4 BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 



viridis x were also more or less common. The nurserymen pulled up 

 most of the weeds before flowering, so that it was not possible to 

 determine positively the relative frequency of the different grass 

 species for each plat. The commonest dicotyledons were MoUugo 

 verticiUata, 1 Poriulaca oleracea, 1 Amamnthus retroflexus, 1 A. Tiyoridus, 1 

 A. graecizans, 1 A. blitoides, 1 and Euphorbia glyptosperma. 1 



INJURY TO PINES BY SULPHURIC ACTD APPLIED AT OR AFTER GERMINATION. 



In the following cases sulphuric acid was applied to the beds after 

 some pine seedlings had come up. Because of the great irregularity 

 of germination in many beds the time of germination can be given 

 only approximately. It represents as far as possible the date by 

 which enough seedlings had appeared to constitute a fair stand. 

 Most of the experimental plats were sown with jack pine. The 

 results with this species appear in Table II. 



Table II. — Effect of sulphuric acid on seedlings of jack pine, at Halsey, Nebr. 



Num- 

 ber of 

 plats 

 treated. 



Time of treatment. 



Fluid 

 ounce of 

 acid per 



square 



foot. 



Volumes 

 of water. 



Result. 







0.172 

 .086 

 .086 

 .043 

 .043 

 .043 

 .086 

 .043 

 .043 

 .086 

 .043 

 .043 

 .021 

 .021 

 .011 

 .011 

 None. 



| 128 



I 2-56 

 128 



I 256 



| 512 

 | 1, 024 





4 





All killed. 















2 





Nearly all killed. 









4 





if any killed. 





f....do .". 









4 





f More killed than in preceding 

 \ experiment. 



















2 





Germination, 11.8 per cent. 









2 





Germination, 13.8 per cent. 



2 















Half of the plats in Table II which were given the stronger solu- 

 tions were sprinkled lightly with water immediately after each treat- 

 ment. This watering had no evident effect in the plats treated with 

 the 128-volume solution, but in four plats which received the 256- 

 volume solution, followed by sprinkling, the stand of seedlings was 

 more than twice as great as on four adjacent plats which were given 

 the acid treatment only. 



The results in the plats treated with the 51 2- volume solution 

 indicate that a total of 0.043 ounce of acid per square foot applied 

 before germination was complete was sufficient to prevent the appear- 

 ance of some of the latest germinating seedlings, while 0.021 ounce 

 in two applications had little or no effect. Further tests would be 

 necessary to prove that injury can be caused by these very weak 

 treatments. 



1 Determinations made by Mr. P. L. Ricker. 



