Endophytic presence of Discula quercina on Declining Quercus cerris

The presence of Discula quercina on dormant buds and twigs of declining Quercus cerris was studied on two test sites. A number of fungi, including some endophytic ones, were isolated in association with D. quercina as part of the total oak mycoflora: Acremonium spp., Diplodia mutila, Phomopsis quercina, Hypoxylon mediterraneum, Cylindrocarpon sp., Phoma cava and Trichoderma viride plus some less frequent species. The distribution of these fungi did not appear to be related to the altitude of the test sites studied: sea level and 600 m a.s.l., nor to the differing composition of the site vegetation. Discula quercina was isolated both from the twigs (18.02% from woody tissue; 5.82% bark tissue) and from the buds (11.62% embryo; 14.55% bud scales). The results indicate that D. quercina is able to live in symbiosis with its host. Although the colonization of the aerial parts of Q. cerris is possible through infection with wind-borne inoculum, leaf infection can also occur through overwintering mycelium migrating to the leaves mainly from the buds, but also to a lesser extent from the twigs.