Mar. 25, 1915 Dissemination of Chestnut-Blight Fungus 525 
(11) By making possible long exposures the water spore traps offered 
some advantages over the exposure-plate and aspirator methods. The 
presence of spores of the chestnut-blight fungus, however, was never 
shown by this method unless the period of exposure included a period 
of ascospore expulsion. 
(12) The failure to obtain colonies of the Endothia parasitica from the 
water spore traps exposed during dry periods, as well as the fact that 
only ascospore colonies were indicated in the aspirator and exposure- 
plate tests, points to the conclusion that pycnospores are not generally 
prevalent in the air at any time. If present they certainly would be 
detected by the prolonged exposure of water spore traps. 
(13) The time immediately following a rain, when the bark is still 
moist, would appear to be a favorable one for new infections, since the 
supply of moisture would offer opportunity for germination of spores. 
It is a noteworthy fact that it is only during this favorable period for 
germination that the dissemination of ascospores takes place. 
(14) All of these experiments point to air and wind transport of the 
ascospores of the chestnut-blight fungus as one of the very important 
methods of dissemination and substantiate the conclusions of Rankin 
(15, 16) and Anderson (1,2). It can now be said with absolute certainty 
that following each warm rain of any amount ascospores are carried 
away from diseased trees in large numbers. Since they have been 
obtained in large numbers at distances of 300 to 400 feet from the source 
of supply, the conclusion of the authors that they may be carried much 
greater distances is justified. During dry periods wind dissemination of 
ascospores does not occur at all or sinks to a very insignificant minimum. 
LITERATURE CITED 
(1) ANDERSON, P. J. 
1913. Wind dissemination of the chestnut blight organism. In Phytopathol- 
ogy, V. 3, Mo. 1, p. 68. 
(2) - and Bagcocx, D.C. eye ; 
1913. Field studies on the dissemination and growth of the chestnut blight 
fungus. Penn. Chestnut Tree Blight Com., Bul. 3, 1912, 45 p., 14 pl. 
(3) Burrus, T. J., and Barrett, J. T. 
1909. Ear rotsof corn. Ill. Agr. Exp. Sta. Bul. 133, p. 65-109, 11 pl. 
Futon, H. R. ; 
i ote Recent notes on the chestnut bark disease. Penn. Chestnut Blight 
Conf., Rpt. of Proc., 1912, p. 48-56. 
F. D. 
ts) ee A method of determining in analytic work whether colonies of the chest- 
nut blight fungus originate from pycnospores or ascospores. In 
Mycologia, v. 5, no. §, Pp. 274-277, pl. 98-101. 
and GARDNER, M. W. 
1913. The relative prevalence of pycnospores and ascospores of the chestnut 
blight fungus during the winter. In Phytopathology, v. 3, no. 6, 
p. 296-305, pl. 26-28. Preliminary note in Science, n. s., V. 37, 10. 
963, P- 916-917. I913- 
1914. The longevity of pycnospores of the chestnut-blight fungus in soil. In 
Jour. Agr. Research Vv. 2, 0. I, p. 67-75. 
d StupHALTER, R. A. : 
for aint as carriers of the chestnut-blight fungus. In Jour. Agr. Research, 
v. 2, no. 6, p. 405-422, 2 fig., pl. 38-39. Preliminary note in Science, 
n. S., V. 38, NO. 973, Pp. 278-280. 1913. 
as 
o aera ee and importance of the chestnut bark disease. U. S. Forest Serv., 
(Misc. Publ.], 8 p. 
(6) 
