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Phytophthora ramorum in England and Wales: which environmental variables predict county disease incidence? Chadfield, V, Pautasso M.  Forest Pathology. 2011. 

Phytophthora ramorum is the oomycete pathogen responsible for Sudden Oak Death on the West Coast of the USA and Sudden Larch Death in the British Isles. It also causes twig dieback and leaf blight on a series of ornamental hosts (e.g. Rhododendron, Viburnum, Pieris and Camellia) commonly grown in plant nurseries, traded by garden centres and cultivated in public and private gardens. The role of the plant trade in the dispersal of P. ramorum has been well documented, but there is a need for regional analyses of which environmental variables can predict disease expression in the trade and in the wild, so as to be able to better predict the further development of this worldwide plant health issue. In this study, we analyse data on the incidence of P. ramorum (2002–2009, thus before the reports in Japanese larch plantations) in counties in England and Wales as a function of environmental variables such as temperature and rainfall, controlling for confounding factors such as county area, human population and spatial autocorrelation. While P. ramorum county incidence in nurseries and retail centres was positively related to county area and human population density, county incidence in gardens and the wild did not show such correlations, declined significantly towards the East and was positively correlated with disease incidence in the trade. The latter finding, although not conclusively proving causation, suggests a role of the trade in the dispersal of this pathogen across English and Welsh landscapes. Combined together, P. ramorum county incidence in the trade and in the semi-natural environment increased with increasing precipitation and with declining latitude. This study shows the importance of environmental variables in shaping regional plant epidemics, but also yields results that are suggestive of a role of people in spreading plant diseases across entire countries.

Reference

Isolation of Phytophthora lateralis from Chamaecyparis foliage in Taiwan
J. F. Webber, A. M. Vettraino, T. T. Chang, S.E. Bellgard, C. M. Brasier, A. Vannini

Article first published online: 11 JUL 2011

DOI: 10.1111/j.1439-0329.2011.00729.x

Summary

Following the discovery in 2008 of Phytophthora lateralis in forest soil under old-growth yellow cedar (Chamaecyparis obtusa var. formosana) in north-east Taiwan, further sampling was undertaken in the same region. Soil, root and symptomatic foliage samples were collected from five separate sites where C. obtusa was the dominant species in cloud forests at ca. 1800–2500 m. Soil and fine root samples were baited with cedar needles; both direct isolation and cedar needle baiting were used on foliage samples. Phytophthora lateralis was obtained from soil at three of the sites, but only from three of the 27 soil samples overall. Only one of 25 root samples yielded the pathogen, and this was associated with infested soil. Three foliage samples with symptoms visible as dark brown to black frond tips also yielded P. lateralis; these came from two different sites. This is the first record of P. lateralis infecting the foliage of C. obtusa. Moreover, when some of the symptomatic Chamaecyparis foliage segments were incubated, sporangia of P. lateralis formed on the necrotic tissues, sometimes in the axils of needle segments. The study provides evidence that P. lateralis has both a soil/root infecting phase and an aerial or foliar infecting phase in Taiwan, which is consistent with its unusual combination of water-dispersed (non-papillate) and aerially dispersed (caducous) sporangia. It also demonstrates the importance of investigating the biology, aetiology and ecological behaviour of Phytophthoras in their native, endemic environments.

Reference

Forestry Commission News 10 JUNE 2011 
Among the key new tree pests and diseases to emerge in Britain in recent years are Phytophthora ramorum, Phytophthora kernoviae, Phytophthora lateralis, acute oak decline, bleeding canker of horse chestnut caused by the bacterium Pseudomonas syringae ...

Strategy launched to tackle pest and disease threats to Britain's trees

Roaches Estate bilberry plants hit by fungal disease

Bilberry plants at a Staffordshire beauty spot have been infected by a rare fungal disease.

Phytophthora pseudosyringae has killed some plants near Roach End on the Roaches Estate, near Leek. The disease does not harm humans or animals.

People have been asked to help prevent the disease spreading by avoiding contact with the shrubs, although the area remains open to the public.

more....

http://www.bbc.co.uk/news/uk-england-stoke-staffordshire-13571880