36 



in the turf were several inches in diameter (Plate V). It was because 

 of the presence of these weeds and the few remaining dandelions 

 that these two plats were again combined and " sprayed off " four 

 times during the season with the iron sulfate solution, using one and 

 one-half pounds of sulfate to each gallon of water. No attempt 

 was made to spray the entire area of the two plats, only the dandelion 

 plants and other weeds being sprayed. The usual blackening of 

 of the grass followed each spraying, but disappeared after a short 

 time. However, this " spraying off " method has the disadvantage 

 of leaving the lawn streaked or spotted with black for a few days 

 (See Plate VI). At the time of the third spraying (July 10) it was 

 noted that all of the old dandelions had been killed; but quite a 

 number of young plants were appearing just within the border 

 of the plats. Nearly all of these young plants were within three 

 feet of the border of the sprayed plats, and apparently came from 

 seeds of dandelion plants in the unsprayed lawn adjoining. Follow- 

 ing the third spraying, in July, it was observed that because of favor- 

 able weather conditions the spray solution was particularly effective 

 in killing the foliage of the weeds. All of the dandelion and narrow- 

 leaved plantain foliage was killed. The foliage of broad-leaved 

 plantain was badly injured. The patch of cranesbill or wild geranium 

 located in Plat 3, also showed serious foliage injury. 



During the latter part of the season rains were frequent, causing 

 a vigorous growth of grass, and also forcing the growth of a 

 number of seedling dandelion plants in the sprayed area. The 

 sprayed area, with its darker green grass, presented a much more 

 even and pleasing appearance than did the adjoining unsprayed 

 lawn where the dandelion plants were very thick. 



AFTER-TREATMENT OR RENOVATION MEASURES ON PLATS 2 AND 3. 



Methods of renovation or after-treatment were started on April 4. 

 Plats 2 and 3 were divided crosswise into four sections or areas 

 each 25 x 30 feet. The following diagram shows the location and 

 treatment accorded each section. 



Section A was retained as a check. No treatment. 



Section B was treated with 40 pounds of a complete fertilizer 

 having a composition of 3-10-12. 



Section C was treated with 50 pounds of ground limestone. 



