A Biochemical Investigation into the Possible Relationship Between Black Spot Resistance and the Distribution of Polyphenolic Compounds within the Genus Rosa

Abstract

The disease blackspot has been described by many as the most serious disease of roses, and has been known for more than a hundred years. The disease has apparently become more destructive in recent years because of the greater susceptibility of many of the modern varieties. The name blackspot is very descriptive of the disease. From one to several brownish-black spots with radiating fibrillose margins develop on the upper and sometimes on the lower surfaces of the leaves. In heavy infections extensive areas of the leaves may blacken and die. In some of the more susceptible varieties spots occur on the sepals, petals, and young stems as well as on the leaves. The black colouration is due to the production of sap pigments in the host cells (Brooks 1953).