3o8 



Some Potato Diseases. 



ground resting-spores of the fungus would be liberated into the 

 soil and future crops thereby endangered. 



The temptation to feed stock with diseased potatoes must 

 also be resisted, otherwise the resting-spores of the fungus, after 

 passing uninjured through the intestinal canal of some 

 animal, would eventually be returned to the land along with 

 manure. 



Land that has produced a diseased crop should receive a 

 liberal dressing of gas-lime, or of ordinary lime if the former is 

 not available. 



Matters outside the sphere of the present communication, such 

 as synonymy, affinities, &c, may be obtained from the following 

 literature on the subject. 



Trabut; in Rev. Gen. Bot. VI., 409, 1 pi. (1894). 



Saccardo & Mattirolo ; in Malpighia, X. (1895). 



Magnus ; in Ann. Bot. XL, p. 87, pi. VII. & VIII. (1897). 



Description of Figures (Plate I.). 



1. Potato partly covered with "black scab" (Oedomyces 

 leproides ). Nat. size. 



2. Section of scabbed portion of a potato, showing the uneven 

 surface, x 5. 



3. Section through a nodule of the scab, showing cavities con- 

 taining resting-spores of the fungus. x 50. 



4. Portion of tissue of a nodule containing resting-spores. 

 x 700. 



5. Spores of the fungus, x 500. 



II.— Bacteriosis of Potatoes. 



Bacilhis solanaccarum (E. F. Smith). 



A bacterial disease of potatoes which is very widely spread 

 and destructive in the United States has, unfortunately, been 

 recorded from several localities in this country during the present 

 season. 



The earliest indication of the presence of the parasite is the 

 sudden wilting of the leaves, which soon hang limp and shrivel 

 up. This is followed by discoloration and collapse of the stem. 

 If a stem is split down at this stage, brown streaks, corresponding 



