I plan to use a lime-sulfur spray this year to get a head start on the control of blackspot and mildew. When should I spray?
As your Editor wrote in this newsletter in 1991, “In 1990, your Editor had more blackspot than usual and decided to use a dormant spray between growing seasons to help control these diseases. Lou Roth, a Consulting Rosarian and fine exhibitor of roses, advised me that he used Ortho’s Orthorix Spray, a Lime-Sulfur Fungicide. His normal formula involves spraying in winter when the roses are completely dormant with a solution of 5 tablespoons of Orthorix Lime-Sulfur and 5 tablespoons of Volck Emulsified Oil to a gallon of water. He follows up in late winter or early spring with a repeat spray of one tablespoon to a gallon of water of Orthorix only. The spray should be applied to canes, crown and the soil or mulch around the plant. I followed this prescription for Orthorix only in the winter of 1990-91 and early spring 1991. It was my observation that blackspot and powdery mildew were minimal in 1991 and were easily controlled during the growing season with my normal spray program.” It is
