First report of ‘Candidatus Phytoplasma pyri’ (pear decline) in Canada
Pear seedlings (Pyrus communis) which are selected for the Canadian breeding programme (managed by Agriculture and Agri-Food Canada) are routinely tested for virus and virus-like diseases by the laboratory of the NPPO (Sidney Laboratory of the Canadian Food Inspection Agency). Virus testing of the selected plant material is initiated at the same time propagation starts. In early 2007, samples from 2 pear seedling selections which had been submitted in 2005 to the breeding programme tested positive for phytoplasmas. Additional tests confirmed the presence of ‘Candidatus Phytoplasma pyri’ (associated with pear decline – EPPO A2 List). Further studies on young trees which had been propagated from this material were conducted. It was found that one pear selection had 39 nursery trees (out of 79 – 49%) infected by ‘Ca. P. pyri’, while the other selection had 27 infected trees (out of 96 – 28%). On the seedling trees from which the material had originally been propagated, typical symptoms of pear decline (i.e. premature foliage reddening) could be observed. In 2007 and 2008, samples (leaves, dormant shoots, roots) were also collected from research and commercial pear orchards in Southern Ontario. As a result, ‘Ca. P. pyri’ was detected in several pear cultivars from different sites, suggesting that pear decline has probably been present for some time in Ontario. This is the first time that pear decline is reported from Canada.
The situation of ‘Candidatus Phytoplasma pyri’ in Canada can be described as follows: Present first detected in 2007, occurs in several pear cultivars and locations in Southern Ontario.
Sources
Hunter DM, Svircev AM, Kaviani M, Michelutti R, Wang L, Thompson D (2010) First report of pear decline caused by ‘Candidatus Phytoplasma pyri’ in Ontario, Canada. Plant Disease 94(5), p 634.