SOURCES OF APPLE BITTER-EOT INFECTIONS. H 



2 to 5 cm. and widths varying from 1 to 1.5 cm. The growth from 

 the inoculation in the 1-year branch was even greater, the dead area 

 being nearly 6 cm. in length. The control slits were beginning to 

 heal. 



On account of the writer's absence from Arkansas, the inoculated 

 branches were not again examined until April 1, 1915. At that time 

 the inoculated slit and control slit on 1-year-old twigs were not to be 

 found, the twigs having been removed when the trees were pruned 

 in March. The remaining cankers were the same size and apparently 

 in the same condition as in the preceding autumn. The blackened 

 bark presented the same sunken appearance and was still joined to 

 the bark of the adjacent apparently healthy portions of the branch. 



By May 10 there was no change in the general appearance of the 

 cankers except that the blackened bark was no longer connected 

 with the adjacent uninjured bark. There was a distinct fissure run- 

 ning entirely about the cankers, separating the blackened bark from 

 the adjacent bark except at the extreme ends of the cankered area. 

 This isolation of the dead bark was undoubtedly due to the fact 

 that the branch had resumed growth, whereas the fungus had not. 

 By May 21 the delimiting fissure was more pronounced, though 

 the blackened bark was not wholly isolated. On this date the 

 cankered branches were cut oS, brought into the laboratory, and 

 placed in moist chambers. At the end of 24: hours acervuli of the 

 fungus appeared in all three of the cankers. Cultures from the 

 conidia showed all the characters of GlomereUa eingulata. Three 

 of these cankers and one control were photographed and are shown 

 in Plate V, fi.gures 1, 2, and 3. 



Another series of inoculations was made in Arkansas on June 18, 

 1915. The same technique was employed as in the experiments of 

 1914. The spores used in the inoculations were ascospores from cul- 

 tures made from a canker on June 4 and conidia from cultures made 

 from a canker on May 21. The plan of the experiment was as 

 follows : 



Three slits were inoculated with ascospores. 

 Three slits were inoculated with conidia. 

 Three slits were not inoculated. 



This plan was carried out on three varieties — Ben Davis, Jona- 

 than, and Missouri. The moistened cotton covering the slits was 

 removed on June 23. Only 2-year-old branches were employed. The 

 weather was cool and accordingly not very favorable to the growth 

 of the fungus. 



On July 8 all of the control slits were begimiing to heal. In the 

 case of the Ben Davis there was a band of dark sunken bark ex- 

 tending a distance of 2 mm. about each inoculated slit. About the 



