304 Report of the Botanical Department of the 



the bark at the region of severest injury, and the barl<; was loosened 

 on the windward and sometimes also on the leeward side as shown on 

 Plate VII. The wood was not cleft, and sometimes only the periderm 

 and outer cortex were cleft and loosened. The trees had not been 

 injured in extreme cold weather, because during that winter the 

 injury occurred before the middle of January. However, the cases 

 observed near Glens Falls were slightly different in that the injury 

 involved a longer portion of the trunks and was sometimes confined 

 to the region nearly midway between the ground and first crotches, 

 as shown in figure B on Plate XIV. It seems as though the bending 

 might have occurred higher up or over a greater length than it did 

 in the western part of the State, possibly due to the frozen condition 

 of the trees and ground at the time of injury. Since the location of 

 the region of maximal bark-tension may determine the place of injury, 

 it appears possible that the tensions were more widely distributed 

 in this case. 



When a late summer drought retards bark growth or its complete 

 adjustment to the increased circumference of the new wood produced 

 in early summer, smooth bark may not only have a high transverse 

 tension when the winter or dormant season begins but its lenticels 

 may also be in such a state of incompleteness as to permit excessive 

 evaporation throughout the following winter, and especially during 

 a windy winter thaw. The bark on trees in wet situations may be 

 in a similar condition on the approach of the dormant season, owing 

 to -abnormally late growth of wood in mid-summer. In view of 

 Bernbeck's observations and experiments which show that the bend- 

 ing of twigs and branches by the wind results in excessive loss of 

 water and consequent injuries on the windward side of shoots, it is 

 very likely that imperfect lenticels and a high bark tension increase 

 the liability to such injuries. The type of bark injuries which oc- 

 curred on smooth-barked, thrifty pear trees in the winter of 1910-11, 

 and which resulted in much blackened bark on the west side of trees 

 as described above for some Medina orchards, seems to be of this 

 type. During the winter of 1909-10 a similar though less extensive 

 injury developed on the south side of young pear, apple, plum and 

 cherry tree trunks and ascending branches in the western part of 

 this State; while in the Hudson B.iver Valley about Poughkeepsie 

 and Milton, the injury occurred on the north side of trees during the 

 same winter. In the winter of 1909-10 as well as in that of 1910-11, 

 partial or complete winter thaws occurred during strong winds. In 

 the former the wind was very high from the south during several days 

 of open weather in late winter in the western part of the State, and 

 in the latter the wind was from the west in the same region during a 

 January thaw. Such injuries are usually called " sun-scald " and 

 are attributed to an injuriously high temperature induced in such 

 bark by the sun, but since the injuries may also occur on the north 



