The effect of Eutypella parasitica on the wood decay of three maple speciesNikica Ogris
, Jožica Gričar
, Miha Humar
, Barbara Piškur
, Ana Brglez
Povzetek: Eutypella parasitica R.W. Davidson & R.C. Lorenz is the causative agent of Eutypella canker of maple, a destructive disease of maples in Europe and North America. The fungus E. parasitica is known to cause wood stain and decay. However, it is not known how effectively it decomposes the wood of the most widespread maple species in Europe. Wood samples of Acer pseudoplatanus L., A. platanoides L., and A. campestre L. were exposed to four isolates of E. parasitica and nine other fungal species for comparison, according to the modified EN 113 standard. After 15 weeks of incubation, mass loss and microscopical analysis of samples showed evidence of colonization and different wood decay potentials among fungal species. A highly significant positive correlation was found between mass loss and moisture content for all fungal species. Similarly, the measured cell wall thickness correlated well with the calculated mass loss of the samples. On average, the fungal species caused the lowest mass loss in A. pseudoplatanus (10.0%) and the highest in A. campestre (12.6%) samples. Among the samples exposed to E. parasitica isolates, the highest mass loss was recorded in A. pseudoplatanus (6.6%). Statistical analysis showed significant differences in mass loss and moisture content between different E. parasitica isolates. Based on the results of staining, we discuss the type of decay caused by E. parasitica. Although E. parasitica isolates caused smaller mass loss of samples compared to other more effective decay species, we should not disregard its capability of degrading maple wood. Because E. parasitica usually infects the lower portion of the trunk, which is the largest and most valuable part of the tree, any damage can cause significant economic and resource loss.
Ključne besede: wood decay, mass loss, moisture content, mini-block test, decay test, Acer spp., Eutypella parasitica, fungi, light microscopy, scanning electron microscopy
DiRROS - Objavljeno: 13.07.2020; Ogledov: 1100; Prenosov: 717
Celotno besedilo (8,28 MB)
Eutypella parasitica and other frequently isolated fungi in wood of dead branches of young Sycamore Maple (Acer pseudoplatanus) in SloveniaAna Brglez
, Barbara Piškur
, Nikica Ogris
Povzetek: Eutypella parasitica R.W. Davidson and R.C. Lorenz is the causative agent of Eutypella canker of maple, a destructive disease of maples in Europe and North America. The fungus E. parasitica infects the trunk through a branch stub or bark wound. Because the fungal community may have an impact on infection and colonization by E. parasitica, the composition of fungi colonizing wood of dead branches of sycamore maple (Acer pseudoplatanus L.) was investigated in five sampling sites in Slovenia. Forty samples from each sampling site were collected between the November 2017 and March 2018 period. Isolations were made from the wood in the outer part of dead branches and from discoloured wood in the trunk that originated from a dead branch. Pure cultures were divided into morphotypes, and one representative culture per morphotype was selected for further molecular identification. From a total of 2700 cultured subsamples, 1744 fungal cultures were obtained, which were grouped into 212 morphotypes. The investigated samples were colonized by a broad spectrum of fungi. The most frequently isolated species were Eutypa maura (Fr.) Sacc., Eutypa sp. Tul. and C. Tul., Fusarium avenaceum (Fr.) Sacc., Neocucurbitaria acerina Wanas., Camporesi, E.B.G. Jones and K.D. Hyde and E. parasitica. In this study, we distinguished species diversity and the fungal community. There were no significant differences in the diversity of fungal species between the five sampling sites, and branch thickness did not prove to be a statistically significant factor in fungal species diversity. Nevertheless, relatively low Jaccard similarity index values suggested possible differences in the fungal communities from different sampling sites. This was confirmed by an analysis of similarities, which showed that the isolated fungal community distinctly differed between the five sampling sites and between the different isolation sources. Eutypella parasitica was isolated from all five investigated sampling sites, although Eutypella cankers were observed in only three sampling sites, indicating the possibility of asymptomatic infection.
Ključne besede: fungal composition, invasive species, diversity, fungal communities, molecular identification, frequencies, Jaccard similarity index, Eutypella parasitica, analysis of similarities, colonization
DiRROS - Objavljeno: 26.05.2020; Ogledov: 1304; Prenosov: 807
Celotno besedilo (937,18 KB)
In vitro interactions between Eutypella parasitica and some frequently isolated fungi from the wood of the dead branches of young Sycamore Maple (Acer pseudoplatanus)Ana Brglez
, Barbara Piškur
, Nikica Ogris
Povzetek: The ten most frequently isolated fungi from the wood of the dead branches of Acer pseudoplatanus L. were tested in dual cultures to evaluate their in vitro antagonistic activity against Eutypella parasitica R.W. Davidson and R.C. Lorenz, the causative agent of a destructive disease of maples in Europe and North America. The tested fungi, treated also as challenge isolates, were Diaporthe sp., Eutypa sp., Eu. maura, E. parasitica, Fusarium avenaceum, Neocucurbitaria acerina, Neonectria sp., Peniophora incarnata, Petrakia irregularis, and Phomopsis pustulata. The antagonistic ability of each challenge isolate was evaluated by calculating an index of antagonism (AI) based on the interaction type in the dual cultures. The results of competition between the fungal isolates were quantified after re-isolations from the interaction zone (s). The dual cultures revealed two main types of competitive interactions: Deadlock, consisting of mutual inhibition after mycelial contact or at a distance, and replacement, reflecting in the inhibition of E. parasitica, followed by partial overgrowth by the replacing fungus. Statistical analysis showed significant differences in average AI and s of challenge isolates between different dual culture assays. Based on the results of the antagonism index, Eutypa sp., Eu. maura, Neonectria sp., and P. incarnata had the highest inhibitory effect on E. parasitica growth and were recognized as the most promising candidates for further biocontrol studies of E. parasitica. The mycelium of E. parasitica at the interaction zones remained mostly viable, except in dual cultures with Eutypa sp., F. avenaceum, and Neonectria sp., where re-isolations did not yield any colony of the E. parasitica isolate. Based on the results, we assume that E. parasitica is a weak competitor, which invests less energy in direct mycelial competition. We discuss the potential of the observed antagonists as a possible biocontrol of Eutypella canker of maple. Nevertheless, additional experiments should be performed for a solid conclusion about competitive ability of E. parasitica and usefulness of antagonists as biocontrol.
Ključne besede: Eutypella parasitica, dual culture, hyphal interaction, deadlock, replacement, competition, antagonism, inhibition, re-isolation, biocontrol
DiRROS - Objavljeno: 19.10.2020; Ogledov: 675; Prenosov: 446
Celotno besedilo (2,92 MB)
Spremljanje koncentracije askospor glive Eutypella parasiticaTine Hauptman
Povzetek: Gliva Eutypella parasitica izvira iz Severne Amerike in povzroča bolezen, imenovano javorov rak. V Sloveniji so jo prvič našli leta 2005, zdaj je razširjena po vsej državi, izkoreninjenje bolezni ni več mogoče. Da bi preprečili nadaljnje širjenje bolezni in zmanjšali število novih okužb, je treba okužena drevesa posekati. Pri tem velja navodilo, da okuženi del debla izrežemo vsaj 50 cm nad rano in pod njo, izrezani del pa nato na mestu sežgemo ali pa položimo na gozdna tla tako, da je rakava rana usmerjena proti tlom. Učinkovitost slednjega ukrepa smo želeli preverjati s spremljanjem koncentracij askospor glive E. parasitica v zraku, pred izvedenim ukrepom in po njem. Spremljanje ni bilo uspešno, tako da učinkovitosti ukrepa ne moremo potrditi. V prispevku predstavljamo metode spremljanja in razpravo o morebitnih razlogih za neuspešno lovljenje askospor glive E. parasitica.
Ključne besede: javorov rak, Eutypella parasitica, monitoring, volumetrični vzorčevalnik, Slovenija
DiRROS - Objavljeno: 08.03.2021; Ogledov: 745; Prenosov: 259
Celotno besedilo (392,15 KB)