Botany in the Experiment Station. 85 



effect of Peaches and Plums, February, 1899, was the result of some 

 investigations durhig 1898. Dr. Duggar showed that a weak Bor- 

 deaux mixture was effective in preventing or greatly lessening the 

 peach leaf curl (Exoasciis dcfonnans). He also brought out the 

 interesting fact that leaves of peach. and plum were both injured by 

 improper spraying in such a way as to produce small circular holes 

 in them resembling the eff'ect of the shot-hole fungus. 



This work on The Prevention of Peach Leaf Curl was continued 

 by Dr. \V. A. Murrill, who was appointed assistant for the year 

 1899-1900 during Dr. Duggar's absence in Europe, and his results, 

 which confirmed and extended the earlier ones, were published in 

 Bulletin No. 180, March, 1900. Dr. Murrill began a study of the 

 injuries to shade trees in cities from various causes during his con- 

 nection with the Experiment Station. This work was continued by 

 him afterward during a stay in Europe, and in 1902 a Bulletin, No. 

 205, Shade Trees, was published. Many devices for protecting trees 

 are illustrated. 



The injuries to a great variety of plants due to the soil fungus 

 Rhizoctonia were found to be so great from gradual accumulation 

 of material that a special Bulletin, No. 186, was published upon this 

 subject in January, 1901, The Sterile Fungus Rhizoctonia as a 

 Cause of Plant Diseases in America. This was a joint bulletin by 

 Dr. Duggar and Mr. F. C. Stewart of the Geneva New York Ex- 

 periment Station. The disease is described on about twenty differ- 

 ent hosts in America, and a short history of its occurrence in Europe 

 and America is given. 



Dr. Duggar resigned in 1901 to enter Government work; Mr. 

 Clayton O. Smith was assistant, 1901-02, and Mr. J. M. Van Flook 

 was assistant 1902-03. Mr. Van Hook gave especial attention to 

 the " wilt disease " of ginseng, and this work led to the study of 

 other diseases of this new and important crop, which were found to 

 be surprisingly large for a plant so recently brought into cultivation, 

 and which has so few^ fungus enemies in a state of nature. Bulletin 

 No. 219, Diseases of Ginseng, June, 1904, was the result of this 

 work. 



In 1903, Mr. H. H. Whetzel was appointed assistant in this work, 

 and he has prosecuted the investigations with great vigor and suc- 

 cess. His first bulletin was No. 218, Onion Blight, April, 1904, 

 which deals with a serious disease of the onion crop caused by 

 Peronospora sclilcidcniana. A study was made of the conditions 

 favoring the infection and .spread of the disease and recommenda- 



