Update on the situation of fireblight in Emilia-Romagna (Italy)
Fireblight (Erwinia amylovora - EPPO A2 quarantine pest) was first reported in Emilia-Romagna, which is an important region of fruit production in Italy, in 1994 (see EPPO RS 95/114). The disease was initially reported at a limited number of foci (5 in 1994, 6 in 1995 and 30 in 1996). But 1997 was characterized by an unforeseen and severe explosion of the disease as 721 foci were officially reported. A great majority of these cases (90 %) concerned pears (Pyrus communis cvs. Abate Fétel, William, Conference, Doyenné du Comice, Kaiser Alexander, Max Red Bartlett, Passe Crassane, Santa Maria, and Guyot), however a few cases have also been found on ornamentals (Crataegus, Cotoneaster, Pyracantha, Mespilus, Cydonia, Sorbus and Stranvaesia). It was noted that Crataegus is particularly at risk in this region, as a wild plant but also as a newly introduced species in some fruit-growing areas of the Po Valley as part of programmes for environmental restoration. Several hypotheses have been suggested to explain such a severe outbreak: 1) the bacterium has spread from the few cases identified between 1994 and 1996; 2) despite numerous inspections, the bacterium remained unnoticed; 3) the bacterium had been present for some time on latently infected plants or as an epiphyte and when the inoculum reached a certain level the disease exploded as a result of favourable climatic conditions or cultivation techniques. In particular, it was stressed that this outbreak followed periods of late frosts, hail, violent thunderstorms and that abundant and repeated secondary blooms were observed practically during the whole vegetative season.
Sources
Calzolari, A.; Finelli, F.; Mazzoli, G.L. (1998) A severe unforeseen outbreak of fireblight in the Emilia-Romagna region.
Fontani, A.; Montermini, A.; Calzolari, A. (1998) Fireblight on ornamental plants in Emilia-Romagna.
Abstracts of papers presented at the 8th International Workshop on Fire Blight, Kusadasi (TR), 1998-10-12/15, pp 13 ; 32