DISEASES OF PEARS 



PROFESSOR M. F. BARRUS 

 Department of Plant Pathology, Cornell University, Ithaca, N. Y. 



KIRK BLKJIIT 



Fire blight is, without doubt, one of 

 the most destructive diseases of pears in 

 this country. The losses from the disease 

 amounts to millions of dollars every year. 

 Not only are large blocks of nursery pears 

 often absolutely destroyed, but young 

 trees may become affected at any stage 

 of their growth and even old trees are 

 seriously injured if not killed outright. 

 The disease attacks pears, apples, 

 quinces, hawthornes, and other cultivated and wild species of the 

 apple family, and is reported to occur on plums, cherries, and a 

 few other plants. It is most destructive to pears and quinces 

 although apples may suffer severely from blossom and twig blight. 

 Some varieties of apples show injury to the limbs and the body, 

 especially when they are young. None of the cultivated varieties 

 of pears seem to be immune, although some are injured more 

 severelv from the disease than are others. 



Symptoms of the Disease 



During the dormant season one can detect the disease by the 

 presence of dry brown leaves clinging to the infected branches, 

 while the healthy branches are bare. At this time a distinct crack 

 in the bark often separates the diseased area from the healthy. The 

 disease may also appear on the trunk or limbs as cankers that are 

 sunken areas of varying size separated from the healthy parts by 

 this definite . crack. On cutting into the canker one will usually 

 find that the bark is dry and brown and that the dead area extends 

 to the wood below. Oftentimes there will be sprouts or spurs that 

 spring from the tree within the cankered area. These are always 



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