Depositional and weather-resisting qualities of some copper fungicides affecting the control of peach blight

Abstract

does not appear. First page follows. Introduction In the tests reported in this paper, comparisons were made between the depositional and weather-resisting qualities of bordeaux and three so-called fixed copper fungicides used to control peach blight caused by the fungus Coryneum beijerinckii Oud. Each fixed copper preparation was combined with a supplement to increase the tenacity, or weather resistance, of the deposit. Studies on Deposition On Peach Twigs.—In field tests conducted for three seasons, water suspensions of basic copper sulfate A,3 basic copper sulfate Z (containing zinc), cuprous oxide, and bordeaux mixture were applied in mid-November to peach trees after most of the leaves had fallen. One-half per cent of a cream-type oil emulsion, designated as supplement A4 was added to basic copper sulfate A. One and one-half per cent of an emulsive oil, supplement B, was added to basic copper sulfate Z and to cuprous oxide. The emulsifying agents and other ingredients of these supplements are unknown to the writer. Except in the first year of the tests, each preparation was applied to three randomized plots with an ordinary orchard sprayer operated at a pressure of 450 to 500 pounds per square inch. In addition to these treatments, basic copper sulfate Z, suspended in an emulsive oil which was then emulsified in water (1 gallon of oil to 1 gallon of water), was applied by means of vapor-spraying equipment. This machine produces a finely divided mist by injecting the preparation into an air stream, which issues from ducts at the side of the machine.