DANGEROUS INTERNATIONAL FOREST TREE DISEASES 67 



Among the great number of forest diseases which wield a perma- 

 nent influence on Austria's economy, the following should be especially 

 mentioned : 



Armillaria mellea Vahl. ex Fr. 



Chrysomyxa rhododendri De By. 



Fomes annosus (Fr.) Cke. 



Lophodermium pinastri (Schrad. ex Fr.) Chev. 



TrichoscyphellawiUkommii (Hart.) Nannf. 



Damping-off, which causes damage in forest nurseries. 



It is worth noting the unimportance of chestnut blight (Endothia 

 parasitica (Murr.) P. J. & H. W. And.) in Austria. 



In the author's opinion the following diseases are of international 

 importance and should be discussed in detail : 



Cenangium ferruginosum Fr. 

 Chondroplea populea (Sacc.) Kleb. 

 Guignardia aesculi (Peck) Stewart 

 Phacidium infestans Karst. 



Dieback of Pines 



Cenangium ferruginosum Fr. (German term: Kief erntriebsterben. ) 

 In the spring and summer of the year 1960 Cenangium ferrugi- 

 nosum. appeared particularly among Pinus nigra in Austria. This 

 fungus is usually a saprophyte. It occurs occasionally as a parasite 

 and then wreaks heavy damage. In 1956, Spaulding explained the 

 cause of this disease as lack of water or dryness. The outbreak of 

 the disease is also furthered by insect injuries. Thus the trees must 

 already be weakened. 



The following dates can be found in literature for the epidemic 

 occurrence of this fungus on Pinus sylvestris and P. nigra : 



1891/93 in North Germany 



1926/28 in East Prussia 



1933/34 in North and Central Germany 



1928/29, 1939, 1948, and 1960 in Austria 



The last devastating occurrence of this fungus in Austria was 

 during the spring and summer of 1960. It affected all the regions 

 containing Pinus nigra. The first symptom was the discoloration 

 of the needles near the tree top. The color of the needles was 

 yellowish gray to brownish ochre and the discoloration started from 

 the base of the needles. In many cases the terminal buds dried up 

 and in a comparatively short time the tree died. The infection must 

 have started in autumn or early spring. The mycelium infects the 

 bark and causes the destruction of the youngest shoots. The diseased 

 trees can easily be detected at a great distance. Pine trees from the 

 fifth year onwards are liable to infection by this fungus. 



The disc-shaped fruit bodies — apothecia — usually burst out in 

 quantities near the needle-bed and their color varies from yellowish 

 brown to black. The apothecia have a diameter of 1.5 to 3 mm., 

 the club-shaped asci are rounded off at the top (60 to 80/a long, 10 to 

 12/a wide, eight spores in an ascus). The length of the spores is 

 from 10 to 12/a, their width from 5 to 7fi and the paraphyses are 

 thickened at the top. 



