Sporothrix inflata, a root-inhabiting fungus of Quercus robur and Q. petraea
The anamorphic fungus Sporothrix inflata, known as a soil-borne fungus with worldwide distribution, was isolated for the first time from the cortex and central cylinder of living and dead roots of healthy and diseased oak trees (Quercus robur and Q. petraea). Isolation frequencies of S. inflata from oak roots varied according to the health status of trees, oak species, study sites, soil depth and root diameter. Colony morphology and growth rate of isolates are influenced by colony age and type of culture medium.
The mycobiota in nonmycorrhizal roots of healthy and declining oaks
A detailed survey of the mycobiota in roots of declining and healthy-looking oak trees was conducted at two sites in eastern Austria that clearly differed in humus and soil type and pH. Overall colonization of living and dead oak roots was 97.7% and 98.5%, respectively. Colonization frequency of the cortex was nearly twice that of the central cylinder in living roots. The species assemblage comprised 126 fungal taxa. Species composition varied greatly be- tween sites and less between living and dead roots from the same site. Fungal association on living roots at Nieder- weiden was dominated by Cadophora fastigiata Lagerb. & Melin, which occurred in 50% of roots, and Cylindrocarpon destructans (Zinssm.) Scholten. Together with Cryptosporiopsis melanogena Kowalski & Halmschlager and Basidio- mycete R157, these two species were also the major components in dead roots. At Patzmannsdorf, the fungal commu- nity in living roots was dominated by Cystodendron sp. 1, Cadophora-like R018, and Cryptosporiopsis radicicola Kowalski & Bartnik, whereas in dead roots Xylaria hypoxylon (L. ex Hooker) Grev. was the dominant species. No sub- stantial differences were found between the root mycobiota in healthy and declining trees. Apart from Armillaria ostoyae (Romagnesi Herink and Cylindrocarpon destructans, the majority of isolated species were considered endophytes or saprophytes that are most likely not involved in the dieback of oak roots.
Oak decline: I. Fungi associated with various disease symptoms on overground portions of middle‐aged and old oak (Quercus robur L.)
Fungi colonizing overground portions of Quercus robur art presented separately for each of the following types of disease symptoms: leaves with atrophy and necrotic areas, dead branches, dead tops of branches, dead water sprouts, local necrotic areas in bark and phloem, locally dead and discoloured sapwood in debarked places, local discolorations inside sapwood, extensive nec-rotic areas on stems, dead trees. Over 80 species of fungi were found in all, mainly from As-comycotina and Deuteromycotina. Connected with each type of symptom there were several species of fungi which were more frequent than the remaining ones. In most cases fungi seem to be of secondary importance in development of symptoms characteristic for oak decline.