512 
Journal of Agricultural Research 
Vol. XXIV, No. 6 
Tabi^E II .—Approximate order 
of foliage susceptihility to arsenical injury 
1. Cabbage. 
2. Sugar beet. 
3. Potato. 
4. Apple. 
5. Pear. 
6. Tomato. 
7. Rutabaga. 
8. Turnip. 
9. Cherry. 
10. Plum. 
11. Pea. 
12. Squash. 
13. Cucumber. 
14. Peach. 
15. Bean. 
Something about the condition of plants of the same kind seems to 
vary at times to make them more or less susceptible. This accounts 
for some apparent discrepancies between Tables I and II. Repetition 
for confirmation is recognized as of fundamental importance in all 
scientific experiments, but is indispensable in studies of arsenical injury. 
Tabi^B III.— Fruit trees sprayed with copper aceto-arsenite and with calcium arsenite to 
show relative susceptibility of different species 
Injury. 
Name of tree. 
Copper aceto-arsenite a.4 Caldum arsenite 1.2 
gni to I liter of water. gm. to i liter of water. 
Apple, McIntosh. 
Crab apple, Transcendent 
Cherry, Montmorency.... 
Cherry, Royal Ann_ 
Pear, Hemish Beauty. 
Plum, Bradshaw. 
Very slight 
None. 
Moderate. . 
Slight. 
Very slight 
Very bad.. 
Moderate. 
Do. 
Very bad. 
Nearly defoliated. 
Moderate. 
Defoliated. 
For the variety used, the order of injury here indicated is plum, 
cherry, pear, apple, and crab, of which the plum is distinctly most 
susceptible. From the conflicting reports of other investigators it seems 
likely that this order will vary according to the variety used. We 
made no tests on the peach, as no trees were available, but it is quite 
generally conceded that it is more tender than any of the fruits named 
in Table III. 
Roses were sprayed several times for a comparison with apple. 
Harrison’s yellow rose seemed about like Okabena apple in susceptibility, 
and the Rugosa a little more tender. 
DIPFJSRKNCES in varieties of the SAME SPECIES 
It is important to know if arsenical spray injury on any variety that 
happens to be chosen will be the same on other varieties under similar 
conditions. Among apples it is quite generally conceded that Ben 
Davis is especially susceptible, though strictly comparative data are not 
abundant in the literature. 
In our work we have had many opportunities for comparing suscep¬ 
tibility of apples, and we have Aoroughly tested Alexander, Ben 
Davis, Charlottenthaler, Gano, Hybemal, Tieby, McIntosh, McMahon, 
Okabena, Oldenburg, Rome, Shiawassee, Wagener, Tetofsky, Yellow 
Transparent, Greenwood, Crab, Hyslop crab, and Transcendent crab. 
Of these the crab apples have shown themselves distinctly more 
resistant than the standard apples, especially the Transcendent, which 
is almost in a class by itself. Among the standard varieties Ben 
