DE2653652A1 - METHODS OF SELECTIVE WEED CONTROL AND SELECTIVE HERBICIDES - Google Patents

Description

The invention relates to a method for selective weed control and selective weedkillers which contain as active ingredient a mixture of a triazine derivative and a substituted N-alkyl-N'-arylurea.

It is known that N-alkyl-N´-arylureas have a herbicidal effect (DL-PSen

100 871 and 100 142). A herbicidally active mixture consisting of N-methyl-N'-phenylurea and 2,4-dichlorophenyl-4-nitrophenyl ether (DL-PS 101 531) is also known. Among the weed killers available in agricultural practice today, the herbicides based on triazine derivatives can mostly be 233- (s8999) -FSBk funds used are expected.

A disadvantage of such triazine compounds is that they have a relatively high residual effect on future crops, e.g. cereal plants. After years of use, some herbicide-resistant weed species are selected under the influence of these agents, especially grasses such as barnyard millet (Echinochloa crus galli) or wind stalk (Apera spica venti). Finally, N-alkyl-N´-arylureas are ineffective against some important weed species and are not very selective towards the crop in question, especially at high doses.

The invention is based on the object of specifying improved weedkillers for the eradication of monocotyledonous and dicotyledonous weeds in corn, cereal, legume and potato crops which do not have the disadvantages of previous compositions.

The object is achieved according to the invention by weedkillers which, as active ingredient, are a mixture

a) one or more triazines of the general formula I. with

R [high] 1 = halogen, in particular chlorine, methoxy and methylthio

and

R [high] 2 and R [high] 3 = simultaneously or independently C [low] 1 - C [low] 4-alkyl

and

b) one or more N-alkyl-N´-arylureas of the general formula II with

R [high] 4 = halogen, methoxy, trifluoromethyl, methyl or nitro and

n = an integer from 0 to 2

contain,

the weight ratio of the two components a: b being 1: 9 to 9: 1 and preferably 1: 3 to 3: 1.

The active ingredients according to the invention can be prepared for use in various application forms such as solutions, emulsions, suspensions, powders, pastes or granules, which are produced, for example, by mixing the active ingredients with various auxiliaries such as liquid solvents or solid carriers or surface-active substances such as emulsifiers and dispersants. If water is used as the solvent, organic solvents can also be used as auxiliary solvents. The liquid solvents used are aromatic compounds such as xylene, toluene, chlorobenzene, petroleum fractions, alcohols such as methanol, butanol or the like, or strongly polar solvents such as dimethylformamide, dimethyl sulfoxide or the like. in question. As solid carriers For example, kaolin, aluminum oxide, talc, whiting, highly dispersed silicic acid and silicates can be used. Polyoxyesters of fatty acids, polyoxyethers of fatty alcohols such as alkylaryl polyglycol ethers, alkylsulfonates and arylsulfonates can be used as emulsifiers. Lignin, sulphite waste liquors and methyl cellulose, for example, can be used as dispersants.

The active ingredients according to the invention can be used in concentrated or diluted form. In general, the dose used contains 2 to 75% active ingredient, based on the mixture.

The agents according to the invention are effective against grass-like weeds such as, for example, chicken millet (Echinochloa crus galli) or wind stalk (Apera spica venti), although the effect is only mediocre when the individual components of the mixtures are used individually. In comparison with the herbicidal action of the individual components, the agents according to the invention have a pronounced synergistic effect.

Among the other advantages, it should be emphasized that the mixtures according to the invention also show increased effectiveness against dicotyledonous weeds, the treated crops such as maize (Zea mays), cereal plants such as wheat (Triticum sesitivum L.), rye (Secale cereale L.) and about Legumes such as beans (Phaseolus vulgaris) or peas (Pisum sativum) remain without any damage after treatment. At the same time, the negative residual effect on future crops is also reduced.

The invention is explained in more detail below on the basis of exemplary embodiments.

The following compounds were used for the tests:

I. N-methyl-N´-phenylurea (Defenuron)

II. 2-chloro-4-isopropylamino-6-ethylamino-s-triazine (zeazin)

III. 4.6-bis-isopropylamino-2-methylthio-s-triazine (selectin)

IV. 2-chloro-4.6 bis-ethylamino-s-triazine (Herbex)

V. 2-methylthio-4-ethylamino-6-t-butylamino-s-triazine (Igran, terbutrin)

VI. <formula>

VII. <formula>

VIII. <formula>

IX. <formula>

X. N´-3 (3-chloro-4-methylphenyl) -N, N´-dimethylurea (Dicuran)

XI. 2,4-dichlorophenyl-4´-nitrodiphenyl ether + N´-4. Dichlorophenyl-N-methyl-N-butylurea (Mixi Tok S)

XII. Diphenyl ether + 2-chloro-4,6-bis-ethylamino-s-triazine (Trazalex)

XIII. 2.6-Dinitro-N, N-dipropyl-4-trifluoromethylaniline + N´- (3,4-dichlorophenyl) -N-methoxy-N-methylurea (Trinulan)

example 1

Mustard (Sinapis alba L.), chicken millet (Echinochloa crus galli), corn (Zea mays) and pea (Pisum sativum) seeds were sown in flower pots and placed in a greenhouse. Before the seeds emerged, the soil surface was sprayed with different doses of the combinations of the active ingredient I with the substances II, III, IV and V and, to compare the effect, with different doses of the individual active ingredients I, II, III, IV and V. After the herbicidal effect became recognizable, i.e. on the 14th day after application, the degree of plant damage was determined by gravimetric analysis. From the data obtained on the average weight of the treated plants and the control samples, the percentage herbicidal activity was calculated using Abbot's formula:

percentage herbicidal effect = K-P / K times 100 (%),

In the

K is the average weight of the plants in the control sample and

P is the average weight of the treated plants

mean.

The results obtained are given in Tables I and II.

Example 2

The procedure was as in Example 1. The results are given in Table III.

Example 3

The following compounds were used for the investigations:

I. N-methyl-N´-phenylurea (Defenuron)

II. 2-chloro-6-ethylamino-4-isopropylamino-s-triazine (zeazin).

The procedure was as in Example 1. Mustard (Sinapis alba L.) was chosen as the test plant. The ED [deep 50 values were recorded graphically in a known manner. The results are shown in Table IV.

Example 4

To demonstrate the synergistic effect, the active ingredients I and V were used individually and together in the ratios 1: 1, 1: 3 and 3: 1. Analogously to Example 1, the surface of the soil in which the chicken millet (echinochloa crus galli) had been sown was treated with a dose series of the substances mentioned and their combinations. After the occurrence of the herbicidal action, the degree of plant damage was determined by gravimetric analysis and the percentage herbicidal action and the ED [low] 50 values for the individual components and their combinations were calculated.

The existence of a synergistic effect is evident from the comparison of the ED [low] 50 values expected for a simple additivity and the experimentally determined ED [low] 50 values. The expected ED [low] 50 value was calculated from the concentration of the components in the mixture and their individually obtained ED [low] 50 values. The Finney formula was used for the calculation.

The test results are given in Table V.

Is ED [low] 50 setpoint / ED [low] 50 actual value> 1, there is a synergistic effect of the tested weedkillers.

Example 5

Connections examined:

I. 2-methylthi-4-ethylamino-6-6-butylamino-s-triazine (terbutrine, Igran)

II. N-phenyl-N-methylurea (Defenuron) and mixtures thereof.

The effect of the herbicides was determined by four successive small field tests (10 x 2.5 m). Aqueous suspensions of the mixtures to be examined were applied with a backpack syringe kept at a propane-butane working pressure of 2 to 3 atmospheres. The area was evenly sprayed with 2 l of the aqueous suspension. The effect against wind stalk was determined before harvesting the plant culture in question (wheat) after shooting the wind stalk panicles by adding the field wind stalk individuals per m [to the power of 2]. The results of the field trials (carried out in Pezinok, Slovakia) are given in Table VI.

Example 6

The procedure was as in example 5 with the exception that the investigations were carried out in Kos (Slovakia). The results are given in Tables VII and VIII.

Example 7

The effect of herbicidal mixtures on the wheat yield was determined by small field tests. The procedure was as in Example 5. The events are given in Tables IX and X.

Table 1

Herbicidal effect of the individual components

Table II

Herbicidal effects of mixtures

Table III

Percent herbicidal effect of mixtures

Table III (continued)

Table III (continued 2)

Table III (continued)

Table IV

Herbicidal effect of mixtures on mustard (Sinapis alba L.) depending on the percentage of the individual components

Table V

Synergism of mixtures, determined on barnyard millet (Echinochloa crus galli)

Table VI

Table VII

Table VIII

Table IX

Table X

Results of the wheat yield study (Caucasus variety)

Claims (3)

1. Selective herbicides for combating monocotyledonous and dicotyledonous weeds in corn, cereal, legume and potato crops, characterized in that they are a mixture as the active ingredient (a) a triazine of general form I. with R [high] 1 - halogen, especially chlorine, methoxy and methylthio and R [high] 2 and R [high] 3 = simultaneously or independently C [low] 1-C [low] 4-alkyl and (b) an N-alkyl-N´-arylurea of the general formula II with R [high] 4 - halogen, methoxy, trifluoromethyl, methyl or nitro and n - an integer from 0 to 2 contain, the weight ratio of the two active ingredient components a: b being 1: 9 to 9: 1. 2. Herbicides according to claim 1, characterized in that the weight ratio of the two active ingredient components a: b is 1: 3 to 3: 1. 3. A method for the selective control of monocotyledonous and dicotyledonous weeds in corn, cereal, legume and potato crops, characterized in that a mixture according to claim 1 or 2 is applied either directly to plants or by soil treatment.