ERADICATING THE COMMON BARBERRY 19 
the river. It was possible to pour the solution only in the upper side 
of this bush, and the ground was first scored slightly to keep it 
from running off too rapidly. 
On September 28, only three days after the application of the 
sodium arsenite. the State leader of barberry eradication in Michi- 
gan wrote that the " large bushes looked sick and the smaller ones 
looked sicker." In the summer of 1923 they were inspected again, 
and no signs of life were detected in any of them. 
On a farm about 12 miles northwest of Kichland Center, Richland 
County, Wis., about 118 escaped barberry bushes were treated with 
sodium-arsenite solution on October 14, 1922. Most of these bushes 
were growing in an open pasture and some of them were unusually 
large. The soil was a shallow loam over limestone. The roots of 
most of the bushes penetrated crevices in the limestone, so that 
digging would have been extremely difficult. Water for the treat- 
ment was hauled into the field in a tank wagon, and the solution 
was mixed at the rate of about 1 gallon of " 8-pound " material to 
50 gallons of water. For mid-sized bushes only 2 gallons of this 
solution was used, although the largest ones received as much at 14 
gallons. It had been raining previous to the date of treatment and 
the ground was very wet. After the treatment the weather re- 
mained cool. The cost was as follows : 
Sodium arsenite (" 8-pound "), 10 gallons at $1.25 $12. 50 
Labor, 21 man-hours at 50 cents 10. 50 
Team and wagon, 5% hours at 50 cents 2. 63 
Total cost 25.63 
Number of bushes treated 118 
Sodium arsenite per bush pint 0. 68 
Cost per bush $0. 217 
Examination of this area in 1923 and again in 1924 showed that 
most of the mid-sized bushes had been killed but that nearly all 
of the large bushes as well as some of the mid-sized ones were only 
partially killed. Some shoots on every bush treated were killed, 
but occasional shoots survived. So far as known this is the only 
failure of sodium-arsenite solution, applied as here stated, to kill 
barberries, and large quantities of this chemical have been used 
since for this purpose. The explanation is that the arsenic was not 
absorbed by the plants in sufficient quantity. Whether this was due 
to the formation of insoluble calcium, iron, or other compounds of 
arsenic before the plant could absorb it, or to the wetness of the soil 
at the time of treatment, or to the lateness of the season, is debat- 
able. It appears probable that all three factors were responsible. 
Because of the lateness of the season, transpiration and therefore 
absorption of moisture by the plant were very limited. The moisture 
already in the soil prevented the arsenic solution from rapidly reach- 
ing the roots of the plants, and before growth started the following 
spring much of the sodium arsenite had been rendered insoluble. 
* SODIUM CHLORIDE 
Common salt (sodium chloride, NaCl) has long been used as a 
herbicide. The salt used in these experiments was a coarse, crushed 
rock salt and also a finelv ground rock salt. Crushed rock salt comes 
