249 
cherry leaf-blight (Cylindrosporiwm padi Karsten). 
The leaf-bliglit of cherries caused by the same species of fungus as 
that producing plum leaf-blight, is very widespread. Scarcely a wild 
species of the genus Prunus is entirely exempt from the disease, and at 
all stages from seedlings in the seed bed to old bearing trees, cultivated 
cherries are subject to its attacks. The greatest variation exists, how¬ 
ever, as regards the susceptibility of different varieties, some being 
nearly exempt and others, as the English Morello, materially damaged 
by it. Remarkable cases of immunity are sometimes observed. Of 
seedlings used for budding, only the Mazzard seems in any serious de¬ 
gree damaged by the disease. In unfavorable years the defoliation is 
so serious as to render the first year’s growth of stocks almost insig¬ 
nificant. Mazzard seedlings of the second year are also badly attacked. 
The greatest damage probably occurs where Mazzard stocks are budded 
with susceptible varieties, in which case the cumulative effects of the 
disease appear. It should be noted here, however, that the cherry 
leaves attacked by the parasite remain attached to the stocks long- 
enough to take on the yellow autumn tints characteristic of foliage 
from which the valuable ingredients of potash and phosphoric acid 
have been removed.* It is probable, although no experiments have to 
my knowledge been made to establish it, that the premature fall of the 
leaves does not entail so great a loss to the cherry seedling as does 
the fall of the pear foliage, which drops while still green. 
The experiments in the prevention of this disease, extending over a 
period of two seasons, were made upon the two well-known kinds of 
stocks, Mahaleb and Mazzard. In 1891 only the stocks not yet budded 
were treated, while in 1892 the stocks budded in the fall of 1891 were 
sprayed, suitable control being left. 
For record of budding see pp. 258, 200. Bordeaux mixture and am- 
moniacal solution of standard strength were employed in 1891; ammo- 
niacal solution of standard strength and Bordeaux of one-third strength 
in lS92.f 
MAHALEB CHERRY STOCKS. 
1891 .—One row of 449 stocks was planted and treated with fungicides 
at the dates described for all the stocks on p. 263. One-half, excepting 
controls, received 6 and the other 3 sprayings. One-half were treated 
Avith ammoniacal solution, the other with Bordeaux. As mentioned in 
Bulletin No. 3,f where an account of this experiment has already been 
* According to the prevailing views of tlie physiological botanists, Pfeifer, Saelis, 
Detmer, Wiesner, and others, the valuable mineral constituents of leaves are with¬ 
drawn from them at the same time as they become yellow and before they fall to the 
ground; hut the recent paper of Wehmer, Die dem Landfall voranf(jehende vermeint- 
liche Blattentleerung. <fBer. d. deutsch. dot. Gesellsch. 10 Jahrg., Heft. 3, pp. 152-168, 
indicates that the grounds for this belief may not have been sufficiently proven, and 
the whole subject needs further investigation. 
t See p. 262 for formula? of all fungicides used. 
fOp. cit., p. 58. 
