This section is from the book "The Gardener's Monthly And Horticulturist V26", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
Hot water at a temperature of about 1200 I find the most effective remedy I have ever tried for destroying insects on plants in the greenhouse. The plants may be either immersed in it, or the hot water may be applied with a plant-syringe, which is the more convenient of the two modes of applying it. If applied with a plant-syringe the water may be a few, say lo°, hotter. While death to insects the hot water seems not to injure the plants in the least. I find one drenching of hot water with a plant-syringe has been sufficient to rid plants of red spider, where time after time cold water drenchings had been in vain.
At the last meeting of the Indiana Horticultural Society, in December, an extensive amateur fruit grower of this vicinity spoke of having used hot water - pouring a quart about the root of each tree - for the borer, which of course was done in early spring while the trees were yet dormant. In this manner he went over his young peach orchard of several thousand trees; and while the trees had previously suffered badly from the borer, he never saw signs of them afterward.
New Albany, Indiana.