270 Bulletin 145. 



Recent critical study, however, shows that an entirely different injurious 

 pear-leaf fungus is very probably much confused with the leaf-blight. 

 I would suggest that the name leaf-blight may well be confined to the 

 well-known disease about which so much has been written, and that 

 the term leaf-spot may appropriately be used to denote the fungus to 

 which I wish here to call special attention. 



This leaf-spot is not one of those fungi of minor economic import- 

 ance to be wholly neglected, or which should secure attention at the 

 hands of botanists alone. Nevertheless, in this country it had not 

 been mentioned in the bulletins or other economic publications until the 

 notes sent out from this laboratory last year;* yet it has been casually 

 mentioned in several German works.f I do not find anywhere, how- 

 ever, that it has received deserved attention from the economic point 

 of view, being entirely overlooked or neglected in this country. 



While studying some pear diseases during the summer of '95, Pro- 

 fessor Atkinson found this leaf-spot abundant in the orchards of 

 Ithaca and vicinity, and before the close of the summer he observed 

 it at Syracuse and Geneva, where considerable injury was done to the 

 foliage of orchard trees. 



During the season of '96 and '97 I have continued observations 

 upon this leaf-spot, and it proves to be a disease of considerable 

 importance, and a fungus widely distributed. To the ordinary 

 observer the character of the spots may not seem to differ materially 

 from those of the leaf-blight, but careful observation will readily 

 distinguish them. The mature leaf-spot as it appears on the green 

 leaves is usually larger, more sharply defined, and somewhat angular, 

 being roughly limited by subdivisions in the venation. See figures 

 157 and 1 58.1 The spots may show three fairly well differentiated 

 zones of color. The center is grayish white, and herein appear the 



*')Atkinson, Geo. F.— Leaf-spot of Pear. Garden and Forest, X. pp. 

 73-74, 1897. 



2)Du<<gar, B. M. — Another Injurious Leaf-spot of Pear. Report Proceed- 

 ings West. N. Y. Hort. Soc, 1897. 



f )Sorauer, P. — Pflanzenkrankheiten, Zweite Auflage, II. p. 390. 



2)Tubeuf, K. F. Von. — Diseases of Plants Induced by Cryptogamic Para- 

 sites (English edition) p. 



it Figures 157, 166, 168, and the frontispiece are from photographs made 

 hy Professor Geo, F, Atkinson. 



