THE ASCOSPORE AND OTHER FUNGI 249 



of spores in spring. These are likely to develop in the 

 tissues of the buds, blossoms, and young twigs, often caus- 

 ing serious damage. 



Sometimes a curious mushroom stage of the fungus de- 

 velops in connection with the mummied fruits upon the 

 ground. Great numbers of tiny mushroom-like objects 

 develop from the mycelium. In these the winter spores 

 or ascospores are produced. Apparently this stage is not 

 generally present, and is not necessary to the yearly cycle 

 of the fungus. 



Evidently one of the chief preventive measures with 

 this disease is the gathering of all the mummied fruits in 

 winter. By doing this, by thinning the fruit, and by spray- 

 ing with self-boiled lime-sulphur wash, most of the injury 

 may be avoided. 



PEAR LEAF BLIGHT 



The foliage of pear and quince trees often becomes 

 spotted with brown in summer, and the spotting sometimes 

 is so extensive that the leaves turn brown and fall off. 

 When this occurs over the whole tree and is not at first 

 confined to a single branch, it is generally caused by a fungus 

 that attacks the leaves early in the season and continues 

 to develop until the end of summer, causing the disease 

 known as the Pear Leaf Blight. This fungus is a distinct 

 species of parasitic plant which at first causes small reddish 

 spots to appear upon the leaves. These spots gradually 

 grow larger and turn brown and often cause the whole leaf 

 to become brown and dead. The fungus also develops 

 upon the fruit, causing it to crack open. Fortunately this 

 disease may be almost entirely prevented by spraying with 

 fungicides. 



