Pseudodidymella fagi in Slovenia : first report and expansion of host rangeNikica Ogris
, Ana Brglez
, Barbara Piškur
Povzetek: The fungus Pseudodidymella fagi is spreading in Europe and causing leaf blotch of European beech, Fagus sylvatica. Between 2008 and 2017, outbreaks of P. fagi were observed on European beech in Switzerland, Germany (also on F. orientalis), Austria, and Slovakia. In Slovenia, leaf blotch symptoms were first observed on F. sylvatica in 2018. P. fagi was identified as the causal agent of the observed symptoms in Slovenia by morphological examinations together with sequencing of the internal transcribed spacer (ITS) region of the rDNA. This study links the fungus to the expansion of the known distribution of the disease to Slovenia, and based on in vitro pathogenicity trials, also to a new potential host, Quercus petraea. The pathogenicity tests confirmed F. sylvatica and F. orientalis as hosts for P. fagi, but not Castanea sativa, where pathogenicity to F. orientalis was proved for first time in vitro. Although Koch%s postulates could not be proven for C. sativa, it seems to be partially susceptible in vitro because some of the inoculation points developed lesions. Additionally, damage to Carpinus betulus related to P. fagi near heavily infected beech trees was observed in vivo but was not tested in laboratory trials. Based on the results and our observations in the field, it is likely that P. fagi has a wider host range than previously thought and that we might be witnessing host switching.
Ključne besede: Pycnopleiospora fagi, leaf blotch, pathogenicity test, inoculation test, Fagus orientalis, Fagus sylvatica, Quercus petraea, mycopappus-like propagule, Carpinus betulus, host switching
DiRROS - Objavljeno: 23.08.2019; Ogledov: 6; Prenosov: 4
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Gradivo ima več datotek! Več...
Daily climate data reveal stronger climate-growth relationships for an extended European tree-ring networkJernej Jevšenak
Povzetek: An extended European tree-ring network was compiled from various sources of tree-ring data from Europe, northern Africa and western Asia. A total of 1860 tree-ring chronologies were used to compare correlation coefficients calculated with aggregated day-wise and month-wise mean temperature, sums of precipitation and standardised precipitation-evapotranspiration index (SPEI). For the daily approach, climate data were aggregated over periods ranging from 21 to 365 days. Absolute correlations calculated with day-wise aggregated climate data were on average higher by 0.060 (temperature data), 0.076 (precipitation data) and 0.075 (SPEI data). Bootstrapped correlations are computationally expensive and were therefore calculated on a 69.4% subset of the data. Bootstrapped correlations indicated statistically significant differences between the daily and monthly approach in approximately 1% of examples. A comparison of time windows used for calculations of correlations revealed slightly later onset and earlier ending day of the year for the daily approach, while the largest differences between the two approaches arise from window lengths: Correlations calculated with day-wise aggregated climate data were calculated using fewer days than the monthly approach. Differences in the onset and ending dates of periods for the daily and monthly approaches were greater for precipitation and SPEI data than for temperature data.
Ključne besede: tree rings, dendroclimatology, tree-ring network, daily climate data, climate-growth relationships, dendroTools
DiRROS - Objavljeno: 21.08.2019; Ogledov: 4; Prenosov: 1
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Rdeči osip duglazije (Rhabdocline pseudotsugae)Barbara Piškur
, Nikica Ogris
, Ana Brglez
Ključne besede: varstvo gozdov, karantenski organizmi, duglazija, Pseudotsuga menziesii, gliva, Rhabdocline pseudotsugae, rdeči osip duglazije
DiRROS - Objavljeno: 08.08.2019; Ogledov: 42; Prenosov: 1
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