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Forest Pathology Early View article first published online: 6 Jan 2012

Susceptibility to Phytophthora cinnamomi of the commonest morphotypes of Holm oak in southern Spain
M. S. Serrano, P. De Vita, M. D. Carbonero, F. Fernández, P. Fernández-Rebollo, M. E. Sánchez

DOI: 10.1111/j.1439-0329.2011.00758.x

Summary

The four main morphotypes of Holm oak (Quercus ilex subsp. ballota) present in Andalusia (expansa, macrocarpa, microcarpa and rotundifolia) were infected with Phytophthora cinnamomi to determine their susceptibility to the root pathogen. No large differences were found among the four morphotypes in the infection of roots, which always showed a high degree of necrosis. However, the different responses of the foliage to infection separated the four morphotypes of Holm oak into three groups: very susceptible (microcarpa), susceptible (expansa) and moderately susceptible (rotundifolia and macrocarpa). The natural hybrid Q. ilex ballota–Q. faginea exhibited a low level of root and foliar symptoms when infected with P. cinnamomi. Quercus faginea could be considered as a source of resistance to P. cinnamomi in future breeding programmes.

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Cardinham woods cope with disease and flood aftermath

BBC News story 23 December 2011

The Forestry Commission is having to fell around 11,000 diseased Japanese Larch trees in woods in Cornwall.

If they are not removed, the commission said the disease phytophthora ramorum could spread from the site at Cardinham, near Bodmin.

The woods are still recovering after floods 13 months ago.

The commission said the disease could cause extensive damage and mortality to trees and other plants across the United Kingdom.

Toby Bowen-Scott, who is in charge of the tree felling operation in the Cornish woods, said: "In a normal day we'll fell 120 to 160 tonnes of woods a day, which could be five or six lorry loads of timber going out of the woods each day from one machine."

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Forest Pathology Early View article first published online: 19 Dec 2011

Pathogenicity of Phytophthora multivora to Eucalyptus gomphocephala and Eucalyptus marginata

Scott, PM, Burgess TI, Barber PA, Shearer BL, Stukely MJC, Hardy GESJ, Jung T

Phytophthora multivora is associated with the rhizosphere of declining Eucalyptus gomphocephala, Eucalyptus marginata and Agonis flexuosa. Two pathogenicity experiments were conducted. The first experiment examined the pathogenicity of five P. multivora isolates and one Phytophthora cinnamomi isolate on the root systems of E. gomphocephala and one P. multivora isolate on the root system of E. marginata. In the second experiment, the pathogenicity of P. multivora to E. gomphocephala and E. marginata saplings was measured using under-bark stem inoculation. In Experiment 1, the P. cinnamomi isolate was more aggressive than all P. multivora isolates causing significant loss of fine roots and plant death. Two P. multivora isolates and the P. cinnamomi isolate caused significant losses of E. gomphocephala fine roots 0-2 mm in diameter and significantly reduced the surface area of roots 0-1 mm in diameter. One P. multivora and the P. cinnamomi isolate significantly reduced the surface area of roots 1-2 mm in diameter. Two of the P. multivora isolates significantly reduced the number of E. gomphocephala root tips. In E. marginata, the length and surface area of roots 0-1 mm in diameter and number of root tips were significantly reduced by P. multivora infestation. Rhizosphere infestation with the P. multivora isolates and P. cinnamomi isolate on E. gomphocephala, and one P. multivora isolate on E. marginata, did not significantly influence the foliar nutrient concentrations. In Experiment 2, under-bark inoculation with P. multivora caused significant lesion extension in E. gomphocephala and E. marginata saplings, compared to the control. We propose that P. multivora is inciting E. gomphocephala and E. marginata decline by causing fine root loss and subsequently interfering with nutrient cycling throughout the plant. The impact of fine root loss on the physiology of plants in sites infested with P. multivora requires further research.

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Forest Pathology Early View article Dec 18, 2011

Potential susceptibility of Australian flora to a NA2 isolate of Phytophthora ramorum and pathogen sporulation potential

Ireland, KB, Hüberli D, Dell B, Smith IW, Rizzo DM, Hardy SGEJ

Article first published online: 18 DEC 2011

Summary

Phytophthora ramorum is an invasive plant pathogen and the cause of considerable and widespread damage in nurseries, gardens and natural woodland ecosystems of the USA and Europe. It is considered to be a significant plant disease as it could cause biodiversity loss and severe economic losses in plant industries in areas where it is not yet known to exist, such as Australasia. Foliar susceptibility and sporulation potential were tested using detached-leaf assays for 70 Australian native plant species sourced from established gardens and arboreta in California using a NA2 isolate of P. ramorum. Correa‘Sister Dawn’, Eucalyptus regnans, Isopogon cuneatus, I. formosus, Leptospermum scoparium, L. lanigerum and Melaleuca squamea were identified as potentially highly susceptible host species. Hedycarya angustifolia, Olearia argophylla, Phyllocladus aspleniifolius, Pittosporum undulatum and Podocarpus lawrencei were identified as potentially resistant. All 70 species were able to be infected with P. ramorum, as confirmed by reisolation. Putative sporulating hosts include five members of the Myrtaceae, Agonis flexuosa, Corymbia ficifolia, Eucalyptus haemastoma, E. delegatensis and E. viminalis. As a part of a precautionary strategy, the potentially highly susceptible species found in this study are suitable candidates for targeted surveillance programmes in high-risk incursion areas of Australia and within the global horticultural trade.

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Deadly tree disease found at Blubberhouses

Wharfedale Observer December 14th, 2011  By Jim Jack

A deadly plant disease that was only identified in the UK last year has been found in trees at Blubberhouses.

The Forestry Commission has confirmed that the condition, caused by a fungus-like organism, has been discovered in Lawson cypress trees in the village – in what is only the second confirmed outbreak in England.

The disease has decimated trade in ornamental Lawson cypress trees in the US states of Oregon and California, where the species is native.

The Forestry Commission has now issued Plant Health Notices to landowners at Blubberhouses – including the British Canoe Union, Yorkshire Water and owners of private land alongside the River Washburn, near Fewston Reservoir.

The notices require the felling and destruction of the trees and the Forestry Commission says everyone is co-operating.

Head of the commission’s plant health service, Dr John Morgan, said: “Phytophthora lateralis is one of several destructive plant pathogens that have entered the UK in recent years, many of which have been associated with the growth in the international trade in live plants.

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Tree disease found in Moneyscalp Woods, Tollymore

29 November 2011  BBC News Northern Ireland by Mike McKimm

 

An outbreak of killer tree disease P. ramorum has been confirmed at a new location in Northern Ireland.

The latest discovery at Moneyscalp Woods, part of Tollymore forest park in County Down, was confirmed following an earlier aerial survey of all woodlands.

Fourteen hectares of Japanese larch trees are to be felled immediately to prevent the disease spreading.

The new outbreak is far south of all the previous infections - a real concern for the forest service.

It was hoped that the disease could be contained in an area centred around Country Antrim in the north east of Northern Ireland. 

Finding an outbreak so far away from the main infected area now raises fears that more diseased areas could be revealed when the trees start to produce needles next spring.

Six public woodlands and eight private sites in Northern Ireland have already been affected by P. ramorum which targets Japanese larch trees.

 

The disease has been found at Moneyscalp Woods, part of Tollymore forest park
More tuart dieback culprits found

ScienceNetwork Western Australia 28 November 2011

A new Phytophthora fungi species might be a significant factor in tuart decline of tuart trees.

Murdoch University Tuart Health Research Group's Peter Scott at has found that Phytophthora multivora might be a large contributing factor in tuart decline. Other contributing factors include site clearing, insect pests, fire damage, site degradation, groundwater modification and climate change. The species’ name refers to its impact on several host species: tuart, jarrah and Banksia attenuata.

Mr Scott’s study was funded through the Australian Research Council and used pathogenicity trials that test for the damage one organism or species can inflict upon another.

The trial he used incorporated Koch’s postulates. This is a list of four criteria that are tested to determine whether an organism is a pathogen to a particular species. The criteria dictate that the pathogen must be present in all diseased organisms but not healthy ones, that it must be isolated, that it must cause disease when introduced into a healthy organism and that it must be reisolated from the inoculated host. Mr Scott stated that Phytophthora multivora was isolated, introduced into healthy tuart seedlings and then reisolated.

“Inoculated seedlings then showed similar disease symptoms as trees suffering tuart decline and Phytophthora multivora was reisolated.”—Peter Scott. Flickr: Clare Snow

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Schoolgirl science helps prevent kauri disease

The Aucklander Thursday, November 17, 2011

While watching the news, Alvina Pau'uvale had a brainwave that would lead to an award-winning science project - and may save our most precious trees.

The report said a disease was killing kauri in the Waitakere Ranges. Tamaki College's head girl looked at how the problem was being contained and found room for improvement.

Auckland Council agrees. It's looking at closing walking tracks in winter, installing more raised wooden paths and closing some tracks in the ranges from October to December 12.

Alvina, 18, won first prize at the 2011 Auckland Science and Technology Fair. She is one of four Aucklanders chosen for Genesis Energy's Realise the Dream competition - a quest to find the country's best high school scientists.

"I found research that had already been done and started thinking about how PTA [the killer fungus attacking the trees] was spread and whether humans were transmitting it."

Alvina explains that PTA - Phytophthora taxon Agathis - was dormant from 1974 until it began causing kauri dieback in 2006.

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December 2011 New Plant Pathology article

Genetic diversity, sensitivity to phenylamide fungicides and aggressiveness of Phytophthora ramorum on Camellia, Rhododendron and Viburnum plants in Spain.

A. Pérez-Sierra, L. A. Álvarez, A. Vercauteren, K. Heungens and P. Abad-Campos

Phytophthora ramorum has been detected in official plant health surveys on Rhododendron, Viburnum and Camellia in ornamental nurseries in northern Spain since 2003. A collection of 94 isolates of P. ramorum was obtained from 2003 to 2008 from plants with symptoms at different geographical locations. Isolates were identified based on morphology and sequence of the rDNA ITS region. Mating type, genetic variation, sensitivity to phenylamide fungicides and aggressiveness of these isolates were determined. All isolates belonged to the A1 mating type, ruling out the possibility of genetic recombination. Seven microsatellite markers were used to study genetic diversity; three out of the seven microsatellite markers were polymorphic within the Spanish population of P. ramorum. This study confirms that all Spanish isolates of P. ramorum belonged to the EU1 lineage. Twelve intralineage genotypes were detected, five that are unique to Spain (EU1MG38, EU1MG41, EU1MG37, EU1MG39 and EU1MG40) and seven that are also present in at least one other European country (EU1MG1, EU1MG29, EU1MG22, EU1MG13, EU1MG2, EU1MG18 and EU1MG26). Genotypes EU1MG37, EU1MG39 and EU1MG40 were isolated from Rhododendron from one region; EU1MG38 and EU1MG41 were isolated from Camellia from two different regions. Isolates of genotype EU1MG38 were resistant to metalaxyl and mefenoxam. The level of genetic diversity within the Spanish population of P. ramorum is limited and indicates a relatively recent clonal expansion.

 

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New Plant Pathology article

Two novel and potentially endemic species of Phytophthora associated with episodic dieback of Kwongan vegetation in the south-west of Western Australia. 

A. J. Rea, T. I. Burgess, G. E. St J. Hardy, M. J. C. Stukely and T. Jung

Plant Pathology Volume 60, Issue 6,pages 1055–1068, December 2011

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