Material. Stone lime, flowers of sulphur.

Apparatus. Granite kettle, stirring-rod.

Self-boiled lime-sulphur differs from the lime-sulphur wash in Exercise XL chiefly in that there is no artificial heat applied and all of the cooking that the solution undergoes is done by the heat generated by the stone lime in slaking. This is used only as a summer spray, and is proving very satisfactory for use on the peach against the scab and brown rot. The formula that is most often used is

Laboratory formula. Weigh out two and one-half ounces of the flowers of sulphur and two and one-half ounces of stone lime. Place the lime and the sulphur in a granite vessel and add enough cold water to slake the lime, stirring constantly to prevent burning. Cover the granite kettle, so as to retain as much of the heat as possible. Watch the mixture closely, and as soon as an orange-colored liquid begins to gather on the surface add enough more water to make a gallon. Do not use hot water or allow the mixture to stand after the lime is slaked or before dilution. In this spray we do not want soluble sulphides to form, because these will injure the foliage as well as the fruit. How does this solution differ from the one in Exercise XL? Describe the color of each solution and note any differences. Why should cold water be used instead of hot water? Why is the prevention of the formation of soluble sulphides especially important? Discuss.

Reference

Special Bulletin No. 61, Michigan Agricultural Experiment Station.