ANNUAL REPORT, 1944-45 17 



This indicated that conditions within the tanks changed so as to favor growth 

 of the Citrobacter rather than E. coli. The bacteriological results were about the 

 same for all three compartments, as to both numbers and types of bacteria re- 

 covered. 



Laboratory Service, July 1, 1944, to June 30, 1945. (James E Fuller.) 



Milk samples, bacteria counts 170 



Ice cream samples, bacteria counts 79 



Water samples, bacteriological tests 148 



Total 397 



DEPARTMENT OF BOTANY 

 A Vincent Osmun in Charge 



Diseases of Trees in Massachusetts. (M. A. McKenzie and A. Vincent Osmun.) 

 The Dutch Elm Disease Problem. As of Jul}' 1, 1945, the Dutch elm disease 

 caused by the fungus Ceratoslomella ulmi (Schwarz) Buisman, has been isolated 

 from 54 trees in 19 municipalities in Massachusetts as follows-: 



Berkshire County 1941 1942 1943 1944 1945 



Alford 1 2 



Egremont 3 2 3 



Great Harrington 116 2 



Hancock 1 



Lenox 2 



Mount Washington 1 



Pittsfield... 3 ■ 



Richmond. 5 



Sandisfield 1 



Sheffield 1 5 



Stockbridge 2 



West Stockbridge 1 



Williamstown . 1 



Hampden County 



Holyoke 2 



Longmeadow 1 



Southwick 2 



Springfield 2 



Westfield.. 1 



West Springfield 2 



In both Berkshire and Hampden Counties the spread of the disease is favored 

 by the relatively unbroken continuity of elm population in valleys; and the pros- 

 pect appears that in Hampden County, because of additional complications, the 

 disease if unchecked may become more prevalent than in Berkshire County. 



Certain conditions favor control, but not exclusion, of the disease in the eastern 

 part of the State. In general, elms are more restricted there to plantings of 

 ornamental and street trees. Such trees are likely to be better cared for by either 

 private or public agencies. Also, in metropolitan areas, as contrasted with rural 

 areas, elm in woodpiles favorable for breeding of bark beetles which carry the 

 disease fungus, is not so common, and usually there is less movement of elm logs 

 which might be infested with the carrier beetles. Additional factors affecting 

 disease distribution throughout the State are yet to be evaluated. 



