Značilnosti glive Chalara fraxinea in možnosti zatiranja jesenovega ožiga : doktorska disertacija

Hauptman, Tine (author), Jurc, Dušan (mentor)

V devetih jesenovih semenskih sestojih in klonski plantaži poljskega jesena jebila ocenjena poškodovanost jesenov zaradi glive Chalara fraxinea, raziskovan pa je bil tudi vpliv drugih škodljivih organizmov in dejavnikov na proces propadanja jesenov. V klonski plantaži se je proučevala tudi domnevna individualna odpornost posameznih jesenov ter obrambni mehanizmi (zgodnje odganjanje listja, zgodnje odpadanje listja ter zaviranje rasti patogena v gostiteljskih tkivih), ki bi lahko bili vzrok odpornosti na jesenov ožig. Z laboratorijskimi testi se je proučeval vpliv temperature na glivo C. fraxinea,preverjala se je možnost toplotnega zatiranja patogena, testirala so se različna sredstva za kemično zatiranje glive, med drugimi glivami, ki naseljujejo jesenova tkiva, pa se je iskalo njenega antagonista. Povprečni delež odmrle krošnje v semenskih sestojih je variiral med 7,2 in 38,7 %, mortaliteta je bila v povprečju 1,9 %. V klonski plantaži poljskega jesena so bile odkrite velike razlike v poškodovanosti posameznih klonov. Leta 2012 je npr. delež poškodovane krošnje variiral med 14,2 in 83,3 %. Omenjeni obrambni mehanizmi niso bili potrjeni kot vzrok odpornosti. Ugotovljeno je bilo, da v procesu propadanja jesenov pomembno sodelujejo mraznice, in sicer Armillaria gallica, A. cepistipes in A. mellea, in da jesene vse bolj ogrožajo tudi jesenovi podlubniki. Laboratorijski testi so pokazali, da so optimalne temperature za rast glive med 20 in 22 °C, temperature nad 28 °C pa so za uspevanje glive previsoke. Poskusa toplotne obdelave sadik in okuženih poganjkov velikega jesena v vodi sta pokazala, da je možno s primernimi načiniobdelave (npr. 10 ur pri 36-40 °C) uničiti glivo v okuženih tkivih, pri tem pa se preživetja sadik ne ogrozi. Z merjenji temperatur v in na sadikah velikega jesena v naravi je bilo ugotovljeno, da vroča poletna obdobja lahko ovirajo razvoj jesenovega ožiga. Rast glive C. fraxinea in oblikovanje apotecijev teleomorfa Hymenoscyphus pseudoalbidus sta izmed osmih testiranih fungicidov najbolje zavirali sredstvi z aktivnima snovema karbendazim in prokloraz. Rast apotecijev je zelo učinkovito preprečila tudi 24-urna obdelavaokuženih jesenovih pecljev v 0,25 % raztopini uree. 13 od 19 testiranih gliv je v dvojnih kulturah preraščalo kolonije glive C. fraxinea, dve pa sta s kolonijami glive C. fraxinea oblikovale inhibicijske cone. Predvideva se, da je med temi glivami za biološko zatiranje jesenovega ožiga najbolj primerna gliva Hypocrea sp.

• Language: Slovenian
• Keywords: glive, Chalara fraxinea, Hymenoscyphus pseudoalbidus, jesenov ožig, Fraxinus spp., temperatura, fungicidi, urea, zatiranje, individualna odpornost, Slovenija, disertacije
• Work type: Dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [T. Hauptman]
• Year: 2014
• Number of pages: XIV f., 121 str.
• PID: 20.500.12556/RUL-72570
• UDC: 630*44:630*41(043.3)=163.6
• COBISS.SI-ID: 797047
• Publication date in RUL: 29.09.2015

Secondary language

• Language: English
• Title: Characteristics of the fungus Chalara fraxinea and possibilities for the control of ash dieback

Abstract

Damage of ash trees caused by Chalara fraxinea was observed in nine ash seed collecting stands and in clonal plantation of narrow-leaved ash. Other harmfulorganisms and factors that influence the ash decline process were also looked for. In clonal plantation, individual resistance of ashes and defence mechanisms, such as early flushing in spring, early leaf shedding and ability to inhibit growth of pathogen in host tissue were also investigated. In laboratory experiments the temperature effect on C. fraxinea was studied, possibilities for thermal control of the pathogen were examined and different products for chemical control of the fungus were tested. Furthermore, within the group of other fungi, which were isolated from diseased ash tissue, antagonist of the pathogen was sought. Mean dead crown share in ash seed collecting stands varied between 7.2 and 38.7%, mean mortality was 1.9%. Big differences in damage between clones were observed in clonal plantation. For example, mean damaged crown share in 2012 varied between 14.2 and 83.3%. Assumed defence mechanisms were not confirmed as a cause of resistance. Fungi from genus Armillaria, namely A. gallica, A. cepistipes and A. mellea proved to be importantly involved in ash decline process. It was discovered that ash bark beetles also represent a growing threat to ashes. Laboratory experiments showed temperature interval of 20-22 °C to be optimal for pathogens growth, while temperatures above 28 °C seem to be too high for the development of the fungus. Hot water treatments of sapling and diseased shoots of common ash demonstrated that proper heat treatment (10 hours at 36-40 °C, for example) can destroy pathogen inside the host tissue without compromising the survival of saplings. Measurements of temperature in and on common ash saplings in nature demonstrated that hot summer weather periods can inhibit ash dieback development. Among eight tested fungicides, growth of C. fraxinea as well as development of Hymenoscyphus pseudoalbidus apothecia was most efficiently inhibited by the products with active ingredients carbendazim and prochloraz. Development of apothecia was successfully prevented also by the 24-hour treatment of diseased leaf petioles in 0.25% urea solution. C. fraxinea colonies in dual cultures were overgrown by 13 out of 19 tested fungi, while two additional fungi formed with C. fraxinea colonies inhibition zones. Among them, Hypocrea sp. seems to be the most suitable for the biological control ofash dieback.

• Keywords: fungus, Chalara fraxinea, Hymenoscyphus pseudoalbidus, ash dieback, Fraxinus spp., temperatura, fungicides, urea, control, individual resistance, Slovenia