22 



INTRODUCTION. 



From experiments conducted at this Station during the years 1909 

 and 1910 by G. T. French, then Assistant Botanist, and reported in 

 Bulletin No. 335, the conclusion was drawn that the spraying of 

 lawns with iron sulfate solution to kill dandelions is unlikely to prove 

 successful in New York. The apparent failure to kill large, vigorous 

 plants was explained upon the ground that spraying merely kills 

 the leaves, and therefore has only a starving effect upon the roots in 

 the same manner as frequent cutting. However, a survey of the 

 literature of the subject prior to 1912, the time the experiments dis- 

 cussed in this bulletin were started, revealed the almost unanimous 

 recommendation of the use of iron sulfate solution as an effective 

 means of controlling dandelions in lawns. Ir>. 1907, Bolley, in North 

 Dakota, reported the results of experiments conducted between 1896 

 and 1907. It was stated by this author that a new method of fight- 

 ing dandelions, namely, spraying them thoroly at stated intervals 

 with a differential spray solution made by dissolving two pounds of 

 iron sulfate in one gallon of water will give success, and that the grass 

 need not be injured. This work was more fully discussed in 1908 

 and some additional measures of control suggested. Again, in 1909, 

 Bolley reported that on large lawns spraying dandelions with iron 

 sulfate is quite practical and the cost, using field sprayers, is less than 

 for mowing. Note was also made of the fact that the iron sulfate 

 has a beneficial effect upon the grass in the direction of the preven- 

 tion of certain diseases of blue grass. In Rhode Island, Adams (1909) 

 found that dandelions may be held in check and practically eradi- 

 cated from lawns by spraying four or five times during the season 

 with a twenty per ct. solution of iron sulfate, but that complete 

 eradication cannot be expected because of the fact that the lawns 

 are reseeded by wind-blown seeds. This investigator reported no 

 injury to the grass when the spraying was done about two days after 

 mowing. Experience demonstrated that the most effective spraying 

 was made in the spring when leaf growth was vigorous and the first 

 buds ready to open. Reseeding of the lawn after spraying was also 

 advised. 



According to the report of Pammel and King (1909) two sprayings 

 with a twenty per ct. solution of iron sulfate killed many of the dande- 

 lion plants in a plat of lawn at Ames, Iowa. Chickweed, also, was killed. 



