Sapwood Nematodes in Diseased Oak Stands in Austria : Recent Advances in Studies on Oak Decline. Proceedings of an International Congress / Luisi, Nicola

Bari

1993

S. 521

Bandaufführung

77236

Sapwood nematodes were isolated in Eastern Austria from wood samples of twigs, stems and trunks of oaks (Quercus petraea (Matt.) Liebl. and Quercus robur L.) showing oak decline symptoms. A number of nematodes were correlated with the status of oak decline. Bursaphelenchus fraudulentus (Ruehm) J.B. Goodey and three other species were identified. Sapwood nematodes are transferred by insect vectors, especially by Scolytidae, Buprestidae and Cerambycidae. To isolate sapwood nematodes, the sapwood of oak tree samples were cut into cubes of approximately 1 Kubikcentimeter and watered in Baermann funnels for 24 hours. Up to 924 nematodes per 50g wood substance could be found. In comparison to literature, this amount is exorbitant. Since the number of nematodes is correlated to the status of oak decline, earlier conclusions concerning the role of Bursaphelenchus fraudulentus should be reconsidered. Tests on malt agar showed that sapwood nematodes are able to transport Ceratocystis spores and can therefore act as vectors, too. Sapwood nematodes were cultured in Petri dishes on Ceratocystis sp. or Botrytis mycelium for further inoculation tests. At present, pathogenicity tests are being carried out on young oaks plants in climatic chambers using up to 3,000 nematodes per tree.