190 Agricultural Experiment Station, Ithaca, N. Y. 



External indications of their presence. Illustrated bj 



examples and pliotograplis. 

 How they pass the winter. 

 Conditions favoring their development. 

 Methods of dissemination. 

 Methods of study in the laboratory. Illustrated by 



specimens. 

 Methods of treatment. 



Potato Diseases. 



(Criven at the second Fredonia School.) 



(By E. G. Lodeman.) 



A. Seal. — T>ViQ to 2i iwngw^ {Oospora scabies). 



Nature of the fungus. It lives both in the tubers and in the 

 soil. 



Treatment of the tubers ; of the soil. 



Where it is worst ; effects of much stable manure ; often 

 worse whei'e lime or ashes have been used, probably because 

 these materials modify the acidity of the soil. 



Clean seed, clean land, and rotation are the soverign remedies. 



There is a scab which is produced by insects. 



B. Early Blight. — Caused by a fungus {Macrosr)oriior)i Sola^ii). 



Features of the disease ; appears early in the season, in small 

 spots, and causes the leaf to shrivel as if suffering from 

 drought ; spreads slowly ; tubers do not rot. It is the com- 

 monest disease of potato tops. 



The flea-beetle and its relation to the disease. 



The remedy. Spraying with Bordeaux mixture. 

 -C. Late BligJU, Rot. — Caused by a fungus {Phytoplithora infestans). 



This is the potato disease of history, and it once caused a famine 

 in Ireland. Known for a half century. 



Usually appears after the middle of July ; attacks large areas 

 of the leaf ; spreads rapidly, causing vines to wilt down ; 

 tubers contract a dry rot. 



How it is treated. Bordeaux mixture is a specific. Treat- 

 ment of tubers in the cellar ; lime and plaster ; heating. 



