54i2 Report of the Mycologist of the 



Tlie experiments at Ames, Iowa, were conducted at the Agri- 

 cultural College. Maj 26, 1896, G. macpojms from New York 

 was inoculated on Yellow Transparent, Grimes' Golden, Duchess of 

 Oldenburg, Whitney's No. 20 and Pirus coronaria. A large 

 number of leaves on one tree of each variety were inoculated. In 

 each case, some of the leaves were rubbed on both surfaces with the 

 moistened cedar-apple horns, while others were inoculated by making 

 punctures with a sterilized scalpel. On the same date, other trees 

 of the same varieties were inoculated in • the same manner with 

 G. macrojms collected in Iowa. All of the inoculations, except 

 those on Pirns coronaria^ failed. But the Pirus coronaria trees 

 were so completely covered with Roestelia that scarcely a single 

 perfect leaf could be found. What part of this was due to artificial 

 inoculation, and what part to natural inoculation, it is impossible to 

 say. It simply shows that the season was a favorable one for 

 Poestelia. 



The results of our experiments at Ames are entirely in accord 

 with those obtained by Dr. Halsted and Prof. Pammel. Taken in 

 connection with our experiments on Long Island, they show that 

 some varieties (notably Yellow Transparent) are wholly exempt 

 from Roestelia pirata and that there is good reason for believing 

 that the absence of Poestelia from cultivated apples in Iowa is not 

 due wholly to unfavorable climatic conditions, but chiefly to the 

 fact that the varieties grown there are not susceptible to the disease. 

 The severe climate of this section has obliged orchardists to abandon 

 all except the most hardy varieties. These are mostly either Russian 

 varieties or varieties which have originated in the North-AVest. How- 

 ever, the fact can not be overlooked, that Wealthy, a variety shown 

 by our experiments to be very susceptible on Long Island, is fre- 

 quently planted in Iowa, Wisconsin and Minnesota and is there 

 exempt from Poestelia. We have by no means a complete solution 

 <if this curious problem. 



In the Long Island experiments it is interesting to note, that 

 while some varieties showed themselves wholly exempt and others 

 were very susceptible, there were also varieties which presented 

 intermediate degrees of susceptibility — Yellow Transparent showed 

 no sign of Poestelia ; Maiden's Blush and Wealthy cont;'acted the 

 disease readily and matured aecidiospores ; on Ben Davis and Red 

 Astrachan the Poestelia started to grow but never reached maturity ; 

 on Red Pippin only part of the aecidiospores matured. 



