ENDOTHIA CANKER OF CHESTNUT 573 
random in New York and Pennsylvania showed no preponderance of 
cankers on any particular side of the trees. (Anderson and Babcock 
[1913] and Rankin [r914]). 
Effect of season.— Beginning with June, 1912, inoculations were made 
at Charter Oak, Pennsylvania, in every month of the year. Twenty-five 
or more inoculations were made each time, with each of the following 
inocula: (1) ascospores, (2) pycnospores, (3) agar containing mycelium, 
(4) diseased bark. The spores were inoculated by making a suspension 
of them in water and inserting a few drops into a stab made with 
a knife in the bark; the other inocula were inserted into a small 
slit in the bark. In Table 3 are shown the results for the year, the plus 
sign meaning that infection resulted and the minus sign meaning that 
it failed. Where the results are marked positive, over fifty per cent of 
TABLE 3. ReEsu._ts or MONTHLY INOCULATIONS 
hy u 
o oO 5 
5 a uw Q a P 
Inoculum ; a g 3 ; 4 g g 5 S|. 
g)e/R)/ B/S) 5/8) 8/8/38) B/S 
S/S/e4/8a@/d6/2/0)S/ea al ala 
Ascospores...........4-. +i +i +i +fi—f}—);—jy—}—l—l +] t+ 
By chospores.v.c. ooeseael Seo SE S| Se Se a eee + 
Mycelium in culture..... +e) +) +)—f—-)}—-}4+)—-i—t +l] + 
Diseased bark........... +i ey +i ty ei +t] +] tity titi] ot+ 
the inoculations produced cankers in every case except in the January 
inoculations with mycelium, of which only a very small percentage were 
successful. A similar set of experiments at Napanoch, New York, gave 
like results. The results indicate that infection from spores does not 
occur during the six months from October to March, inclusive. Appar- 
ently, then, even if spores.should gain access to wounds during the winter, 
infection would not necessarily result. Very little difference between the 
percentage of cankers produced was noticed during the remaining months 
of the year. 
Development of the canker | 
If the inoculum is diseased bark or agar containing mycelium, the canker 
usually begins to show externally in about two weeks after inoculation 
in summer. If either kind of spores are used, the canker does not show 
until after three to five weeks. A longer time is required in the cool 
months of spring and autumn. The canker appears first as a darker 
area about the point of inoculation. In dry periods this affected part 
soon sinks and at the same time the bark takes on a reddish color. In 
