30 



BULLETIN 169, U. S. DEPAETMENT OF AGRICULTURE. 



before sowing and did no perceptible damage to pines or pine seed. 

 This was true even in series 508, plat G, in which 0.75 fluid ounce per 

 square foot was applied six days before sowing and evaporation 

 allowed for only three days before sowing. The effect of formalin on 

 the weed stand seemed approximately equivalent to that obtained 

 with one-half or one-third the volume of sulphuric acid. As the 

 weight of H 2 S0 4 per fluid ounce of acid used was at least four times 

 as great as the weight of HCHO in the formalin, the formaldehyde 

 appears rather more effective, weight for weight, in keeping down 

 weeds. The radical difference in the type of action of the formalin 

 against the pines renders impossible any direct comparison with acid. 



LIME-SULPHUR SOLUTION. 



The results in series 519, plats R and S (Table VI), are contra- 

 dictory. Injury to pines from fairly heavy applications of lime-sulphur 

 at the time of sowing can probably be prevented by sufficient water- 

 ing during the germination period. The injury to weeds occurred 

 despite heavy watering. 



EXPERIMENTS AT MORRISVILLE, PA. 



During the season of 1912, in pursuance of recommendations by 

 the writer, tests with sulphuric acid were conducted by Mr. R. E. 

 Lee, under the direction of Mr. John Foley, forester of the Pennsyl- 

 vania Railroad, at the nursery near Morrisville, Pa. Sulphuric acid 

 only was used. All treatments tested resulted in a decreased stand. 

 The results of very weak treatments on beds given ordinary nursery 

 watering are shown in Table VII. 



Table VII. 



-Evidence of injury to pines by sulphuric acid applied at the time of sowing, 

 Morrisville, Pa. 



Plat. 



Num- 

 ber of 

 plats 

 aver- 

 aged. 



Species. 



Sowing 

 to germi- 

 nation. 



Acid per 



square 



foot. 



"Watering. 



Final 

 stand, 

 taking 

 average 

 of checks 

 as 100. 



Decrease 

 in stand 

 appar- 

 ently 

 due to 

 acid. 



Series 631.. 



! \ 



16 

 21 



7 

 17 



7 

 14 



1 



1 

 1 

 1 



1 

 1 



Pinus ponderosa 



do 



Days. 



6 to 9 



6 to 9 



6 to 9 



9 to 10 



16 to 21 



7 



9 to 12 



11 



8 to 10 



Fluid oz. 

 0.031 

 .042 

 .083 

 .083 

 .083 

 .083 

 .083 

 .083 

 .083 



.188 



.25 



.375 



.188 



.25 



.375 



Only as in ordi- 

 • nary nursery 

 practice. 



0.15 inch, twice 

 daily. 



( 91 

 95 

 90 

 55 

 27 

 74 

 63 

 56 

 62 



34 

 26 

 4 

 [ 83 

 53 

 45 



Per cent. 

 9 

 5 





do 



10 



Series 632.. 

 Series 633.. 

 Series 634.. 



Pinus resinosa 



Pinus strobus 



Pinus sylvestris. 

 do 



45 

 73 

 26 

 37 



Series 636.. 

 Series 637 . . 

 Series 638: 

 A 



Picea excelsa 



Pinus sylvestris 



do 



44 

 38 



66 



D 



do 





74 



c 



do 





96 



G 



do 





17 



F 



do 





47 



J 



do 





55 













