26 
BULLETIN 1451, U. S. DEPARTMENT OF AGRICULTURE 
of water were killed. However, it should be noted that all of these 
treatments were applied in July and September, and that half a 
pound in 1 gallon was equally effective in September, whereas 0.4 
of a pound in 2 gallons applied in May did not kill any bushes. It 
may be that the barberry is more susceptible to sodium dichromate 
late in summer or that the amount of soil moisture at time of treat- 
ment is the controlling factor. 
By the time these results were obtained, other chemicals (sodium 
chloride, kerosene, and sodium arsenite) had proved so satisfactory 
that the experiment was discontinued. It is believed, "however, that 
sodium dichromate as a herbicide deserves further study. It is 
easy and safe to handle and is relatively cheap when bought in 
bulk. It was quoted to the writers at T to 8 cents a pound. Trans- 
portation costs would be low. 
Relatively small quantities of sodium dichromate seem to be suffi- 
cient to cause death in plants. Its extreme toxicity to trees when 
injected into the trunk also suggests that it may be of value in land- 
clearing operations to replace sodium arsenite, the extremely poison- 
ous nature of which makes its use inadvisable. 
KEROSENE ACID SLUDGE (SULPHURIC ACID) 
Kerosene acid sludge is a heavy, dark-colored, oily liquid contain- 
ing a considerable quantity of sulphuric acid. It is a by-product 
from the refining of kerosene and may be obtained from refineries. 
The price quoted was 7 cents a gallon; however, as it must be 
shipped in glass carboys or other acid-proof containers, the trans- 
portation costs are considerable. 
In the greenhouse 40 cubic centimeters of kerosene acid sludge, ap- 
plied to the soil surface in 8-inch pots containing small barberries, 
killed the plants in three days. This dose was the estimated equiv- 
alent of about 0.9 of a gallon to a mid-sized bush in the field. Table 
5 gives the results of the field treatments. 
Table 5. — Summary of treatments of individual, marked barberry bushes with 
kerosene acid sludge (sulphuric acid) 
Date of 
treatment 
Nov. 3,1921 
t Quan- 
Date of final l^f. 
observation £«£ 
bush 
I Gallons 
June 29,1923 I 0.83 
Do I do 
Aug. 2,1922 July 3,1923 
Do ! do 
Total... 
1.43 
1.00 
1.00 
Method 
of appli- 
cation 
Drench. 
—do.... 
-do.... 
..do..- 
Bushes cut 
off or left 
standing 
Location of area 
Cut off.... Black Earth, 
Wis. 
Standing do. 
Cut off ; Gurnee, 111. 
Standing., i do 
Bushes 
treated 
Bushes 
killed 
12 
12 
G 
6 
4 | 
31 
2a 
Per- 
centage 
killed 
100 
100 
66 
S3 
90 
As may be seen, 90 per cent of the 31 bushes treated were killed. 
Of the three that survived the old crowns were entirely killed, but 
sprouts arose from the large lateral roots just outside of the area to 
which the chemical was applied. Kerosene acid sludge is extremely 
corrosive, destroying any organic material that it touches. It is 
possible that its killing power is due chiefly to this property and that 
