16 MASS. EXPERIMENT STATION BULLETIN 441 



Laboratory Service, July 1, 1946 to October, 1946. (James E. Fuller.) 



Water samples, bacteriological tests 22 



This service was discontinued in October, 1946. 



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. In 1941 the Dutch elm disease, caused by 

 the fungus Ceratostomella ulmi (Schwarz) Buisman, was discovered in Massa- 

 chusetts. One diseased tree was found in Alford, Berkshire County, just over the 

 line from New York State. As of July 8, 1947, the disease has been isolated from 

 502 trees of 52 municipalities in 8 counties of Massachusetts. The spread of the 

 disease from year to year is shown by the following table: 



Cumulative Totals 



Year 



Trees Towns Counties 



1941 „ 1 1 1 



1942.._ - 7 5 2 



1943 _ 11 6 2 



1944 — 43 15 2 



1945 - 85 24 3 



1946 .-- 381 47 8 



1947 (July 8) ...__ 502 52 8 



Until 1946, occurrence of the disease in Massachusetts was limited to the 

 Connecticut Valley and the area between this boundary and the New York State 

 line. Currently, however, affected trees were discovered in Quincy and more 

 recently in nearby towns in Norfolk County as well as in Plymouth and Bristol 

 Counties. Since the principal known vector of the causal fungus is a bark beetle, 

 Scolytus mnltistriatus, which has been known to be present in eastern Massachu- 

 setts from about 1900, the diseased trees in that section of the State may be 

 regarded as more than individual isolated cases such as sometimes occur inde- 

 pendently of the major area of disease and beetle vector infestation. On the basis 

 of experience, increase in the number of diseased trees locally parallels closely 

 the build-up of beetle population if the causal fungus is present. 



An important part of the work is now, and must continue to be, the explora- 

 tion of possible further spread of the disease in Massachusetts, as well as obtain- 

 ing additional data in areas where trees are known to be affected. Detailed reports 

 are furnished to the Massachusetts Department of Agriculture, to local officials, 

 and to private citizens involved, regarding findings in individual municipalities, 

 with special reference to need for action in retarding the spread of the disease. 



Experiments are in progress in cooperation with the Department of Entomology 

 on the use of spray materials tor the control of carrier beetles. 



The investigation of disease resistance deserves further attention. Thus far, 

 however, other commitments have precluded studies to determine evidence of 

 possible resistance to disease in elms of Massachusetts. 



Other Tree Problems. Fifty-three diseases of twenty-nine species of trees, in- 

 cluding eight diseases of elm, were identified from approximately 450 specimens 

 and inquiries received during the year. The Cephalosporium wilt of elm was 



