January 6, 2005
Source: European Plant Protection Organization (EPPO), Reporting Service, 2004 No. 9 [edited]

2004/136 Results of 2003 surveys on quarantine pests in Latvia

During 2003, several surveys for different plant quarantine pests were carried out in Latvia (for 2002 results see EPPO RS 2003/119).

Beet necrotic yellow vein benyvirus (rhizomania - EPPO A2 list)

51 samples were collected from 41 beet production farms from a total area of 1397.7 ha. The virus was not found. Absent, confirmed by survey.

_Erwinia amylovora_ (EPPO A2 list)

No fireblight was found in surveys of 125 sites with fireblight host plants (_Cotoneaster_, _Crataegus_, _Cydonia_, _Malus_, _Mespilus_, _Pyrus_, _Sorbus_). 484.3 ha were visually inspected and 149 samples were taken and
tested for the presence of the bacterium. _E. amylovora_ was not found.

_Clavibacter michiganensis_ subsp. _sepedonicus_ and _Ralstonia solanacearum_ (both EPPO A2 list)

64 seed-potato production farms were inspected and 195 samples were taken for detection of potato ring rot and brown rot. _C. michiganensis_ subsp. _sepedonicus_ [Cms] was found in the fields of 7 farms (17.7 ha). In 2003,
a monitoring programme of ware potatoes for the presence of ring rot and brown rot was initiated. 83 ware potato production farms were inspected and 128 samples were taken. Cms was found in 7 farms (90.2 ha). In all infected sites, control measures are being taken in accordance with EU Council Directive 93/85. In 2003, the Ministry of Agriculture also allocated financial compensations to infested farms in order to reduce their losses
due to the application of compulsory phytosanitary measures. During this survey, _R. solanacearum_ was not found. Cms: Present, found at 6 production sites, under official control. _R. solanacearum_: Absent, confirmed by survey.

_Globodera rostochiensis_ and _G. pallida_ (both EPPO A2 list)

8839 soil samples were collected from 74 seed-potato production farms, 105 ware potato production farms and from 112 nurseries, and then tested. Inspections were also carried out on these sites. The presence of _Globodera rostochiensis_ [Gr] was confirmed in 6 seed potato production farms (2.5 ha), in 2 ware potato production farms (8 ha) and in 4 nurseries (4.6 ha).

Eradication measures are being taken in the infested areas. _G. pallida_ was not found. Gr: Present, found in several production sites (6 seed-potato production sites, 2 ware potato production farms and 4 nurseries), under eradication. Gp: Absent, confirmed by survey.

Source: NPPO of Latvia, 2004-09.

--
ProMED-mail
<promed@promedmail.org>

[Cms is a major pathogen of potato that is very difficult to control. Yield losses are caused by tuber rotting and in individual U.S. crops have been as high as 50 percent. Disease management is predicated on application of
strict phytosanitary measures to ensure that the pathogen is eradicated. Management strategies include planting only pathogen-free potatoes, regularly cleaning and disinfecting all machinery, equipment, containers, vehicles, and storage facilities used during potato production, and discarding potatoes and potato processing waste to reduce inoculum load.

Regarding _Globodera rostochiensis_ and _G. pallida_, these nematodes exact a major toll on potato seed production. At extremely high nematode densities, tubers may become infected, resulting in the appearance of cysts on their surface. In countries that are free of the potato cyst nematodes, quarantines can help prevent their introduction. In countries where their occurrence is localized, quarantines can help prevent further spread.
Eradication of the potato cyst nematodes once they are established in an area seems unlikely. Potato cyst nematodes are among the most difficult pests to control. Once established they are difficult to eradicate, because
they can survive for over 30 years as eggs, protected by the durable cyst wall. Potato cyst nematodes are major pests of the potato crop in cool-temperate areas. More recently, crop rotation has been supplemented by use of resistant potato cultivars and nematicides (fumigants or granular systemic compounds). Methyl bromide is being gradually phased out in favor of other fumigants. There is no known single alternative fumigant, chemical, or other technology that can readily substitute for methyl bromide in efficacy, low cost, ease of use, wide availability, worker safety, and environmental safety below the ozone layer. Research by USDA indicates that multiple alternative control measures will be required to replace the many essential uses of methyl bromide. For pre-plant uses, such measures include combinations of fungicides, herbicides, and insecticides; other fumigants; and non-chemical alternatives, including cultural changes in cropping systems, resistant crops, and biological control.

Note: The 4th link discusses methyl bromide alternatives. Because of the large number of reports, I did not list specific reports in [see also:]. Use _Clavibacter_ and _Globodera_ as search terms.

Links: <http://www.eppo.org/QUARANTINE/bacteria/Clavibacter_m_sepedonicus/CORBSE_ds.pdf>
<http://www.eppo.org/QUARANTINE/nematodes/Globodera_pallida/HETDSP_ds.pdf>
<http://plpnemweb.ucdavis.edu/nemaplex/Taxadata/G053s2.htm#Economic%20Importance:>
<http://www.imok.ufl.edu/LIV/groups/cultural/pests/progress.htm>
- Mod.DH]