34 James Stewart Wiant 



beds 98 per cent of the seedlings were destroyed, the greater part of the 

 loss occurring during the first week after emergence began. Treatments 

 with mercuric chloride and Uspulun caused a considerable reduction in 

 damping-off and a marked increase in final stand. So many seedlings were 

 killed by the second application of Germisan that these beds were dis- 

 carded. Bayer compound and sulfuric acid were distinctly less effective in 

 controlling the disease than were the other chemicals. While the experi- 

 ment was carried out on a small scale and under rather artificial conditions, 

 the results indicated that several of the materials were promising for future 

 tests. 



In 1926 a more extensive experiment was conducted with this species 

 at the Keene nursery, solutions of aluminum sulfate, sulfuric acid, and 

 three mercury fungicides, being used. Damping-off did not appear to any 

 appreciable extent until emergence was nearly complete. 



With the exception of the two weakest applications of sulfuric acid, and 

 treatments 12 and 18 with Bayer compound and mercuric chloride, respec- 

 tively, significant differences in percentage of loss after emergence occurred 

 in all cases (table 9). 



Because of the low incidence of disease in the check plats and the varia- 

 tion within any group of replicates, significant differences in final stand 

 between treated and untreated plats did not occur with treatments 2, 5, 

 12, 15, 17, 18, 19, and 20. 



Slight stunting was noted in several plats treated with the strongest 

 sulf uric-acid solution, and in those plats where second applications of 

 mercuric chloride were made. However, observations made at the end of 

 the second growing season failed to reveal any difference in the size or the 

 appearance of the seedlings on treated and untreated plats. Evidently 

 those seedlings surviving the second application of mercuric chloride were 

 not permanently stunted. 



The experiment showed that certain concentrations of all of the fungi- 

 cides were effective in controlling damping-off, even when applied only at 

 seeding time, and that such treatments did not cause chemical injury. 



Three experiments were conducted with liquid treatments on red pine 

 during the season of 1927. Experiment C was sown on April 21 at the 

 rate of 2700 seeds in each plat, while experiments A and B were sown on 

 May 12 and May 16, respectively, at the rate of 1800 seeds. The results 

 for the three experiments are given in table 10. The percentage of emer-. 

 gence was in all cases somewhat higher in the treated plats. In experi- 

 ments A and B, 60.3 per cent and 38.7 per cent, respectively, of the seedlings 

 which emerged in the checks were destroyed by damping-off, while all 

 treatments reduced the disease to a negligible amount. The final stand 

 for all treatments of experiments A and B was very high, and in all cases 

 was significantly greater than that of the check. The differences between 

 the final stands of the several treatments are, however, not significant. 



