39 



to supplement it with a more extensive trial on larger areas with a 

 power sprayer. Accordingly, six areas of the Station lawn located 

 between walks, drives and buildings, and which were badly infested 

 with dandelions were sprayed four times during the season with 

 iron sulfate solution. At each application 300 pounds of the sulfate 

 were used in 200 gallons of water, and applied with a power orchard 

 sprayer equipped with a single lead of hose 80 feet long, a six-foot 

 spray-pole and a nozzle of the Mistry Junior type. With this outfit 

 the pressure was maintained at about 200 pounds, thereby making 

 it possible to apply the solution in the form of a fine, mist-like spray. 

 The long lead of hose and spray pole enabled the operator to reach 

 all parts of the lawn and to do the work thoroly and rapidly. 



Four applications of the solution were made, on May 14, June 4, 

 June 28 and July 26. Owing to the fact that the power sprayer 

 was no longer available for this work, the spraying was discontinued 

 in July after the fourth application. Judging from the results ob- 

 tained in the smaller experiments, later applications would have 

 been desirable and undoubtedly would have increased the effective- 

 ness of the treatment. 



The results obtained from the use of the power outfit were similar 

 to those obtained with hand sprayers. The grass was somewhat 

 blackened after each application. The dandelion foliage was quite 

 effectively killed, altho a large number of plants recovered after 

 each application and made a growth of leaves three to four inches 

 long before the next application was made. 



Shortly following the first application there was a marked contrast 

 in appearance between the sprayed lawns and some unsprayed lawns 

 nearby. On the unsprayed lawns countless dandelions blossomed 

 and formed seeds which were scattered widely by the wind. The 

 sprayed lawns showed practically no blossoming dandelions and only 

 an occasional large plant still living. Following the fourth spraying, 

 made July 26, and at a time when the lawn soil was comparatively 

 dry, the lawn grasses were badly blackened, and in some places 

 severely injured. This injury to the grass is believed to have been 

 due partly to the dry condition of the soil, and partly to the influence 

 of the light shower which fell during the evening of the day the solu- 

 tion was applied. This experience confirms a previous conclusion, 

 namely, that lawns should not be sprayed with iron sulfate during 

 the hot dry weather of July and August when the lawn soil is dry. 



