INJURY BY DISINFECTANTS TO SEEDS AND BOOTS. 5 



Acid was also used after germination on seed beds of western 

 yellow pine. In the first test the percentage of the seedlings which 

 died during the first 33 days after germination was determined for 

 four plats, as follows: 



Plat VIII-A. — On the twelfth, day after germination, 0.086 ounce of acid in 128 

 volumes of water; repeated on the fourteenth and nineteenth days. Loss, 72 per cent. 



Plat VIII. — Same acid treatment as VIII-A, but sprinkled lightly with water after 

 each application. Loss, 33 per cent. 



Plat 27. — On the sixth and sixteenth days after germination, 0.086 ounces of acid; 

 12, 14, and 19 days after germination, 0.043 ounce of acid; solution in 256 volumes of 

 water. Loss, 21 per cent. 



Plat 28. — No treatment. Loss, 23 per cent. 



While the loss in plat 27 was slightly less than that in the untreated 

 plat there is clear evidence that the acid killed the seedlings, as the 

 parasitic loss in this plat was very much less than in the untreated 

 plat. 



The treatments on Plats VIII and VIII-A were practically dupli- 

 cated on a seed bed 13 days younger, with the result that the losses 

 for the first 20 days were 45 and 47 per cent, respectively, as com- 

 pared with 16 per cent in the nearest check. 



Further tests of sulphuric acid on germinating yellow pine were 

 made during the two following seasons. In the first case, acid in 

 256 volumes of water was tested on beds which had received 0.188 

 ounce of formalin per square foot 40 days before sowing, a treat- 

 ment which in itself had no appreciable influence. The results were 

 as follows: 



Plat 402-S. — Seven and again twenty-five days after germination, 0. 125 ounce of 

 acid. Germination, 64 per cent; loss after germination, 44 per cent. 



Plat 402-N. — Seven days after germination, 0.125 ounce of acid. Germination, 51 

 per cent; loss, 30 per cent. 



Check plat. — No acid. Germination, 68 per cent; loss, 62 per cent. 



In this series, the effect of the acid was clearly to prevent the 

 appearance of the latest germinating seedlings and to kill the young- 

 est seedlings which had already broken through the soil. The heavier 

 loss in the untreated plats is due to heavy parasitism, which the 

 acid treatment almost entirely prevented. 



The following season, using a solution of one part in 256 volumes 

 of water, the following amounts of acid were applied to yellow-pine 

 plats: 0.047 ounce per square foot on two plats three days after ger- 

 mination ; the same amount on two other plats six days after germi- 

 nation; and 0.063 ounce on three plats seven days after germination. 

 No noticeable injury occurred, though counts of the seedlings indicate 

 that a few were probably killed by the acid. 



Most or all of the injury caused by applications after the begin- 

 ning of germination was due to injury to the roots. The light sprin- 

 kling with water just after acid applications, which in a number of 



