olO Agricultural Experiment Station, Ithaca, N. Y. 



The causes of potato scab have been discovered only within 

 recent years. The disease was carefully studied in 1889-90 by 

 H. L, Bolley, who was then assistant botanist of the Indiana 

 Experiment Station. The results of his work appeared in 

 Agricultural Science, 1890, Nos. 9 and 10.* He ascribed the 

 cause of the trouble to a certain bacterium which had the power 

 of injuring tubers while they were in active growth, but later 

 caused little injury. The injuries produced by the microbe are 

 generally rather shallow, not extending deeply into the tissues 

 of the tubers. 



■^*^:^^^^' 



99.— Scab on potatoes. 



Later in the year 1890, Dr. R. Thaxter, of the Connecticut 

 Experiment Station, read a paper upon potato scab in which 

 it was stated that potato scab is due to the work of a fungus. f 

 More recent investigations have verified the work of Thaxter, 

 and it is now the generally accepted belief that practically all the 

 injury which is commonly known as scab is due to a fungus 

 {Oospora scabies, Thax.). This frequently enters deeply into the 

 potato, especially if the infection occurs early in the season when 



*See also N. Dak. Agiic. Exp. Sta. 1891, Dec. Bull, 4, wbich coatains a record 

 of BoUo.y's work and a full l)il)li(){];rai)li.v of tlic wiibjoct. 



t Tbe paper was read Nov. 12, 1890, at Cliaiupaifj;n, III., Ijefore a meeting of 

 the Association of Agricultural Colleges and Experiment Stations. See also a full 

 account in the Ann. Ropt. Conn. Aj^ric. Exp. Station. 1890, pp. 80-95. 



