Rose Stem Canker

New Zealand Herald, Volume LXXVI, Issue 23339, 6 May 1939, Page 10 (Supplement)

Rose Stem Canker

Rose growers usually have enough worries, with insects and diseases to control, but it is just as well to keep a careful watch on tho plants for anything out of the ordinary. Although not a new disease, cases of stem canker have recently., been discovered in Auckland. This disease can reduce plants to stunted malformed specimens, even if they are not killed.

The first sign of decay is usually a purplish discolouration; later the wood turns yellow and then brown. At a later- stago the bark cracks and tissues protrude on which the fruiting bodies of the fungus are formed. The fungus responsible is Coniothyrium rostrum and is identical with the organism which attacks raspberry canes and also causes the graft disease of roses. This latter is a more serious type, especially where largo numbers of plants are propagated by budding. Ihe fungus is transferred with the bud to another stock, then invades the junction of stock and scion. Yellow diseased areas appear, later turning brown. Shoots may wilt and dio, or a largo canker is -formed and the plant becomes very unhealthy. Of all Btocks in common use, the Manetti seems to bo tthe most resistant.