196 REPORT OF THE BOTANICAL DEPARTMENT OF THE 
for each pint of the stock solution; but in bordeaux mixture con- 
taining the same quantity of arsenite of soda solution and of 
lime there was no apparent injury. It is clear that arsenite of 
soda may be much more safely used with bordeaux than with 
lime water. 
Rows treated with bordeaux alone outyielded rows treated with 
arsenite of soda in bordeaux by 34 bushels per acre. This sug- 
gests that the arsenite of soda may have been harmful although 
not showing any effect on the foliage. However, this is very 
doubtful. There is good reason to believe that, in this experi- 
ment, the foliage indications are more reliable than the yields. 
The chief conclusions reached are: 
(1) That paris green is not injurious to potato foliage if ap- 
plied in moderate quantity with lime water or bordeaux mixture 
evenly distributed ; 
(2) That paris green has considerable fungicidal value; 
(3) That arsenite of soda should not be applied to potatoes 
except with bordeaux mixture. 
INTRODUCTION. 
Certain arsenical preparations, when used as insecticides, bear 
an important relation to crop production in the United States. 
It is unquestionably true that many farm and orchard crops 
could not now be successfully grown in a great majority of years 
without some means of preventing the ravages of insect pests. 
This is especially true of the potato crop, because of the depreda- — 
tions of the Colorado beetle. That serious harm from this pest 
can be prevented by the use of certain arsenical compounds has 
been demonstrated bevond question; and when we remember that 
approximately 400,000 acres of potatoes are annually grown in 
New York, baving a value of nearly $16,000,000, we realize the | 
important place that paris green and other insecticidal prepara- 
tions occupy in our farm practice. 
Very much has been said in a vague way about the injuries to 
potatoes and other crops from the application to their foliage of 
arsenical compounds. Undoubtedly such injuries have occurred 
in many instances but whether these have been occasioned by an 
unavoidable effect of the arsenic compounds or whether they 
have been due to a misuse or injudicious application of these com- 
