GB2066075A - Liquid agent for fungicidal treatment of seed - Google Patents

Abstract

Liquid, homogeneous composition for the fungicidal treatment of seed, containing as the fungicidal agent methylbenzimidazole- 2-yl-carbamate in the form of a salt with one or more of the acids: hydrochloric, hydrobromic, hydroiodic or perchloric acid, the salt being dissolved in an alcohol ether of the type <IMAGE> wherein R<1> indicates one of the groups CH3, C2H5, C2H5.CH2, (CH3)2.CH or <IMAGE> R<2 >and R<3> each indicate H or CH3, and n is the integer 1 or 2. The composition, if so desired, may further contain other fungicidal agents or insecticidal agents.

Description

SPECIFICATION Liquid agent for fungicidal treatment of seed For the treatment of seed grain and other forms of seed-in the following for convenience shortly termed "seed"- against fungus diseases, compositions having a content of organic mercury com wounds have been used for a number of years. Such compositions have been availabie both in the form of powders and in liquid form. The latter is to be prefer red, as one achieves thereby a better adherence of the composition to the seed and the nuisances caused by dust are thereby avoided. It is not difficult to prepare liquid fungicidal compositions having a content of organic mercury compounds, as the com pounds used ordinarily for this purpose are soluble in water or in the conventional organic solvents.

The use of organic mercury compounds for fungic idal treatment of seed is inadvisable, however, for one thing on account of the risk of spreading of mercury compounds to organisms and to the soil.

It is known that carbendazim (methylbenzimidazole - 2 - yl - carbamate) is an effective fungicide against a number of diseases which attack germinating seed, and dry compositions for fungicidal treatment of seed having a content of carbendazim either alone or together with other fungicides are known.

It is furthermore known to use suspensions of carbendazim in water or another liquid medium for combating fungus diseases. The use of suspensions presents, however, obvious disadvantages, in particular a tendency to form precipitates, and it is therefore desirableto be able to prepare liquid homogeneous compositions having a content of carbendazim in a concentration sufficient for obtaining a satisfactory fungicidal effect.

In the treatment of seed with a liquid fungicidal composition, it is suitable to use the composition in an amount of 100-500 ml, preferably 100-250 ml, per 100 kg seed. Amounts less than 100 ml are difficult to spread uniformly on 100 kg seed and with more than 500 ml per 100 kg seed, the seed may become so moistthatthe capacity of the treating apparatus is substantially reduced.

The preparation of a liquid homogeneous treating composition containing carbendazim presents, however, serious difficulties owing to the fact that carbendazim is practically insoluble in all conventional solvents. For instance, its solubility in benzene is 36 mg per liter and in ethanol 300 mg per liter.

It is known that carbendazim, which is a very weak base, can form salts with acids and thatthese salts are soluble in water or in aqueous acids. When these salts are dissolved in water a hydrolysis will, how ever, soon take place with precipitation of the free carbendazim. This precipitation can be prevented by adding an excess of acid, but such strongly acidic solutions (pH about 3) are not suitable as composi tions for fungicidal treatment of seed, as the acid excess will have a germinating-inhibiting or -preventing effect and, furthermore, may result in corrosion of the treating apparatus.

Instead of water or aqueous acids, the use of media such as ketones, amides, xylene, alcohols, alkylated naphthalene or glycols has been proposed.

Solutions in such media are not suitable either as fungicidal seed treating compositions, for one thing because the necessary concentrations of carben- dazim in the composition cannot be attained, and for anotherthing because the said solvents can have a detrimental effect on germination.

In the specification to Danish patent application No. 2165/74 it has been proposed to prepare carbendazim-conta in ing fungicidal compositions, including seed treating compositions, by preparing first an adduct of carbendazim and a sulfonic acid having at least 8 carbon atoms, and then preparing from this adduct, which is insoluble in water, the agents used in practice, e.g. solutions in organic solvents. Thus, as compositions for fungicidal treatment of seed especially solutions in dimethylformamide (DMF) or dimethyl sulfoxide are proposed.

The necessary, separate preparation of this carbendazim adduct complicates the preparation of said seed treating solutions and make it more expensive, and the costs are further increased by the fact that the adduct preparation is performed with a not negligible loss of carbendazim which in itself is rather expensive. Furthermore, the use of solvents as DMF and dimethyl sulfoxide in liquid compositions for fungicidal treatment of seed is unsuitable on account of the risk of detrimental effects on the germinating power of seed. The same applies to a number of the other organic solvents specifically proposed for liquid fungicidal compositions-such as for instance methylpyrrolidone.

Surprisingly, it has now been found according to the invention that salts of carbendazim with hydrochloric acid, hydrobromic acid, hydroiodic acid and perchloric acid are easily soluble in alcohol ethers of the type

where R' indicates one of the groups CH3, C2H5, C2H5.CH2, (CH3)2.CH or

R2 and R3 each indicates H or CH3, and n is the integer 1 or 2. It is, therefore, possible with said salts and said alcohol ethers and without addition of excess acid to prepare homogeneous stable solutions containing up to about 20% carbendazim, which is quite sufficient for the purpose of fungicidal seed treatment. No germination-inhibiting effect of the composition has been observed.

Accordingly, the invention relates to a liquid homogeneous composition for the fungicidal treatment of seed, containing the fungicide carbendazim (methylbenzimidazole - 2 - yl - carbamate) and possibly other fungicides or insecticides, which composition is characterized by the features recited in the characterizing part of claim 1.

Contrary to what is the case in the process disclosed in application no. 2165/74, it is not necessary first to prepare an adduct, with the difficulties and costs involved thereby, since the preparation of the composition according to the invention can easiiy take place, for instance, by only stirring carbendazim into the selected alcohol ether and then adding while stirring the selected acid in the molar ratio 1:1.

Within a short time the carbendazim is dissolved in the form of the corresponding salt. The dissolution process can be accelerated by using a small excess of the acid. Use of a large excess of acid should be avoided, not only on account of the abovementioned drawbacks but also on account of the fact that the solubility of the carbendazim salt is thereby reduced as a result of common ion effect.

It is not necessary to use the acids in question in anhydrous form. Thus use can be made, for instance, of 30% aqueous HCI, 45% aqueous HBr o r 70% aque- ous HClO4. A substantially higher water content in the treating compositions than the one produced thereby is, however, not suitable as the solubility of the carbendazim salts is then reduced.

The liquid homogeneous treating composition may in addition to carbendazim contain other fungicides or insecticides, provided that these are, as such, soluble in the alcohol ethers in question or form soluble salts with the acids in question. For instance, the seed treating composition according to the invention may, in addition to carbendazim, contain the fungicid "Imazalil" (1 - [Xss - (allyloxy) - 2,4 dichlorophenethylj - imidazole) in the form of a salt with one or more of the stated acids.

The invention is further illustrated by means of the following examples: Example I.

A solution is prepared from the following ingre dients: Carbendazim, 90% industrial 10.0 g Ethyleneglycol methyl ether 83.8 g Hydrobromic acid, aqueous 47,7% 9,0 g Rhodamin (for colouring) 0,4g 103.2 9 = 100 ml The preparation is carried out by stirring carbendazim into the ethyleneglycol methyl ether, whereupon the hydrobromic acid is added. No precipitation takes place even when the solution is left for standing for a considerable period at -10 C.

The solution is suitable for fungicidal treatment of wheat grain against bunt (Tilletia caries) and of rye grain against stem smut (Urocystis occulta), and for fungicidal treatment of both kinds of grain against Fusarium nivale and Septoria nodorum. A dose of 200 ml treating composition for 100 kg seed grain is recommended.

Example 2.

In the same manner as described in Example 1 a solution is prepared from the following ingredients: Carbendazim, 90% industrial 10.0 g Ethyleneglycol monoethyl ether 82.6 g Perchloric acid, aqueous 69.8% 7,3 g Rhodamin 0.2 g 100.19 = 100 ml Upon storage of the solution for a longer period at -1 0 C no crystallization takes place. The solution can be used as in Example 1.

Example 3.

In the same manner as described in Example 1 a solution is prepared from the following ingredieints: Carbendazim, 90% industrial 5.0 g Imazalil, 90% industrial 5.0 g Ethyleneglycol monoethyl ether 84.5 g Hydrobromic acid, aqueous 61,5% 5.9 g Rhodamin 0.4g 100.8g = 100 ml The solution is stable to cold down to -10 C. The solution can be used for fungicidal treatment of barley grain against stripe disease (Helmintosporium gramineum) and Fusarium nivale at a dose of 100 ml per 100 kg barley.

Example 4.

In the same manner as described in Example 1 a solution is prepared from the following ingredients: Carbendazim, 90% industrial 3.7 g Imazalil, 99% industrial 3.4 g Conc. hydrochloric acid 37% 3.1 g Ethyleneglycol methyl ether 88.5 g Rhodamin 0.3 g 99.5g =100 ml The solution is stable to cold down to -1 0 C. The solution can be used for fungicidal treatment of bar ley grain against stripe disease and Fusarium nivale at a dose of 150 ml per 100 kg barley.

Example 5.

In the same manner as described in the preceding examples, a solution of the following composition is prepared: Carbendazim, 90% industrial 5.6 g Hydroiodic acid, aqueous 57.5% 6.1 g Ethyleneglycol monoethyl ether 88.1 9 Rhodamin 0.2 g 100.0 g Upon storage at -10"C no crystallization takes place. The solution has the same field of application at the same dosage as in Example 1.

Example 6 In the same manner as described in the preceding examples, a solution of the following compositiqn is prepared: Carbendazim, 90% industrial 6.6 g Hydrobromic acid, aqueous 47,7% 5.6 g Diethyleneglycot monoethyl ether 93.4 g Rhodamin 0.2 g 105.8 g = 100 ml The solution has the same field of application as in Example 1. The dosage is about 300 ml per 100 kg seed. The solution is stable to cold down to -1 0 C.

Claims (2)

1. A liquid, homogeneous composition for the fungicidal treatment of seed, containing the fungicide carbendazim (methyl - benzimidazole - 2 - yl carbamate) and possibly other fungicides or insecticides, said composition being characterized in that it contains the carbendazim in the form of a salt with one or more of the acids: hydrochloric, hydrobromic, hydroiodic or perchloric acid, dissolved in an alcohol ether of the type

where R1 indicates one of the groups CH3, C2Hs, C2Hs.CH2, (CH3)2.CH or

and R3 each indicates H or CH3, and n is the integer 1 or 2.

2. Aseed treating composition as claimed in claim 1, characterized in that it contains the fungicide 1 - [p - (allyloxy) - 2,4 - dichlorophenethyl] - imidazole in the form of a salt with one or more of the stated acids.