In this graduation thesis we are trying to determine the causes of sessile oak(Quercus petraea) dieback in the local unit Adlešiči and in this way contribute to better forest management. In the fall of 2006 and 2007 we visited the stand several times with special attention to presence of fungi that form their fruit bodies at that time of the year. In the spring 2007 we also performed sample gathering of potential disease agents on the declining trees in the time of their cut down. At the Slovenian Forestry Institute we microscoped samples of fungal fruitbodies that were gathered, took their pictures, and on the base of their characteristics and with the help of determination keys we found out their identity. Nine different fungal species were determined, which are known to accompany the process of oak decline. The current alarming state of the stand is also the consequence of the anthropogenic origin and other negative anthropogenic influences on the forest. As the primary pathogen on oak roots we determined the fungus Collybiafusipes for the first time in Slovenia. With unusually fast development on sessile oak and its large frequency we considered chestnut blight (Cryphonectira parasitica) to be an important factor of dieback. The other pathogens and saprophytic fungi were found on dead and dying thin branches on crown tops: Colpoma quercinum, Coryneum elevatum, Cryphonectria parasitica, Fusicoccum quercus, Hercospora taleola and Botryosphaeria melanops. Some of these fungi are beneficial in healthy stands, but are also frequent companions of decaying oaks and are causing injuries on branches in crowns of the weakened trees.

V diplomskem delu smo poskušali odkriti vzroke propadanja gradna (Quercus petraea) v KE Adlešiči in s tem dati prispevek k poznavanju teh gozdov. V ta namen smo jeseni leta 2006 in 2007 opravili obhode sestoja pri čemer smo bili pozorni na trosnjake gliv, ki se v tem času razvijejo. Spomladi leta 2007 smo nabrali vzorce potencialnih povzročiteljev bolezni s propadajočih dreves v času njihovega poseka. Nabrane vzorce smo na Gozdarskem inštitutu Slovenije mikroskopirali, slikali in na podlagi trosov in trosišč določili. Našli in določili smo 9 vrst različnih gliv, ki so bolj ali manj znane kot spremljevalke pojava propadanja hrastov. V sestoju na trenutno zaskrbljujoče stanje pomembno vplivata njegov antropogen nastanek in drugi škodljivi antropogeni dejavniki. Prvič smo v Sloveniji kot primarnega patogena na hrastovih koreninah določili hrastovo korenovko (Collybia fusipes), pogoste paso tudi poškodbe korenovca zaradi mraznic (Armillaria spp.). Z neobičajno hitrim razvojem in močno razširjenostjo na deblih in vejah nastopa kostanjev rak (Cryphonectira parasitica), kot pomemben dejavnik propadanja gradna. Na odmrlih tankih vejicah v krošnji smo determinirali ostale patogene in saprobe:Colpoma quercinum, Coryneum elevatum, Fusicoccum quercus, Hercospora taleola, in Botryosphaeria melanops. V vitalnih sestojih so nekatere od teh gliv koristne, vendar so tudi pogoste spremljevalke propadanja hrastov in povzročajo odmiranje vej v krošnjah oslabelih dreves.