34-2 



Bulletin 167 





INFLUENCE OF TAP-HOLE INFECTION UPON THE FLORA OF SAP 



For the purpose of this series of experiments 6 trees were 

 tapped with unusual precaution to avoid infection in the hole at 

 the time of tapping. The spouts used were of galvanized iron 

 and were thoroughly sterilized before using, but remained un- 

 disturbed and without protection, other than the bucket cover, 

 during the season. Bright tin buckets provided with covers 

 were used. They were thoroughly washed and scalded at fre- 

 quent intervals, usually daily, in order to prevent the accumu- 

 lation of organisms, which otherwise occurs in the buckets as 

 the season advances. There was, of course, the usual oppor- 

 tunity for increasingly heavy contamination of the flowing sap 

 by organisms developing in the tap-hole and spout. The in- 

 terval between scalding the bucket and plating the sample varied 

 somewhat with the temperature but was usually about five hours. 

 The progress of infection is shown in table 5. It is interesting 

 to note that most of the colonies developing in the sap from tree 

 number 3 were of a single species. It seems probable that this 

 organism was carried into the tap-hole at the time of tapping 

 and became established there to the practical exclusion of other 

 species. 



TABLE 5. ORGANISMS FROM TAP-HOLE AND SPOUT PFU CC. OF MAPLE SAP 



The figures given above indicate that in most cases the 

 infection in tap-hole and spout is slight during the early part ^^ 



