I. SI. 



■KOI KCIION ACAIXsr KL\N<;l. 



^ inch across appear on niajjle leaves, and turn hlack in 

 Aii<^ust, retaining a lighter tint on their herders. The leaves 

 fall earlier than is usual. On the fallen leaves during winter 

 and the following spring numerous sporocarps develop on the 

 hlack spots, and they open in long cracks in damp weather. 

 Tiie spores whieii issue from tiiem in the spring germinate on 



Fig. 23G. — lilnjtimna acerhium, Fr., on ii leaf of iVorway Maple. Tiie dark blotches 

 (a) are siirrouuded by a dead lighter coloured zoue {h). 



the leaves and produce fresh spots as hefore. The parasite 

 appears to he an annual, and is very common. 



The damage done is mostly due to reduced assimilating 

 powers of the leaves and is relatively unimportant. 



Where the dead leaves are swept up and burned, as in parks 

 and gardens, the disease does not spread, but in places where 

 dead maple leaves are allowed to lie about in ditches, etc., it 

 may recur annually to the detriment of the beauty and shade 

 of the trees. 



