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Summary of the 5th Sudden Oak Death Science Symposium

The 5th Sudden Oak Death Science Symposium, held in Petaluma, CA June 19 – 22, 2012, brought together researchers, regulators, land managers, and industry representatives from throughout the world working on Sudden Oak Death (SOD), Phytophthora ramorum (the pathogen known to cause SOD), and other related forest and nursery pests.  The Symposium included 52 talks and 25 posters from top researchers around the globe as well as a “SOD:  Biosecurity Concerns and Forest Restoration” field trip, where attendees heard about international plant hunters and biosecurity risks related to plant hunting and walked through a local preserve, learning about long-term system changes and restoration efforts following SOD outbreaks.  There was also a community “Ask the Expert” evening session where the public was able to talk one on one with researchers and outreach specialists, and a special tanoak session was offered on Friday, focusing on the history, values, and ecology of tanoak. 

Highlight findings from the meeting included the discovery of a 4th P. ramorum lineage, the announcement that pathogen sporulation has been found on non-symptomatic Japanese larch needles, and learning that 85 percent of the Marin Municipal Water District’s susceptible habitat is now infested.

 

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Eye in the sky targets damaging tree disease in Cumbria

Forestry Commission UK, June 6 2012

A Forestry Commission team has flown sorties over Cumbria as part of wide-ranging measures to tackle the spread of a deadly disease of larch trees.

The flights by a helicopter involved experts taking hundreds of aerial images of local woodland to spot tell-tale signs of infection caused by a fungus-like pathogen, Phytophthora ramorum (P. ramorum), which kills larch trees very quickly.

The lethal disease was first discovered on larch trees in the UK in 2009 in South West England, and since then six sites have been identified in Cumbria. Containment and early felling is vital because infected larch trees produce huge numbers of the spores that spread the disease. These can be spread some distance from tall trees by the wind and in mists, risking rapid spread of the infection to large numbers of other trees.

 

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'Wonder drug' tried on kauri 'HIV'

Hawke's Bay Today, June 11, 2012 by Patrick O'Sullivan

Havelock North Plant & Food Research scientist Dr Ian Horner is using a technique developed for orchards to attempt to control an organism devastating kauri forests.

"It is a very significant disease," he said.

"It will kill kauri trees - it doesn't muck around. It seems to be a wide range of situations that kauri are being diseased and killed."

The newly discovered Phytophthora taxon Agathis (PTA) was first discovered in 1ha of a partially logged kauri forest on Great Barrier Island in the 1970s. "My understanding is there is now 30ha affected on the island.

"It was initially misnamed and seen as a fairly minor problem. As it turns out, it is the same organism we are now finding in kauri forests in many parts of the Northland and Auckland regions."

He had already worked with the late Landcare scientist Dr Ross Beever, who was in the vanguard of a response when the severity of the disease was discovered in 2006.

 

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Early view Plant Pathology article 11 June 2012

Detecting asymptomatic ink-diseased chestnut trees by the composition of the ectomycorrhizal community
L. Scattolin ,E. Dal Maso, S. Mutto Accordi, L. Sella, L. Montecchio

The research was performed in a new and isolated ink disease outbreak. Nine sweet chestnuts of comparable age, growing under same environmental and site conditions, and belonging to three phytosanitary classes (healthy, infected but asymptomatic and symptomatic) were randomly selected. Their ectomycorrhizal community was monitored during two periods, with regard to species abundance, to verify whether the community composition can be useful as an ink disease bioindicator. From the 216 samples, 29 ectomycorrhizal species were recorded, with abundances that changed with the health status of the tree. The results demonstrated that the mycorrhizal community composition was highly related to the ink disease level, allowing the consideration of the use of this parameter as a tool for the quick detection and control of the early stages of the disease.

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Plant Disease July 2012 Disease Note

First Report of Phytophthora cambivora Causing Leaf and Stem Blight and Root Rot on Taiwan Cherry (Prunus campanulata) in Taiwan
J.-H. Huang, P.-J. Ann, Y.-H. Chiu, and J.-N. Tsai

Plant Disease 2012 96:7, 1065-1065

Taiwan cherry or Formosan cherry (Prunus campanulata Maxim.) is a beautiful ornamental tree that is native to Taiwan. In spring 2005, a severe disease was observed on 1- to 3-year-old seedlings of Taiwan cherry in a garden in Tungshih, Taichung, Taiwan. Infected plants showed symptoms of greenish water-soaked spots on leaves that became dark brown, 2 to 3 cm in diameter. Infected leaves withered and fell to the ground in 3 to 5 days and young shoots showed symptoms of withering and drooping. Infected roots showed symptoms of necrosis. Severely infected plants eventually died. A Phytophthora sp. was isolated consistently from diseased samples of Taiwan cherry and associated soil. Six isolates of Phytophthora, of the A1 mating type (1), were isolated from single zoospores. More....

 

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Early view Plant Pathology article 31 May 2012

The morphology, behaviour and molecular phylogeny of Phytophthora taxon Salixsoil and its redesignation as Phytophthora lacustris sp. nov.

J. Nechwatal, J. Bakonyi, S. O. Cacciola, D. E. L. Cooke, T. Jung, Z. Á. Nagy, Á. Vannini, A. M. Vettraino, C. M. Brasier

Since its first isolation from Salix roots in 1972, isolates of a sexually sterile Phytophthora species have been obtained frequently from wet or riparian habitats worldwide and have also been isolated from roots of Alnus and Prunus spp. Although originally assigned to Phytophthora gonapodyides on morphological grounds, it was recognized that these isolates, informally named P. taxon Salixsoil, might represent a separate lineage within ITS Clade 6. Based on phylogenetic analyses and comparisons of morphology, growth-temperature relationships and pathogenicity, this taxon is formally described here as Phytophthora lacustris sp. nov. Isolates of P. lacustris form a clearly resolved cluster in both ITS and mitochondrial cox1 phylogenies, basal to most other Clade 6 taxa. Phytophthora lacustris shares several unusual behavioural properties with other aquatic Clade 6 species, such as sexual sterility and tolerance of high temperatures, that have been suggested as adaptations to riparian conditions. It appears to be widespread in Europe and has also been detected in Australia, New Zealand and the USA. It was shown to be weakly or moderately aggressive on inoculation to Alnus, Prunus and Salix. The extent of P. lacustris’ activity as a saprotroph in plant debris in water and as an opportunistic pathogen in riparian habitats needs further investigation. Its pathogenic potential to cultivated fruit trees also deserves attention because P. lacustris has apparently been introduced into the nursery trade.

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New Disease Reports article 21 May 2012

Natural stem infection of Lawson cypress (Chamaecyparis lawsoniana) caused by Phytophthora ramorum

CM Brasier and JF Webber

The introduced pathogen Phytophthora ramorum has been the cause of dieback and mortality of millions of live-oak and tanoak trees in near-coastal native forests in California and Oregon since 1995 (Frankel, 2008).  P. ramorum has also spread across Europe, mainly within the ornamental nursery trade. From 2003 onwards, P. ramorum was found infecting rhododendron, Vaccinium and a range of broadleaf woodland trees outside nurseries in Britain (Brasier et al., 2004). In 2009, large areas of mature and juvenile plantation larch (mainly Japanese larch, Larix kaempferi) in southwest England, Wales and Northern Ireland were confirmed as infected with the pathogen (Webber et al., 2010). This development has resulted in the felling of over two million trees. Infection of other tree species has occurred adjacent to the larch, apparently due to high levels of P. ramorum inoculum produced from larch foliage (Webber et al., 2010).  More...

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Films launched to tackle Phytophthora threat to our countryside (UK)

A group of over 20 organisations from the public sector, charities and the private sector have got together to produce two videos to help tackle the threat posed to our plant nurseries, gardens, woodlands and countryside from two devastating Phytophthora pathogens, Phytophthora ramorum and Phytophthora kernoviae.

The short film has been produced specifically to engage with people who have little previous knowledge of plant diseases but who are interested in our beautiful countryside and what they can do to help stop the spread of the diseases.

The longer film is aimed more at professionals who work in environments where the diseases may be present or that could easily be contaminated. It describes the diseases in more detail and offers advice on appropriate biosecurity measures to help prevent the spread. It may also appeal to those studying life sciences at college or university.

The films are part of the Defra/Forestry Commission Tree Health and Plant Biosecurity Action Plan and the Defra Phytophthora ramorum and Phytophthora kernoviae disease management Programme.

Link to film website
New 2012 Canadian Journal of Plant Pathology article

Genome sequences of Phytophthora enable translational plant disease management and accelerate research.

Niklaus J. Grünwald, 2012.

Whole and partial genome sequences are becoming available at an ever-increasing pace. For many plant pathogen systems, we are moving into the era of genome resequencing. The first Phytophthora genomes, P. ramorum and P. sojae, became available in 2004, followed shortly by P. infestans in 2006. Availability of whole genome sequences has provided rapid and immediate advances in several areas also resulting in many practical applications and critical new insights. Availability of comparative genome data facilitated discovery of new classes of effectors, such as the RxLR-dEER and crinkler effector families. Genome data also enabled development of molecular markers for population genomic approaches that provided critical new insights into the evolutionary history of species and clades of Phytophthora. Several select examples of advances resulting from comparative genomic approaches in a concerted effort of the Oomycete research community are reviewed.

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You're not barking... that tree really is pink

The Sun (UK) By Andrew Snell, May 2, 2012

 

AN ARTIST really brightened up one English village — by painting a 300-year-old oak tree bright PINK.

Henry Bruce spent two weeks painting the 21-metre high tree, which is suffering from decay.

The 35-year-old said the work was to raise awareness of an infection which is killing trees across the country.

He said: “I am passionate about raising awareness of the phytophthora problem, which will affect many landowners.”

The tree is part of an exhibition in the grounds of the Delamore Estate in Cornwood, Devon.

Delamore founder Gavin Dollard said: “Landowners across the South West are felling seven square miles of Japanese Larch to combat the tree killing fungus which was discovered in 2002.

“Nearly 1,000 acres of infected larch have been removed by the Forestry Commission, while private landowners have been ordered to fell 4,000 acres of timber by March, some 300,000 tons.

“There is no compensation whatsoever for landowners, the sculpture will make the issue facing landowners known to the public.

“We pride ourselves on bringing a fresh, thought-provoking and diverse collection of art to the public every year.

“Henry’s work will not only be truly stunning and visable from right across the Estate, it also raises a little known challenge which is close to my heart.”

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