April 1, 2003
From: Journal of Phytopathology Vol. 152 (1) [edited]

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

M. Fiori <fiorim@uniss.it> and A. Schiaffino Dipartimento di Protezione delle Piante, Universita degli studi di Sassari, Via E. De Nicola, 07100 Sassari, Italy.

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, pit soft rot, and a brownish-black color in the petioles and leaf veins.

Only 2 of 21 isolates were pathogens. 1 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 isolates DPP 23ef and DPP 24m, strain type CFBP 2046 and DPP 281, isolated from pepper fruit, belonged to RFLP group 12, whereas DPP 29, also isolated from pepper fruit, was included in RFLP group 1.

[Taxonomic studies indicate that Ecc can be transferred to the new genus _Pectobacterium_ (_P. carotovorum_ subsp. _carotovorum_, Pcc). Thus Ecc and Pcc are synonyms. Ecc is ubiquitous, causing disease in glasshouse crops and appears to be present at low frequency in various regions of Italy. 2 pepper isolates of Ecc characterized in this report were pathogenic in tomato, thus possibly putting that crop at risk. Diagnosis of the disease requires careful analysis, because the tomato pith pathogen, _Pseudomonas corrugata_ can be confused with Ecc. Ecc survives readily in field residues.

Disease management depends upon use of hypochlorite-treatment of seeds, avoidance of wounding, and early detection of the pathogen. Should an outbreak occur in glasshouse production units, all plants should be
destroyed, and the crop should be treated with fixed copper sprays. At the close of production, all plant residues should be removed and subjected to solarization for at least 45 days during summer. - Mod.DH]