Aktuelle Forstschutzprobleme im Frühjahr 2006

Wien

2006

S. 2-5

9 Abb.

Artikel aus einer ZeitschriftUnselbständiges Werk

200132576

Enormous amounts of snowfall, occurring in two waves during winter 2006, led to outraging snow break in many parts of Austria, affecting both young and old stands. An increase of bark beetle problems, especially Pityogenes chalcograpus, is expected. Damage by frost impact was observed in young stands of Douglas fir in the Burgenland and Lower Austria and in stands of European larch, mostly in Styria. Douglas fir was damaged by winter frost as well as frost drought. The weakened or dying parts of Douglas fir where often infested by secondary factors like small bark beetles (Pityophthorus pityographus) and Phomopsis bark disease (Phomopsis pseudotsugae). The reasons for liability to frost can be found in the long, hard winter of 2005/2006 and a perennial slight infestation of the trees by Woolly Aphid (Giletella cooley) and Sooty needle cast (Phaeocryptopus gäumanni). Remarkable is the noticeable occurrence of spider mites on Douglas fir, found only rarely so far. In 2003, due to drought stress in urban areas, there was an increase of infestations by Leopard Moth (Zeuzera pyrina) mostly on ash, maple and lime trees. An outstanding outbreak of Z. pyrina along an avenue in a suburb of Vienna led to intensive sanitary felling of a large number of trees. Like every year in some parts of Austria moths of the genus Yponomeuta occured in masses predominantly on Prunus padus, which often lead to defoliation and total wrapping of trees with web. The moth Gelechia turpella was observed in Vienna on an old poplar wrapping the stem completely with web of the pupating larvae. A mass outbreak of the weevil Otiorrhynchus ligustici, which is an agricultural pest, was observed in a village near Gänserndorf/Lower Austria. The surrounding gardens were infested by hundreds of beetles which were more of an annoyance than a damaging pest. Willlow anthracnosis, caused by Pollaccia salicicola, is reported from willows in Styria, Austria.