30 



BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 



Not 



treated. 



Treatment 

 No. 1. 



Treatment 

 No. 2. 



are put away at the close of work. A coating of linseed oil, very 

 thoroughly dried, should also prevent the charring of wood. Acid 

 which gets on the hands does no harm if washed off at once with water. 

 In applying treatments on a large scale the sprinklers used should 

 have the holes in the rose or sprinkler head enlarged, to permit 

 faster work. 



In trying out the treatments in the foregoing lists, Nos. 1 and 2, 

 the most promising, should be tested first. If both fail, the other 

 treatments should be tried. If the acid solutions 

 cause the soil to effervesce, some of the other treat- 

 ments should be tried at once, as on such a soil the 

 acid is likely to fail. 



The treatments should be applied to small plats 

 which are intermingled with untreated plats for com- 

 parison. For test plats, 3 by 4 feet has been found a 

 convenient size. Good results can be obtained with 

 even smaller areas than this, but all plats should be 

 at least 2 feet wide. An arrangement of plats which 

 the writers have found satisfactory is shown in figure 1 . 

 The seed for each plat, treated and untreated, should 

 be measured out separately, so that all plats will get 

 equal quantities of seed. Then the number of seed- 

 lings living on each plat at the end of the season will 

 show which treatment is most valuable. In watering, 

 shading, and in every other way treated plats should 

 be handled just like the untreated beds, to make the 

 test a fair one. 



As soon as the seedlings begin to drop their seed 

 coats, plats treated with acid, copper sulphate, or zinc 

 chlorid should be examined for chemical injury to the 

 roots of the seedlings. 1 If such chemical injury is 

 found to occur, two courses will be open: (1) To test 

 the same treatment again, watering the treated plats 

 thoroughly every day from sowing till germination 

 is complete; or, (2) to abandon the treatment which 

 caused injury and try to get sufficient control of the 

 disease by a weaker treatment or by another dis- 

 infectant. Treatments 6, 7, and 8 are inserted especially for use at 

 places where acid causes injury and where frequent watering is not 

 practicable; they are reasonably certain not to cause injury to seed- 

 lings under any circumstances. 



Not 



treated. 



Treatment 

 No. 3. 



I 



Treatment 

 No. 4. 



' 



Not 

 treated . 



Fig. 1.— Suggested 

 arrangement of test 

 plats. 



i The method of detecting chemical injury and illustrations of injured and uninjured seedlings have 

 been given in a previous publication: Hartley, Carl. Injury by disinfectants to seeds and roots in sandy 

 soils. U. S. Dept. Agr. Bui. 169, p. 9, pi. 1. 1915. This bulletin can be obtained by sending 5 cents in 

 coin to the Superintendent of Documents, Government Printing Office, Washington, D. C 



