02799nas a2200181 4500008004100000022001400041245011500055210006900170260002900239300001200268520220300280100001502483700001502498700001302513700001702526700001902543856005502562 2012 eng d a1439-032900aBehaviour and survival of Phytophthora cambivora inoculum in soil-like substrate under different water regimes0 aBehaviour and survival of Phytophthora cambivora inoculum in soi bBlackwell Publishing Ltd ano–no3 a

Phytophthora cambivora is a soil-borne pathogen responsible for root and collar rot of woody species including Castanea spp., on which it causes Ink disease. P. cambivora does not produce chlamydospores, and the prevalence of a single mating type in nature limits the production of oogonia and oospores. Thus, survival of P. cambivora, in the absence of suitable hosts, relies mainly on sporangia, zoospores and mycelium. However, inoculum survival in soils or substrates represents a major factor in disease epidemics and is probably dependant on environmental factors. The aim of this article was to study the behaviour of P. cambivora in a peat-based substrate (PbS) in the absence of a host, under controlled conditions, and by varying the substrate water regimes. Total inoculum in the substrate was quantified by qPCR, using customized rDNA primer sets, whilst zoospores were quantified after elution, and their vitality was determined by a specific staining procedure. Inoculum infectivity was assessed using chestnut root baits. Results indicated that during the initial 48 h after infestation (matric potential, pF 1.2; 70% water content), the inoculum level increased producing microsporangia and mycelium before decreasing, regardless of the water regime applied. The number of free zoospores increased over a period of (maximum) 7 days after substrate inoculation. Vitality of zoospores declined to 45% at day 18, with no statistical differences amongst water regime treatments. Both rDNA and zoospore number increased in flooded samples at day 23, illustrating the vitality of the inoculum. Inoculum was able to infect chestnut root baits up to 45 days at pF 1.2 and 3.5, before and after flooding, but at pF 6.3, only in the absence of flooding. Although based on experiments carried out in microcosms, these results highlight an unexpected resistance of P. cambivora zoospores to environmental constraints. Furthermore, the infectivity ability of the inoculum to survive in PbS over time even in the absence of the host adds relevance to the risk of movement of soil and substrates associated with plant trading worldwide.

1 aVannini, A1 aBreccia, M1 aBruni, N1 aTomassini, A1 aVettraino, A M uhttp://dx.doi.org/10.1111/j.1439-0329.2012.00768.x00891nas a2200133 4500008004100000245006200041210006100103300001400164490000700178520044400185100001500629700001900644856009400663 2001 eng d00aInk disease in chestnuts: impact on the European chestnut0 aInk disease in chestnuts impact on the European chestnut a345–3500 v763 aA resurgence of ink disease in chestnuts in Europe has been noted since the end of the last century. This lethal disease is currently limiting the establishment of new groves and is threatening the survival of old ones. This paper discusses the impact of the disease and current knowledge about its aetiology and epidemiology. It gives information on the existing variability in tolerance in selected hybrid clones and in wild populations.1 aVannini, A1 aVettraino, A M uhttps://forestphytophthoras.org/references/ink-disease-chestnuts-impact-european-chestnut