297 
It is reasonable to suppose that the three sorts of spores 
have three diverse and important offices to perform. Ag 
to the ascospores, there can be no doubt that they germin- 
ate upon the leaves of the plum tree in spring and start the 
new growth that sometime afterward bears the septoria 
spores. The phoma or winter spores may be of sexual 
nature, and perform the office of the male element in orig- 
inating the ascophorous stage of development, but this is 
conjecture based only on the time and mode of occurrence. 
It seems probable that the septoria spores are for the im- 
mediate and rapid distribution of the fungus to all suitable 
surfaces for its growth in the vicinity. If so the spores 
ought to germinate with readiness, but several attempts 
have proved unavailing when they were sown upon or in 
water. Some other method of germination, however, may 
bring better success. 
In the light of the present knowledge of its life history, 
two reciprocating methods of combatting the fungus seem 
to commend themselves. Bury or burn the fallen leaves 
before the first of the next May, to prevent the fungus from 
surviving the winter and germinating in the spring, and 
then spray the foliage during May and June, or even long- 
er, with some fungicide to prevent stray spores from start- 
ing the fungus in the leaves. If it is too much trouble to 
gather and burn the leaves, much may evidently be accom- 
plished by plowing them under in late fall or early spring. 
It is impossible to say what fungicides will prove efficient, 
as none have been tried, but a solution of hyposulphite of 
soda or sulphide of potassium will probably serve as well 
for trial as any. The application should be renewed after 
showers have washed off the preceding one. 
So far as now known this fungus is confined to America. 
It was described in 1876 by Mr. Chas. H. Peck,! who gath- 
ered it in the Adirondack mountains on the leaves of the 
wild black cherry. A very similar species, if not identically 
the same, has been described:by Mr. Ellis? on leaves of the 
129th Rep. N. Y. State Museum, p. 48. 
“Amer. Naturalist, Vol. XVI, 1882, p. 811; Ellis’ N. Amer. Fungi, No. 
1151. The length of the spores as given by Hllis, is 30 to 50 mu, and by 
Peck, .002 to.003 inches—50 to 75 mu, while my own measurements of simi- 
lar material to that used by Peck give 35 to 60 mu. My examination of a 
large amount of material gathered from different varieties of plum, cherry, 
apricot, and peach, at different times in summer and fall, leads me to think 
that these differences of measurement are sufficiently explained by the vari- 
able vigor in the growth of the fungus at different times and on different 
hosts, which to a considerable extent influences the size of the spores, as it 
also does the appearance of the spots. Aside from the size of the spores, 
the only material distinction between the two, according to the descriptions, 
_is that 8, Pruni is said to have 4 to 6-septate spores. But an examination of 
the specimens in N. Am. Fungi shows the spores to be simple, as in S. 
cerasina, and the contrary statement is possibly due to an error. From this 
examination of material and literature it seems safe to consider 8. Pruni a 
synonym of §. cerasina. 


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