A Massive Mortality Of Beech (Fagus sylvatica) In County Zala

Thematic Co-ordinator: Dr. Ferenc Lakatos

During the years 2003-2004, a mass decline occurred in the beech stands of Hungary. There is only one similar phenomenon mentioned in Hungarian forestry literature, dating back to the 1800s.

The present decline, even though with differing intensities, was observed all over Hungary. It primarily appeared in beech stands on sites just along the tolerance limits for this tree species. The most significant damage was formed in the western regions of the country, especially in the vicinity of Zalaegerszeg, within. During the period between 2003 and 2006, almost 120,000 gross cubic metres of infected timber had to be cutted by the Zalaerdő Lim. Company in this area.

The decline is a result of a typical damage chain. Direct symptoms are caused by two insect species: Agrilus viridis and Taphrorychus bicolor; moreover by a fungus species: Biscogniauxia nummularia. Massive propagation of these secondary damage factors and secondary pathologic agents was facilitated by a decrease in beech vitality, which came as a consequence of the draught periods characterising the first half of the decade.

Typical Symptoms Of The Decline

Bark loss
White stains on the bark

Minor sap leakage (at larval entry openings)
Larval galleries under the bark (galleries by Agrilus viridis)

Galleries under the bark (galleries by Taphrorychus bicolor)
Emergence holes (on the left of the coin: e.h. of Agrilus viridis; on the right: e.h. of Taphrorychus bicolor)

A black discolouration of the bark (by Biscogniauxia nummularia apothecia)
Longitudinal lesions opening up saliently on the bark

We carried out our field research with the support of Zalaerdő Lim. in their Zalaegerszeg Forest Management Area, chiefly in their Csács Forestry District.

Our institute has made extensive work efforts to describe this set of symptoms, so far unknown in Hungarian forestry literature, and how this disease progresses, to identify the species generating it, to study the climate extremities which promote their massive propagation, as well as to find the possible interrelations of this process of complex decline. We have studied the expected future of these forest stands, and have come up with recommendations in order to prevent any similar decline.

translated from Hungarian by Volford, Péter (B.Sc.For.)