34 
The Colorado Experiment Station 
Old lawns on poor soil, where much bare ground and weeds 
occur, will sometimes demand plowing or spading the soil, re¬ 
moving roots and rubbish and fertilizing well. This is preferably 
done in late autumn and should be followed the next spring by 
thoro harrowing or raking and the sowing of the best grade o 
lawn grass seed. 
• (b) By applying about one, teaspoonful of gasoline or kero¬ 
sene in the crown of each plant by means of an oil can. This may 
be done at any time during the growing season and is especially 
effective in killing the older and larger plants which would sprout 
up if cut off. Care should be taken to apply only enough to kill 
each plant, as an excess will cause dead spots in the lawn grass. 
(c) By digging the dandelion plants as deeply as possible at 
least once each season, preferably in spring just before blooming. 
This will kill a fair percentage of the plants and will prevent those 
which sprout from blooming during the season. A second digging 
in autumn before the end of the growing season will destroy a 
still larger number and greatly weaken the survivors. Digging 
may be done in such a way as to remove the entire plant and thus 
destroy it at one operation. This is the method employed in some 
of our large city parks where the dandelion is controlled over 
large areas. 
(d) By prevention of seed production of plants growing on 
the premises. This can be accomplished by early digging, the 
use of gasoline on individual plants, frequent clipping of the lawn 
and picking the flower heads while in bloom at least once a week, 
and by early spraying with a suitable herbicide. 
]3y spraying badly infested lawns at least three times 
at intervals of about two weeks, using a solution of iron sulphate 
in water, U/ d pounds to the gallon. The most effective results 
have generally been secured in late summer. Apply the spray in 
the form of a fine, forcible mist which will drive the solution down 
into the crowns of the plants. Cloudy, damp weather is favorable 
if the application is not followed by rain within 12 to 24 hours. Use 
a spray pump with brass fittings and do not put the solution in 
galvanized iron, tin or iron vessels. All utensils should be thorolv 
rinsed with water after using and the working parts of the pump 
kept well oiled. Wear old clothing and gloves while applying 
the spray and avoid getting any of it On walks, curbings and foun¬ 
dations nr other objects where a rusty stain would be objection¬ 
able. 
(f) According to our experiments, the cheapest and most ef¬ 
fective method of eradicating the dandelion from a lawn, when 
