Bull. Spec. CORESTA Congress, Yokohama, 1996, p. 157, P6

Influence of magnesium on symptoms developed on tobacco (N. tabacum) by a potato virus Y isolate (PVY)

SEITA, Institut du Tabac, Bergerac, France
In a tobacco growing area of Central France, the appearance of symptoms typical of the "brown stems" disease, usually caused by necrotic strains of PVY, was reported on dark air-cured variety PB D6, reputedly resistant. The impossibility to reproduce symptoms of the disease on tobaccos provided with a balanced fertilization suggests that this viral disease is related to a non-balanced fertilization in which magnesium seems to play a major role. Experiments realized in hydroponic conditions demonstrated that the causal virus isolate expressed symptoms only on magnesium-deficient tobacco plants. Addition of magnesium by foliar spray or directly into the nutritive solution was able to prevent the expression of symptoms for newly grown leaves.