| population structure suggests reproductively isolated lineages of phaeocryptopus gaeumannii. | a survey of the genetic diversity and population structure of the douglas-fir swiss needle cast pathogen phaeocryptopus gaeumannii was conducted with single-strand conformational polymorphisms (sscp) to screen for variability in mitochondrial and nuclear housekeeping genes. thirty host populations representing the natural range of douglas-fir as well as locations where the tree was planted as an exotic were sampled. sequencing of sscp variants revealed that the method accurately detected both si ... | 2006 | 17256581 |
| the systematic position of phaeocryptopus gaeumannii. | phaeocryptopus gaeumannii, causal agent of the douglas-fir foliar disease swiss needle cast, is the only known pathogenic species of the genus. current classifications place phaeocryptopus in the venturiaceae (pleosporales), typified by the apple-scab pathogen venturia inaequalis. all core members of this family have hyphomycetous anamorphs. we sought to confirm these relationships by means of phylogenetic analyses of the small (ssu) and large (lsu) subunits and internal transcribed spacer (its) ... | 2007 | 17682777 |
| the histopathology of phaeocryptopus gaeumannii on douglas-fir needles. | germinating ascospores of phaeocryptopus gaeumannii produce suprastomatal appressoria from which penetration pegs enter needles. initial infection occurs between late may and early jul and coincides with budbreak and shoot elongation. colonization within needles is exclusively intercellular and increases continuously during jul-may. no intracellular hyphae or haustoria were observed, but hyphae closely appressed to mesophyll and palisade cell walls are abundant by 3-5 mo after initial infection. ... | 2008 | 18751550 |
| predicting swiss needle cast disease distribution and severity in young douglas-fir plantations in coastal oregon. | abstract swiss needle cast (snc), caused by the fungus phaeocryptopus gaeumannii, is producing extensive defoliation and growth reduction in douglas-fir forest plantations along the pacific northwest coast. an snc disease prediction model for the coastal area of oregon was built by establishing the relationship between the distribution of disease and the environment. a ground-based disease survey (220 plots) was used to study this relationship. two types of regression approaches, multiple linear ... | 2003 | 18943159 |
| a climate-based model for predicting geographic variation in swiss needle cast severity in the oregon coast range. | abstract since the early 1990s, swiss needle cast disease caused by phaeocryptopus gaeumannii has been increasing in douglas-fir plantations in the oregon coast range. considerable variation in disease severity across the affected area often has been noted. we investigated the influence of site microclimate on fungal colonization as a basis for this variation with a combination of seedling inoculation and field studies. development of p. gaeumannii ascocarps on inoculated seedlings subjected to ... | 2005 | 18943355 |
| simultaneous one-tube quantification of host and pathogen dna with real-time polymerase chain reaction. | abstract phaeocryptopus gaeumannii is a widespread foliar parasite of douglas-fir. although normally innocuous, the fungus also causes the defoliating disease swiss needle cast in heavily infected needles. the extent of p. gaeumannii colonization in douglas-fir foliage was estimated with real-time quantitative polymerase chain reaction (pcr) using taqman chemistry. in order to derive a normalized expression of colonization, both pathogen and host dna were simultaneously amplified but individuall ... | 2002 | 18944147 |
| comparison of biochemical, molecular, and visual methods to quantify phaeocryptopus gaeumannii in douglas-fir foliage. | abstract a recent epidemic of swiss needle cast along the oregon coast has prompted efforts to quantify foliar infection and colonization of the causal agent phaeocryptopus gaeumannii. in this paper, we compare four methods to quantify colonization of douglas-fir foliage by p. gaeumannii: fruiting body abundance, ergosterol content, dot blot analysis, and taqman based real-time quantitative polymerase chain reaction (pcr). results from the four techniques were all significantly correlated. fruit ... | 2003 | 18944165 |
| impact of swiss needle-cast on growth of douglas-fir. | phaeocryptopus gaeumannii, the cause of swiss needle-cast, is widely distributed in plantations of douglas-fir in many parts of the world. nevertheless, information remains limited on its precise effect on stand growth, particularly in relation to regional climate, and on its consequent economic cost. in new zealand, the spread of p. gaeumannii over a period of ≈30 years following its discovery in 1959 was closely monitored, and the timing of its arrival in different forests is known. this infor ... | 2011 | 20923368 |