Fungal species associated with the decline of Austrocedrus chilensis in Patagonia, Argentina: Preliminary results

RAJCHENBERG M., C. BARROETAVEÑA, P.P. CWIELONG, M. ROSSINI, D. CABRAL, A. SÍVORI

Carcans, Francia

Conferencia; Proceedings of the 9th International Conference of Butt and Root Rots; 1997

Institute National de la Recherche Agronomique, Int. Union of Forestry Research Organizations, Conseil Regional d´Aquitaine

The decline of the native Austrocedrus chilensis (Cupressaceae) was investigated. The root systems of 21 trees in three stands were totally excavated and samples of healthy, decaying and/or rotten roots of varying diameters (including main, secondary and tertiary roots, and fine roots) were taken. Isolation of fungal species from the sapwood were attempted in 4 selective media (MEA, CMA+benomyl, CMA+antibiotics1, CMA+antibiotics2). Also, samples of soil and fine roots taken from 33 declining stands and in 23 neighbouring healthy trees selected along the distributional range of A. chilensis were studied to specifically survey the presence of pythiaceous fungi. Cylindrocarpon didymum, Scytalidium lignicola and a Dematiaceous species were the more frequent Deuteromycetes isolated, together with Coniophora arida and two undetermined Basidiomycetes. Pythiaceous fungi were frequently isolated, but only Pythium elongatum and Phytophtora pseudotsugae were frequent enough so as to suspect a possible relationship with the disease. Phytophtora species were unabundant, but were recovered more frequently from declining tress than from healthy ones.