New pathogen of sunflower in Italy
In central Italy near Perugia, a wilt disease has been observed in a sunflower (Helianthus annuus) field during summer 1993. The disease is characterized by a yellowing of the leaves as plants approached flowering. Large areas of the leaves turned light green, usually beginning at the apex and margins and extending inward. Subsequently, leaf margins turned necrotic and diseased plants were stunted with smaller heads. The disease was confined to a small area of a field, and observations carried out showed that plants were moderately or severely infected. The causal agent has been identified as Phialophora asteris f. sp. helianthi. The disease has once been reported from Manitoba (CA) in 1968 (Hoes, 1972) and this is the first report of Phialophora asteris f. sp. helianthi in Italy and Europe.
Sources
Tosi, L.; Zazzerini, A. (1995) Phialophora asteris f. sp. helianthi, a new pathogen of sunflower in Italy.
Plant Disease; 79(5), 534-537.
Hoes, J.A. (1972) Sunflower yellows, a new disease caused by Phialophora sp.
Phytopathology, 62(9), 1088-1092.