HK1010469A - Control of corn borers by 1-aryl pyrazole or 1-heteroaryl pyrazole compounds - Google Patents

Description

Control of corn borer with 1-arylpyrazole or 1-heteroarylpyrazole compounds

The present invention relates to a method for protecting corn.

There is a need to prevent corn borer infestation, particularly those of the borer family such as european corn borer [ latin name: ostrinia species, such as Ostrinia nubilalis (hereinafter European corn borer), southwestern corn borer and Lesser corn stem borer. These different corn borers present similar problems. Corn borer larvae can consume 40% of the total plant leaf tissue, thereby substantially reducing photosynthesis and subsequent yield. The consumption of ears by late infection can further reduce yield. European corn borer can also penetrate into the stem to take food; this penetration weakens the stalks and breaks in storms or windy weather, resulting in reduced yield.

Moreover, since pest feeding occurs in the spiro-ring neutralization tunnels of the stalks which are not readily observable, the pests are not obvious and therefore it is possible to consider the insecticidal treatment unnecessary or to select the insecticidal treatment for such an inappropriate time that larvae are not controlled until they enter the spiro-ring ears of the plant or penetrate into the hard stalks.

The cryptic effect of european corn borer and the difficulty in correctly selecting the timing of foliar application of insecticides, makes it desirable to have a long-term and sustained protection of corn against european corn borer; and further to avoid the unexpected entry of the european corn borer into the volutes and stems of plants. However, the available pesticides that must be applied to the leaves to control european corn borer do not provide a useful period of protection of more than one or two weeks.

This difficulty with respect to the correct choice of application time can be overcome by application to the plant soil, but the method is hardly expected to be effective in preventing european corn borer when moderate doses of active ingredient are used due to the time interval (2 to 4 months) between application of the product to the soil and infection of european corn borer, and the distance (0.7m to 2.5m) between leaves from the soil to be fed by the larvae of european corn borer.

In the present description and claims, the word "maize" and the word "maize" are equivalent. The words "maize", "corn", "maize plants", and "maize seeds" encompass all developmental stages and parts of the plant, including seeds, leaves, stalks and maize steady grain.

It is known that maize plants can be protected with heterocyclic insecticides, as described in patent applications WO87/3781, 93/6089, 94/21606 and European patent application 295117.

It is an object of the present invention to provide an effective method of treating corn to control european corn borer, although this method is currently highly biased.

Another object of the present invention is to provide a method for treating corn to control european corn borer with high efficiency.

It is another object of the present invention to provide a method for the long term effective treatment of corn for the control of european corn borer.

These and other objects are more fully described in the specification of the present invention.

It has been found that these objects can be adjusted and achieved by the present invention.

The present invention is directed to a method of controlling corn borers (e.g., european corn borers) that infest or are susceptible to infestation or are expected to infest corn plants, and a method of protecting corn plants from corn borers (e.g., european corn borers) by applying an effective amount of a 1-arylpyrazole insecticidally active ingredient to, near or around previously planted corn seeds.

The present invention is also directed to a method of reducing and/or preventing the formation of tunnels in corn stalks by applying an effective amount of a 1-arylpyrazole insecticidally active ingredient to, adjacent or around previously planted corn seeds.

Still further objects of the present invention are a method of controlling corn borer (e.g., european corn borer) infesting or maturing susceptible or predicted to infest corn plants, and a method of protecting mature corn plants against corn borer (e.g., european corn borer) by applying an effective amount of a 1-arylpyrazole insecticidally active ingredient in the vicinity of the seed of the corn sown at the time of sowing.

1-arylpyrazole compounds which can be used according to the invention are compounds of the formula (I):wherein: r₁Is CN or methyl; r₂Is S (O)_nR₃；R₃Is alkyl or haloalkyl; r₄Selected from hydrogen atoms, halogen atoms, and possibly-NR₅R₆，C(O)OR₇，-S(O)_mR₇Alkyl, haloalkyl, -OR₈or-N ═ C (R)₉)(R₁₀) A group of (a); r₅And R₆Independently selected from the group consisting of hydrogen atom, alkyl, haloalkyl, -C (O) alkyl, -S (O)_rCF₃(ii) a Or R₅And R₆Together form a divalent group into which one or more heteroatoms may be inserted; r₇Selected from alkyl or haloalkyl; r₈Selected from alkyl, haloalkyl or hydrogen atoms; r₉Selected from hydrogen atoms and alkyl groups; r₁₀Selected from phenyl or heteroaryl, optionally substituted with one or more hydroxy, halogen, -O-alkyl, -S-alkyl, cyano, or alkyl groups or combinations thereof; x is selected from nitrogen atom and C-R₁₂A group; r₁₁And R₁₂Are respectively selected from halogen atoms or hydrogen atoms; r₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, -S (O) qCF₃，-SF₅(ii) a m, n, q, r are each independently selected from 0, 1, and 2; if R is₁When it is methyl, R₃Is haloalkyl, R₄Is NH₂，R₁₁Is Cl, R₁₃Is CF₃And X is N. The conditions of claim 1 are included for reasons of biological effect.

The alkyl and alkoxy groups in formula (I) are preferably lower alkyl and alkoxy groups, i.e.groups with one to four carbon atoms. The haloalkyl and haloalkoxy groups likewise preferably have one to four carbon atoms. The haloalkyl and haloalkoxy groups may carry one or more halogen atoms, preferred such groups include-CF₃and-OCF₃。

Preferred 1-arylpyrazole groups for use in the present invention are those of formula (I) wherein: r₁Is CN; and/or R₄is-NR₅R₆(ii) a And/or R₅And R₆Independently selected from hydrogen atom, alkyl, haloalkyl, -C (O) alkyl，C(O)OR₇(ii) a And/or X is C-R₁₂(ii) a And/or R₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, or-SF₅。

Particularly preferred 1-arylpyrazole groups for use in the present invention are those of formula (I) wherein: r₁Is CN; r₄is-NR₅R₆；R₅And R₆Independently selected from hydrogen atom, alkyl, haloalkyl, -C (O) alkyl, C (O) OR₇(ii) a X is C-R₁₂；R₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, or-SF₅。

Specific pyrazole derivatives which can be used in the control of European corn borer within the scope of the present invention include 5-amino-3-cyano-1- (2, 6-dichloro-4-trifluoromethylphenyl) -4-trifluoromethylsulfinylpyrazole. This particularly preferred insecticide for use in the present invention is hereinafter referred to as compound a.

The preparation of the compounds of formula (I) can be carried out according to any of the processes described in International patent publications WO 87/03781, WO 93/06089 and WO 94/21606, as well as European patent publications 0295117, 0403300, 0385809, and 0679650, German patent publication 19511269 and U.S. Pat. Nos. 5,232,940 and 5,236,938.

As noted above, the 1-arylpyrazoles of the present invention must be applied in the vicinity of the seed of the corn being sown. In practice, this means that the active ingredient should be applied to the corn seed to be planted (before sowing, optionally as a direct treatment of the corn seed) or as a soil treatment after sowing the corn seed.

It is advantageous to apply the active ingredient to the soil at or after the sowing of the corn seeds so that a ratio of active ingredient in the soil of from about 0.01kg/ha to about 1kg/ha, preferably between 0.02 and 0.3kg/ha, is provided.

Advantageously, the above-described 1-arylpyrazoles can be formulated into flowable compositions, wettable powders, microemulsions and the like, which are applied to soil, water and/or foliage and provide the desired plant protection. The formulations comprise a compound of the present invention admixed with an inert, agronomically acceptable solid or liquid diluent. The preferred dosage form for soil application is a granule or liquid dosage form.

Descriptions of possible formulations can be found in patent applications WO87/3781, 93/6089, 94/21606 and in European patent application 295117.

For example, wettable powders, powders and concentrates of powders of the active ingredients of the invention may be prepared by grinding together a 1-arylpyrazole compound of formula (I) with from about 1 to 20% by weight of a solid anionic surfactant. One suitable anionic surfactant is the dioctyl ester of sodium sulfosuccinate. The formulation also includes from about 85% to about 99% by weight of an inert solid diluent such as montmorillonite, attapulgite, chalk, talc, kaolin, diatomaceous earth, limestone, silicates or the like, and other adjuvants as hereinbefore described.

As described above, the 1-arylpyrazoles of the present invention can also effectively control European corn borer when applied to corn before sowing. The corn can be processed, in particular by coating or embedding or soaking in liquid or pasty preparations of defined nature and subsequently dried. Particularly suitable are corn comprising 2 to 1000 g/liter, preferably 5 to 800 g/liter.

The invention is particularly advantageous as it provides for long term treatment. Protection is achieved according to the invention for a period of time corresponding to a maize plant growing about 2 to 3 meter stems.

The following examples are provided to illustrate the invention.

Example 1

Corn was sown in a 3.51 storage tank and grown in the greenhouse. Granules of Compound A (1.5% w/w) were applied to the soil surface after sowing at a rate corresponding to 120g/ha of active ingredient. The European corn borer egg masses are placed on the leaves 3-4 weeks after the plants germinate. The number of culworms holes caused by european corn borer was counted 4-5 weeks after infection (when the plants were higher than 2 meters).

Untreated controls, and plants treated with granules of Terbutos (1120g/ha) and Imidacloprid (500g/ha) had on average 5.3, 5.5 and 5.6 wormholes/stalk, respectively. While the plants treated with compound a had an average of 0.4 wormholes/stem.

Example 2

Corn seeds were treated with compound a at a rate of 500 grams of compound a per load of seed. Then, the experiment was performed as described in example 1. Finally, the plants had an average of 1.3 wormholes/stalk. Untreated plants had an average of 4.1 wormholes/stalk.

Example 3

Corn seeds were treated with compound a at a rate of 500 g/shoulder seed. Then, the seeds were sown and allowed to grow for 90 days, and then the damage against European corn borer was evaluated. The untreated control group had an average of 20.3 wormholes per 10 stalks and 72.5% of the stalks were damaged. The seeds treated with compound a developed plants with an average of 6.5 wormholes/10 stalks (68% control) and damaged stalks of only 32.5%.

Example 4

Corn is sown in the field and allowed to grow. The granules of compound A were applied to the soil surface at the time of sowing at a ratio of 120g AI/Ha active ingredient, and a part of the plants were subjected to furrow opening treatment and strip treatment. All plants were infected 48 days after sowing with European corn borer egg blocks at a ratio of 50-100 eggs/plant. Specimens were collected at 77 days of sowing and examined for the number of wells per ten plants and the percentage of plants infected with pests. The data are shown in table 1. Percent (%) control was calculated as follows: % control [ (% infected untreated plants) - (% infected treated plants ]/(% infected untreated plants)

TABLE 1

Treatment of	Number of wormholes per 10 stalks	% infected plant	% control
				Compound A tape treatment	1.0	8	82
Compound A furrowing treatment	1.5	15	67
				Untreated control	8.5	45	-

Example 5

Corn is sown in the field and grown. The granules of compound A were applied to the soil surface at the time of sowing at a ratio of 120g AI/Ha active ingredient, and a part of the plants were subjected to furrow opening treatment and strip treatment. All plants were infected with European corn borer egg blocks at a rate of 50-100 eggs/plant 74 days after sowing. The number of wells per ten plants and the percentage of plants infected with pests were sampled and examined 103 days after sowing. Percent (%) control was calculated as in example 4. The results are shown in Table 2

TABLE 2

Treatment of	Number of wormholes per 10 stalks	% infected plant	% control
				Compound A tape treatment	0.3	3	96
Compound A furrowing treatment	2.5	18	75
				Untreated control	9.8	73	-

Example 6

Corn is sown in the field and grown. The granules of compound A were applied to the soil surface at a ratio of 120gAI/Ha of active ingredient during sowing, and a part of the plants were subjected to furrow opening and strip treatment. All plants were infected with European corn borer egg blocks at a ratio of 50-100 egg blocks/plant 91 days after sowing. The number of insect wells per ten plants was sampled and checked at 127 days after sowing. Untreated plants had an average of 4.3 wormholes per 10 cobs. The plants banded and furrowed with compound a had on average 2.8 and 2.3 wormholes per 10 spikes, respectively.

Claims (15)

1. A method of controlling corn borer infesting or susceptible to infestation or expected to infest corn plants comprising applying to, around or near pre-planted corn seeds an effective amount of a compound having the formula:wherein: n is a radical of₁Is CN or methyl; r₂Is S (O)_nR₃；R₃Is alkyl or haloalkyl; r₄Selected from hydrogen atoms, halogen atoms, and possibly-NR₅R₆，C(O)OR₇，-S(O)_mR₇Alkyl, haloalkyl, -OR₈or-N ═ C (R)₉)(R₁₀) A group of (a); r₅And R₆Independently selected from the group consisting of hydrogen atom, alkyl, haloalkyl, -C (O) alkyl, -S (O)_rCF₃(ii) a Or R₅And R₆A divalent group having one or more hetero atoms is bonded together; r₇Selected from alkyl or haloalkyl; r₈Selected from alkyl, haloalkyl or hydrogen atoms; r₉Selected from hydrogen atoms and alkyl groups; r₁₀Selected from phenyl or heteroaryl, optionally substituted with one or more hydroxyl, halogen atoms, -O-alkyl, -S-alkyl, cyano, or alkyl groups or combinations thereof; x is selected from nitrogen atom and C-R₁₂A group; r₁₁And R₁₂Are respectively selected from halogen atoms or hydrogen atoms; r₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, -S (O)_qCF₃，-SF₅(ii) a m, n, q, r are respectively selected from 0, 1 and 2; if R is₁Is methyl, R₃Is haloalkyl, R₄Is NH₂，R₁₁Is Cl, R₁₃Is CF₃And X is N.

2. A method of protecting corn from corn borer comprising: applying an effective amount of a compound of formula (I) on, near or around previously planted corn seeds:

wherein the substituents are as defined in claim 1.

3. A method according to claim 1 for reducing and/or preventing wormholing in corn stalks comprising: applying an effective amount of a compound of formula (I) on, near or around previously planted corn seeds.

4. The method of any preceding claim, comprising: applying the compound of formula (I) at the time of sowing the corn seeds.

5. The method of any preceding claim, comprising: applying the compound of formula (I) to treat soil after the corn seeds are sown.

6. A method of protecting a corn plant against corn borer according to claim 1 comprising: applying to the corn seed prior to planting a compound of formula (I).

7. A method according to any preceding claim wherein the corn borer is Ostrinia nubilalis.

8. The method of any preceding claim, wherein:

R₁is CN; and/or

R₄is-NR₅R₆(ii) a And/or

R₅And R₆Independently selected from hydrogen atom, alkyl, haloalkyl, -C (O) alkyl, C (O) OR₇(ii) a And/or X is C-R₁₂(ii) a And/or

R₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, or-SF₅。

9. The method of any preceding claim, wherein:

R₁is CN;

R₄is-NR₅R₆；

R₅And R₆Independently selected from hydrogen atom, alkyl, haloalkyl, -C (O) alkyl, C (O) OR₇；

X is C-R₁₂；

R₁₃Selected from halogen atoms, haloalkyl groups, haloalkoxy groups, or-SF₅。

10. A process according to any preceding claim, wherein the compound of formula (I) is 5-amino-3-cyano-1- (2, 6-dichloro-4-trifluoromethylphenyl) -4-trifluoromethylsulfinylpyrazole.

11. A method according to any preceding claim, wherein the active ingredient is applied to the soil such that there is a proportion of active ingredient of from about 0.01kg/ha to about 1 kg/ha.

12. A method according to any preceding claim, wherein the active ingredient is applied to the soil such that there is a proportion of active ingredient between 0.02 and 0.3 kg/ha.

13. A method according to any preceding claim, wherein the active ingredient is applied such that the corn seed contains 2 to 1000 g/q of the active ingredient.

14. A method according to any preceding claim, wherein the active ingredient is applied such that the corn seed contains 5 to 800 grams/q of the active ingredient.

15. Composition for use in a method according to any one of the preceding claims, comprising from 0.0001 to 95% by weight of active principle of formula (I) as defined in the preceding claims.