Franceschini, S., Webber, J. F., Sancisi-Frey, S., Brasier, C. M. (2013), Gene × environment tests discriminate the new EU2 evolutionary lineage of Phytophthora ramorum and indicate that it is adaptively different. Forest Pathology. doi: 10.1111/efp.12085

A new evolutionary lineage of the destructive introduced tree pathogen Phytophthora ramorum, EU2 lineage, was recently discovered attacking larch and other hosts in Northern Ireland and south west Scotland, UK. Sixteen ‘medium × agar concentration × incubation temperature’ stress environments were tested to find a rapid and repeatable method to discriminate the known EU2 lineage from the EU1, NA1 and NA2 lineages in culture, in particular from the EU1 already prevalent across the UK; and to investigate whether EU2 might be adaptively different. At 28°C on both Carrot agar and V8 juice agar, the mean radial growth rates of all four lineages were significantly different, with NA2 > EU2 > EU1 > NA1. At this temperature, EU2 colonies were not only phenotypically distinct from EU1 and all other lineages but on average grew three times as fast as EU1. This indicates that EU2 is adaptively different from EU1. Twelve days growth in the environment ‘V8A/2% agar/28°C gave excellent discrimination of all four lineages in three repeat experiments, including clear discrimination of EU2 from EU1. Each lineage exhibited a distinctive colony pattern. The utility of this test environment was examined further by screening fresh UK isolates of unknown lineage from new larch outbreak sites alongside standard isolates. The lineage assignments predicted were corroborated by gene sequencing and RFLP profiling. These results also revealed that the EU2 lineage was present at several new larch sites in south west Scotland, whereas isolates from geographically adjacent areas such as the Isle of Mull, north west Scotland, the Isle of Man and north west England were all of EU1 lineage.

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The New Zealand Herald  By Geoff Cumming, Nov. 30, 2013

Reports of Tane Mahuta's demise may be premature but death could be just a stray boot away. The dieback disease threatening the forest kings of northern New Zealand is as bad as it gets: once the algae-like microbes infiltrate the kauri's root system, there is no cure. By the time symptoms show - leaf yellowing, canopy loss, withered branches, bleeding lesions and collar rot - it is likely too late.

Talk to scientists and agencies beavering away on the response and the messages are at once frightening and encouraging. The disease is a new species of phytophthora, from the Greek for plant destroyer. Different strains have devastated everything from strawberries, tomatoes and potatoes to forest giants like jarrah in Australia, oak trees in Europe and North American chestnuts.

The soil-borne variety attacking our kauri, known for now as PTA, has spread to 11 per cent of kauri stands in the Waitakere Ranges. It has footholds in the Waipoua Forest, home of Tane Mahuta, on Great Barrier Island (where it was first observed in the 1970s but mis-identified), in the Russell Forest and on private bush lots in Auckland and Northland.

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Isle of Man Today- October 15, 2013

A disease that affects larch trees is continuing to ravage the island’s forestry, with about 50 hectares of trees felled and sweet chestnut, beech trees and garden shrubbery plants also affected.

The government has said that 50 per cent of the island’s larch population is now infected with the disease, phytophthora ramorum, also known as sudden oak death.

Area forester Jason Bolt said: ‘Sweet chestnut, beech and shrubbery plant species in gardens such as rhododendron have also been found to be infected in the island.’

Along with Dutch elm disease, phytophthora ramorum is one of two diseases affecting the island’s trees.

In addition, the Department of Environment, Food and Agriculture remains worried about the threat of a third, ash dieback.

Senior forester John Walmsley said: ‘To date we have felled thousands of trees clear felling an area of approximately 50 hectares throughout the forest estate due to phytophthora ramorum.

‘A further 20 to 30 hectares will be felled in the coming months and plans are being drawn up to deal with the most recent infected areas identified from our 2013 aerial surveys.

‘In an effort to contain the disease, the department has been and is continuing the clearfelling of infected areas as they are identified and as soon as is practical.

‘The public are requested to follow basic precautions during the problem, such as keeping to footpaths if requested to do so, keeping dogs on leads when walking in woodland areas and cleaning footwear and their animals before visiting other sites.’
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First Report of Phytophthora Taxon Walnut in Lombardy, North Italy

Dr. Beatrice Ginetti, Prof. Alessandro Ragazzi, and Prof. Salvatore Moricca

The park Boscoincittà, Milan, North Italy (136 m a.s.l., 45º 29' 06" N, 9º 5' 32" E) has an area of 110 hectares and includes tree stands, wood clearings, trails and watercourses. Recently, common walnut (Jugland regia) trees in the park have begun to suffer from a progressive dieback that has caused roughly 90% mortality. Aerial symptoms were: stunted growth, loss of vigor, crown thinning and bark cankers with tarry exudates on the lower stem. The xylem tissue of trees showed large necrosis and flame-shaped discolouration below the bark. Since the dieback seemed caused by Phytophthora, samples were taken from 3 symptomatic trees and, by baiting, from the nearby soil and watercourses. Isolations from apple baits were carried out after a week. Isolations taken from tissue at the edge of active lesions of the trees were transferred on the selective medium V8A-PARPNH (1) and incubated at 24ºC. Cottony colonies appeared after 3 days and single hyphal tip derivatives were transferred to V8A for a further 4-7 days.

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