BLACK SPOT OF GLOBE ARTICHOKE - A CALCIUM-DEFICIENCY DISORDER

Experiments were performed with field-grown artichoke (Cynara scolymus L.) cv. Capitan to determine whether the black spot disorder was asso ciated with calcium deficiency in receptacles. Ageing of the plants an d size of heads contributed to lower Ca levels of receptacles. Recepta cles with lower amounts of Ca were more affected by the disorder. Glob e artichoke infection by artichoke latent virus (ALV) and/or broad bea n wilt virus strain french artichoke (BBWV-FA) resulted in decreases i n both the relative water content (RWC) of leaves and the Ca content o f receptacles, and in increased black spot incidence. In addition, a w ind-screen and an anti-transpirant spray (composed of a wax emulsion a nd a spreader/sticker surfactant) increased the RWC of leaves and brac ts and the Ca content of receptacles, and also significantly reduced t he incidence of necrosed buds. These data support the view that Ca def iciency is involved in the occurrence of black spot disorder.