US2017506A - Insecticide - Google Patents

Description

Patented Oct. 15, 1935 UNITED STATES INSECTICIDE Lindley E. Mills, Midland, Mich., assignor to The I Dow Chemical Company, Midland, Mich, a, corporation of Michigan No Drawing. Application June 26, 1933,

' Serial No. 677,690

5 Claims.

The invention relates to improvements in insecticidal compositions; and particularly to oil emulsions for use against insects such as aphids, red spider, mealy bug, codling moth, thrips, etc. Aqueous oil emulsions have the disadvantage of burning foliage at oil concentrations sufficiently high to kill insects effectively. This is particularly the case when the sulphonation value of the oil is below 85. It has, therefore, been proposed to prepare emulsions having a. lower oil content, so as to have a lower burning effect, and yet retain their insecticidal properties, by incorporating therewith other well-known insect poisons such as arsenicals, nicotine derivatives and plant extracts, phenols, and a variety of organic compounds having a higher toxicity than the oil.

Emulsions prepared according to such proposals have met with indifferent success for various reasons. When an arsenicalis included in the emulsion, and the composition used on fruit trees, a poisonous residue remains on the foliage after evaporation of the insecticide. This of course necessitates the expense of cleaning the fruit before sale. In the case of nicotine derivatives, and plant extracts generally, the added expense incurred by their use could not be economically justified, and furthermore, some of the plant extracts such as pyrethrum, are unstable in sunlight.

Emulsions including a phenol were unsatisfactory because the amount of phenol that could be included therein was limited by the foliageburning effect of the added compound itself. It was, therefore, a question of balancing the factor of higher toxicity of the phenol as against the toxicity of the oil replaced, with the factor of the foliage-burning effect of the phenol against that of the oil replaced. Moreover, in all cases the toxic values of such compositions were, at best, merely the sum of the values of the separate ingredients.

Not finding a satisfactory solution among the foregoing mixtures, it was then proposed to use a refined oil, or a petroleum fraction of higher sulphonation value, and thereby obtain an oil which could be used in concentrations having satisfactory killing power but which would have a lesser tendency to burn foliage. This procedure has not resulted in the development of a satisfactory insecticidal oil emulsion, and of course the highly refined oils or narrow cuts of petroleum are more costly because of the expense of the extra refining procedure and the larger quantity of oil used to obtain the desired toxicity.

It is therefore among the objects of this invention to provide an effective, inexpensive composition comprising a petroleum fraction and a. second ingredient, having a greater toxic value than the compositions heretofore known in the art at concentrations non-injurious to foliage. To-the accomplishment of the foregoing and related ends the invention, then, consists of the composition of ingredients hereinafter fully described and 5 particularly pointed out in the claims.

I have found that when ortho-dichlorobenzene is incorporated with a petroleum fraction in an emulsion, a composition is produced having a high toxic value with no burning effect on foliage. The percentage of ortho-dichlorobenzene which I include with the petroleum fraction in an oil emulsion is, generally-between one-third and onehalf the weight of the petroleum fraction used. The quantity of petroleum fraction used will depend in general upon the sulphonation value thereof, the higher this value the more of the fraction required to obtain the same toxicity. I can use petroleum fractions having a sulphonation value at any point above 50, preferably be- 20 'tween about and about 85. Ordinarily, the per cent by weight of petroleum fraction inthe finished emulsion ready for spraying will not exceed about 1.5 per cent and thequantity of ortho-dichlorobenzene will not exceed about 0.8 25 per cent.

It is an established fact that insecticidal emulsions containing slightly. more than two per cent of an oil having a sulphonation value below eighty-five will burn foliage sprayed therewith. 30 Certain foliage, such as that of the pear, apple, and other fruit trees, in humid weather will not safely tolerate even this low a concentration. A satisfactory killing effect can not, be attained with an oil having a sulphonation'value above 35 at concentrations below 2 per cent. Orthodichlorobenzene used alone will produce severe burning at concentrations above 1.0 per cent, and will not kill effectively even at this concentration. However, in the composition prepared 49 according to the present invention, the oil concentration is ordinarily below 1.0 per cent, and preferably below 0.8 per cent, except in the case of highly refined oils having a high sulphonation value. The concentration of ortho-dichloroben- $5 zene is always below about 0.5 and preferably below 0.3 per cent. Thus, the concentration of both oil and ortho-dichlorobenzene as sprayed on foliage is far below that at which any burning effect will be encountered.

Now, at such low concentrations of oil and orthodichlorobenzene it would be expected that the toxicity of the emulsion would be very low. However, we have found that a pronounced increase is produced in the toxicity of a petroleum 5 fraction by incorporating ortho-dichlorobenzene therewith, the toxicity of the mixture being greater than that of the sum of the individual components, as shown in the following table.

The table shows the comparative mortality of 60 varying concentrations of mixtures of oil and ortho-dichlorobenzene as against the individual ingredients. All of the figures given in the table indicate percentages, the percentages of oil and of ortho-dichlorobenzene being by weight present in the emulsion as sprayed onto foliage. The per cent mortality was determined in the following manner:-

Wingless adult females of the bean aphid (Aphis rumicis) were placed on a disc of cotton flannel in a petri dish and sprayed under identical conditions with aqueous emulsions containing varying concentrations of oil and orthodichlorobenzene. After having been sprayed for 15 seconds, the aphids were removed from the flannel with a camel's hair brush and placed on a nasturtium leaf mounted in a wide-mouth bottle having a small amount of water in the bottom thereof. The number of dead and'living aphids on the leaves at the end of 24 hours was then determined.

which will give an emulsion having a particle size of 6 to 8 microns is desirable, and the caseinates produce approximately this size of particle. If the emulsions have a much smaller particle size,

. they do not break rapidly enough to have the best 5 killing effect.

The optimum percentage ranges of ingredients in my finished emulsion are as follows:

Per cent by weight 10 Petroleum fraction 0.5 to 1.5 Ortho-dichlorobenzene 0.1 to 0.8 Emulsifying agent 0.02to 0.04 Water 97.66 to 99.38

Table Composition 25 on Mortality o-oanol, Mortality j Oil 000E401: Mortality 1.00 82 1.00 82 0. I6 70 0. 25 3 0. 70 0. 25 97 o 0. 50 04 0. 50 1 0. 50 0. 00 02 0. 28 34 0. 12 0. 20 0. 7B 07 l. 00 24 1. 00 24 60 Ortho-dichlorobenzene 20 Sodium caseinate. 2 Water 18 The preparation of the foregoing concentrate is accomplished by dissolving the emulsifying agent in water and then slowly adding the mixture of a petroleum fraction and ortho-dichlorobenzene to the water solutionwith rapid agitation. The concentrate is to be incorporated with 80 parts by weight of water to prepare a solution of proper strength for spraying on foliage. The finished emulsion therefore contains:

Per cent by weight Petroleum fraction. 0.75 Ortho-dichlorobenzene' 0.25 Sodium caseinate 0.025 Water 98.975

Sodium caseinate is employed as an emulsify: ing agent, but other salts'of casein, such as the potassium, calcium, or ammonium salts can also be used, as well as other known emulsifiers, such as linoleates, oleata, etc. An emulsifying agent Other modes of applying the principle of my invention may be employed instead of those ex- 35 plained, change being made as regards the materials employed, provided the ingredients stated by any of the following claims or the equivalent of such stated ingredients be employed.

I therefore particularly point out and distinctly 40 claim as my invention:-

1. A composition of matter adapted to be mixed with water and an emulsifying agent to form an emulsion suitable for use as a plant and tree spray comprising a petroleum distillate and ortho-di- 5 chlorobenzene.

2. A composition of matter suitable for use as a plant and tree spray comprising up to about 1.5 per cent of a petroleum fraction having a sulphonation value above 50, up to about 0.8 per 60 cent of ortho-dichlorobenzene, an emulsifying agent, and water.

3. A composition of matter suitable for use as a plant and tree srray comprising up to about 1.5 per cent of a putroleum fraction having a sul- 5 phonation value .LbOVB 50, up to about 0.8 per cent of ortho-dichlorobenzene, a water soluble salt of casein, and water.

4. ,A composition of matter suitable for use as a plant and tree spray comprising by weight: 60

- Per cent A petroleum fraction 0.5 to 1.5

Ortho-dichlorobenzene 0.1 to 0.8

An emulsifying agen-t 0.02 to 0.04