24 BULLETIN 1451, IT. S. DEPARTMENT OF AGRICULTURE 
ing that the average bush was about 2 feet in diameter at the base 
and that only 20 pounds of salt had been used on each, it was found 
that less than 7 pounds was used on each square foot of crown area. 
This was a smaller dose than had been decided on as a result of 
marked-bush treatments, and therefore some failures might have 
been expected. 
Barberries were planted at Galena, 111., about 1844, and from 
these plantings seeds were carrie'd and bushes became established 
on many of the surrounding farms. On one of the farms there were 
about 300 bushes, distributed in a pasture on a ^steep, rocky hillside. 
A few cedars and hardwood trees also were growing here. During 
the early part of the summer of 1922 these bushes were cut down 
and an effort was made to dig them. However, the roots- were so 
firmly and deeply embedded in the limestone outcroppings that the 
digging was unsuccessful from the standpoint of eradication (pi. 
13, B). Within a short time a large number of sprouts had arisen 
from the broken ends of roots left in the ground, and it was con- 
cluded that salt should be applied in an effort to eradicate them. 
This was done October 24 and 25, 1922. At this time most of the 
sprouts had attained a height of 6 to 12 inches. -In view of the 
fact that most of the crowns of the original bushes had been re- 
moved, the sprouts were very much scattered, and it was necessary 
to apply much more salt to insure killing than would have been 
required had the old bushes been left undisturbed. In the applica- 
tion of the chemical an attempt was made to heap a small quantity 
around each sprout. The costs were as follows: 
Salt, 55 hundredweight at 90 cents $49. 50 
Labor, 21 man-hours at 50 cents 10. 50 
Hauling charges 5. 00 
Total cost 65. 00 
Number of bushes treated 300 
Salt per bush pounds— 18.3 
Cost per bush $0,217 
When this area was inspected in June, 1923, many new sprouts 
were found coming from cut roots that had not sprouted prior to 
the time of treatment and therefore had not been treated. No living 
sprouts were found in the treated areas. In this area, as can be seen 
from Plate 12, B, much salt was applied near cedar trees, some of 
which were either partially or entirely killed. This was true of 
some trees that were more than 10 feet from any of the salt. 
SODIUM DICHROMATE 
The chromates have not been much used as herbicides, although 
they are known to be extremely toxic to plants. Rumbold (12) 
found them to be the most toxic of a considerable number of chemi- 
cals injected into chestnut trees. This she found particularly true 
of potassium dichromate, which, according to her tests, proved to be 
more toxic than potassium chromate. From this it seemed possible 
that a dichromate might be an effective poison for barberries. 
Sodium dichromate (Na 2 Cr 2 07.2H 2 0), which is cheaper than the 
potassium salt, therefore was selected for trial in the greenhouse. 
In greenhouse tests it was found that 5.2 grams, or the estimated 
equivalent of about 1 pound in the field for an average bush, would 
