ANNUAL REPORT, 1940 27 



Other Tree Problems. Seventy-one fungus diseases of thirty-five species 

 of trees or other woody plants, including twelve diseases of elm, were identi- 

 fied from more than 600 specimens and inquiries received during the year. 

 Cephalosporium sp. was isolated from elms of 16 municipalities in which the 

 wilt disease caused by this fungus was not previously known to occur, 

 making a total number of 152 cities and towns in which the disease has 

 been found in Massachusetts. The progress of the disease in individual 

 mature trees was found to be far from uniform. In experiments also, trees 

 subjected to controlled conditions were found to be affected in varying 

 degrees following inoculation with the causal fungus. The latter observa- 

 tions suggest the significance of resistant individuals, while field observa- 

 tions suggest that additional factors involved in susceptibility include 

 winter injury and drought. 



Preliminary experiments on another wilt disease of elm, caused by 

 Verticillium sp., showed more extensive injury to maples inoculated with 

 the fungus, in pots under controlled conditions. The Verticillium wilt 

 disease of elm is believed to be caused by the same fungus which causes 

 the disease of maple known as Maple Wilt as well as other diseases re- 

 sulting from infection of the water-conducting tissues in numerous addi- 

 tional plants. When elms and maples were inoculated with the fungus 

 isolated from elm, the elms died back somewhat but never completely, 

 while the maples were sometimes killed. The isolation of Verticillium sp. 

 from trees of six municipalities in which the fungus had not been reported 

 previously, increased to 77 the total number of cities and towns where the 

 Verticillium wilt disease of elm is now known. 



During the year, experiments and observations of a fungus, Phomopsis 

 Gardeniae, as a cause of injury to gardenias were reported," ^ including 

 in one instance a review of previous publications on this fungus. 



The sycamore disease, caused by Ceraiostomella sp., reported in New 

 Jersey and elsewhere has not been found in Massachusetts as yet although 

 so far as is known, no organized search has been made here. 



A disease of maple known as Bleeding Canker has aroused widespread 

 interest throughout the State. The fungus, Phytophthora cactorum, has 

 been described as the cause of this disease by F. L. Howard and N. 

 Caroselli.* A fungus believed to be the same species has been isolated in 

 laboratory studies made from collections of elm, maple, and beech in 

 Massachusetts, but no specific experimental work has been undertaken by 

 this Station. The problem is recognized as a serious one since remedial 

 treatment of affected, highly prized specimen trees may be desirable. 

 Meager experimental work and the paucity of published data have re- 

 sulted in a demand that work be undertaken by public agencies on this 

 problem. The whole subject of tree therapeutics as well as the highly 

 speculative and much misunderstood practice of tree injection is involved 

 in M.i> prol)!eni, which demands more concentrated attention tlian can l)e 

 ])roh'-a!ily accorded to this research as a side line dominated by other 

 major work. It is recognized, however, that the demand for investigation 



^ McKenzie, Malcolm A., Jones, Linus H. and Gilgut, Constantine J. Phomopsis Gardeniae 

 in relation to gardenia culture. Plant Disease Reporter 24:3:58-62. February 15, 

 1940. (Contribution No. 363.) 



'McKenzie, M. A., Jones, L. H. and Gilgut, C. J. Study practical gardenia canker 

 control as disease increases (illus.). Flor. Rev. Marcli 28, 1940. (Contribution No. 367.) 



< Phytopathology 30:11. 1940. 



