Forstschutz Aktuell Nr. 23
Ch. Tomiczek, H. Krehan
In many parts of Austria severe damage by larch canker and larch aphids can be observed. In younger stands (up to 40 years) heavy attack leads to premature loss of needles and to dieback of shoots or even of the whole tree.
Because of samples sent in and field investigations the institute of forest protection has a good overview of important recent pests and diseases occuring in Christmas tree- plantations. Like in the past few years, fir aphids were found all over Austria. Especially in Styria, Salzburg, the Tyrol and Upper Austria not only Xmas tree plantations, but also regular forests were infested. In most cases the Silver fir migratory adelges, Dreyfusia (Adelges) nordmannianae was the reason for the damages, but also other Dreyfusia species were found. Severe damage was caused by feeding of Green needle weevils (Polydrusus spp.), and the Gregarious spruce sawfly (Pristiphora abietina) could be found too.
A very important disease, also occuring since a couple of years, is the Grey mould (Botrytis cinerea). Often, herbicides were reason for damage mainly as regards fir trees. By way of contrast, in 1999 the Green spruce aphid (Liosomaphis abietinum) and the Spruce needle rust (Chrysomyxa abietis) have only minor importance.
Ch. Tomiczek, A. Pfister
Because of snow- and ice break in winter 1995/96 many Scots pine stands were predisposed to secondary pests and diseases. At the moment a complex of beetles like Phaenops cyanea, Pissodes piniphilus, Ips acuminatus, Ips sexdentatus, Tomicus piniperda and T. minor damages mainly Pinus sylvestris stands in Eastern and Southern Austria.
Ch. Tomiczek, A. Pfister
In Carinthia (Southern Austria) and Lower Austria damage by Melolontha sp. to broadleaved trees along roads could be observed. Most affected were different oak species and cherry trees.
H. Krehan, C. Holzschuh
In two of three investigated areas in Lower Austria pheromone trap catches (LINOPRAX and LINOWIT) indicated that the Ambrosia bark beetle T. laeve is already widespread in these regions. In early spring the pheromone catch rate was even higher than that of T. lineatum. In 1999 the flight activity of this "Asian bark beetle ended in the last week of April.
An exotic Cerambycidae-beetle, introduced into USA, inflicts serious damage to broad leaved trees. In the meantime the beetle was found in packing material in England. The paper gives a short discription of biology and damage symptoms.
H. Krehan, C. Holzschuh
In 1998 more than 100 000 m3 of Siberian Larch (Larix sibirica) were imported from Russia. In the process of phytosanitary control, the inspectors found 6 new species of longhorn beetles (Cerambycidae) one new buprestid beetle and one woodwasp (Siricidae) on the logs. Among the Cerambycidae Xyloterechus altaicus seems to be the most dangerous because it attacks healthy trees, tends to serious outbreaks and causes decline in larch forests. The other species listed in the text are not considered to be primarily attacking pests.
Organisms use to fill their living space abundantly. Indigenous game like chamois or ibex amplifies ist living space to "substitute biotops. They colonize many medium- elevated mountains which are obviously less suitable. These colonies are able to remain there in spite of the damages they cause to the vegetation because of the ambiguos situation of legislation. A similar legislative problem is the limitation of hunting by hunting- districts as well as by shooting- time in order to regulate game with a large seasonal wandering- area.The residling by elk (Alces alces) in the nowadays cultivated landscape causes ecological and legistic problems, as well as the methodical colonisation and uncontrolled extention of the beaver (Castor fiber). Conflicts of interest between land- users and nature- protection about management and compensation require legal regulations in advance. Such adjustments are also lacking for the conceivable colonisation by exotic ungulates like muntiak (Muntiacus reevisi) that is already present in Austria and the chinese- water- deer (Hydropotes inermis).
W. Stagl, Th. Cech
Damage to stems of Grey Alders (Alnus incana (L.)Moench) by wild boars is reported from the riparian forests along the river Danube in Austria. Since the Grey alders have been suffering from a dieback of the crown for four years now the contribution of the damage caused by wild boars to this phenomenon is being discussed.
Th. Cech, M. Brandstetter
At present there are five monitoring plots in Upper and Lower Austria, where the Alder Phytophthora was confirmed. Between 1997 and 1998 there was a slight decrease of the epidemics, whereas from 1998 to 1999 the percentage of diseased trees increased considerably. In addition, some cases of dieback of Common Alders with conspicuous long bark necroses on the south stem side are reported. This damage appeared after a frost event in April 1998.
In forest stands, in parks and in streets terminal dieback and leaf blight of different broadleved trees caused by Apiognomonia could be observed in many parts of Austria. Most effected were Platanus, Tilia and Fagus.
In Austria, the most common control method of bark beetles is to cut trap trees. The disadvantages of this method are the high costs, the loss of timber and the lower acceptance of these trees by beetles of the second generation. In Austria, Pheromone traps are controversial while they are recommended in other countries. Experiences in bark beetle control during the last years showed that there could be more danger than assumed coming from reflighting beetles after their first breeding in May. In case of good climate conditions, beetles of the first generation can reflight from June on. So it is possible that the beetles which bored into a trap tree in May, could reflight before the trapping tree is transported to a saw mill, thus reducing the efficiency of trap trees.
Especially on trees with thin bark severe damage was observed, when protection tubes were not removed early enough. Prunus and Sorbus showed longitudinal cracks and fungus infections.
Young Douglas fir stands in Southern and Eastern Austria were damaged by early winterfrost or frost drought.
In the year 1998, the Institute of Forest Protection of the Federal Forest Research Centre Vienna tested new pheromones for mass-trapping of bark beetles. Some pheromones of Fytofarm Ltd., called Ecolure for Ips typographus and Pityogenes chalcographus were compared to Pheroprax and Ipsowit. A pheromone for combined trapping of Ips typographus and Pityogenes chalcographus called Ecolure PCIT achieved the same results as Chalcoprax in trapping Pityogenes chalcographus, but not as good results in trapping Ips typographus. The results for Ecolure IT for trapping of Ips typographus on a research area in the district of Baden were as good as those of Pheroprax and Ipsowit, while in another area, in the district of Horn, the results were not as good as for Pheroprax and Chalcowit.