is recommended as a means of removing the few plants which sur- 

 vive sprnving. 



SPRAYING LAWNS. 



Spraying with iron sulfate solution will usually prove effective 

 when carefully, persistently and intelligently done. 



NUMBER OF TREATMENTS AND TIME OF MAKING THEM. 



Our experiments indicate that at least three (or, usually, five) thoro 

 applications during a season are necessary to eradicate the dandelions 

 from the average lawn in this state. To be the most effective, the 

 spraying should be repeated as soon as the dandelion plant has re- 

 gained new foliage and just before it is full grown usually when the 

 leaves are three or four inches long. This forces the plants to use up 

 their reserve food stored in the roots, and eventually starves them. 

 On the Station lawns, which were exposed to dandelion seeds from 

 adjoining untreated lawns, it was found necessary to spray every 

 second or third year, and to supplement the spraying with other con- 

 trol measures. 



The time of application appears to be important. In our tests, the 

 best results were secured when the first application was made in 

 early spring after the central blossom buds were formed, but before 

 blossoming. The first application should be followed by two or three 

 later ones at intervals of three to four weeks during the spring grow- 

 ing season, and one or two others in late summer or fall. The last 

 application should be made late enough in the summer or fall to 

 prevent the plants from recovering before the close of the growing 

 season. 



A suitable day for spraying is one on which there is little wind and 

 slight probability of rain for several hours. The sky may be either 

 cloudy or clear. A heavy dew the following night is advantageous. 

 Spraying should be discontinued during periods of drought in mid- 

 summer, when the grass is inactive and soil is very dry. Serious 

 injury to the grass may result from spraying at such times. As far 

 as possible, it should be arranged to spray two or three days after 

 mowing and to mow two or three days after spraying. 



STRENGTH AND QUANTITY OF SOLUTION, AND MANNER OF APPLICATION. 



The spray solution is prepared by dissolving one and one-half 

 or two pounds of iron sulfate (also called copperas and green vitriol) 



