Triazinyl vat dyestuffs

The present invention relates to novel herbicidal compositions which contain, as an active substance, at least one s-triazine derivative.

The use of s-triazine derivatives to control weeds and unwanted plants is known. If the substituents of positions 2 and 4 of the s-triazine ring are generally amino groups, usually monosubstituted, or disubstituted, the 10 substituents of position 6 are different and determine the classification of these substances into chlor-s-triazines, alkoxy- (usually methoxy). ) -striazine, alkylthio- (usually methylthio) -s-triazine, alkylthio- (usually methyltic-s-tria-^{! S}zine, azido-s-triazine, etc. Of the known methylthio-striazines, we mention: 2-amino-4-Isopropylaniino-6-rnetylIlo-s-triazine, of the known chloro-s-triazines, we mention 2-ethylamino-4-isopropylamino-6-c] or -s-triazine (a-20). trazine), and of the known methoxy-s-triazines we mention 2-amino-4-isopropylamino-6-methoxy-s-triazine. These triazine derivatives used so far in the form of different herbicidal compositions exhibit mediocre activity and reduced selectivity. Thus, the use of 2-amiiio-4-isopropylamino-6-methylmercapto-s-triazine in corn crops is not indicated due to the reduced selectivity of this substance. On the other hand, the product 2-ethylamino-4-isopropylamino ~ 6 ~ chloro-s-triazine has no action against meis (digitaria), one of the most important weeds.

The herbicidal compositions, according to the invention, eliminate these disadvantages by the fact that, in order to increase the herbicidal activity and selectivity, at least one s-triazine of formula I is constituted:

N Λ NW

H₂N - HN - C (CH₃)₃

N where symbol X represents a chlorine atom, a methoxy group or a methylthio group, in a proportion of 0.1 ... 95® / w by weight, together with support substances, solvents, diluent56466

LEI PRICE 3.50 years, suspending agents, emulsifiers, watering agents, adhesives, thickening agents. r The following are 3 examples of obtaining the active substance and preparing the compositions, in which parts are understood as parts by weight, and the temperatures are given in degrees Celsius.

Example 1. Preparation of 2-amino-4-tert-butyl-6-chloro-1,3 ^ -triazine.

in 3 000 parts by volume toluene, 330 parts 2-amino-4, 6-dicl-or-l, 3, 5-triazine are suspended, the suspension obtained is treated at 10 ° C with 300 parts tertbutylamine, drop by drop , and then stirred for 14 hours at 40 ° C. The formed precipitate is removed by filtration, and the filtrate is evaporated to a small volume and then allowed to stand.

The crystallized reaction product is separated by filtration and washed with toluene and hexane. This product has a melting point of 145 ... 146 ° C.

Example 2. Preparation of 2-amino-4-tert-butylamino-6-methoxy-1> 3,5-triazine.

Starting from 38 parts sodium and 1,800 parts by volume methanol, a solution of sodium methylate is prepared. In this solution, 302 parts of 2-amino-4-tert -butylamino-6-chloro-1,3,5-triazine ^ prepared as described in Example 1. The reaction mixture is boiled under reflux for 30 minutes. 24 hours and then dilute with 4 000 parts water. The fine crystalline reaction product is separated by filtration, washed with water and dried. This product has a melting point of 138 ... 140 ° C.

Example 3. Preparation of 2-am'mo-4-tert-butylamino-6-methylmercapto-1,3,3-triazine.

Starting from 38 parts sodium and 1 500 parts by volume isopropanol, a solution of sodium isopropylate is prepared. At 0 ° C, 85 parts methylmercaptan are poured into this solution. 302 parts of 2-amino-4-tert -butylamino-6-chloro-1,3,5-triazine prepared as described in example 1 are then added to the solution and the reaction mixture is kept for 14 hours at 80 ° C. The reaction mixture is then diluted with 3,000 parts water and cooled, and the precipitate formed is separated by filtration.

The colorless reaction product is washed with water. This product has a melting point of 142. ... 144 ° C.

The following herbicidal compositions were prepared from the products obtained according to the above examples:

Wettable powders

In order to prepare a water soluble wettable powder, mix the following and finely grind the following ingredients:

- 50 parts of the active substance according to the invention;

- 20 parts of highly adsorbent silica;

- 25 parts bolus alba (kaolin);

- 1.5 parts l-benzyl-Z-stearlbenzenimadazole 6,3-sodium disulfonate;

.— 3.5 parts of the condensation product of p-tertoctillenol and ethylene oxide.

Concentrates for emulsions.

a) An amount of 40 parts of an active substance, of formula 1 above, is mixed with 10 parts of a mixture consisting of an anionic surface aotative agent (preferably the calcium salt or the magnesium salt of the acid monolayerbenzenmonosultonic) and from a nonionic surfactant (preferably a sorbent monolayer polyethylene glycol ether), and the mixture obtained is dissolved in a small volume of xylene. The product obtained is made with xylene up to a volume of 100 ml. so as to obtain a clear solution, which can be used as a concentrate for spray-applied compositions and which - by pouring into water - produce a stable emulsion;

b) the slightly soluble active substances can be incorporated into emulsions concentrates based on the prescription of. lower:

- 20 parts active substance;

- 70 xylene parts;

- 10 parts of a mixture consisting of a condensation product of alkylphenols with ethylene oxide and calcium dodecylbenzenesulphonate.

.These ingredients mix with each other. By diluting the product with water to the desired concentration, a spray emulsion is obtained.

Granulated preparations

a) An amount of 7.5 g of an active substance of formula 1 above is dissolved in 100 ml. acetone, and the acetone solution thus obtained is applied on 92 g of granulated paste (with the granulation corresponding to the sieve with 9,5 ... 19 mesh / cm). The obtained mixture is mixed well and the solvent is then removed in a rotary evaporator. In this way, a granulated preparation with an active substance content of 7.5% is obtained.

b) for, to prepare a granulated product based on polymers egg concentration of 10%, dissolve an amount of 1 050 ...

100 g. from a technical active substance of formula I in a volume of 2 liters of trichlorethylene, and the solution obtained is sprayed into a fluidized layer granulator on 9 230 g, from a previously introduced, porous, granulated, porous, thyroformaldehyde resin in the granulator, the spray pressure having a value of 1.5 atm. By heating the fluidizing air to a temperature of about 50 ° C, the solvent is removed.

c) to produce a granulated preparation with a concentration of 7.5% and a mass. higher specification, prepare a mixture of 770 g of a solid technical substance of formula I, 500 g of barium sulfate, 5

000 g urea and 7 730 g. powdery, porous acrylic polynitrile and the mixture obtained is pressed on a roll and then ground to the desired granulation.

Herbicidal compositions, prepared as before ¹⁰above, they were biologically tested as follows: a number of plant seeds were sown in pots in the greenhouse.

in the case of tests before dawn, after a period of one day from ¹⁵at the time of sowing, the soil was treated by spraying with a spray solution containing an active substance at a certain concentration, prepared in accordance with ₉the recipes above.

In the case of post-emergence tests, the treatment was performed with the same spray solution, but after a time period of about 10 ...

Test after emergence the following significance:

- 1 .. .2 = no damage;

- 3., .4 = transient damage;

- 5 .. .7 = severe damage;

- 8 .. .9 - the destruction of the plants, in the present experiments, the results indicated in the table for the triazines according to the present invention were obtained, in comparison with the known 1,3,5-triazines, which from a chemical point of view are those closest to the triazines of this invention.

The compound of Example 1 compared to 2-amino-4-isopropylamino-6-methylmercapto-1,3-triazine (compound A) and 2-ethyl amino-4-isopropylamino-6-odor-1,3, 5-triazine (= A'trazine).

The compound of example 1 shows a considerably more extensive activity with respect to the weeds than that of the compound A known, without harming the crops of maize. The known Atrazine product does not affect the seedling (digitaria), one of the most important weeds, while the compound 1

TABLE 1

<td></td><td colspan="2">Compound 1</td><td colspan="2">Compound A (known)</td><td colspan="2">atrazine (Known)</td>

<td>kg active substance / ha</td><td> 2</td><td> 1</td><td> 2</td><td> 1</td><td> 2</td><td> 1</td>

<td>Zea mays</td><td> 2</td><td> 2</td><td> 2</td><td> 1</td><td> 1</td><td> 1</td>

<td>Digitaria</td><td> 9</td><td> 9</td><td> 9</td><td> 8</td><td> 2</td><td> 1</td>

<td>Panicum</td><td> 9</td><td> 5</td><td> 8</td><td> 5</td><td> 7</td><td> 6</td>

<td>Poa</td><td> 9</td><td> 9</td><td> 8</td><td> 8</td><td> 9</td><td> 9</td>

<td>Alopecurus</td><td> 9</td><td> 9</td><td> 8</td><td> 8</td><td> 9</td><td> 9</td>

<td>gallium</td><td> 9</td><td> 9</td><td> 7</td><td> 4</td><td> 9</td><td> 9</td>

<td>Caîendula</td><td> 9</td><td> 9</td><td> 8</td><td>β</td><td> 9</td><td> 9</td>

<td>Chrysanthemum</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td>

<td>Ipomoea</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td>

the seeds from the time of sowing, when the plants were in the stage with 2 ... 3 leaves.

The obtained results were evaluated after a period of 20 days from the time of sowing. 25

The biological effects were noted with the help of a numerical scale from 1 to 9, destroying this weed altogether, both at a concentration of 2kg / ha and at a concentration of lkg / ba.

The compound of Example 2 compared to 2-amino-4-isopropylamino-6-chloro-1, 3,5-triazine (compound B).

Test after sunrise TABLE 2

<td></td><td colspan="3">Compound 2</td><td colspan="3">Compound B (known)</td>

<td>kg. active substance / ha</td><td> 3 .</td><td> 1,5</td><td> 0,75</td><td> 3</td><td> 1,5</td><td> 0,75</td>

<td>Avena</td><td> 9</td><td> 9</td><td> 8</td><td> 9</td><td> 7</td><td> 7</td>

<td>Zea. mays</td><td> 2</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td>

<td>Digitaria</td><td> 6</td><td> 6</td><td> 3</td><td> 4</td><td> 3</td><td> 1</td>

8

<td>Poa</td><td> 9</td><td> 9</td><td> 9</td><td> 7</td><td> 6</td><td> 4</td>

<td>Alopecurus</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 8</td><td> 6</td>

<td>gallium</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 8 .</td><td> 4</td>

<td>Calendula</td><td> 9</td><td> 9</td><td> 9</td><td> .9</td><td> 9</td><td> 9</td>

<td>Chrys anthemum</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td>

<td>Ipomoea</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td><td> 7 ..</td>

Compound 2 shows a considerably more extensive action on the weeds than on the test before, on the rise of compound B used as a comparison standard.

TABLE 3

<td></td><td colspan="2">Compound 2</td><td colspan="2">Compound B (known</td>

<td>kg active substance / ha</td><td colspan="2"> 3 ( 1,5</td><td colspan="2">3 S 1.5</td>

<td>Avena</td><td> 9</td><td> 9</td><td> 9</td><td> 8</td>

<td>Zea mays</td><td> 2</td><td> 1</td><td> 3</td><td> 2</td>

<td>Poa</td><td> 9</td><td> 9</td><td> 9</td><td> 8</td>

<td>Alopecurus</td><td> 9</td><td> 9</td><td> 9</td><td> 7</td>

<td>gallium</td><td> 9</td><td> 8 .</td><td> 7</td><td> 5</td>

<td>Calendula</td><td> 9</td><td> 9</td><td> 9</td><td> 9</td>

<td>Chrysanthemum</td><td> 9 .</td><td> 9</td><td> 9</td><td> 9</td>

<td>Ipomoea</td><td> 9</td><td> 9</td><td> 9</td><td>9 I</td>

that of known compound B.

In the pre-emergence test method, the selective herbicidal action of Compound 2 is considerably better than that of Compound of Example 3 compared to 2-amino-4-isopr &amp; pilamiao-6-methoxy-1,3-triazine (Compound C).

Test before sunrise TABLE 4

<td></td><td colspan="2">Compound 3</td><td></td><td colspan="3">Compound C (known)</td>

<td>kg active substance / ha</td><td>2 days</td><td> 1</td><td> 0,5</td><td>2 I</td><td> 1</td><td> 0,5</td>

<td>Avena</td><td> 8</td><td> 7</td><td> 4</td><td> 6</td><td> 5</td><td> 3</td>

<td>Digitaria</td><td> 9</td><td> 6</td><td> 3</td><td> 4</td><td> 3</td><td> 3</td>

<td>Boa</td><td> 9</td><td> 8</td><td> 5</td><td> 7</td><td> 5</td><td> 3</td>

<td>Alopecurus</td><td> 9</td><td> 7</td><td> 4</td><td> 4</td><td> 4</td><td> 3</td>

<td>gallium</td><td> 5</td><td> 3</td><td> 2</td><td> 4</td><td> 4</td><td> 3</td>

<td>Calendula</td><td> 9</td><td> 6</td><td> 3</td><td> 4</td><td> 4</td><td> 3</td>

<td>Chrysamhomum</td><td> 9</td><td> 9</td><td> 7</td><td> 9</td><td> 9</td><td> 7</td>

<td>Ipomoea</td><td> 9</td><td> 9</td><td> 5</td><td> 4</td><td> 4</td><td> 4</td>

<td>Stellaria</td><td> 9</td><td> 9</td><td> 7</td><td> 9</td><td> 6</td><td> 6</td>

<td>Gossypium</td><td> 2</td><td> 1</td><td> 1</td><td> 4</td><td> 2</td><td> 1</td>

In the case of the application of compound 3 on cotton crops (gossypium), in comparison with compound C, it is observed that the known compound exhibits a considerably lower selectivity than that of the compound according to the present invention.

In general, a herbicidal composition has an active substance content of 0.1 ... 95 ° /₀ by weight.

Herbicidal compositions are capable of combating - more efficiently than known 1,3,5-triazines - parasitic herbs and weeds from useful plant crops, for example from the crops of sugar cane, potatoes, rice, corn, peas, sugar beet, cotton, groundnuts, cabbage, cereals, carrots, or can be used even in orchards and viticulture.

The quantities of active substances applied are 0,2 ... 6 kg active substance / ha, and preferably 0,3 .... 4 kg active substance / ha.

The three compounds of Examples 1, 2 and 3 above as active substances for herbicidal compositions, both for the selective destruction and elimination of weeds from plant crops, as well as for the total destruction and avoidance of unwanted growth of plants. In this case, weeds also mean unwanted crops, for example plants previously grown. The compounds defined above are also suitable as active substances that exert other inhibitory influences on plant growth, and especially defoliation - for example in the case of cotton - accelerating the maturation through premature drying (for example in the case of potatoes) , as well as decrease of fruit production, delay of flowering, prolongation of the harvesting period and improvement of the storage resistance of the cultivated and harvested products. The use of compositions for inhibiting plant growth can sometimes lead to an increase in harvest not only by weed destruction, but also by the fact that these compositions combat the factors that would stimulate the growth of plants grown in an unwanted direction, such as a high temperature. or abundant fertilization. On the other hand, the application of herbicidal compositions for the destruction of the tenacious weeds, for a longer time, can be important when the selectivity of the herbicidal composition is not high enough to avoid a reduction of the crop in the case of the cultivated plants when applying the respective composition.

The compositions according to the present invention, intended to influence the growth of plants and their use as herbicides, can be used in the form of solutions, emulsions, suspensions or powdering agents. The form of the preparations intended for application is determined entirely by the purpose of use. The preparations intended for direct application should ensure only a fine dispersion of the active substance, in the event of complete suppression of plant growth, or premature drying, as well as in the case of defoliation, the activity of the agents used can be intensified by using phytotoxic fillings through themselves, such as, for example, fractions of mineral oil with a high boiling point to gilded hydrocarbons; on the other hand, when aiming at selective weed control to increase selectivity, inert fillers are used compared to the weeding plants.

A series of solvents, in particular alcohols, such as ethyl alcohol, isopropyl alcohol, is used to prepare the solutions; ketones, such as acetone or cyclohexanone; aliphatic hydrocarbons, ca. for example, lamp oil, and cyclic hydrocarbons, such as benzene, toluene, xylene, tetrahydronaphthalene, alkylnaphthalenes, as well as gilded hydrocarbons, such as trichlorethane, ethylene chloride and, finally, mineral or vegetable oils, or mixtures thereof. up.

The aqueous preparations are in particular in the form of emulsions or dispersions. The substances are homogenized as such or in one of the solvents mentioned above, preferably with the help of watering agents and dispersing agents, after their incorporation into water. as canonical emulsifiers or dispersing agents, for example, quaternary ammonium compounds may be used; As antonic milking agents or dispersing agents, soaps, soft soaps, long-chain aliphatic monoesteres of sulfuric acid, alkyl-omatic sulfonic acids, long-chain alkoxyacetic acids may be used; As nonionic emulsifiers or dispersing agents, polyethylene ethers of fatty alcohols or ethylene oxide condensation products may be used. On the other hand, concentrates consisting of the active substance, an emulsifier or a dispersing agent, and possibly a solvent, and which are suitable to be diluted with water before application can be prepared.

The powder compositions can be prepared by simultaneously mixing or grinding the active substance with a solid filling. As a solid filler, talcum, diatomaceous earth, kaolin, bentones, calcium carbonate, boric acid, tricalcium phosphate, as well as wood flour, cork flour, coal and other materials of plant origin are used. The active substances can be applied to um-floats and with the help of a volatile solvent. By adding watering agents and protective colloids, powdered preparations and pastes can be suspended. give in water and can be applied by spray.

Because in the series of active substances, according to the present invention, both solid and liquid substances, which exhibit approximately the same erbioid activity, can readily prepare both liquid concentrates for aqueous emulsions, as well as powdered or paste concentrates for aqueous suspensions. with a high content of the active substance.

The granulated products can be prepared in a very simple way, by dissolving an active substance of formula i in an organic solvent, followed by the application of the solution thus obtained on the surface of granulated minerals, such as atapulgituL, silica, granicalcium, bentonite, etc. . and subsequent evaporation of the organic solvent.

It should be mentioned that granulated polymer preparations can also be used. These preparations are obtained in the following way: the active substances of formula I are mixed with polymerizable compounds (urea / formaldehyde, diciandiamide / forimaldehyde, melamine / formaldehyde, etc.), after which a polymerization is performed under gentle conditions, which does not involve the active substances, granulation taking place during gel formation. It is more advantageous, however, to proceed in the following manner: porous, finite granular polymers (such as ureolormaldehyde resins, acrylic polynitrile, polyesters, etc.), which possess a certain surface and a favorable adsorption and desorption behavior, which it can be preset, it is impregnated with the active substances, which are, for example, in the form of solutions (in a solvent with a low boiling point), afterwards removing the solvent.

These polymer granulated preparations can also be applied with the aid of powdering plants, when they are in the form of microgranules with apparent densities, preferably of 300 .... 600 g / liter. Powdered application on large areas cultivated cereal egg can also be executed using the help of airplanes.

It is understood that in these granulated preparations, other products such as other pests, fertilizers, surface active agents or substances intended to increase the specific weight (such as barium sulphate) may be added.

The granulated preparations can also be obtained by compacting the filling with active substances and with additives, followed by a feeding operation.

The various preparations for application can be better adapted to the purpose of use, by adding substances that improve dispersion, adhesion, resistance to meteoric waters, and possibly penetration capacity, such as, for example, fatty acids, resins, watering agents. , glue, casein or alginates. Also, the biological effect of these preparations can be increased by adding substances, which influence the growth of plants, as well as fertilizers.

In order to enhance the activity of the compositions according to the present invention, and to broaden their range of activity, some known herbicides can be added, for example:

A) Urea derivatives:

- N- (phenyl-N^r, N'-dimethylurea;

- N- (4-chlorophenyl) -N ', N'-dimethylurea;

- N- (3, 4-'-dichlorophenyl) -N', N'-dimethalurea;

- N- (4-olorophenyl) -N'methoxy-N'-methylurea;

- N- (3,4-dichlorophenyl) "N'-methoxy-N'-methyl-, urea;

- N-pbromophenyl-N'-methoxy-N'methylurea;

- N- (4-bromo-3-chlorophenyl) -N'-me toxii-N 'methylurea;

- N-4-chlorophenyl) -N'methyl-N-butylurea;

- N- (4-chlorophenyl) -N'-methyl-N '-isobutyl- / network;

- N-4- (chlorophenoxyphenyl) -N ', N'-dimethylurea.

B) Substituted triazines - 2-chloro-4,6-biS "(ethylamino) -s-triazine;

- 2-chloro-4-ethylafmino-6-isopropylatninp-striazine;

- 2-cl or-4,6-bis- (methoxypropyl amino) -striazine;

- 2-methoxy-4,6-bis- (isopropylamino) -striazine;

- 2-diethylamino-4-isopropylacetamido-6-methoxy-s-triazine;

—^; 2-isopropylamino-4-tethoxylethylamino-6-methylmercapto-s-triazine;

- 2-methylmercapto-4,6-bis- (isopropylamino) -s-triazine;

- 2-methylmercapto-4,6-bis- (ethylamino) -striazine;

- 2-methylmercapto-4-sttilamino-6-isopropylamino-s-triazine;

- 2-methoxy-4,6-i) is (ethylimino) -s-triazine;

- 2-methoxy-4-ethylamino-6-isopropylaminos-triazine;

- 2-Chloro-4_&gt;6-bis- (jzopropÎ'lamino) -S'-Îriazina.

These triazines can be mixed with the substances of formula I, according to the present invention, in a ratio between 1:10 and 20: 1.

C) Phenols - dinitro-sec-butylphenol or its salts ί - · pentachlorphenol or its salts.

D) Carboxylic acids - 2, 3, 6-trichlorobenzoic acid and its salts;

- the 2, 3, 5, 6-tetrachlorobenzoic acid and its salts;

- 2-retinoxy-3, 5, 6-trichlorobenzoic acid and its salts;

- 2-methoxy-3,6-dichlorobenzoic acid and its salts;

- 3-nitro-2,5-dichlorobenzoic acid and its salts;

- 3-amino-2,5-dichlorobenzoic acid and its salts;

- 2-methyl-3,6-dichlorobenzoic acid and its salts;

- 2,4-dichlorophenoxyacetic acid, its salts and esters;

- 2,4,5-trichlorophenoxyacetic acid, its salts and esters;

- (2-iOeti) -4-chlorophenoxy) -acetic acid, its salts and esters;

- 2- (2,4,5, -trichlorophenoxb-propionic acid, .salt salts and esters - 2 ', 2^r2- (2,4.2-trichlorophenoxy) -ethyl dichloropropionate;

- 4- (2,4-dichlorophenioxy) -butyric acid, its salts and esters;

• - 4- (2-methyl-4-chlorophenoxy) -butyric acid, its salts and esters.

L ·) Derivatives of carbamic acid - isopropyl ester of carbanilic acid;

- isopropyl ester of m-chlorcarbanilic acid;

- 4-olor-2-butynyl ester of mclorcarbanilic acid;

- Isopropyl ester of m-trifluoromethylcarbanilic acid.

F) Various compounds - 2,3,6-trichlorophenyl acetic acid;

- Chloroacetic acid dialylamide;

- maleic acid hydrazide;

—- disodium salt of methyl arsenic acid;

- borates;

- J-aminotriazole;

- pyrazine derivatives, such as pyramine,

- endo-oxo-hexahydrof.tsalic acid;

- diphenitacetic nitrile;

- Treflan;

- N-methoxymethylene-N-doracetyl-2,6-diethylaniline;

- the swing;

- planavine;

- dimethyl ester of tetrachlorphthalic acid;

- 4-trifluoromethyl-2,4'-dinotrodiphenyl ether;

- 2,4-dichloro-4'mtroidophenyl ether; ;

- 3-cyclohexy'-6-methyluracil;

- 3-cyclohexyl-6-sec-butyluracil;

- 3-cyclohexyl-5-bromuracil;

- 3-cyclohexyl-5-chloruracil;

- 3-isop.roipil-5-chloruracil;

¹⁰ - 3-isopropyl-5-bromuracil and other known uracils.

The advantages of herbicidal compositions according to the invention are the following:

- wide spectrum of activity, allowing the destruction of tenacious weeds;

- good selectivity;

- reduced phytotoxicity to the crop plants, making it possible to apply it²⁰ maize crops.