HOW FURTHER RESEARCH MAY INCREASE THE EFFI 

 CIENCY OF THE CONTROL OF THE CHEST- 

 NUT BARK DISEASE. 



BY riiOFESSUU W. 11OWA14D JKANKIN, Cornell UiticcritUy, llhaca, N. Y. 



Mr. Chairman, Ladies and Gentlemen: Up to this time investi- 

 gations concerning the chestnut tree canker disease and the 

 causal fungus have not brought forth facts as rapidly as we 

 could wish. It was the opinion of the conference held at Albany, 

 N. Y. last October that we did not have facts enough about the 

 disease and that scientific research was the one thing needed. To 

 emphasize this point we may consider some important phases of 

 the disease which are yet little understood, but the knowledge of 

 which is fundamental to devising efficient control methods. Con- 

 cerning the means of spread of the fungus from one tree to 

 another we have nothing except secondary evidence. Most writ- 

 ers have theorized on the different methods by which the conidia 

 or summer spores might be carried from one tree to another and 

 a neAV infection started. Reasoning by analogy with what is 

 known of the behavior of many fungi, such agencies as borers, 

 birds, ants and the wind, etc., have been suggested but in no wise 

 proved to be responsible. It seems that the ascospore stage has 

 not been considered by any writer in the dissemination of the 

 fungus, yet this stage follows the conidia very quickly and is the 

 more abundant fruiting stage which is formed in the red or brown 

 pustules on the surface of the cankers. Under moist conditions 

 the ascospores are shot forcibly out in the air where they can be 

 caught up by the wind and carried for a considerable distance. 

 The speaker found the ascospores being shot from mature pus- 

 tules during every rainy period last summer. These spores ger- 

 minate readily in rain water producing a new mycelium of con- 

 siderable length in fifteen hours. The question at once arises, 

 why could not these ascospores once shot into the air be carried 

 long distances and owing to their abundance cause a large ma- 

 jority of the infection? The time of year at which new infec- 



