‘ ; 
New York AGRICULTURAL EXPERIMENT STATION. 235 
belonging to the plant physiologist rather than to the horticulturist. 
Clark’ has studied this phase of the subject and has drawn the 
following conclusion: 
“The amount of injury done to a given species will depend on 
the following considerations, provided always that carefully pre- 
pared bordeaux mixture has been used: 
“1. The specific susceptibility of. the protoplasm of the plant to. 
poisoning by copper. 
“2. The solvent propertics of the cell sap on copper hydroxid. 
“3. The permeability of the epidermis or cuticle to these cell 
contents when the conditions are favorable for their exosmosis, 
and for the entrance of the copper after its solution is affected. 
“4. Weather conditions following spraying, particularly condi- 
tions as regards moisture (dew, etc.), providing the conditions for 
the exosmosis of some of the contents of the cells of the leaf.” 
ANOMALIES OF OCCURRENCE. 
In the study of bordeaux injury in field and laboratory, many 
anomalies are found, and in no phase greater than in its local 
occurrence. The expression is often heard from men who have 
lost heavily from the injury, “I have sprayed just as in past 
seasons when I have had no injury.” The damage is severe in 
some seasons, and in others scarcely occurs at all; it is to be found 
in some localities in a certain season and not in others; in some 
orchards and not in others though the treatments have been much 
the same; some report dry seasons most favorable for the injury, 
others, wet; even in an orchard seemingly uniformly sprayed in 
all respects, parts of the trees may be injured and not all; there 
is a great difference in individual trees, some seeming to be far 
more susceptible to injury than others; in some seasons the injury 
is most severe on the fruit and in others on the foliage. A variety 
with immune fruit may have foliage very susceptible to injury. 
Sometimes the injury is not to be found until several weeks after 
spraying, while in other cases it may be detected within a few 
days. Strangest of all, not infrequently very weak bordeaux mixture 
causes greater injury than a much stronger one used under similar 
conditions, though usually the stronger the mixture, the greater 
the injury. Some cases of injury result from the first spraying 
after blossoms drop and others from a second or third spraying. 
pr Aclatke (13). 
