49 



EFFECT OF IRON SULFATE SOLUTION UPON LAWN GRASSES AND 



CLOVERS. 



At the outset it should be stated that the clovers, including yellow 

 trefoil and low hop clover (Trifolium procumbens), are killed by spray- 

 ing with iron sulfate solution. No spraying with iron sulfate on 

 lawns should be attempted unless the owner is willing to sacrifice, 

 temporarily, the white clover (commonly called white dutch clover). 



The first effect of the solution upon the lawn grasses is to cause a 

 certain amount of blackening and discoloratiori immediately follow- 

 ing each application. This discoloration lasts for only a few days, 

 after which the grass regains its normal green color. Later, in our 

 experiments, spraying was invariably followed by a more vigorous 

 growth of the grass which was noticeable for at least a part of the 

 first season following spraying, and, in one instance, during the second 

 season. This better growth of the grass was invariably associated 

 with a darker green color which was held during the entire season. 

 The beneficial effect of iron sulfate solution upon grass has been 

 observed and commented upon by other experimenters. Bolley 

 (1909), in reporting it, mentions the fact that in North Dakota the 

 iron sulfate solution had a very beneficial effect in the prevention 

 of certain fungous diseases which attack blue grass. 1 



Aside from the temporary blackening, no serious injury to the 

 grass occured except in one instance, mentioned elsewhere in this 

 bulletin, when the spray solution was applied while the lawn soil was 

 very dry; and in one other case when the solution was applied in too 

 ^beral quantity, causing some injury to the grass roots. Fortunately, 

 both of these conditions can be readily avoided by selecting suitable 

 periods for the spraying, and using care in applying the solution. 

 Another form of injury, usually so slight as to be negligible, is that 

 which occurs at 'the tips of leaf blades recently cut off by the mower 

 or broken by excessive tramping. 



TOXIC ACTION OF IRON SULFATE. 



As regards the toxic action of iron sulfate upon the roots of dande- 

 lion plants in sprayed lawns, the writer will not venture an opinion 

 since the experiments yielded no evidence upon this interesting point. 



*In this connection it is interesting to note that, in some experiments made by 

 Waite (1910), the addition of iron sulfate to self -boiled lime-sulfur solution sprayed on 

 apple foliage caused the leave.3 to become darker green and hang on the trees longer. 



