1875.] REPOKT ON PEARS. 39 



The blight has been unusually prevalent the past year. The origin and 

 nature of this disease which has become the bane and terror of all fruit- 

 growers is still involved in much obscurity ; but the results of the obser- 

 vations of the microscopist seem to establish the theory that it is a 

 fungus. 



Prof. Taylor, of Washington, D. C, pronounces it " a local fungus fer- 

 mentation of the genus torula — and which may be developed under any 

 one of a number of causes. Every condition which will prevent the bark 

 or shoots from ripening will foster under high temperatures in the pres- 

 ence of organic acid (which is always present in green or unripe wood), 

 and vegetable nitrogeneous matter one or more species of Torulacic 

 fungi. Stagnant water in the ground containing the drainings of decom- 

 posing organic matter is alwa3's charged with Torulacic breeding spores 

 and germinal matter which, if absorbed by the roots, will certainly con- 

 taminate the sap of the tree. When small branches are attacked it may 

 prove best to remove them, but the main branches and trunk may be 

 saved by prompt action. 



The stained bark should be removed as soon as observed and before the 

 stain has girdled the branch or trunk, as maybe. If not removed, the 

 sapwood will be poisoned. In the case of atmospheric blight, that is when 

 the fermentation is produced from the immediate action of high temi^er- 

 atures on the outer bark, favored by previous conditions, the fermenta- 

 tion will proceed from the sui'face to the interior, but in the case of root 

 absorption the fermentation will proceed from the sapwood to the exte- 

 rior. The removal of the tree to a more favorable place, or drainage will 

 probably save the affected tree in the case of root absorption." 



Barry, in his work on Fruit Gardening, says : " Blight has never been 

 known to originate on the dry, sandy loam of Long Island, not even with 

 heav}- manuring, the drought of mid-summer alwa3's ripening the shoots 

 so complete!}' that the leaves drop oft" long before frost commences." 



As early as 1867, Mr Thomas Meehan presented the theory that the 

 fire blight was the work of an extremely active parasitic fungus . 



President Hoopes. in 187u, in his address to the fruit growers of Penn- 

 sylvania, demonstrated from the observations of the microscope that the 

 disease is of fungoid origin. 



This theory is also confirmed by Dr. J. Gibbons Hunt. Chairman of 

 the Microscopical Section of the Philadelphia Academ}^ of Natural Sci- 

 ences, in a letter to the editor of the Gardener's Monthly, dated June 

 21st, 1875. 



What are the predisposing causes of this fungus growth, and what are 



