Symptomatological Observations and Possible Roles of Ophiostoma minus Hedgc. (Ascomycetes / Ophiostomatales) and Tomicus piniperda L. (Coleoptera / Scolytidae) in the Dieback of Scots Pine in the Orleans Forest (France)

1989

3 Abb., 3 Tab., 23 Lit. Ang., Fr, Zfsg. En, Fr

Unselbständiges Werk

2819

200014640

The dieback of Scots pine (Pinus sylvestris L.) in the Orleans Forest (France) are characterized by the fall of the bark, the presence of black granulations on the sapwood surface and with a bluestain inside. The foliage generally turns yellow after the bark has fallen, but sometimes before. The trees located in poor sites seem to be preferentially stuck, but many dominanct trees also. Two potentially pathogenic fungi were isolated from the dying trees : Ophiostoma minus (hedgc.) Syd. et Syd. and Leptographium wingfieldii Morelet. The relationships between O. minus and the dieback lead to hypothesize that this fungus may have a role in the disease, in spite of the failure tp reproduce the symptoms by artificial localized inoculatins. Tomicus piniperda seems to play a positive role in the dissemination of O. minus from one plot to another in the forest. Nevertheless, the relationships between these 2 organisms seems to be fortuitous and the role of the beetle in introducing the fungus in the healthy trees is unknown. A study of the early symptoms and of the first stages of disease is necessary.