1892.] PUBLIC DOCUMENT — No. 33. 227 



attacked some of his potatoes in 1890, though in a less 

 serious form. It attacked, during August, as Mr. Howe 

 informs me, many other fields in Hadley, where it appears 

 to have been quite general. The report from various parts 

 of the State of the appearance of potato ' ' blight " without 

 the "rot" leads one to ask if this disease may not have 

 been much more widely spread than is known ; and the 

 especial object of this note is to call the attention of others 

 to it, and to ask readers of this report to forward at once to 

 the station specimens of any potato plants which are ob- 

 served to be attacked in this way. A careful watch will be 

 kept in Hadle} 7 for the disease, and arrangements will be 

 made to give it the attention it deserves should it reappear. 



Another Disease of Cucumbers. — In connection with the 

 study of the powdery mildew of the cucumber, above de- 

 scribed, there were received from Dr. Jabez Fisher of Fitch- 

 burg specimens of cucumber plants which were attacked by 

 a still more serious disease than the mildew, and one appar- 

 ently much more difficult to control. 



This disease is characterized by a dwarfed and stunted 

 appearance of the shoots attacked. The young fruits be-- 

 come deformed and distorted, and some of the leaves which 

 reach a considerable size, perhaps because they are attacked 

 late, turn yellow and die. Sometimes a plant will push out 

 a new and vigorous shoot which may grow for a time, but 

 sooner or later is pretty sure to succumb. Over the lower 

 surface of these yellow leaves may be seen, on close exami- 

 nation, a delicate, white, glairy film, which recalls by its 

 appearance a very thin dried streak of some albuminous 

 substance. Microscopic study of this film shows it to be a 

 web of very fine interlacing fungus threads, closely adherent 

 to the surface of the leaf. No spore formation was ever 

 observed on the leaves as they come from the forcing-house ; 

 but when a fresh leaf, covered with a well-developed film, 

 was placed in a moist chamber, the threads gave rise in two 

 or three days to numerous short, erect stalks, irregularly 

 scattered along their sides. These stalks taper somewhat 

 toward their tips, which are rounded or slightly knobbed, 

 and bear the elliptical or rather kidney-shaped spores of the 

 fungus. These spores, when placed in water, swell up by 



