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[1] _Clavibacter michiganensis_ subsp. _michiganensis_ - Netherlands: new incursion
[2] _Pseudomonas syringae_ pv. _syringae_ - Italy


[1] _Clavibacter michiganensis_ subsp. _michiganensis_ - Netherlands: new incursion
Date: January 2008
Source: European Plant Protection Organisation (EPPO) Reporting Service 1/2008/005 [edited] <http://archives.eppo.org/EPPOReporting/2008/Rse-0801.pdf>

_Clavibacter michiganensis_ subsp. _michiganensis_ found in the Netherlands

In December 2007, the presence of _Clavibacter michiganensis_ subsp. _michiganensis_ (EPPO A2 List) was suspected on tomatoes (_Lycopersicon esculentum_ cv. Bizarr) grown at one propagation company and 4 fruit producing companies in the Netherlands. The identity of the pathogen was then confirmed by using the EPPO diagnostic protocol with an improved purification method. This outbreak is not linked to the previous one reported in April 2007 (see EPPO RS 2007/090). The possible source of infection is still being investigated, but is most likely related to contaminated seeds of the cultivar 'Bizarr,' which have been produced in Bolivia. As the outbreak was detected at an early stage, phytosanitary measures were taken immediately to eradicate the disease.

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[2] _Pseudomonas syringae_ pv. _syringae_ - Italy
Date: November 2007
Source: The American Phytopathological Society, Plant Disease 2007; 91(11), 1518 [edited] <http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-91-11-1518B>

[Reference: A Garibaldi et al: First report of syringae leaf spot caused by _Pseudomonas syringae_ pv. _syringae_ on tomato in Italy.
Plant Dis 2007; 91(11): 1518; DOI: 10.1094/PDIS-91-11-1518B]

In the spring of 2006 and 2007, grafted and nongrafted tomato plants (scion cv. Cuore di Bue, rootstock _Lycopersicon lycopersicum_ x _L. hirsutum_ cv. Beaufort) displaying stem and petiole necrosis were observed in many commercial greenhouses in the Piedmont of northern Italy. Initial symptoms that developed 2 to 10 days after transplanting consisted of water-soaked circular lesions (2 to 3 mm in diameter) on stems and petioles. These lesions eventually coalesced into brown-to-black areas as much as one cm in diameter. In some cases, necrotic areas progressed from stem petioles to leaf tissues. Thereafter, plants wilted and died within a few days. In some greenhouses, more than 80 percent of young plants exhibited symptoms and production was severely reduced.

Tests were performed on 2 to 3 sections of symptomatic tissue from stems and petioles from 20 affected plants. _Pseudomonas_ spp. were consistently isolated identified by biochemical and biological assays. The isolates also caused severe necrotic lesions on lemon fruits and lilac leaves. The bacteria were identified as _Pseudomonas syringae_ pv. _syringae_. Also, repetitive-sequence PCR [polymerase chain reaction] indicated that the isolates belong to pattern 4 of _P. syringae_ pv. _syringae_.

The pathogenicity of 3 isolates was tested twice by spraying 35-day-old healthy tomato plants (cv. Cuore di Bue) with inoculum.
Ten grafted and 10 nongrafted plants were inoculated. Six days post-inoculation, stem lesions, similar to those seen in the field, and leaf spots were observed on all bacteria-inoculated plants, but not on the controls. Leaf tissues did not develop symptoms.
Isolations were made from the lesion margins and the resulting bacterial colonies were again identified as _P. syringae_ pv. _syringae_.

To our knowledge, this is the 1st report of syringae leaf spot [in tomato] caused by _P. syringae_ pv. _syringae_ in Italy as well as in Europe [but see comment below]. A bacterial spot of tomato caused by _P. syringae_ pv. _syringae_ has been reported in the United States.

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[_C. michiganensis_ subsp. _michiganensis_ (CMM) causes bacterial canker on field and glasshouse tomatoes resulting in up to 70 percent yield loss. Its host range also includes a number of wild relatives of tomato and solanaceous weeds, which may serve as pathogen reservoirs. The bacterium was first described in North America and has since also been found in various locations worldwide. This wide distribution accounts for a high risk of new incursions, as demonstrated by the situation in the Netherlands.

Symptoms on tomato include wilting and/or desiccation, necrotic lesions with resulting cankers on the stems, and discolouration and degeneration of vascular tissues. Fruits may fail to develop or drop prematurely and may develop bleaching or spotting. The pathogen is spread by water, mechanical means during cultivation, and is seed transmitted at a rate of around one percent. Seedlings from contaminated seed appear healthy, symptoms appear only as plants approach maturity. The bacterium survives for a long time in plant debris and on equipment and remains viable for at least 8 months in seeds. Disease management relies on the use of clean seed (certified or treated), plant hygiene measures and elimination of sources of inoculum. Resistance germplasm is available but has not yet been incorporated to any significant degree into commercial cultivars.

The genus also includes a number of other plant pathogenic species, for example potato ring rot is caused by _C. m._ subsp. _sepedonicus_, and ratoon stunt of sugarcane is caused by _C. xyli_ subsp. _xyli_.

Both _Pseudomonas syringae_ pv. _syringae_ (PSS) and the closely related _P. s._ pv. _tomato_ can cause leaf-speckling diseases on tomato and can also infect capsicum. When both pathogens are present, they do not appear to counteract each other. PSS has been reported previously in Italy (Buonaurio & Scortichini, 1994, Plant Pathology 43, 216-9) and the USA on capsicum seedlings. While these plants frequently recovered and economic losses were not incurred, the disease caused on tomato is apparently much more serious with symptoms as described above. PSS is a common epiphyte on both leaves and seeds of many plants. Seed transmission is suspected for PSS in both tomato and capsicum. PSS is also known to cause diseases of citrus, stone fruit, and mango. A more serious soft rot of capsicum is reported to be caused by _P. s._ pv. _capsici_. Additional pathovars are known that can affect other crops, for example soybeans, beans, and mulberries.

The current scientific name for tomato is _Solanum lycopersicum_, however a number of synonyms and previous names are still in use as well (see link below).

Maps
Netherlands:
<http://worldatlas.com/webimage/countrys/europe/lgcolor/nlcolor.htm> and <http://healthmap.org/promed?v=52.2,5.6,6>
Italy:
<http://www.aboutromania.com/ItalyMap.gif>  and <http://healthmap.org/promed?v=42.8,12.1,5>
Europe:
<http://www.greece-map.net/europe/europe-map.gif>
Worldwide distribution of CMM (September 2006):
<http://www.eppo.org/QUARANTINE/bacteria/Clavibacter_m_michiganensis/CORBMI_map.htm>

Pictures
CMM canker on tomato, photo gallery:
<http://www.eppo.org/QUARANTINE/bacteria/Clavibacter_m_michiganensis/CORBMI_images.htm>
PSS leaf spots on capsicum:
<http://apps.omafra.gov.on.ca/english/graphics/crops/agriphones/uploaded/august15f4.jpg>
Bacterial speck on tomato by _P. s._ pv. _tomato_:
<http://www.apsnet.org/education/IntroPlantPath/PathogenGroups/bacteria/images/fig15.jpg>

Links
CMM incursions in the Netherlands:
<http://www.minlnv.nl/portal/page?_pageid=116,1640321&_dad=portal&_schema=PORTAL&p_file_id=24804>
and
<http://archives.eppo.org/EPPOReporting/2007/Rse-0705.pdf>
CMM canker data sheet:
<http://www.eppo.org/QUARANTINE/bacteria/Clavibacter_m_michiganensis/CORBMI_ds.pdf>
_Clavibacter_ taxonomy and species list:
<http://www.bacterio.cict.fr/c/clavibacter.html>
Fact sheet on bacterial diseases of tomato (with pictures):
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Tomato_Bacterial.htm>
_Pseudomonas_ taxonomy and species list:
<http://www.bacterio.cict.fr/p/pseudomonas.html>
Scientific name of tomato:
<http://www.plantnames.unimelb.edu.au/Sorting/Lycopersicon.html>
EPPO quarantine and alert lists via:
<http://www.eppo.org/QUARANTINE/quarantine.htm>.  - Mod.DHA]