370 | : [ AssEMBLY 
diseases are identical in origin. There are slight differences in the 
action owing to differences in the nature of the trees, but [ have been 
unable to make sufficiently extended observations to state them ex- 
actly. The disease seemed to-progress about as rapidly in the apple 
as in the pear, but owing to the hairiness of the former, as already 
stated, accurate comparisons were not practicable. A different 
method of comparison was also tried. On August 7 a drop of virus 
from pear was placed in the center of a slice of Baldwin apple and 
of Bartlett pear, and the slices kept moist under bell jars. The ex- 
tension of the disease spots over the surface did not differ much in 
rapidity, but was more conspicuous on the pear. In the Jatter it 
rapidly reduced the tissues to a semi-fluid condition, while in the 
apple it broke them down very slowly. But we cannot say that the 
results might not have been quite different or even reversed by tak- 
ing different varieties of the two fruits, or trying the experiment at 
an earlier date. A more obvious difference is shown in the leaves 
and wood of the apple not turning blackish when killed by the blight 
as do those of the pear, but to a dark brown, a difference apparently 
due to the ¢hemical constitution of the two. | 
APPLE Scap AND Lear Buicur. 
Lusicadium dendriticum, Eckl. 
This disease is very similar to that on the pear, and it is quite 
possible that the difference in the growth of the fungus, which en- 
titles it toa different specific name, is due to the influence of the 
plants on which it lives. It is usually more abundant on the upper 
surface of the leaf than on the lower, which is so covered with close 
pubescence as to obscure its early stages. 
The rusty or scabby spots on ripe apples continue to grow 
throughout the winter, or as long as the apple is sound, but new 
spots do not appear to arise; so no harm comes from placing perfect 
and spotted apples together in the same bin. According to Mr. 
Hatch of Wisconsin from five per cent of Dutchess to as much as 
ninety-nine per cent of Fameuse and Walbridge scab injuriously in 
bad years.* In some years there is almost a total loss of the crop 
from this cause, while in almost every year an appreciable part is 
rendered unmarketable. 
The growth and reproduction of the fungus has been studied by 
Sorauer,t but without learning how it obtains entrance to the tissues. 
A very complete statement of the habit of the fungus, and of the 
injury done to the several varieties of apples, has recently been pub- 
lished by Trelease.t The same remedies suggested for pear scab 
are applicable here. 

* First Annual Report Wis. Agric. Exper. Station, p. 52. 
+ Quoted by Frank, in Krankheiten der Pflanzen, p. 587. 
{ First Annual Report Wis. Agric, Exper, Station for 1883, pp. 45-56. 
