Estudio de los suelos y de las especies de Phytophthora en relación al mal del ciprés.

LA MANNA, LUDMILA; GRESLEBIN, ALINA G.

Esquel, Chubut, Argentina

Congreso; I Reunión sobre ecología, conservación y uso de los bosques de ciprés de la cordillera (EcoCiprés); 2005

Austrocedrus chilensis forests in Argentina suffer a widespread mortality known as “mal delciprés”. The aims of this work were to characterize soils and to isolate Phytophthora species indeclining cypress stands. Five sampling sites with pure cypress forests expressing “mal delciprés” were selected in NW of Chubut Province. In each of them, declining andasymptomatic plots were established. Two control sites were also estabished. Soil profileswere characterized in each plot. Isolation of Phytophthora species was attempted from soil andstreams of declining and control plots. Sites showed a great edaphic variability, includingsoils developed from different parent materials: volcanic, alluvial and glacifluvial depositsand andesite. Decline was associated to poorly drained soils in most sites, except one where itwas associated to excessively drained soils. Two Phytophthora species were recorded. P.syringae was isolated from soil and/or streams in 3 declining and 1 control stands. P.gonapodyides was isolated from water of 4 of the 6 surveyed streams. If analized as a forestdecline process, poorly drained soils may act as a predisposing factor for “mal del ciprés”. Onthe other hand, Phytophthora species may act as a contributing factor causing chronic rootreduction but this aspect should be studied.