PRELIMINARY STUDIES ON BLACK SPOT OF GLOBE ARTICHOKE

Studies were conducted to determine the cause of an apparently new dis order of globe artichoke (Cynara scolymus L.) characterised by a local ised black necrosis in the receptacle of the flower buds. The effects of single and mixed infections by artichoke latent potyvirus (ALV) and broad bean wilt virus-French artichoke (BBWV-FA) in buds with necrosi s of three globe artichoke cultivars were studied. Virus-free plants d eveloped diseased buds irrespective of whether the plants were 1 or 2 years old, but the presence of ALV and/or BBWV-FA significantly increa sed black spot occurrence on 2-year-old plants. Virus effects were dep endent on cultivar, cv. Capitan being less susceptible to virus infect ion than cvs Camus de Bretagne and Castel. The head size of the globe artichoke was found to be related to the rate of necrosis. with a high er incidence for terminal buds. ALV and BBWV-FA did not cause the diso rder but favour its development probably by weakening plants through i ncreased leaf transpiration. The results are discussed in relation to a possible physiological disorder exacerbated by the presence of ALV a nd/or BBWV-FA.