these compositions to contain compounds already used and known for uses other than those quoted in the present invention, thus becoming adaptable to cheaper and simpler registration processes.

A further highly desirable requirement is that such compositions contain active ingredients provided with an action mechanism that is such as to minimize the risk of resistance from pathogenic fungi.

Calcium and ammonium nitrate are compounds that have been known for some time in agriculture for their fertilizing properties and are widely applied directly in solid form on land intended for herbaceous crops like wheat, barley and maize in order to increase crop yield and the green colour of the leaves.

Using these compounds to treat some species of pathogenic fungi is known. They are nevertheless particular fungal species that are generally present in the soil, such as or example Sclerotium rolfsii.

Patent application WO96/13169 discloses a method for inhibiting the growth of organisms that are harmful to plants comprising spraying the plants with an aqueous solution containing urea and at least one divalent cation salt, one of which is calcium nitrate. The aqueous solutions are nevertheless rather concentrated and the efficacy thereof has been tested only in relation to bacterial infections.

Patent US6,358,538B1 discloses the use of calcium nitrate or ammonium nitrate per protecting plants from fungal infections by spraying aqueous solutions of such compounds onto the plant.

The fungistatic effects of ammonium nitrate on its own or in combination with urea against certain fungi are described in Karel Veverka et al., "Sensitivity of Fungi to Urea, Ammonium Nitrate and their Equimolar Solution UAN", Plant Protect. Sci., vol. 43 January 1 , 2007, pages 157- The objectives stated above and further objectives that will be defined better below have been achieved by the invention that is the object of the present invention, as will be disclosed below.

SUMMARY OF THE INVENTION

In a first aspect, the present invention relates to a method for protecting fruit-bearing arboreal or shrubby plants against fungal infections, comprising at least one step (i) of spraying at least one arboreal plant and/or at least one shrubby plant with 150-2,000 l/ha of an aqueous composition (A) comprising 1 -15% by weight of at least one active ingredient selected from ammonium nitrate, calcium nitrate and mixtures thereof, in which said at least one step (i) is carried out prior to the appearance of fruits on the plant.

In a further aspect thereof, the present invention refers to the use of an aqueous composition (A) as disclosed above for protecting fruit-bearing arboreal or shrubby plants from fungal infections caused by at least one fungus selected from Taphrina deformans, Ventuha inaequalis, Cycloconium oleaginum (=Spilocaea oleae), Monilia sp., Botrytis cinema, Phomopsis sp., Oidium tukeri.

DETAILED DESCRIPTION OF THE INVENTION

In the present description and the appended claims, the percentages are considered to be expressed by weight, unless otherwise indicated.

In the context of the present invention, "protecting plants from fungal infections" refers to preventing the occurrence of fungal infections and/or treating fungal infections that are already taking place, with consequent reduction of the incidence and/or seriousness of the plant diseases.

The active ingredient concentration in the aqueous composition (A) refers to the total quantity of active ingredient in the composition.

In one embodiment, the at least one step (i) can comprise spraying at least one arboreal and/or at least one shrubby plant with 500-1 ,500 litres/hectare of an aqueous composition (A) as disclosed above.

In one embodiment, the method according to the invention can comprise at least one step (i) of spraying at least one plant with an aqueous composition (A) comprising 2-8% by weight of at least one active ingredient as disclosed above.

In one embodiment the at least one step (i) can be carried out during the phase of vegetative stasis of the at least one plant or during the period of vegetative development of the plant, prior to the appearance of fruits.

The "phase of vegetative stasis" is defined as the period of least metabolic activity of the plant, which in most cases corresponds to the winter season. Generally, the phase of vegetative stasis starts with the fall of the leaves and ends with the opening of the vegetative buds.

The "phase of vegetative development" refers to the phase in which there is growth activity of all the vegetable organs that make up the fruit-bearing plant. The phase of vegetative development ends when the leaves start to fall.

In one particular embodiment, when the at least one step (i) of the method according to the invention is carried out during the phase of vegetative development of the plant, said at least one step (i) can be carried out after the appearance of the buds and until flowering.

Alternatively, the at least one step (i) can be carried out during the phase of vegetative stasis of the plant, preferably on the bare branches. In the context of the present invention, "bare branches" are defined as branches on which about less than 10% of the leaves that are present during the step of vegetative development is present, preferably the bare branches are completely devoid of leaves.

The step (i) of the method can preferably comprise spraying the areal part of at least one arboreal plant and/or at least one shrubby plant.

The method according to the invention can be carried out to treat plants in the field or in a greenhouse. The method can accordingly be carried out in any temperature, humidity and pressure condition, generally at the environmental temperature and pressure conditions of the period of the year in which the method is carried out.

According to one embodiment, the method according to the invention can comprise at least one step (i) of spraying at least one plant with an aqueous composition (A) comprising ammonium nitrate and calcium nitrate. It has been surprisingly observed that when the active ingredients disclosed above are used in combination they have a synergic effect that reinforces the antifungal effect of the individual active ingredient. Preferably, the aqueous composition can comprise calcium nitrate and ammonium nitrate in a weight ratio comprised between 1 :5 and 5:1 , more preferably comprised between 1 :3 and 3:1 .

In one embodiment, the aqueous composition (A) can further comprise < 15% by weight, preferably 0.5-15% by weight, more preferably 2-14% by weight, more preferably 2-10% by weight, still more preferably 3-7% by weight, of at least one adjuvant agent selected from urea, amino acids, wetting agents and mixtures thereof. In one preferred embodiment, the aqueous composition (A) can comprise urea, in the quantities stated above. It has been observed that urea has an effect of reinforcing the activity of the active ingredients, in particular of the ammonium nitrate, and an effect of stabilizing the aqueous composition.

The aqueous composition (A) can comprise 1 -15% by weight, preferably 2-8% by weight, of active ingredient and 0.5-15% by weight of urea, preferably 2-14% by weight, more preferably 2-10% by weight, still more preferably 3-7% by weight in which the active ingredient is ammonium nitrate and in which the molar ratio ammonium nitrate:urea is comprised between 3.5:1 and 1 .5:1 .

This aqueous composition can further comprise calcium nitrate as the active ingredient, in which the quantity of active ingredient refers to the sum of the quantity of ammonium nitrate and calcium nitrate.

The aqueous composition (A) can be prepared by solubilising in water the at least one active ingredient, that is in solid form, as powder or granules, and possible further adjuvant agents. Solubilisation can be conducted in equipment known to the person skilled in the art, in variable temperature and pressure conditions, generally at a temperature of about 25°C and pressure of about 101 .3 kPa.

The water used in the aqueous composition (A) can be mains water or well water.

Calcium nitrate in anhydrous or hydrated form can be used to make the aqueous composition (A). Even if hydrated calcium nitrate is used in the preparation, the quantity of calcium nitrate in the aqueous composition (A) refers to the anhydrous form of Ca(NO₃)₂.

Generally, the aqueous composition (A) can be marketed in a concentrated form to be then subsequently and suitably diluted at the moment of use.

Accordingly, in one embodiment the method according to the invention can comprise a step (0) of providing an aqueous composition (A) comprising 1 -15% by weight, preferably 2-8% by weight, of at least one active ingredient selected from ammonium nitrate, calcium nitrate and mixtures thereof, in which the step (0) is carried out upstream of the at least one step (i).

In one embodiment, the step (0) can be carried out by diluting with water an aqueous composition comprising > 15% by weight, preferably 15-90% by weight, more preferably 65-85% by weight at least one active ingredient as disclosed above. In one embodiment, the step (0) can comprise diluting in water at least one of the following aqueous compositions comprising:

(1 ) 20.0 - 25.0% by weight of ammonium nitrate;

3.0 - 6.0% by weight of urea; and

water q.s. to 100% by weight;

(2) 38.0 - 45.0% by weight of calcium nitrate;

28.0 - 35.0% by weight of ammonium nitrate;

and water q.s. to 100% by weight;

and

(3) mixtures thereof.

Alternatively, the step (0) can be carried out by dissolving in water the suitable quantities of at least one active ingredient as disclosed above and of the possible further adjuvant agents.

In one embodiment, the at least one fruit-bearing or shrubby plant treated with the method according to the invention can be at least one fruit- bearing or deciduous shrubby plant.

In a further embodiment, the at least one fruit-bearing plant can be selected from Vitaceae, Rosaceae, Drupacee and Pomacee, preferably from Vitis vinifera, Prunus persica, Malus domestica and Pyrus.

The method according to the invention can be particularly suitable for protecting the fruit-bearing plants from fungal infections caused by at least one fungus selected from Taphrina deformans, Venturia inaequalis, Cycloconium oleaginum (=Spilocaea oleae), Monilia sp., Botrytis cinerea, Phomopsis sp. and Oidium tukeri, preferably from Taphrina deformans and Venturia inaequalis (=Spilocaea pomi).

In a specific embodiment thereof, the method according to the invention can be used to protect peach trees against fungal infections caused by Taphrina deformans.

In a further specific embodiment thereof, the method according to the invention can be used to protect apple trees against fungal infections caused by Venturia inaequalis (=Spilocaea pomi). In one embodiment, the method according to the invention can comprise a plurality of steps (i), each of which can be carried out prior to the appearance of fruits on the plant as disclosed above.

In one version, the method according to the invention can comprise 1 - 5 steps (i), preferably 2 - 4 steps (i).

In a further aspect thereof, the present invention refers to the use of an aqueous composition as disclosed above to protect fruit-bearing arboreal or shrubby plants from fungal infections caused by least one fungus selected from Taphhna deformans, Venturia inaequalis, Cycloconium oleaginum, Monilia sp., Botrytis cinerea, Phomopsis sp., Oidium tukeri, preferably irom Taphrina deformans, Phomopsis sp. and Venturia inaequalis.

The use for protecting fruit-bearing arboreal or shrubby plants from fungal infections refers to an aqueous composition (A) comprising 1 -15% by weight of at least one active ingredient selected from ammonium nitrate, calcium nitrate and mixtures thereof and to the variants of the aqueous composition (A) disclosed above.

The Applicant has surprisingly observed that the reproductive structures (asci and ascospores) oiTaphrina deformans and Venturia inaequalis treated with an aqueous composition as disclosed above show a break of the cell walls due to an energetic contact action coming from the exterior. This type of action enables a priori the probability of resistance phenomena to be reduced, which are generally determined by causes of a biochemical and endogenous nature.

The present invention disclosed below with the help of some embodiments that do not have a limiting character.

Measurement methods

Calculation of the % of diseased leaves: ten branches of each plant were selected and marked at random, on these branches the total of the diseased leaves and of the healthy leaves was counted. The number of diseased leaves was finally recorded as a percentage of the total, the latter being equal to 100.

In the case of leaf curl, leaves were considered to be diseased on which a characteristic red colour appeared, with clear deformation of the leaf, leafroll and leaf curl.

In the case of apple scab, leaves were considered to be diseased on which the appearance of black spots was noted.

Example 1

Worldwide, peaches are one of the most popular types of fruit, which are consumed everywhere by people and drive a market that, if nectarines are included, involves production of not less than 21 million tonnes a year. Wherever peaches and nectarines are cultivated, they are sensitive to a fungal disease known as "leaf curl", which is caused by a fungus whose scientific name is Taphrina deformans. Unless leaf curl is correctly controlled by suitable fungicides in environmental conditions that are favourable to leaf curl, it can lead to an almost total loss of leaves, with consequent compromised production of peaches and may lead to the withering or death of entire plants within a few years. It is estimated that most of the chemical impact of fungicides on the peach trees is due to the need to control leaf curl. Nevertheless, most of the active substances used in the world to control this disease (for example Ziram, Thiram, Iprodione, Procymidone, Dodine) in various countries are about to be or have already been listed on the "suspected list" of products that will be banned and/or severely restricted and/or have restricted efficacy because of resistance problems.

The experiment was conducted by spraying with a standard motor pump plots each containing about a hundred trees that were as homogeneous as possible with about 0.5 litres/tree of the aqueous compositions obtained by solubilizing in water the quantities of active ingredient shown in Table 1 on the bare branches of the peach tree in late autumn after the leaves had fallen. The treatment protocol conducted is shown in Table 2, together with the result of the evaluation of the leaf curl symptoms conducted at the start of the following spring (23 March). The efficacy percentage was calculated as a percentage reduction of the diseased leaves after setting the control (e.g. 1 E) equal to zero.

Table 1

Table 2

Owing to the moment of application of the aqueous compositions of examples 1 A-1 C in autumn/winter when there is no hanging fruits, the fruits obtained from blocks 1 A-1 C is by definition free of chemical substance residues.

Nevertheless, the action of the calcium nitrate and ammonium nitrate compounds as such is clear, but also that of the calcium nitrate:ammonium nitrate = 1 :1 .33 mixture that demonstrates a certain synergic effect between the two active ingredients. Example 2

A mixture (A) having the following composition (% by weight):

- 42.0% calcium nitrate;

- 32.0% ammonium nitrate;

- 5.0% urea;

- 7.0% mixture of amino acids; and

- co-formulants and tackifiers q.s. to 100%

was dissolved in water and used to treat the control of the occurrence of Taphrina deformans on the peach tree. The concentration used is set out in Table 3. The plants were sprayed by an industrial motor pump with the solution in a quantity of about 1000 litres/hectare.

The treatment protocol conducted is shown in Table 4, together with the result of the evaluation of the leaf curl symptoms conducted at the start of the following spring (April). The efficacy percentage was calculated as a percentage reduction of the diseased leaves after setting the control (e.g. 2C) equal zero.

Table 3

Table 4

Example 3

A further test in field conditions was conducted to prevent and/or treat the occurrence of the aforesaid "Apple scab", a fungal infection of apple trees caused by Spilocaea pomi { Venturia inaequalis). The test was run on apple trees that were treated with about 1000 litres/hectare on different dates with an aqueous solution obtained by diluting 5I of the following mixture with each 100 litres of water:

- 21 .75% by weight of ammonium nitrate;

- 4.5% by weight of urea;

- 4.0% by weight of amino acids; and

- water q.s. to 100% by weight.

The treatment protocol is set out in Table 5, together with the result of the evaluation of the percentage of leaves affected by scab seven days after each treatment. The efficacy percentage was calculated as a percentage reduction of the diseased leaves after setting the control at zero.

Table 5

Examples 4 and 5

In order to evaluate the efficacy of the composition according to the invention on diseases caused by different fungi, specific laboratory tests were run. The materials and techniques used to run these tests are commonly known as the "poisoned substrate" method. In accordance with this method, discs of mycelium measuring 5 mm in diameter were removed from pure colonies of fungi grown in Petri dishes. Subsequently, said discs were placed in the centre of Petri dishes the substrate (agar) of which contained an aqueous solution comprising the components shown in Table 6.

Table 6

Total growth of the colonies was measured after seven days of incubation in a thermostatic cell at 20°C and compared with the untreated control, i.e. the same fungus grown in Petri dishes having a pure substrate without additions. The results are shown in Table 7, the reduction percentage is defined as a reduction of the surface of the colonies placed on the surface of the control = 100.

For each of the species of assayed fungi, three hypotheses were compared, i.e. the non-treated control and the two hypotheses corresponding to Examples 4 and 5, the product concentrations of which are expressed as weight/weight % of product/substrate:

Table 7

Examples 6 and 7 The following aqueous compositions were tested on apple trees affected by "apple scab" caused by Spilocaea Pomi.

Aqueous compositions were sprayed the same day on apple trees, for three successive applications 7 days apart, during a life phase of the plant comprised between pre-flowering to loss of the petals. For the application, a motor pump carried on the back was used that distributed a volume of 1000 litres of aqueous composition per hectare.

The evaluation was conducted at T3+7, i.e. seven days after the last treatment, evaluating the incidence of disease (% of diseased leaves) and the seriousness thereof (diseased % of the surface of the leaf). The results are shown in Table 8.

The numbers followed by the same letter are not statistically different from one another by P=0.05% in the Duncan test.

At the tested concentrations, urea alone had no fungicide effect. The best results were obtained with a mixture of ammonium nitrate and urea, showing a certain synergy between these compounds in a molar ratio of respectively approximately 2:1 .

Claims

1 . A method for protecting fruit-bearing arboreal or shrubby plants against fungal infections, comprising at least one step (i) of spraying at least one arboreal plant and/or at least one shrubby plant with 150- 2,000 l/ha, preferably 500-1 ,500 litres/hectare, of an aqueous composition (A) comprising 1 -15% by weight of at least one active ingredient selected from ammonium nitrate, calcium nitrate and mixtures thereof, in which said at least one step (i) is carried out prior to the appearance of fruits on the plant.

2. The method according to claim 1 , wherein the aqueous composition (A) comprises 2-8% by weight of at least one active ingredient.

3. The method according to claim 1 or 2, wherein the at least one step (i) is carried out during the phase of vegetative stasis of the plant or during the phase of vegetative development of the plant prior to the appearance of fruits.

4. The method according to any one of claims 1 -3, wherein the at least one step (i) is carried out after the opening of the vegetative buds and until flowering.

5. The method according to any one of claims 1 -3, wherein the at least one step (i) is carried out during the phase of vegetative stasis of the plant, preferably on bare branches.

6. The method according to any one of claims 1 -5, wherein the aqueous composition (A) comprises calcium nitrate and ammonium nitrate, preferably in a ratio by weight comprised between 1 :5 and 5:1 , more preferably comprised between 1 :3 and 3:1 .

7. The method according to any one of claims 1 -6, wherein the aqueous composition (A) further comprises < 15% by weight, preferably 0-5- 15% by weight, more preferably 2 - 14% by weight, more preferably 2- 10% by weight, more preferably 3 - 7% by weight, of at least one adjuvant agent selected from urea, amino acids, wetting agents and mixtures thereof.

8. The method according to any one of claims 1 -7, wherein the aqueous composition (A) comprises urea.

9. The method according to any one of claims 1 -8, wherein the aqueous composition (A) comprises 1 -15% by weight, preferably 2-8% by weight, of active ingredient and 0.5-15% by weight, more preferably 2

- 14% by weight, more preferably 2-10% by weight, more preferably 3

- 7% by weight, of urea,

in which the active ingredient is ammonium nitrate and the molar ratio of ammonium nitrate:urea is comprised between 3.5:1 and 1 .5:1 .

10. The method according to claim 9, wherein the aqueous composition (A) comprises calcium nitrate.

1 1 . The method according to any one of claims 1 -10, wherein the at least one fruit-bearing plant is selected from Vitaceae, Rosaceae, Stone fruits and Pome fruits, preferably among Vitis vinifera, Prunus persica, Malus domestica and Pyrus.

12. The method according to any one of claims 1 -7, wherein said fungal infection is caused by at least one fungus selected from Taphrina deformans, Venturia inaequalis, Cycloconium oleaginum Monilia sp., Botrytis cinerea, Phomopsis sp. and Oidium tukeri, preferably from Taphrina deformans, Phomopsis sp.and Venturia inaequalis.

13. The method according to any one of claims 1 -8 comprising a plurality of steps (i), preferably 1 -5 steps (i), more preferably 2-4 steps (i).

14. A use of an aqueous composition as described in any one of claims 1 - 10 to protect fruit-bearing arboreal or shrubby plants against fungal infections caused by at least one fungus selected from Taphrina deformans, Venturia inaequalis, Cycloconium oleaginum, Monilia sp., Botrytis cinerea, Phomopsis sp., and Oidium tukeri, preferably from Taphrina deformans and Venturia inaequalis.