CHEMICAL HERBICIDES 
Tus is comparatively a new way of fighting weeds and further 
experiment is needed for discovery of all its merits. Professor 
Henry L. Bolley, Botanist at the State Experiment Station of 
North Dakota, states that “the preliminary field trials at this 
Station in 1896, were, perhaps, the first experiments of the kind 
conducted in any country.” Soon afterward the discovery was 
made in France by M. Aimé Girard that Copper sulfate would kill 
Wild Mustard if applied when the foliage was tender. Since then, 
in many parts of this country and Canada and in European coun- 
tries, experimenters have been at work, trying the effects on various 
plants of different chemicals, seeking to find the reason why the 
treatment succeeds in some cases and not in others, and to learn how 
it can be most economically and effectively used. Such experiment 
has proved the worth of the following chemicals as weed-killers, or 
herbicides : 
Common salt (Sodium chloride). This is the cheapest, handiest, 
and safest of herbicides, but not the most useful; for, when applied 
in sufficiently large amounts to kill a pernicious plant such as the 
Orange Hawkweed, it may also kill other plant-life and so permeate 
the soil as to check all agricultural growth for a season. Its de- 
structiveness lies in its power to absorb the moisture in the soil and 
from the plant tissues, so that they die of thirst; therefore, if it is 
to be effectual, it should be applied in hot, dry weather. Small 
areas of Quack Grass and Canada Thistle may sometimes be 
entirely destroyed by salting freely and then allowing cattle and 
sheep to bite down the salted herbage, repeating the operation as 
often as new shoots appear. In places where it is needful to expel 
all plant growth, salt may be used in the form of hot brine, the 
solution being so strong as to show forming crystals on its surface. 
Copperas, or Green vitriol (Iron sulfate). This chemical, being 
a by-product of the iron and steel industry, is comparatively cheap, 
13 
