رویان

بزرگترین مجله کشاورزی اینترنتی

رویان

بزرگترین مجله کشاورزی اینترنتی

Phytophthora kernoviae

An unnamed Phytophthora disease - Phytophthora kernoviae Brasier, Beales, and Kirk

 

Beech tree with
necrotic bark

Rhododendron
leaves

Rhododendron
damage I

Rhododendron
damage II
An unnamed Phytophthora disease
As discussed in the Gallery page for Phytophthora alni, this pathogen is one of the emerging European threats to North American forests. This pathogen was discovered in 2003 during surveys in Great Britain for the sudden oak death pathogen, Phytophthora ramorum. It was detected when scientists tested cankers on both a European beech (Fagus sylvatica) and rhododendrons. The species was named after the pathogen was isolated and proved to be new species. The origin of the pathogen is unknown.

After P. kernoviae was first detected in Cornwall, more than 5,000 plant samples from forests and nurseries were tested for both P. ramorum and P. kernoviae. This survey and testing program led to discovery of approximately 370 infected sites, many of which were nurseries or garden centers (Clover 2005). Early optimism that the disease was confined to south-west England and south Wales received a blow in September 2004 when infected plants were found at a nursery in northwest England. This might mean that the pathogen could have been distributed to other, as yet unknown, locations (Forestry Commission 2005).

In Great Britain, all samples submitted are now routinely analysed for both Phytophthora ramorum and Phytophthora kernoviae (Forestry Commission 2005). The United States is now doing the same (J. Jones, USDA APHIS, pers. comm. March 2005).

Although it produces similar symptoms, Phytophthora kernoviae is genetically distinct from Phytophthora ramorum and belongs to a different Phytophthora grouping (Forestry Commission 2005).

At this early stage, the known host range for Phytophthora kernoviae is more limited than that for P. ramorum, but P. kernoviae appears to causing more severe disease on some of these hosts, for example, lethal bark infections on beech and aerial dieback of rhododendron stems (Forestry Commission 2005). Hosts at present include the North American native tulip tree (Liriodendron tulipifera); and several European trees with congeners which are also found in North America: Fagus sylvatica, Quercus robur, Q. ilex (foliar infections), Rhododendron, Magnolia stellata, and Michelia. It has also been detected on the South American Gevuina avellana, a member of the Protea family (Forestry Commission 2005).

Sources
Forestry Commission, 2005. Plant Health: Phytophthora kernoviae Frequently Asked Questions. At www.defra.gov.uk/planth/pkfaq.htm. Accessed on December 9, 2005.

Clover, C. 2005. London Telegraph, Nov. 10 - http://news.bbc.co.uk/1/hi/england/cornwall/3997687.stm.
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