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 associated with calcium deficiency in receptacles. Ageing of the plants and size of heads contributed to lower Ca levels of receptacles. Receptacles with lower amounts of Ca were more affected by the disorder. Globe artichoke infection by artichoke latent virus (ALV) and/or broad bean wilt virus strain french artichoke (BBWV-FA) resulted in decreases in both the relative water content (RWC) of leaves and the Ca content of receptacles, and in increased black spot incidence. In addition, a wind-screen and an anti-transpirant spray (composed of a wax emulsion and a spreader/sticker surfactant) increased the RWC of leaves and bracts and the Ca content of receptacles, and also significantly reduced the incidence of necrosed buds. These data support the view that Ca deficiency is involved in the occurrence of black spot disorder,