1890.] PUBLIC DOCUMENT — No. 33. 223 



It seems at present prol)alile that excess of moisture tends 

 to produce the scab, rather through its influence in render- 

 ing the soil heavy and clinging, than in any more direct 

 way ; and it is recommended that, to secure a smooth crop, 

 potatoes be planted in light, porous soil, kept well stirred. 



Observations will be continued next season, in the light 

 of past experience, 



3. Fungous Diseases on Station Farm. 



The following notes include only such diseases as attacked 

 crops grown on the station farm during the past season with 

 sufficient violence to produce results of economic importance. 

 Many fungi, of course, were found, whose presence was of 

 no practical importance to the various plants on which they 

 occurred ; but a few produced striking results by their 

 abundance and vi^or. The meteorological conditions of the 

 season were peculiarly favorable to the development of 

 fungi. 



1. The smut of barley and oats ( Ustilago segetum Pers.*) 

 attacked both of those grains on the east fields and on the 

 experimental plats to such an extent that the "smutted" 

 heads formed a very appreciable portion of the whole. Even 

 were the aflected heads but a small fraction of one per cent. 

 of the whole, the loss on a large field would be sufficient to 

 justify attempts to save it, as a little calculation will show. 

 The parasite under consideration appears on the fruiting 

 heads of the small grains, and, when ripe, presents only the 

 mass of black spores characteristic of the smuts, which com- 

 pletely replaces the substance of the seed. The enclosing 

 seed coats burst open, and the spores are carried in all 

 directions by the wind, finding lodgement on the surrounding 

 plants and soil. Although the smut spores ripen consider- 

 ably earlier than does the grain in the sound heads, grain 

 from a smutted field is sure to have them adherins: to its 

 surface and entangled in the tuft of hairs at its end, espe- 

 cially if smutted heads have been mixed with the sound ones 

 in threshing. Unless they are present in very large numbers, 



* It may be explained that the scientific name of a plant consists of three parts, the 

 name of the ginius or group of closely related plants to which it belongs, the name 

 of its particular kind or species, and the name (in full or abbreviated) of the person 

 or persons to whom it owes the name. 



