EKADICATING THE COMMON BARBERRY 13 
height of a bush can not be taken alone as an indication of its vigor, 
as this is dependent to a great extent on the amount of light it 
receives, as well as on soil conditions. Barberries growing in the 
shade of trees usually are taller though less vigorous than bushes 
growing in direct sunlight. Browsing or cutting back also may 
affect the height of a bush. Likewise, the diameter of individual 
stalks is not a character that can be used, as the stalks seldom at- 
tain a diameter of over 2 inches, and new stalks are being produced 
continually around the periphery of the clump. 
The diameter of the clump or bush at the surface of the ground 
was therefore taken as an index, and a bush with a diameter of 12 
inches at the base was arbitrarily selected as an average-sized one. 
All treatments were made on this basis, and the results are those 
which may be expected when bushes of this size are treated. For 
larger or smaller bushes more or less of the chemical would be 
required to give the same results. 
A few chemicals that appeared especially satisfactory from the 
field tests on marked bushes were tried out on a larger scale. For 
this purpose fields were selected where numerous barberries were 
growing wild. Only one chemical was used in a field, and all bushes 
were treated in the same manner. The quantity applied to an in- 
dividual bush was determined by the size of the bush, using as a 
basis the most satisfactory treatment for an average bush as deter- 
mined by previous tests. In this way there was obtained not only 
an idea as to the action of the chemical on bushes of various sizes 
but also an indication of the cost of treating areas of escaped bar- 
berries. These tests were made in various localities in Wisconsin, 
Iowa, Illinois, Michigan, and Ohio. 
CHEMICALS USED 
Thirty-seven different chemical substances that were tested are 
reported in this bulletin. Others were tried either in the green- 
house or in the field or both, but the results are not reported. Trials 
with some have not yet been completed. Some mixtures obtained 
from different firms were tested, but the results are not given be- 
cause the composition is not known to the writers. None of these 
latter preparations, however, were so satisfactory, from the stand- 
point of either effectiveness or cost, as the best reported in this 
bulletin. 
The following is a list of the chemical substances in the order in 
which they will be discussed in this bulletin : 
Inorganic salts. — Borax and boric acid, calcium chloride, ferrous sulphate, 
mercuric chloride, sodium arsenite, sodium chloride, sodium dichromate. 
Acids and acid formers. — Kerosene acid sludge (15 per cent sulphuric acid), 
phenol, picric acid, sulphur (inoculated). 
Gas-forming suostances. — Calcium carbide, calcium cyanide, carbon bisul- 
phide, paradichlorobenzene, sodium cyanide. 
Oils and other organic suostances. — Ammonium picrate, benzene, creosote 
oil (light), metacresol, orthodichlorobenzene and metadichlorobenzene, petro- 
leum fuel oil, furfural (furfur aldehyde), petroleum gas oil, gasoline, kerosene, 
monochlorobenzene, nitrobenzene, paranitrochlorobenzene, orthonitrotoluene, 
paratoluenemonosulphonic acid, paratoluenesodiumsulphonate, paratoluenesul- 
phochloride, orthotoluidine, paratoluidine, water-gas drip-oil, and water-gas tar. 
