GNOMONIA 203 



which develops on the dead leaves the following spring. In 

 addition another conidial form grows on the branches, thus 

 furnishing the spores by which the leaves are infected. 



The form on twigs has been known as Discula platani 

 (Sacc.) ; the spore-clusters are produced in small cavities 

 situated under the lenticels. The spores are elliptical, 

 hyaline, 8-12 X 3-4*5 /* 



The form on living leaves, called Gloeosporium nervisequum 

 (Sacc.), is the stage that does all the mischief; the spores are 

 hyaline, narrowly club-shaped, 11-15X4-6 /*. 



The highest or ascigerous stage of the fungus is called 

 Gnomonia veneta (Kleb.). The perithecium is flask-shaped, 

 sunk in the tissue of the leaf, the tip of the neck bursting 

 through to the surface, asci clavate containing eight spores in 

 two rows; spores elliptic-fusiform with a septum very near to 

 one end, dividing the spore into two cells, one very large, 

 the other minute, 12-16x4-6 //. 



Still another conidial form is described as occurring on the 

 dead leaves. The reader is referred to the original account 

 for full details. 



This disease attacks the American plane (Platanus occiden- 

 talis}, also P. acerifolia, commonly planted in England, and 

 usually considered to be the Oriental plane, P. orientalis. 



The spread of the disease can be checked in the case of 

 nursery stock by spraying with Bordeaux mixture. 



Klebahn, Pringsh.Jahrb.^ 1905, p. 515. 



Bird cherry leaf blight. The leaves of Prunus avium, the 

 bird-cherry, are often attacked by a fungus, which until quite 

 recently has been known as Asteroma padi (D. C). Klebahn 

 has proved, by means of pure cultures, that the above-named 

 fungus is in reality only the conidial stage of an ascigerous 

 fungus, Gnomonia padicola (Kleb.). 



The conidial form of the fungus forms discoloured patches 

 on the leaves, which in consequence fall quite early in the 

 season ; in instances where the attack is severe, the trees are 

 often completely denuded of leaves by midsummer. For- 

 tunately this disease has not as yet attacked the cultivated 

 cherry. 



In the Asteroma condition, the upper surface of infected 

 leaves bear one or more patches of superficial, brownish 

 mycelium, which radiates on all sides in irregular, fan-like 



