Bacterial stem rot in greenhouse pepper (<i>Capsicum annuum</i> L.) in Sardinia (Italy): occurrence of <i>Erwinia carotovora</i> subsp. <i>carotovora</i>

Abstract

An unusual bacterial disease was observed in pepper plants during research carried out in greenhouses in central-north Sardinia. The characteristics were: the presence of lesions and exudates on stems, soft rot of the pith, and a brownish-black colour in the petioles and leaf-veins. Only two isolates of 21 were pathogens. One was obtained from exudate present on the stem and the other from pith. Experimental infections revealed that the bacterial isolates were particularly aggressive in the stems and fruit of pepper and tomato. Biochemical, physiological and serological tests in conjunction with fatty acid profile analysis confirmed that they were Erwinia carotovora subsp. carotovora (Jones) Bergey et al. The product of 434 bp polymerase chain reaction (PCR) enabled a preliminary identification of isolates to be made. Restriction fragment length polymorphism (RFLP) analysis of amplification products showed that the isolates DPP 23ef and DPP 24m, strain type CFBP 2046 and DPP 281, isolated from pepper fruit, belonged to the RFLP group 12, whereas DPP 29, also isolated from pepper fruit, was included in RFLP group 1. Measures to prevent and control this recently introduced disease are suggested in the conclusion of this paper