Pine Decline in Austria : Disease/Environment Interactions in Forest Decline. Proceedings of a Workshop of the Working Party Disease/Environment Interactions in Forest Decline IUFRO 7.02.06, Vienna, Austria, March 16-21, 1998

1999

S. 83-94

9 Abb., 6 Lit.

Unselbständiges Werk

200085349

Decline of Pinus sylvestris and Pinus nigra is a phenomenon known for more than hundred years from afforestations in the Eastern parts of Austria. It has mostly been attrubuted to attacks of bark invading fungi, especially Gremmeniella abietina and Cenangium ferruginosum. The recent epidemic started in 1990. Scots pines as well as Austrian pines are affected. At the beginning Scots pines were heavily attacked by Cenangium ferruginosum, whereas Austrian pines showed twig-, branch- and crown dieback caused by Sphaeropsis sapinea. Annual investigations of the microfungi involved in the decline revealed nearly always Sphaeropsis sapinea as the main pathogenic organism on Austrian pine, which is still actual. On Scots pines the epidemic development of Cenangium ferruginosum decreased in 1991, followed by a complex of bark and wood attacking beetles. Differential diagnoses in 28 pine-stands showed that Phaenops cyanea is the most common primary invader of living bark tissues, causing necrotic discolorations on the stem. Dying trees show blie stain of the wood proceeding from these necroses as well as from galleries of Ips acuminatus and Pissodes piniphilus. The role of mistletoes, root rot fungi, other insects and predisposing climatic factors is discussed. The assessment of crown defoliation on two investigation stands in the years 1992 to 1998 gave some remarkable results. In the one stand, five of 20 Austrian pines died during the investigation period, but all of them had already been moderately or severely derfoliated at the beginning of the assessment. By way of contrast, pines slightly defoliated in 1992 didn 't show a deterioration until 1998. In the other investigation stand none of the trees died between 1992 and 1998. The average defoliation degree remained more or less constant.