No. 33.] | 375 
site, and secondly the loss of a whole crop of leaves at the very 
height of the growing season. A tree must have a vigorous consti- 
tution and be well cultivated and fertilized, indeed, to bear a crop 
of peaches under such a strain. A few large trees on the station 
grounds were so thoroughly filled with the fungus, and also pre- 
viously weakened, that they produced a few tufts of leaves only till 
the fruiting period of the fungus had passed and it became compara- 
tively inactive, when a normal amount of healthy foliage at last ap- 
peared. It was an instance where the growth of the fungus had so 
far outstripped the ability of the tree to supply the required nour- 
ishment that host and parasite were alike suffering. It is a common 
error to ascribe the attacks of fungous diseases to the influence of 
the weather, not considering that each fungus has its appointed sea- 
son of development the same as a higher plant. In fact there is no 
more reason to suppose that it is wholly a matter of temperature and 
moisture that causes the curl to ripen its spores and complete its 
yearly growth before the heats of midsummer arrive, than that the 
same cause regulates the appearance of the peach blossoms. It is 
rather the hereditary habit which even the weather is rarely able to 
alter. 
As it is not known how the disease gains access to the tree, of 
course no preventive measures can be intelligently prescribed. 
When a tree is once infested, however, the disease can be kept in 
check and possibly eradicated, by annually pruning away the ends 
of the branches in spring, thus destroying most of the mycelium 
that has lived through the winter. It is also recommended by 
Frank,* and several American writers, to destroy the diseased 
leaves; a troublesome operation, the utility of which cannot at pres- 
ent be fully demonstrated. Wintert recommends the protection of 
the trees from rain during the unfolding of the leaves, which may 
be practicable in Germany but is not in this country. De Jubain- 
ville and Vesquet add to these the cultivation of the soil and a lib- 
eral supply of ashes or other fertilizers containing potash, which is 
certainly a requisite for complete success, if the trees are to remain 
in full vigor. 
GuMMING oR GUMMOSIS. 
Gumming or gummosis, the terms are synonymous, are the names 
applied to the production of the brown or amber colored gum that 
exudes from wounds on the body, limbs and even fruit of the peaéh, 
as well as other members of the same family, such as the plum, 
cherry and flowering almond. The phenomenon has excited much 
attention and the literature is extended, but the subject is yet by no 
means fully understood. Other duties having prevented my under- 
taking an extended series of experiments in this direction, I shall 
here only state as much of the subject as will convey some idea of 
the bearing of the few results obtained. 
* Krankheiten der Pflanzen, p 526. 
+ Krankheiten der Kultur-Gewiichse, p. 47. 
¢ Maladies des Plantes Cultivées, p. 300, 

