One isolate each of Trichoderma viride, Epicoccum nigrum, Fusarium tricinctum, Alternaria alternata, Sclerotinia sclerotiorum and Cytospora (teleomorph: Valsa sp.) present in epigeous declining oak tissues was evaluated for its ability to control Diplodia corticola (isolate 79). This fungus is the causal agent of cankers, vascular necrosis and dieback on various oak species. Among the isolates tested, T. viride and F. tricinctum showed maximum in vitro inhibition of mycelial growth of D. corticola (isolate 79). Species were also evaluated for their ability to reduce mortality caused by D. corticola (isolate 79) of Quercus cerris and Q. pubescens seedlings under controlled conditions. Two series of inoculations were carried out through wounds in the stem; in the first, the distance between the point of inoculation of the antagonist and the pathogen was 6 cm, whereas in the second series the distance was shortened to 3 cm. In seedlings of Q. cerris and Q. pubescens at a distance of 3 cm, inoculation with F. tricinctum and A. alternata significantly reduced mortality caused by D. corticola (isolate 79). Inoculation of T. viride through artificial cuticular wounds in the stem of seedlings prevented the proliferation of D. corticola (isolate 79) only on seedlings of Q. cerris. All Q. pubescens seedlings treated with T. viride manifested pathological symptoms subsequent to proliferation of D. corticola (isolate 79). These observations indicate that the interactions between endophytes in planta and D. corticola (isolate 79) are complex and merit further study.

Preliminary antagonistic tests of endophytic fungi against Diplodia corticola and silvicultural practices to contrast oak decline. In southern Italy, many oak stands have been affected by the decline syndrome attributed to several biotic and abiotic causes. Various fungal microorganisms, such as Diplodia corticola A.J.L. Phillips, Alves & Luque, were found to be associated with the syndrome, demonstrating either an endophytic asymptomatic or a pathogenetic behaviour, or both, in succession. The objective of this study was to examine a first series of in vitro tests conducted on the antagonistic activity of some endophytic fungi belonging to the species Trichoderma viride Pers.: Fries, Epicoccum nigrum Link., Fusarium tricinctum (Corda) Sacc., Alternaria alternata (Fries) Keissler, Sclerotina sclerotiorum (Libert) De Bary and Cytospora sp. towards D. corticola. These endophytic fungi were obtained from four declining oak woods in Southern Italy. A secondary aim was to define a correct silvicultural interventions to contain decline in the oak stands from which the fungi were extracted. IntroduzioneIl genere Quercus nelle regioni temperate e temperato-calde dell'emisfero boreale, comprende circa 300 specie di alberi e arbusti con foglie persistenti, semipersistenti o caduche, molte delle quali sono diffuse in Europa. In Italia, le formazioni più diffuse sono proprio rappresentate dai boschi a prevalenza di specie caducifoglie del genere Quercus (27% della superficie forestale totale), seguono i boschi a prevalenza di Fagus sylvatica L. (12%) e quelli di altre latifoglie mesofite e mesotermofite (12%) a prevalenza di specie del genere Acer, Carpinus, Ostrya e Fraxinus (Bologna et al. 2004 -Tab. 1). Negli ultimi decenni le cenosi quercine sono state interessate da una grave sindrome nota come "deperimento delle querce", diffusa nell'intero areale italiano delle querce ed in quello di numerosi Paesi europei ed extraeuropei ( Fig. 1 -Luisi 2001, Moreira et al. 1999, Ragazzi et al. 2000, Sicoli et al. 1998, Thomas et al. 2002. In Italia le specie più interessate dal deperimento sono Quercus cerris L. e Q . pubescens Willd. che costituiscono cedui puri e/o misti, nonché, fustaie di grande valore naturalistico e paesaggistico nell'Appennino meridionale. I fattori coinvolti nel deperimento sono numerosi, e di diversa natura: abiotici, biotici ed antropici, che assumono ruoli diversi, agendo come predisponenti (abbandono o errata conduzione colturale, pascolamento irrazionale, condizioni edafiche sfavorevoli, competizione radicale, anomalie meteoriche), scatenanti (susseguirsi di annate siccitose, diffusione di © Forest@ 3 (1): [78][79][80][81][82][83][84][85] 2006.78