i6 The Colorado Experiment Station 
III, and IV, were due in part to uneven application of the spray. 
The original plants which survived the first two sprayings were 
found to be feebly sprouting and were thus easily killed by the 
third spraying on September 21, the original ten plants still alive 
on Plat IV were very feeble but were accompanied by a consider¬ 
able number of new seedlings which had come in since the last 
spraying. 
Plat III, when examined May 23, 1916, showed 112 plants 
capable of blooming while Plat IV had but six. Plat V, treated 
with gasoline, required a second application a few days after the 
first to kill plants missed the first time. While this treatment 
shows a high efficiency, it is relatively expensive, due to the cost 
of gasoline, which was charged for at 25 cents a gallon. The gaso- . 
line was applied by means of an ordinary tin oil can, about one 
teaspoonful to a plant being used. A small spot of grass is killed 
out around each plant by this treatment, but in a few weeks’ time 
this fills in again. When counted May 23, 1916, 173 plants were 
growing on the plat but of these only five were sufficiently large 
and vigorous to bloom, most of the remainder being evidently 
seedlings which had come in since the treatment. 
In the case of Plat VI, the dry iron sulphate, in granular form, 
was sifted on by means of a tin can with perforated cover. The 
first application killed 28 per cent of the plants, while the sur- 
