This section is from the book "The Gardener's Monthly And Horticulturist V22", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
As already stated in our magazine, the writer of this applied pure linseed oil to the scale on hundreds of his apple or pear trees with complete success, while others who have tried it complain that it injures their trees. Here is a modification of the plan by Mr. Tidmarsh, of the Grahamstown Botanic Garden in South Africa. The readers will understand by " paraffin " what we know merely as "coal oil:" "Into a round-bottomed iron pot put eight pounds of soft soap and two quarts of paraffin oil; place the pot over a rather slow fire, consisting of embers only; with a stout stick, vigorously stir the mixture, till the soap has absorbed the whole of the oil; to the resulting paste add 20 quarts of water, boiling, if convenient; the mixture can now be left to simmer till the whole of the soap is dissolved, the result being a milky fluid, with little or no oil visible on the surface; the pot may now be taken off the fire, and stood aside till the liquid is cooled down to about new milk heat. The mixture may now be applied to the infected trees, a garden syringe being used for the purpose; the application should be so managed that every part of the tree may be covered with a thin film of the mixture; to effect this with as little waste as possible, screw on to the syringe, before using it, the rose end having the smallest holes; from which drive the mixture with force through and about the foliage and branches of the trees.
When the plants to be dressed are in pots, let the branches of the trees be held over some vessel, such as a tin bath or a packing-case with a zinc lining, in order that waste of the mixture may be avoided as much as possible. Before removing the plants from over the vessel, shake the branches so as to dislodge any superfluous mixture, then place the plants in a horizontal position, till nearly dry, and thus prevent the oily matter running down the stems of the plant into the soil. Any portion of the liquid that may not be used at the time of making will keep good for months; a scum will form on the surface, but that will disappear on again warming and stirring it. This mixture is not at all difficult to concoct, but to insure a good result it is absolutely necessary to strictly observe the few words printed in italics. It is hardly necessary to observe that the number of pounds of soap and quarts of paraffin and water are simply quoted as proportions, the number of gallons of mixture made at any one time must be in accordance with the number and size of the trees requiring dressing".