Transactions of RHASS Volume 1940 - Page 033
Image details
| Year | 1940 |
|---|---|
| Transcription |
|
| OCR Text |
5-1 THE CONTROL OF PESTS OF FARM AND GARDEN CROPS. grit. When Bordeaux mixture is properly prepared the copper is all precipitated. This is shown by the fact that the blue colour is all in the gelatinous precipitate and that when the precipitate is allowed to settle down the overlying liquid is free from colour. Bordeaux mixture may be mixed with certain oil emulsions, with nicotine sulphate, and with lead-arsenate. Burgundy Mimtura—This mixture is sometimes used in place of Bordeaux mixture, becauSe it does not leave so much objectionable deposit, eSpecially on small fruits, as Bordeaux does. The active principle is again copper, but the sticking powers of Burgundy mixture are not nearly so good as those of Bordeaux mixture. Preparation.—The following formula is commonly used :— Copper sulphate, 2 lb. Sodium carbonate (washing soda), 3 lb. Water, 100 gallons. It is prepared in a similar manner to Bordeaux mixture. The ingredients are dissolved separately and then mixed together. Cheshu'nt Compound—This compound was introduced by the (,‘heshunt Research Station, and prevents many fungoid diseases which have their origin in the soil, such as those which cause the damping off of young plants. Preparation—Eli}: together thoroughly ‘2. parts by weight of finely ground copper sulphate with 11 parts by weight of iinely ground ammonium carbonate, and store for at least twenty-four hours in a tightly stoppcred jar. For use dissolve 1 oz. of this mixture in a little hot water and then make up to 2 gallons with cold water. Only the freshly prepared solution should be used. To prevent waste, only make up the quantity of solution required at one time. The dry mixture will keep indefinitely it is stored in tightly sealed containers. Copper Naphthmate.—Coppcr naphthenate is insoluble in 7 water, but soluble in naphtha, white Spirit, turpentine, &c. it possesses high fungicidal and bactericidal efficiency and is used for treating materials where resistance to rotting in water is essential. For this reason it is used for treating wood, canvas, jute, fishing nets, &c. A 20 per cent solution in white spirit is recommended for the treatment and prevention of dry—rot in wood. For this purpose it is superior to creosote because it can be painted over the wood and acts as a priming coat as well as a pre- servative. Further, it has no harmful effect upon the eyes, skin or clothes, and does not smell strongly like creosote and does not increase the fire risk. One gallon is sufficient for THE CONTROL OF PESTS OF FARM AND GARDEN CROPS. 55 about 200 square feet, and wood once treated is protected for all time. Sandbags and canvas tents are also protected against all forms of rot by impregnating them with a 15 to 30 per cent solution in coal tar naphtha. Concrete may also be protected against growths, such as fungus and lichens, which are apt to form upon damp concrete, by painting it with copper naphthenate solution. Recently copper naph- thenate emulsions have been placed upon the market and have given promising results for treating concrete and sandbags. 'l‘heso emulsions have also given encouraging results as plant sprays. DUSTS. Dusts are applied dry and consist of insecticides or fungicides in the form of fine dry powders often mixed with an inert carrier. It is essential that all dusts should be very finely divided. At least 90 per cent should pass through a 300-mesh sieve. Certain forms of dusts—namely, seed dressing prepara- tions—are now familiar to all farmers. The application of dusts is now extending to all field and garden crops. The spraying of crops is generally recognised as being more efficient than dusting, but requires bulky equipment and the transport of large quantities of water. Dusts, on the other hand, are easier to handle, are immediately ready for use, and, because of the small weight per acre used, are more easily transported. There are two types of dusts—simple mixtures and im- pregnated dusts. The impregnated dusts have the active ingredients combined with inert carriers and are more efficient than the simple mixtures. The preparation of the impregnated dusts requires chemical knowledge and it is not advisable to recommend them for home preparation. Simple mixtures are fairly efficient and can be easily prepared at home. It is essential that in this preparation care should be exercised to mix the ingredients thoroughly. The inert carriers are used to dilute the active ingredients to reduce the initial cost of the dust. The carriers most commonly used are kaolin or china clay, talc, fuller’s earth, bentonite, diatomaceous earth, and gypsum. These sub- stances are all naturally occurring minerals, and, in addition to their fineness of division, possess good sticking powers. Recent research in the United States has shown that the addition of a very small amount of an organic soap greatly increases the sticking properties of a dust. The most Suitable soap for this purpose which is available in this country is butyl-phenyl-phenol-sodium-sulphonate, known as Aresket. It is used at the rate of 1-6 oz. mixed with 100 lb. dust. |
| Title | Transactions of RHASS Volume 1940 - Page 033 |
