VERTICILLIUM WILT OF BRUSSELS SPROUT

A wilt disease of Brussels-sprout plants caused by Verticillium dahliae Kleb, is described. Field observations indicate that the disease is more severe in a wet than in a dry season, the various stages of the pathological symptoms appearing earlier and developing more rapidly. This was corroborated by experiment; under dry conditions the onset of wilt symptoms was delayed and the severity of attack diminished. Since nine different strains and/or species of Verticillium wound-inoculated into Brussels sprouts failed to induce wilt, and since the isolate from this host proved to be non-pathogenic to a wide range of plants usually susceptible to attack by Verticillium spp., it is suggested that the V. dahliae from Brussels sprouts is a distinct physiological strain. Variations in the amounts of the different chemical constituents of the soil (calcium, nitrogen from two different sources, phosphate and potassium) have no apparent effect upon the incidence of disease. The pathogen is not seed-borne but it may be spread by the dissemination of infected plant tissues. Some control measures are suggested and farmers are advised to grow in the infected soil runner beans, cauliflower and broccoli which are resistant to attack by this fungus.