226 AGRICULTURAL EXPERIMENT STATION. [Jan. 



put in the benches, which were then filled with fresh soil. 

 A lot of new cucumber plants were started, and in October 

 were abundantly and spontaneously attacked by the fungus 

 in question. There is little doubt, however, that thorough 

 fumigation will render a house clean, so far as fungi are 

 concerned. 



Various Diseases. 



A New Potato Disease. — Late in July last, Mr. G. D. 

 Howe of North Hadley brought to the station some speci- 

 mens of potato plants whose leaves bore spots in many 

 respects strongly resembling those produced by the rot- 

 fungus in the early stages of that disease. He reported 

 that the disease was spreading over an extensive field and 

 killing the plants. A visit to the field confirmed these state- 

 ments, and showed that those plants which suffered most 

 were those which were nearest maturity, although the foliage 

 had not yet turned yellow from natural causes. Some rows 

 of late potatoes, which were still vigorously growing and 

 very green, although between infected rows, were almost 

 free from the disease. The field had been lately sprayed as 

 a protection against rot ; and another spraying of certain 

 rows was recommended, to test the possibility of checking 

 the spread of the disease by this means. But its spread was 

 so rapid that the plants were killed before time could be 

 found to make the application. The tubers were not affected 

 in any case beyond a probable slight loss of growth, and 

 remained perfectly marketable. A pretty thorough and 

 careful examination of the diseased leaves showed the con- 

 stant presence in the spots of mycelium, from which were de- 

 veloped, on the lower surface of the leaves, spore threads 

 and spores of the form-genus Macrosporium. This was 

 clearly not simply a saprophytic form following the attack 

 of some parasite, but occurred on the very young spots with 

 a truly internal mycelium, and had all the appearance of a 

 true parasite. 



Circumstances made it impossible to study the disease 

 further at the time ; but it seems probable that we have here 

 a new disease of potatoes which may prove of considerable 

 importance. Mr. Howe is confident that the same disease 



