36 MASS. EXPERIMENT STATION BULLETIN 347 



Copper Zeolite, Copper Oxychloride A, and Bordeaux 4-4-50 were compared on 

 the basis of copper content. In the absence of much disease, yield was best without 

 any treatment with cucumbers and tomatoes, while Basi-Cop ranked first with 

 melons. On cucumbers, Cuprocide 54, Bordeaux 4-4-50, and Cupro-K showed 

 the poorest in appearance and yield; on melons, appearance was noticeably inferior 

 only with Bordeaux, while the yields were poorest with Copper Oxychloride, 

 Bordeaux 4-4-50, and Cuprocide 54. With tomatoes, the yields were poorest with 

 Coposil, Copper Zeolite, and Burgundy Mixture, and this was not associated 

 with any greater amounts of early blight. 



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

 Investigations of the diseases of shade and ornamental trees in Massachusetts, 

 begun in the summer of 1935 and continued throughout 1936, were carried on 

 during the past year. Field and laboratory studies centered around the diseases 

 of elm. 



In a recent elm census report, the value estimated for the elms in four Massa- 

 chusetts cities and towns was conservatively placed at $7,300,000. However, 

 in the final analysis, all fiduciary ratings fail in an actual evaluation of elms in 

 New England. Indeed to no small degree, the elms may be said to identify New 

 England, and Massachusetts occupies an important place in this arboricultural 

 identification. Any threat to the elm in this State, therefore, is cause for alarm, 

 and since 1930, when the Dutch elm disease was first discovered in America, all 

 persons interested in our principal shade tree have become increasingly con- 

 cerned as the number of elms known to be affected by this disease has steadily 

 mounted. Up to the present writing (December 1937), the disease has not been 

 found in Massachusetts. Nevertheless, an important part of the work on tree 

 diseases covered by this report has been the preparation of a bulletin' containing 

 basic information concerning the characteristics and spread of the Dutch elm 

 disease. 



It is to be hoped that if the public is adequately informed on the disease, the 

 chances of early report and prompt diagnosis of trees suspected of infestation 

 will be conspicuously favored. Since no adequate treatment is known for affected 

 trees, their prompt removal is imperative in any attempt to control the disease. 

 Such a program is in operation in states where the disease has been discovered 

 and at present, as far as is known, the number of affected elms left standing is 

 almost negligible. The hopeful opinion that control of the disease is not impossible 

 has been expressed by persons charged with the responsibility of the eradication 

 program in the infested areas. However, the privilege of this statement entails 

 the responsibility of constant vigilance, and in actuality control is a corollary to 

 patrol. Any encouragement in the present favorable outlook is justifiable only 

 as long as constantly changing conditions are studied and recorded. 



It would be extremely difficult if not impossible to designate a single feature 

 of the control program in infested areas as the one responsible for its apparent 

 current success, and no attempt will be made to do so. One principal result of the 

 program in uninfested areas like Massachusetts, as well as in areas where the 

 disease is present is profoundly evident: a demand on the part of the public for 

 information and work programs for general tree improvement. Sustained and 

 increasing public interest in tree problems is apparent by the number of inquiries 

 on these matters received from the citizens of Massachusetts. The adoption of a 

 program for the promotion of the health of the tree population comparable to the 

 public health programs for the human population has resulted in many communi- 

 ties throughout the State. Many tree diseases, in particular the Dutch elm disease, 



'Published as Mass. .A.gr. Exp. Sta. Bull. 343, May 1937. 



