Preliminary Studies on Black Spot of Globe Artichoke

Studies were conducted to determine the cause of an apparently new disorder of globe artichoke (Cynara scotymus L.) characterised by a localised 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 (BBWVFA) in buds with necrosis of three globe artichoke cultivars were studied. Virus-free plants developed diseased buds irrespective of whether the plants were 1 or 2 years old, but the presence of ALV and/or BBWV-FA significantly increased black spot occurrence on 2-year-old plants. Virus effects were dependent on cultivar, cv. Capitan being less susceptible to virus infection than cvs Camus de Bretagne and Caste!. The head size of the globe artichoke was found to be related to the rate of necrosis, with a higher incidence for terminal buds. ALV and BBWV-FA did not cause the disorder but favour its development probably by weakening plants through increased leaf transpiration. The results are discussed in relation to a possible physiological disorder exacerbated by the presence of ALV and/or BBWV-FA