722 CONNECTICUT EXPERIMENT STATION REPORT, 



oaks in certain regions entirely killed by the frosts, just as had 

 been the case with the leaves of sycamore trees in 1907. In 

 1910, however, the frosts were much more local in their effects, 

 and in a given region often killed the leaves only on the lower 

 trees and the shrubs, especially those in low places. Shortly 

 after the last of these frosts we visited the white pine planta- 

 tions on the Whittemore estate at Middlebury, and here we 

 found not only small oaks and other trees in low spots with 

 injured foliage, but also the young pines in these low places 

 showed "blight" injury on the tips of their leaves. Often a 

 difference of only a few feet in the level of the ground on 

 which these stood determined whether or not they were injured. 

 We have also noted elsewhere in this Report injury by these 

 frosts to pine seedlings in the seed beds. Whether or not a 

 pine tree is injured by the late frosts seems to be determined 

 by the state of development of the foliage at the time, as well 

 as by the lay of the land and the character of the frost. 

 Previous to 1907 we had some few complaints of pine "blight," 

 which we may attribute to winter injury of the roots, and no 

 doubt drought or other injury to the roots, if severe, produces 

 a similar effect. Hartig, in his Diseases of Trees, English ed., 

 p. in, notes a similar "blight" trouble in Europe, due to frost 

 and drought injury. 



PLUM, Prunus sp. 



BACTERIAL SPOT, Pseudomonas Pruni Sm. This has been 

 reported here before on peach, causing spots on the leaves, and 

 on the plum, causing large black spots on the fruit. In July, 

 1910, it was seen at the Ives farm, Meriden, for the first time 

 causing a shot-hole spotting of plum leaves, similar to that 

 not uncommon on the peach. 



SPRUCE, NORWAY, Picea excelsa. 



Smoke Injury. During the summer of 1910 the writer saw 

 young spruce trees at East Rock Park, New Haven, that had 

 been injured by smoke from a brick kiln about half a mile 

 distant. The injury occurred suddenly on a day when the atmos- 

 pheric conditions were just right for blowing the smoke among 

 the trees. The young leaves of this year were killed and sub- 

 sequently dropped off, but those of the previous year were 



