JPH0840816A - Microorganism-containing herbicide and method for applying the same - Google Patents

Abstract

PURPOSE:To obtain a microorganism-containing herbicide capable of preserving a microorganism having a weed control ability in a high survival rate for a long period and improving the weed control effect of the microorganism, and not requiring its dilution with water on its use. CONSTITUTION:The herbicide contains a microorganism having a weed control ability and at least one of a vegetable oil, a mineral oil, and a silicone as active ingredients. The microorganism having the weed control ability includes microorganisms belonging to the genus Exserohilum or Curvularia, especially preferably Exserohilum monuceras. The concentration of Exserohilum monuceras conidiums is preferably 10<5>-10<10> conidiums/liter in the herbicide, and the concentration of Curvularia conidiums is also preferably 10<10>-10<12> conidiums/liter. The herbicide is directly drop-sprayed at one or several spots of the water surface of a paddy field. The herbicide is effective against the weeds of the genus Echinocloa spp, and is especially effective against the early period growth weeds submerged in the water of a paddy field.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a herbicide containing a microorganism having weed control ability and at least one of vegetable oil, mineral oil and silicone as an active ingredient, and a herbicide therefor. Regarding the weeding method used.

[0002]

2. Description of the Related Art Currently used chemical herbicides have various problems such as emergence of resistant weeds, phytotoxicity to crops, and increase in difficult-to-control perennial weeds due to changes in weed species. Also, due to the growing interest in environmentally friendly agriculture, expectations are growing for biological control of weeds. In recent years, weed control by microorganisms has been studied, and in the United States, Phytophtho, which is the pathogenic microorganism for controlling weeds in the citrus orchard family, has already been used.
DeVine that the chlamydospores of ra Palmivora an active ingredient (Abbo
tt Laboratories) and the pathogenic microorganism Colletotrichum gloeosporioides for controlling legumes in paddy fields and soybean fields.
f. sp. aeschynomene spores of Collego (Ecogen
Company) is commercially available. In addition to this, Colletotorichum gloe is used in China for the control of vegetative vines parasitic on soybean.
Lu-boa No.2, which uses osporioides , is Co for controlling malvazenia mallow , which is a problem weed such as wheat in Canada.
BioMal (Pilom Bios) containing lletotrichum gloeosporioides f.sp. malvae as an active ingredient is commercially available.

Generally, dry spores can be easily formulated as a powdery wettable powder, but in this case, it is necessary to dilute with water or the like at the time of use, so that considerable labor is required. For example, Collego is sold as a set with a powder containing spores as an active ingredient and a solution containing sucrose for suspending it. When using these two ingredients are mixed and diluted with water. There is a need. Moreover, such a dosage form causes powdering. On the other hand, DeVine, which is currently commercialized in the form of a cell concentrate, does not have the problem of Collego, but has the problem that it cannot be stored for a long time (Weed Science 34 (Suppl.1) (1986 ): 15-16).

In recent years, even in Japan, attempts have been actively made to develop microbial herbicides utilizing phytopathogenic fungi whose weeds are hosts. In particular, the development of microbial herbicides for Novie is progressing, and there has been proposed an attempt to formulate the pathogenic bacteria of Novie alone or in a form mixed with the chemical herbicide base according to the formulation of existing chemical herbicides. (JP-A-4-226905 and JP-A-4-360678). However, the dosage forms described in these are similar to the conventional chemical herbicides, and it is considered that they still have problems such as uneven sprinkling at the time of spraying and dusting at the time of dilution.

[0005]

An object of the present invention is to solve the problems of the conventional herbicides and the herbicidal methods, and more specifically, dilute them with water at the time of use. It is an object of the present invention to provide a microbial herbicide which is unnecessary and has excellent storage stability.

[0006]

Means for Solving the Problems The present inventors
Based on the finding that a composition consisting of oils such as mineral oil and silicone is effective for controlling weeds in paddy fields,
Completed the invention and filed an application first (Japanese Patent Application No. 5-333087)
issue). After that, the present inventors further studied the oils, and as a result, it was found that microorganisms can survive in these oils for a long period of time, and that these oils dramatically improve the weed control ability of the microorganisms. The present invention has been completed and the present invention has been completed.

That is, the first aspect of the present invention is a herbicide characterized by containing as an active ingredient a microorganism having weed control ability and at least one of vegetable oil, mineral oil and silicone. Examples of the microorganism having the ability to control weeds used herein include microorganisms belonging to the genus Exerohyrum or the genus Calbularia, and among these, Exerohyram monoceras can be exemplified as a suitable microorganism.

As the weeds of interest, weeds belonging to the genus Mussel can be mentioned. A second aspect of the present invention is a weeding method characterized by applying the above-mentioned herbicide to a paddy field. As a specific spraying method, there is a method of directly dripping and spraying on the paddy field. Hereinafter, the present invention will be described in detail.

The present invention has a composition different from that of the microbial herbicide products already on the market, and by formulating according to the present invention, the herbicidal effect of the microorganism itself having weed control ability is dramatically improved. Also, vegetable oils, mineral oils,
Due to the properties of silicone, the microorganisms rapidly spread the water surface of the paddy field and uniformly exert a herbicidal effect over a wide area. In addition, the formulation according to the present invention enables long-term storage of various microorganisms including those having weed control ability.

The present invention provides a herbicide containing a microorganism, which comprises at least one of the three components of vegetable oil, mineral oil and silicone and a microorganism having weed control ability as an active ingredient. Is. The microbe-containing herbicide of the present invention spreads the water surface rapidly and very widely by the characteristics of these oils by direct dripping on one or several places on the flooded water surface of the paddy field, and yet at the simple interface. The herbicidal effect is far superior to that of the bacterial cell suspension prepared by using the aqueous activator solution. It is considered that this is because plant oil, mineral oil, or silicone itself damages the target weed, and promotes the effect of the microorganism having the weed control ability. In addition, since it is a liquid and is an agent that is dropped directly onto the water surface, there is no danger of powdering when diluted with water during application, and the safety for the operator is very high. Further, since it contains oil, it is particularly effective when using spores having a hydrophobic surface as an active ingredient. Furthermore, since the plant oil, mineral oil, and silicone contained in the herbicide of the present invention float on the water surface for a long period of time and exert an effect, the possibility of contamination of the surrounding water system due to dissolution in water is low and the application amount is extremely low. The small amount has very little impact on the environment. Further, this preparation can be stored for a long period of time at room temperature.

Mineral oils that can be used in the present invention include spindle oil, heavy white oil, light white oil, mineral spirit, mineral terpene, naphthenic oil, paraffin oil, machine oil for agricultural chemicals, and the like. It is not limited. Examples of vegetable oils that can be used in the present invention include, but are not limited to, soybean oil, rapeseed oil, castor oil, cottonseed oil, palm oil, and safflower oil.

As the silicone that can be used in the present invention, silicone oil or silicon oil is generally used. Specifically, silicone oil TSF-451-10 (Toshiba Silicone Co.), silicone oil SAG-47 (Nippon Unicar) are used. Company) and the like, but are not limited thereto. .

The microorganism used in the present invention is not particularly limited as long as it has a weed control ability, but it is preferable to use a microorganism belonging to the genus Exerohyrum or the genus Calbularia.
It is preferable to use a microorganism belonging to Monoceras. Specifically, Excello Hiram Monoceras B026 ( Exseroh
ilum monoceras B026) (FERM BP-4215), Exserohilum monoceras B23
2) (FERM BP-4217), Excello Hiram Monoceras
B263 ( Exserohilum monoceras B263) (FERM BP-421
8), Excello Hiram Monoceras B267 ( Exserohilu
m monoceras B267) (FERM BP-4219), Exserohilum monoceras B276
(FERM BP-4220), Curvularia lun
ata) B-261 (FERM BP -4249), Karuburaria belonging to the genus (Cur
vularia lunata ) B-236 (FERM BP-4248), Curvularia lunata var. aeria ) B-245 (FERM B
P-4247) can be exemplified as a suitable strain.
In the present invention, it is preferable to use conidia of these microorganisms, but ascospores, mycelium pieces and the like may be used instead of conidia. Conidia and the like can be obtained by culturing the above-mentioned microorganism in, for example, potato glucose agar medium, oatmeal sucrose agar medium or the like for about 5 to 10 days. The surface of all the conidia of any of the above strains is hydrophobic, and dusting easily occurs in the dry state. However, the formulation according to the present invention improves such physical properties and facilitates handling. In the case of using Exerohyrum monoceras conidia in the preparation according to the present invention, the content thereof is 1 × 10 ³ to 1 × 10 ¹¹ cells / liter, preferably 1
× 10 ⁵ to 1 × 10 ¹⁰ pieces / liter. On the other hand, when using conidia of the genus Calvaria, the content is 1 x 10
⁵ to 1 x 10 ¹⁵ pieces / liter, preferably 1 x 10 ¹⁰ to 1 x 1
0 ¹² pieces / liter.

In addition to the above, the herbicide of the present invention may optionally contain various additives such as nitrogen sources (nitrates, ammonia, amino acids, etc.) and carbon sources useful for the growth of bacterial cells, or , Substances that promote germination of spores (carboxymethylcellulose sodium salt, sodium naphthalenesulfonate formalin condensate, polyethylene glycol, etc.), and moisturizers (polysaccharides such as hyaluronic acid, proteins such as collagen and lecithin, glycerin, oils and fats) Etc.) can be added and used without any problem.

When mineral oil and vegetable oil are blended and used as oils in the present invention, the composition ratio of both components is such that mineral oil is 99.5% by weight or less, preferably 50 to 99.5% by weight, vegetable oil is 60% by weight or less, It is preferably 0.5 to 50.0% by weight. When mineral oil and silicone are blended and used as oils in the present invention, the composition ratio of both components is
It is 99.5% by weight or less, preferably 85-99.5% by weight, and silicone is 15.0% by weight or less, preferably 0.5-15.0% by weight.

In the present invention, when vegetable oil and silicone are blended and used as oils, the composition ratio of both components is
Vegetable oil 99.5% by weight or less, preferably 85-99.5% by weight,
Silicone is 15.0% by weight or less, preferably 0.5 to 15.0% by weight. In the present invention, when mineral oil, vegetable oil and three silicone components are used as oils, the composition ratio of the mineral oil is 99.5% by weight or less, preferably 50 to 50% by weight.
It is 99.5% by weight. Also, vegetable oil is 60.0% by weight or less, preferably 0.25 to 45.0% by weight, and silicone is 10.0% by weight.
Below, it is preferably 0.25 to 5.0% by weight.

The herbicidal composition of the present invention exerts an effect on all weeds occurring in paddy fields.
In particular, it is effective against weeds of the genus Musca such as Taenia cinerea, Pleurotus cornucopiae, Pleurotus cornucopiae and P. cinerea. The growth stage of the plant to be weeded is not particularly limited, but it is particularly effective for the early stage of growth in which the whole plant is submerged in paddy water. For example, if it is Novie, 2
It has a great effect on the growth stage after the leaf stage. The herbicide of the present invention has no effect on the growth of rice, which is a useful crop in paddy fields.

When the herbicide of the present invention is applied to an actual paddy field, its application method is not particularly limited as long as it is a method capable of effectively controlling weeds, but it may be directly applied by spraying to a paddy field under flooded water. desirable. The time of use of the herbicide of the present invention is not particularly limited, but since it is particularly effective for seedlings submerged in water, it is desirable to use the herbicide after subcultivation, preferably early after rice planting.

When the herbicide is applied in the field,
The application rate is conidia of Exerohyrum monoceras
1 x 10 in quantity²~ 1 x 10^FifteenPcs / 10 are, preferably
1 x 10^Five~ 1 x 10¹¹Cal / 10 are
1 x 10 in the amount of conidia of the genus ^Four~ 1 x 10¹⁹10 pieces
Le, preferably 1 × 10^Ten~ 1 x 10¹³In 10/10 are
It

[0020]

EXAMPLES The present invention will be described below with reference to examples. However, the present invention is not limited to these examples.

[Example 1] Long-term storage test Preparation of spore suspension Exerohyrum monoceras B026 was cultured on potato dextrose agar medium, and the conidia formed were collected and dried, and then spindle oil: castor oil: A silicone oil (Toshiba Silicone Co., Ltd.) = 95: 4: 1 was mixed in a composition to prepare a suspension having a spore concentration of 1 × 10 ⁷ / ml. As a control, a spore suspension (spore concentration: 1 × 10 ⁷ / ml) was prepared at the same time by using an aqueous Triton X-100 solution (0.02% by weight).

Long-term storage of spore suspension 1 ml each of the preparation and the control solution prepared by the above method were placed in a 2 ml brown ampoule tube and stored at 4 ° C, 25 ° C and 40 ° C. At this time, an appropriate amount of conidia in a dried state was also enclosed and stored in an ampoule tube. After removing the composition consisting of oil or TritonX-100 solution by sampling over time (at this time, the oil adhering to the conidia was removed by washing the surface with hexane, so TritonX- The surface of the conidia from which 100 was removed and the conidia stored in a dry state were also washed with hexane.)
The conidia were suspended in a 1% glucose solution, and 25 μl of the suspension was dropped on a slide glass in a wet chamber. After culturing in the dark at 25 ° C for 24 hours, the spore germination rate was measured. For the germination rate, the number of germinated spores in any 50 spores was measured under a microscope, and the percentage was expressed as a percentage. The average of three repetitions of this value was taken and evaluated as the long-term storage stability of the preparation. The results are shown in Table 1.

Table 1 Long-term storage test ───────────────────────────────────── Preparation spore germination rate ( %) After storage for 5 weeks After storage for 8 weeks After storage for 12 weeks ───────────────────────────────────── TritonX-100 aqueous solution stored at 4 ° C Spore suspension at 0 0 0 stored at 25 ° C 0 0 0 40 ° C stored at 0 0 0 Oil composition stored at 4 ° C 95 96 93 Spore suspension stored at 25 ° C 91 98 93 40 ° C stored at 82 84 73 dried spores stored at 4 ° C 94 99 93 93 stored at 25 ° C 89 95 84 stored at 40 ° C 77 2 0 ──────────────────────────── ─────────

Thus, it was found that the herbicide of the present invention is very suitable for long-term preservation of microorganisms. Especially, the higher the storage temperature was, the better the spore storage property was compared to other storage methods.

[Example 2] Test of growth inhibitory effect on Nobie by 1/10000 ares Exechohyrum monoceras conidiospore preparation 10cm x 10cm (1/10000) pots of paddy soil were used to grow Nobie on 1.5 leaf stage After raising the seedlings to a certain degree, the pots were flooded to submerge the plants, and the composition was dropped into each pot for treatment. The contents of each process are as follows. Treatment A: 0.02% Triton X-100 aqueous solution only 10 μl (100 ml
/ R) Dropped.

(Untreated section) Treatment B: 4 × 10 ⁴ conidia of Excellohyrum monoceras B026 (4 × 10 ⁸ ) collected and dried in the same manner as in Example 1
10 μl (100 ml) of 0.02% Triton X-100 aqueous solution
/ Earl) and suspended. Treatment C: Spindle oil, castor oil, and silicone oil (Toshiba Silicone Co., Ltd.) were mixed in a weight ratio of 95: 4: 1, and 10 μl (100 ml / R) of an oil composition was added dropwise. Treatment D: 4 × 10 ⁴ conidia (4 × 10 ⁸ / Arl) of Excello Hiram monoceras B026 recovered and dried in the same manner as in Example 1, spindle oil, castor oil, silicone oil (Toshiba Silicone Co., Ltd. ) Was suspended in 10 μl of an oil composition (100 ml / Ar) blended in a weight ratio of 95: 4: 1, and added dropwise.

The treatments A to D were applied to pots, each of which 10 seedlings were raised. The growth state of Nobie was compared and observed between the pots that had been treated and the untreated pots for 3 weeks after the dropping treatment. At that time, the degree of growth inhibition was determined as a percentage with 0% when there was no difference from the growth situation of Nobie in the untreated pot and 100% when the growth was completely inhibited. The results are shown in Table 2.

Table 2 1/10000 R scale test (Exero Hiram Monoceras) ────────────────────────────── ───── Treatment Growth inhibition rate (%) 1 week 2 weeks 3 weeks ────────────────────────────── ───── A 0 0 0 B 50 40 10 C 65 50 30 30 D 90 80 80 ────────────────────────────── ───── (Note) The numbers in the table indicate the degree of growth inhibition. The day of treatment was designated as day 0.

[0029] In contrast to untreated Nobie grown on the water, the herbicide adhered to the water surface of the treated pot as it grew, and the growth on the water was significantly inhibited, and the whole plant was necrotic. There were also individuals. Further, it was found that by mixing the oil composition and the bacterial cells according to the present invention to prepare a formulation, the effect of inhibiting the growth of the Novier plant alone and the oil composition can be dramatically improved. The treatments A to D had no effect on the growth of rice, which is a useful crop in paddy fields. Calbularia spp. Conidia preparation

A test similar to that of the above-mentioned Exoerohyrum monoceras conidial preparation was conducted. The contents of each process are as follows. Treatment E: 0.02% Triton X-100 aqueous solution only 10 μl (100 ml
/ R) Dropped. (Untreated area) Treatment F: 1 × 10 ⁶ conidiospores (1 × 10 ¹⁰ cells / Ear) of Calbularia sp. B-261 cultured and cultured in the same manner as Exerohyrum monoceras BO26, 0.02 % TritonX-1
It was suspended in 10 μl of an aqueous solution of 00 (100 ml / Ear) and added dropwise. Treatment G: 10 μl (100 ml / R) of a liquid prepared by mixing spindle oil, castor oil and silicone oil (Toshiba Silicone Co., Ltd.) in a weight ratio of 95: 4: 1 was dropped. Treatment H: Calbularia genus collected and dried in the same manner as above
B-261 Conidia 1 x 10 ⁶ (1 x 10 ¹⁰ / are), spindle oil, castor oil, silicone oil (Toshiba Silicone Co., Ltd.) in a weight ratio of 95: 4: 1 Oil composition 10 μl Suspended with (100 ml / R) and added dropwise.

The treatments E to H were applied to pots each having 5 seedlings raised. In the same manner as described above, the growth state of Nobie was compared and observed between the pots that had been treated for 3 weeks after the dropping treatment and the pots that had not been treated, and the degree of growth inhibition was determined. The results are shown in Table 3.

Table 3 1/10000 Earl Scale Test (Calbraria spp.) ──────────────────────────────── ─── Treatment Growth inhibition rate (%) 1 week 2 weeks 3 weeks ──────────────────────────────── ─── E 0 0 0 F 10 40 30 G 40 50 35 H 70 85 85 85 ──────────────────────────────── ─── (Note) The figures in the table indicate the degree of growth inhibition. The day of treatment was designated as day 0.

In the same manner as in the case of Excello Hiram monoceras, the untreated Novier grew on the water, whereas the treated pot showed the growth of the herbicide on the water surface and the growth on the water was significantly inhibited. , And some of them had necrosis of the whole plant. Further, it was found that by mixing the oil composition and the bacterial cells according to the present invention to prepare a formulation, the effect of inhibiting the growth of the Novier plant alone and the oil composition can be dramatically improved. The treatments E to H did not affect the growth of rice, which is a useful crop in paddy fields.

[Example 3] Scale-up test of growth inhibitory effect on Nobies 20 plants of Nobies were sown in paddy soil of 10 cm x 10 cm (1/10000 are) from 1.5 to 2 leaf stages, and then in the daytime. twenty five
75 cm x 100 cm (75/10
The above-mentioned pot was submerged in a flooded pool (000 ares), and the plant was installed at a predetermined position (the depth of water is such that all plant bodies are submerged, approximately 5 cm from the paddy soil surface to the water surface). (A total of 4 pots were installed, one pot at a point 40 cm from the center on the diagonal line in each pool.) The composition corresponding to each treatment group was applied dropwise to the center point of these pools. Then, it was left in the greenhouse for 4 weeks, and the individual live weight of the Novier that remained in each pot was measured to examine the improvement effect of conidia on the Novier growth inhibition effect. The contents of each process are as follows.

Treatment 1: 0.02% Triton X-100 aqueous solution alone 7
50 μl (100 ml / R) was added dropwise. (Treatment Section) Treatment 2: Conidia 7.5 × 10 ⁵ (10 ⁸ / s) of Excellohyrum monoceras B026 collected and dried as in Example 1.
750 μl of 0.02% Triton X-100 aqueous solution (100 ml /
Earl) and then added dropwise. Treatment 3: 75 μl (10 ml / R) of an oil composition containing spindle oil, castor oil and silicone oil (Toshiba Silicone Co., Ltd.) in a weight ratio of 95: 4: 1 was added dropwise. Treatment 4: Conidia 7.5 × 10 ⁵ (10 ⁸ / s) of Exechohyrum monoceras B026 recovered and dried in the same manner as in Example 1.
Earl) is suspended in 75 μl (10 ml / Ear) of an oil composition in which spindle oil, castor oil, and silicone oil (Toshiba Silicone Co., Ltd.) are mixed at a weight ratio of 95: 4: 1.
Dropped.

In order to determine the strength and spreadability of the control effect together, the individual live weight of the Novier remaining in 4 pots (4 pots placed at a position 40 cm from the center) set in each treated pool The average value of was calculated and compared. The results are as shown in Table 4.

Table 4 Scale-up test ───────────────────────────────── Treatment residual solid weight (g) ───────────────────────────────── 1 9.2 2 11.0 3 9.8 4 4.0 4.0 ─ ──────────────────────────────── (Note) The numbers in the table are the average of the four outer pots in each pool. Indicates a value. The day of the dropping treatment was set as the 0th day.

[0038] Subsequent to this, SR Colby ("Calculating Synergistic and
Antagonistic Response of Herbicide Combinations ”
Weeds. 15/1, 1967 pp20-22), the predicted herbicidal effect of the bacterial cells formulated with the oil composition was calculated from the following formula, and the growth inhibitory effect was compared with this. In Table 4, the residual individual live weight of the other treatments is subtracted from the residual individual live weight of Treatment 1 (untreated plot), and the ratio of the value to the residual individual live weight in the untreated plot is calculated as a percentage, and each treatment is calculated. And the growth inhibitory effect in.

E (expected growth inhibitory effect) = X + Y-XY / 100 (X = growth inhibitory effect of only cells (treatment 2 in Table 4) Y = oil composition only (treatment 3 in Table 4) As a result, the expected growth inhibitory effect derived from the growth inhibition effects of treatment 2 (growth inhibition effect = -19.6%) and treatment 3 (growth inhibition effect = -6.5%) (that is, the expected growth of treatment 4). The inhibitory effect) was -27.4%, and the actual growth inhibitory effect of treatment 4 was 5
Compared with 6.5%, it can be seen that the effect of inhibiting the growth of bacterial cells is dramatically improved by the formulation according to the present invention.

As described above, it was revealed that the effect of inhibiting the growth of weeds by plant pathogens was dramatically improved by formulating the preparation according to the present invention. It was also confirmed that the composition according to the present invention spreads the water surface by dropping it at one place in a paddy field under flooded water, and exerts a uniform effect over a wide range. The treatments 1 to 4 had no effect on the growth of rice.

[0041]

INDUSTRIAL APPLICABILITY According to the present invention, it becomes possible to preserve a weed-controlling microorganism for a long period of time with a high survival rate and improve the weed-controlling effect of the microorganism.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location A01N 65/00 F (72) Inventor Yasuko Tsujino 6 Umegaoka, Midori-ku, Yokohama-shi, Kanagawa Japan Tobacco Inc. Plant Development Laboratory Yokohama Center (72) Inventor Yoko Fukuhara 2-6 Umegaoka, Midori-ku, Yokohama-shi, Kanagawa Japan Tobacco Inc. Plant Development Laboratory Yokohama Center (72) Inventor Hiroshi Tsukamoto Yokohama, Kanagawa Prefecture 2 Umegaoka, Midori-ku, Yokohama-shi, Japan Tobacco Inc. Plant Development Laboratory Yokohama Center

Claims (7)

[Claims] 1. A herbicide containing a microorganism having weed control ability and at least one component selected from vegetable oil, mineral oil and silicone as an active ingredient. 2. The herbicide according to claim 1, wherein the microorganism having the ability to control weeds is a microorganism belonging to the genus Exerohyrum or the genus Calbularia. 3. A microorganism belonging to the genus Exerohylam,
The herbicide according to claim 2, which is Excello Hyrum monoceras. 4. The herbicide according to claim 2, wherein the microorganism belonging to the genus Calbraria is Calbraria lunata. 5. The herbicide according to any one of claims 1 to 4, wherein the target weed is a grass weed. 6. A herbicidal method comprising applying the herbicide according to claim 1 to a paddy field. 7. The herbicidal method according to claim 6, wherein the herbicide is sprayed directly onto the paddy field under flooded water.