IRELAND HAS recorded the first infection in the world of a Sitka spruce tree by the plant disease Phytophthora ramorum, commonly known as sudden oak death.
The disease, which has caused extensive damage to forests worldwide since first identified in the US in 1995, was found here only last year, and led to a national aerial and ground survey which confirmed it in Japanese larch at 11 sites in five counties.
Now scientists here also found the disease in a single Sitka spruce tree.
This is the first field record worldwide of it in Sitka spruce, although it was found to be susceptible in laboratory trials.
Most of Ireland’s commercial planting is of Sitka spruce, and an outbreak of the disease in the species could create major difficulties for the industry.
“The infected young tree is approximately two metres in height and significantly it was growing in close proximity and underneath the canopy of a large infected rhododendron bush,” the Department of Agriculture said in a statement.
“It is very likely that disease spores produced by this overhanging infected rhododendron bush were the source of infection of the tree.
"This is the first field record worldwide of P. ramoruminfection in Sitka spruce, although the species had been found to be susceptible in international laboratory trials.
"Spruce in the immediate area of all the Japanese larch outbreak sites have been surveyed and no further P. ramoruminfections have been found. The area around the infected Sitka spruce has been effectively quarantined and monitoring will continue."
The statement said Japanese larch appeared to be particularly susceptible to the disease in all age classes and it had caused significant dieback and death.
However, scientists had also found infected Noble fir, beech and Spanish chestnut trees close to infected Japanese larch and all the infected trees had been removed.
P. ramorumalso infects a great number of other plant species, significantly rhododendrons, causing a non-fatal foliage disease known as ramorum dieback.
Such plants can act as a source of the spread of the disease, with the pathogen producing spores that can be transmitted by wind and rainwater.