720 CONNECTICUT EXPERIMENT STATION REPORT, 1909-1910. 



Very similar results were obtained when either of these insecti- 

 cides was used with "Sulfocide." This spray, even when used 

 without them, at a rate of I to 200 produced more or less injury, 

 and even some on young trees at I to 400. With both potassium 

 sulphide and "Sulfocide" the injury resulting from the addition 

 of the poisons was due to the production of a soluble arsenate 

 which burned the tissues. 



PINE, WHITE, Pinus Strobus. 



So-called "Blight" In our "Report for 1907, page 353, we 

 described the white pine ' 'blight," which was general that year 

 not only in Connecticut but all over New England. We took 

 the view that it was a physiological trouble due to adverse 

 weather conditions (such as winter, drought, and frost injuries), 

 though there were those who believed that it was of a contagious 

 nature, due to fungous attack. We now have data at hand 

 to prove that we were correct. In general this disease becomes 

 evident by the leaves being killed to a greater or less extent 

 from their tip downward, the dead portion turning reddish 

 brown, and also by the undersized leaves, which remain bunched, 

 due to the failure of the branches to lengthen out. 



That the disease is not contagious was suggested strongly in 

 our previous studies, since leaves on one tree may all be badly 

 affected while those of an adjacent tree show no signs of the 

 trouble. This noncontagious nature has been clearly proved by 

 observations made in the station's forest plantation on a lot of 

 white pine trees eight years old, in 1910, from planting. At 

 our request the forester, Mr. Hawes, early in the spring of 

 1908 had all the diseased trees of this plot marked by permanent 

 stakes. There were one hundred and twenty-four of these so 

 marked, but it seems quite likely that some few that showed 

 the disease slightly at the time were not included. We examined 

 them that fall, and found that their condition on the whole 

 seemed somewhat improved, and that there was no general 

 increase of the trouble, though some trees that had not been 

 marked showed signs of the disease. In July, 1909, and again 

 in November, 1910, careful examinations were made of the 

 plot, and the condition of each diseased tree noted. The com- 

 parative condition of these trees as regards foliage is shown 

 in the following table: 



