Reappearance of Erwinia stewartii in the Po valley
Outbreaks of bacterial wilt of maize, due to the A2 quarantine organism E. stewartii, have been reported in the Po valley in 1982, for the first time since the late 1940's (Gasperini, C., Mazzucchi, U. & Bertolini, M. (1982). L'Informatore agrario 38 (48): 23513-23516). Attacks were more or less severe, according to cultivar. The origin of the outbreaks is not established. The need for using clean seed is stressed, and also the fact that, in the absence of the normal North American vector (Chaetocnema pulicaria), other insects must be acting as vectors. This means that the effective forecasting systems developed in North America for chemical control of the vector can almost certainly not be transposed to Italian conditions.
Sources
Instituto di Patologia Vegetale dell 'Università di Bologna