24 
London purple experiment , May 17. 1SS9. 
Check lot. 
1 lb. to 100 gals. 
1 lb. to 200 gals. 
1 lb. to 300 gals. 
1 lb. to 500 gals 
Died. 
Number used, 
47. 
Number used, 
100. 
Number used, 
100. 
Number used, 
50. 
Number used 
50. 
May 19. 
35 
37 
16 
12 
20. 
18 
19 
4 
6 
21. 
i 
• 18 
10 
2 
4 
22. 
10 
11 
9 
10 
23. 
5 
5 
7 
7 
8 
24. 
4 
6 
5 
3 
5 
Total. 
10 
92 
89 
41 
45 
EFFECT ON THE FOLIAGE. 
It is well known to fruit-growers that the leaves of the peach 
are much more sensitive to the scorching effect of the arsenica: 
poisons than those of the apple or plum, and it is important 
to know just how strong a mixture of the common arsenica' 
insecticides that tree will bear under favorable, and also 
under unfavorable, conditions. My experiments on this point 
are incomplete, but they are given here for what they are worth. 
First, two branches of a peach-tree were sprayed May IS 
with London purple mixture, a pound to 100 and a pound to 
200 gallons respectively. A week later no noticeable difference 
could be made out between the condition of the two branches, 
the tips of the leaves in both being somewhat deadened and dry. 
May 20 identical applications were made, with no apparent 
effect on the foliage by May 22. Heavy rains followed, and 
no further observations were made. 
June 6 two other branches were sprayed as before. A heav\ 
rain followed June 8. and more upon the 9th. On the 10th the 
effects of the poison were somewhat apparent on both branches 
reddish discolorations occurring where the fluid had gathered 
in drops and also along the margins of the younger leaves 
Further rains occurred on the 16th and 17th. On the 18th the 
discolored spots had increased in size, those on the brand: 
sprayed with the stronger solution being somewhat larger anc: 
more numerous. Xo leaves had fallen, but those worst affected 
were easily detached, and doubtless would have fallen event¬ 
ually. This loosening of the leaves was evidently due, not tc 
damage to the petiole, but to premature ripening of the leaf,* 
consequent on the chemical injury to the blade. June 8 twe 
other branches were sprayed as before, substituting Paris green 
for London purple in both mixtures. Light rain followed tin 
same day, and more on the 9th. On the 10tli a scorching 
the leaves was somewhat evident, a little more so where the 
stronger mixture was used, while on the 18th the condition oi 
the foliage was practically the same as on those branches 
* Ascertained by studying sections of the petiole. 
