THE MAPLE LEAF-SPOT DISEASE 113 



sliown that this malady may be prevented by early spray- 

 ing with Bordeaux mixture. 



The Sycamore Blight 



Gloeosporium nervisequum 



The tips of branches of sycamore trees often exliibit 

 a peculiar injury in spring, which is commonly attrib- 

 uted to frost. The leaves turn brown, presenting a 

 scorched appearance. The effect is really due to a para- 

 sitic fungus, which produces its fruit in minute black 

 pustules that may be found on the injured leaves. No 

 remedy, except that of cutting and burning affected 

 twigs — impracticable in most cases — has been suggested. 

 The disease is discussed in the report of the Department 

 of Agriculture for 1888 (pp. 387-389). 



The Maple Leaf=spot Disease 



Phyllosticta acericola 



The leaves of various species of maple are often 

 attacked by this fungus, which appears late in spring or 

 early in summer in the shape of minute, blackish circu- 

 lar spots. As the mycelium inside the leaves develops 

 the spots increase in size, and their color often becomes 

 more brownish, the shade differing considerably with 

 the various kinds of maple. Many of them finally 

 become a half inch or more in diameter, and two or 

 more often run together to form a large blotch ; in case 

 of severe attacks so much of the leaf-surface may be 

 affected that the foliage withers and falls from the tree. 



The disease could probably be checked by fungi- 

 cides, but the application of these to large numbers of 

 shade trees is usually impracticable. In nurseries, how- 

 ever, they may be employed. Gathering and burning 

 the fallen leaves helps to check it by destroying the 

 spores. An illustrated discussion of this fungus may be 

 found in the Department of Agriculture Report for 1888, 

 pp. 383-386. 8 



