32 BULLETIN 1451, U. S. DEPARTMENT OF AGRICULTURE 
injure appreciably the barberries growing in the pot. This was 
considered equivalent to an application of 1 pound to a barberry 
bush growing in the field. As this quantity failed to kill the plants 
and as much larger applications would be prohibitive in cost, no fur- 
ther experiments were made with this chemical. 
BENZENE 
Benzene (C 6 H 6 ) was applied to the surface^ of the soil in 8-inch 
pots in which small barberries were growing. An application of 
7 cubic centimeters injured the plants materially, but the results were 
very slow in appearing and the plants eventually recovered. This 
was the equivalent of about 1.4 pounds applied to a bush in the field. 
At a cost of 30 cents a pound a larger application than this would be 
prohibitive in price, and for this reason no further experiments were 
performed with this substance. 
CREOSOTE OIL (LIGHT) 
Creosote oil is a coal-tar product and is used as a wood preserva- 
tive. The material obtained was a light oil that penetrated the soil 
readily. It was quoted at 15 cents per gallon. 
In the greenhouse, 42 cubic centimeters applied to the soil in 8-inch 
pots in which barberries were growing killed the plants in 18 days. 
One treatment was made in the field at Marshall, Wis. Fourteen 
barberry bushes were treated with 1 gallon each, applied as a drench 
to the base of the shoots, which were left standing. The treatment 
was made on May 1, 1922 ; and on June 27, 1923, 11 plants or 79 per 
cent were dead. The action of the chemical was very rapid, and 
the bushes that survived were severely injured. Although the re- 
sults were fairly good, they did not equal those obtained from some 
of the other chemicals. As this material is not so readily available 
nor so cheap as some others, no further tests were made. 
METACRESOL 
Metacresol (C 6 H 4 CH 3 OH) is a light liquid that can be purchased 
in quantity at about 15 cents a pound. In greenhouse experiments 
8 cubic centimeters caused the death of barberries in 8-inch pots in 
seven days. This was a very satisfactory showing except that the 
cost was high. No field experiments were made with this chemical, 
although the results of the greenhouse tests would seem to warrant 
further trials. 
DICHLOROBENZENE (MIXED) 
The dichlorobenzene (C fi H 4 Cl 2 ) was a mixture of the ortho and 
meta forms. It is a light liquid which can be purchased in quan- 
tity for about 10 cents a pound. In the greenhouse 12 cubic centi- 
meters caused the death of the plants in 12 days. Although this 
result was fairly satisfactory, no field tests were made with this 
substance. Though many of the less common organic compounds 
may be efficient herbicides, the difficulty of procuring them in large 
quantity and at short notice is so great that unless they show very 
exceptional herbicidal qualities it is scarcely worth while to consider 
them from a practical viewpoint. 
