Erwinia spp. and a new canker disease of hybrid poplars in Ontario

Abstract

An attempt is made to determine the cause of a new canker and diebaek disease affecting poplar hybrids (Populus spp.) growing in Ontario. Since the disease symptoms appear to be similar to those of a bacterial infection of poplars in Europe caused by Xanthomonas populi Ride, b.icterial species were investigated as possible causal agents of this new dise.ise. Strains of Erwinia herhicola and Erwinia carotovora were associated with branch cankers on affected trees. The hypersensitive reaction on tobacco (Nicotiana tahacum var. Havana) resulting from artificial inoculations of strains of E. carotovora suggests the phytopathogenicity of these strains. Early results from inoculations into rooted poplar cuttings indicated that both strains m.iy be capable of causing discolouration and decay of xy lem tissues but these inoculations did not result in canker formation. Both of these opportunistic org.-inisms may be potential pathogens of poplar under cert.iin conditions.

Characterisation of bacteria from poplars and willows exhibiting leaf spotting and stem cankering in New Zealand

“…These isolates were non-pathogenic and accordingly are considered to be saprophytes as suggested by DYE (1969) and a component of the epiphytic flora of poplar leaves as reported by GIBBONS (1972), DANILEWICZ (1980) and MossELER and HUBBES (1983).…”

Bacteria associated with tarnished plant bug stem lesions on hybrid poplars in Ontario

“…MOSSELER and HUBBES (1983) also commonly isolated bacteria from branch cankers; healthy sections were generally free from bacteria. The preliminary bacteriological tests indicate that a variety of bacteria are associated with TPB stem lesions.…”

“…The microorganisms do not appear responsible for lesion initiation. Inoculation of poplar shoots with four different Enterobacteriaceae isolates failed to produce lesion symptoms (MOSSELER and HUBBES 1983;JuzwiK, unpublished data). Bacteria, however, were not consistently isolated from TPB lesions in Wisconsin (SAPIO et al 1982).…”

“…Bacteria were associated with a new canker disease of hybrid poplars in southern Ontario by MossELER and HUBBES (1983). The problem has been locally referred to as bacterial canker because of this association.…”

“…Microscopic observations of bacterial cankers were reported by MOSSELER and HUBBES (1983). Due to the now known involvement of TPBs in lesion formation we decided to re-examine affected stem tissues of young shoots for bacteria location and tissue disruption.…”