CYLINDROSPORIUM ON STONE FRUITS l6l 
of 191 1 and 1912 before any growth was obtained. Spores were often 
found germinating but when transferred to fresh agar, steriHzed bean 
pods, or sterile sHces of pear, no further growth occurred. Bean, 
potato, malt extract, prune, cherry leaf, and plain agar (agar dissolved 
in tap water), were tried. The plain agar was finally adopted for 
all germination trials since other fungi and bacteria developed to a 
much less extent and the ascospores (which germinated more freely 
than in the other agars) could more often be obtained free from 
contamination. Finally from a single lot of cultures 37 colonies 
developed from germinating ascospores transferred, some to tubes of 
plain agar, others to steamed bean pods and slices of pear. 
The growth was very slow. Nearly a month elapsed before any . 
growth could be seen with the unaided eye. The colonies developed 
as small oval masses similar to those of Cylindrosporium. At first 
great quantities of conidia were produced, but after about two months 
conidial production ceased and the stroma turned dark in most of the 
colonies. Transfers from this stromatic material gave few conidia so 
that difficulty was experienced in obtaining infections the next winter. 
The first inoculations with these pure cultures were made Feb. I, 
19 1 3. A colony from a steamed bean pod was crushed in some sterile 
water and used to inoculate two plants. After two weeks no infection 
was found and the same plants were again inoculated this time with 
spores produced on a very young colony. The drops of liquid left 
discolored spots where placed on the leaves and after seven days 40 
of these spots showed Cylindrosporium acervuli. 
Ascocarps were not found on the other species of Prunus until the 
spring of 1913; so, although several attempts have been made, no 
pure cultures have been obtained from them. Successful inoculations 
have been made with ascospores from leaves of P. virginiana, P. sero- 
tina, P. pennsylvanica, P. domestica, and P. insititia and with a pure 
culture from apothecial conidia from P. insititia infection has been 
produced on P. americana. 
In fact the ascospores are more active in producing infection than 
the conidia of Cylindrosporium. Ascospores from leaves of P. 
virginiana produced abundant infection on plants of P. serotina and 
P. virginiana while conidia formed on the P. virginiana plants from this 
inoculation would not cause the disease on P. serotina although several 
plants were inoculated under exactly the same conditions, and abun- 
dant infection occurred on a plant of P. virginiana inoculated at the 
