Varietal Resistance of Plums to Brown-Rot 373 



had been hanging on the trees since the fall of 191 2. The plums of this 

 lot were buried on October 15, 191 3, near the previous lot and when finally 

 examined were buried from X to i inch deep. The fruit of each variety 

 was kept separate. Lot 3 was made up of 48 apples representing 7 

 varieties. The fruits had been inoculated through wounds in the labor- 

 atory and on October 18, 1913, when entirely rotted, were buried. 



The results obtained were as follows: In the spring of 1 914 no apothecia 

 were found on any of the three lots. An examination of lot i on May 7, 

 1915, showed 4 of the total of 16 fruits producing a total of 71 cups. 

 On further examination these were all found to be growing from the 

 upper side of the sclerotium. Two others, which had been buried 

 deeper, were found to be producing many of the young cups which at this 

 time had not reached the surface of the ground. 



Lot 3 at this time showed no apothecia. On May 12, 191 5, lot 2 was 

 examined; of the total of 106 mummies produced in 1913, 39 were pro- 

 ducing apothecia in abundance. In a number of other instances the 

 sclerotium was present, but was producing no apothecia. Of the 30 

 mummies produced in 191 2, 4, of the Opata variety, were producing a 

 total of 10 cups, while the sclerotia of the Compass and Topa varieties 

 had entirely rotted. At this time lot 3 was also examined, and as no 

 apothecia were being produced an attempt was made to find the sclerotia. 

 Small pieces of the black, leather-like sclerotia were found where 4 of the 

 varieties had been buried, but in all other cases they had entirely rotted. 

 The sclerotium of a Shields crab-apple had a growth of about one-fourth 

 of an inch upon it which appeared very much like that of a young cup, 

 but when this piece was again buried it showed no further development. 



From this experiment we may conclude that for the production of the 

 perfect stage of 5. chierea the mummies must be buried for at least two 

 winters and that mummies which have hung on the tree for one year still 

 have the power of producing apothecia. 



From a horticultural standpoint it is of interest to note that of the 156 

 plum pits buried in 191 3 none germinated in the spring of 1914, but in 

 the following spring 106 produced young plants. Of these, 6 were of the 

 Topa variety which had hung on the tree for one year before burying. 



Measurements were made of asci and ascospores from material col- 

 lected on April 10, 1914. The asci varied in length from 102 to i66/i, 

 and in breadth from 3.5 to 5. 7m- The ascospores varied from 5.6 to 

 8.9/i in length and from 2.9 to 3.8/i in breadth. 



Reference to Table II shows the wide range in ascus and ascospore 

 measurements as determined by various investigators, the asci of Norton 

 ranging from 45 to 60 by 3 to 4/^; of Aderhold and Ruhland (who received 

 their material from Norton), 89.3 to 107.6 by 5.9 to 6.8^, those from the 

 Minnesota Experiment Station, 102 to 166 by 3.5 to 5.7^1, while the 

 upper extreme is reached by Reade (who also obtained his material from 

 Norton), who found the asci ranging from 125 to 215 by 7 to lo/x. 

 9842°— 15 2 



