Some Important Pear Diseases. 



289 



not reproduced, one sees there the essential characteristics of the scab 

 in pronounced form upon the fruit. 



With many varieties of pear, this cracking may accompany the 

 scab as well as the leaf-blight, or, apparently even certain irritating 

 external agencies may produce the cracking, provided the respective 

 agencies affect the pear during the growing period. 



On the fruit the pear scab produces at first merely brownish or 

 olivaceous markings. These discolorations are due, in part, to a short 

 surface growth of the fungus, and to the deadening of the epidermis 



^-J 



169. — A cross section through a scab spot on pear fricit, giving 

 the location and the appearance op the fungus. 



of the pear. Summer Doyenne, illustrated in the frontispiece, shows 

 the characteristic appearance before there is any indication of cracking. 



The figures do not show clearly any of these spots upon the leaves, 

 but the leaves are often severely affected, the spots being usually more 

 abundant in the neighberhood of the midrib on tne under surface. 

 During the past year Professor L. H. Bailey received from Michigan 

 some leaves so badly affected that the fungous growth covered the 

 greater portion of both surfaces, and the leaf was considerably 

 ciurled therefrom. 



Pear scab has been known botanically since 1832, when it was 

 found in Belgium ; but it is only within the past twenty years that it 



