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Forest Pathology Early View article 17 Dec 2013

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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New Plant Disease article January 2014

Dieback and Mortality of Pinus radiata Trees in Italy Associated with Phytophthora cryptogea

C. Sechi, S. Seddaiu, B. T. Linaldeddu, A. Franceschini, and B. Scanu

Plant Disease 2014 98:1, 159-159

Pinus radiata D. Don is a forest tree species native to the Monterey Baja in California. Due to its rapid growth and desirable lumber and pulp qualities, between 1960 and 1980, about 12,000 ha of P. radiata were planted in Sardinia, Italy. The only disease reported on this conifer species has been Diplodia pinea, which causes tip and branch dieback (3). In January 2012, dieback and mortality of 25-year-old radiata pine trees were observed in a reforestation area of about 20 ha located in northern Sardinia (40°43′N, 9°22′E, 600 m a.s.l.). Symptoms included chlorosis, reddish-brown discoloration of the whole crown or dieback starting in the upper crown and progressing downward through the crown, and necrotic bark tissues at root collar. Approximately 25% of the trees were affected. In a first attempt, a Phytophthora species was consistently isolated from the rhizosphere of 23 symptomatic trees, which included necrotic fine roots using oak leaves as bait (4). Afterwards, it was also isolated from phloem samples taken from the margins of fresh lesions at the stem base and upper roots of affected trees using synthetic mucor agar medium (1). Isolation from soil samples of six healthy pine trees randomly selected in the site did not yield any Phytophthora isolate. On carrot agar (CA), Phytophthora colonies were stellate to slightly radiate with limited aerial mycelium.

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Kauri fightback

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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Christmas Trees Threatened by Root Rot

Sci-Tech Today.com    By Allen G. Breed   December 3, 2013

Phytophthora root rot is a stubborn enemy for some Christmas tree growers this year. With no fungicide yet proven effective to control Phytophthora, many growers are turning to species from Europe, Asia that are more resistant. Researchers at Washington State and other universities are hoping to unlock the secrets to some species' rot resistance.

Jeff Pollard trudged up the steep slope and stopped at a desiccated, rust-brown tree. Two months earlier, workers had tagged this Fraser fir as ready for market.

It was going to be someone's Christmas tree. And now it was dead.

"Never get paid back for this tree," he said with a shrug. "Eleven years of work -- gone."

The culprit: Phytophthora root rot, a water mold that, once in the soil, makes it unfit for production.

Pollard has been growing Fraser fir in these western North Carolina mountains for nearly 40 years. To him, it's "the ultimate tree."

But this persistent problem has him looking to a species from the birthplace of old Saint Nicholas himself for a possible alternative. And he's not alone.
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Isle of Man Today - Tree disease is hitting larch, sweet chestnut, beech and shrubs

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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New Plant Disease article

First report of Phytophthora plurivora causing collar rot on common alder in Spain

Mr. Mohammed Masum Ul Haque, Mr. Pablo Martínez-Álvarez, Mr. José María Lomba, Dr. Jorge Martín-García, and Prof. Julio Javier Diez

Phytophthora decline of riparian alder (Alnus spp.) has been reported in several European countries. Death of common alder (Alnus glutinosa) due to Phytophthora alni has also been reported in Spain. During several surveys of alder trees in September 2012, typical die-back symptoms, including sparse small yellowish foliage and the presence of rusty exudates on the bark at the collar and lower stem were observed in A.glutinosa growing on the banks of the river Tera (Langa de Duero, Soria, 41°36′34″N, 3°25′10″W, elevation 851 m) and the river Tormes (La Maya, Salamanca, 40°41′42″N, 5°35′36″W, elevation 833 m). Bark samples plus cambium were taken from the active lesions at collar region, cut into small pieces, dried on filter paper and plated on V8-PARPH agar. The samples were incubated for four days at 20 °C in the dark before obtaining the Phytophthora isolates.

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New Plant Disease article

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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Now available! Proceedings of the Sudden Oak Death Fifth Science Symposium

Citation:  Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. 2013. Proceedings of the Sudden Oak Death Fifth Science Symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 169 p.

The Proceedings of the Sudden Oak Death Fifth Science Symposium provides an update on research to address sudden oak death, caused by the exotic, quarantine pathogen, Phytophthora ramorum. Over 60 submissions present national and inter- national investigations covering pathogen biology, biosecurity, genetics, monitoring, fire ecology, and diagnostics. Several papers on disease status and progress toward nursery and wildland management are also included.

 

http://www.fs.fed.us/psw/publications/documents/psw_gtr243/

Link here to access SOD Science Syposium proceedings on Forest Phytophthoras of the world.

 
Phytophthora-ID (version 2.0) revision

The current implementation of Phytophthora-ID (version 2.0) is completely revised to be faster and more stable.

Phytophthora-ID is a resource for the identification of Phytophthora species and genotypes using BLAST and R. The following resources are currently supported:

 

  • Species identification using the ITS region
  • Species identification using the cox spacer region
  • Placement of either P. ramorum or P. infestans into clonal lineages based on multilocus microsatellite data

 

The site includes carefully curated reference databases for the ITS, the cox spacer region and microsatellite data for P. ramorum and P. infestans.

 
Leave the Forest in the Forest

Snowdonia-Active News Item 26/07/2013

Natural Resources Wales has committed more than £2 million to help fight against a disease that is killing Britain's larch trees. Some 1,200 hectares (almost 3,000 acres) of larch trees have already been felled in Wales since the fungus-like organism, Phytophthora ramorum (P. ramorum), was first discovered here in June 2010.

As part of that fight Natural Resources Wales have launched a campaign 'Leave the Forest in the Forest', that calls on forest visitors to brush off twigs, leaves and any other forest debris from their clothes and cars when they visit any of their managed woodlands.

The video at the foot of the page urges mountain bikers to help stop the spread of tree diseases such as P. ramorum and ash dieback, by cleaning off any debris before they leave, by using a bike wash for example.

Dave Liddy of Natural Resources Wales, said: “Cleaning your bike is good for the bike, but it’s also good for the forest, too."

He added: “Our mountain bike trails are immensely popular and we want to encourage people to keep coming to our woodlands. Our message is a simple one. Enjoy yourselves, but please leave the forest in the forest.”

A further video is aimed at raising awareness of the issue among people who walk in the woods, horse riders or dog walkers.

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