INFLUENCE OF CERTAIN CLIMATIC FACTORS 
31 
No mature perithecia were developed at any of the stations during 
.1914. 
Perithecia and ascospores were produced in abundance at many 
stations during the late winter as well as the spring and summer of 
1915- 
Air temperature had very little relation to the development of 
ascospores. They were matured both in midwinter and in midsummer 
near Washington, D. C, in 1915. 
There is a fairly constant relation between the development of 
ascospores and the amount of atmospheric moisture. 
Perithecia were frequently first observed in the spring, a season 
characterized by high humidity. 
The abundant rainfall during the summer of 191 5 was accom- 
panied by abundant ascospore production. 
The results obtained by Rankin in Ulster County, New York, 
during the summer of 1 91 2 agree with those obtained by the writer in 
1915- 
A comparison of the climatological conditions of Ulster County, 
New York, and Washington, D. C, for three seasons shows that years 
in which ascospores were produced were the years of most abundant 
rainfall and largest number of days with rain regardless of temperature. 
'During the period under investigation dry weather has certainly 
tended to reduce the spread of the chestnut blight by reducing spore 
production. 
From the data presented in this paper the chestnut blight may be 
expected to spread somewhat more rapidly in the Southern States 
than it has in Pennsylvania and the states farther north. 
Bureau of Plant Industry, 
Washington, D. C. 
LITERATURE CITED 
1. Anderson, P. J. Morphology and Life History of the Chestnut Blight Fungus. 
Comm. Invest, and Control Chestnut Tree Blight Disease in Penn. Bull. 7. 
1913- 
2. Anderson, P. J., and Babcock, D. C. Field Studies on the Dissemination and 
Growth of the Chestnut Blight Fungus. Penn. Chestnut Tree Blight Comm. 
Bull. 3, 1913. (Literature cited, p. 45.) 
3. Anderson, P. J., and Rankin, W. H. Endothia Canker of Chestnut. N. Y. 
Cornell Agr. Exp. Sta. Bull. 347: 531-618,/. 77-101, pi. 36-40. 19 14. (Bib- 
liography, p. 611-618.) 
