140 DISEASES OF TREES 



GLCEOSPORIUM NERVISEQUIUM. 1 THE PLANE-TREE 

 FUNGUS 



Plane-trees (Platanus) suffer very frequently from a disease 

 which is characterised by the leaves acquiring brown blotches 

 and dying. From the middle of May onwards one observes 

 that death sets in at certain places, and continues along the 

 nerves of the leaf. Small black spots may then be observed 

 appearing on the dead parts, which are the gonidial cushions of 

 Glceosporium nervisequium. 



Unfortunately we still know very little regarding the develop- 

 ment of this fungus, for even trials at infection have not yet 

 succeeded. 



THE FUNGUS OF THE BLACK (AUSTRIAN) PINE 2 



For a number of years a disease of the black (Austrian) pine 

 has been observed in the south of Norway and throughout the 

 whole of Germany. This disease has constantly been on the 

 increase, but has not yet been thoroughly investigated. It is 

 now a considerable number of years since Dr. C. v. Fischbach 

 sent me diseased branches, and an opportunity for observing 

 the disease was afforded in the forest division of Freising, near 

 Munich, but the investigation yielded no satisfactory results. 

 This disease may find mention here, especially since Dr. Brunc- 

 horst's description is now available. 



The most vigorously growing Austrian pines show a pale- 

 ness in the leaves of the previous year's shoots, whose buds, 

 instead of shooting out, die off. The disease spreads from the 

 tissues of the shoots, having its inception in the cortical tissues. 

 Here infection is very often brought about, as it appears to me, 

 through the agency of a small plant-mite, which bores through 

 the epidermis into the cortical tissues of the shoot to a depth 

 of 12 mm. Infection may, however, also take place easily 

 enough at the base of the leaves, where the epidermis is thin. 



1 Dr. Fr. v. Tavel, Bot. Zeit., 1886, No. 49. 



2 Dr. C. v. Fischbach, Eine neue Krankheit der Schivarzkiefer. Central- 

 blatt fur das gesammt Forstwesen, 1887, p. 435. Dr. Brunchorst, Ueber eine 

 ncue verheerende Krankheit der Schwarzfdhrc. Bergen, 1888. 



