Published online by Cambridge University Press: 27 March 2009
In the past twenty years there has been no noticeable decrease in the number of Helminthosporium infected oat and barley seed samples examined at the Official Seed Testing Station, Cambridge, and in the course of advisory practice. No reduction in the intensity of the seedling diseases caused by Helminthosporium has been noted during the first ten years under review. Formalin and copper carbonate were ineffective as seed disinfectants in reducing seedling mortality, and copper sulphate, although partially effective, had serious phytocidal effects and consequently cannot be recommended. Since the advent of the organo-mercury seed disinfectants a steady improvement in the control of these diseases has been noted, and field tests of such dressings have shown them to be eminently satisfactory. Barley straw infected with H. gramineum has been shown to be a source of secondary infection of barley seedlings.