CHESTNUT BARK DISEASE. 391 
renewal. The enfeebled condition of the chestnut trees and 
their consequent susceptibility to the blight may possibly be 
related to some lessened chemical activity in the bark and newly- 
formed wood, such as the production of tannic acid, for instance. 
If so, then when this has returned to its normal production 
through favorable weather conditions, the blight should gradu- 
ally become correspondingly less aggressive. Under the follow- 
ing heads we shall take up more in detail our ideas of the 
relationship between weakened vitality of the chestnut and 
consequent susceptibility to the blight. 
Winter Injury. We have in a previous Station Report (6) 
called attention to the results of winter injury on fruit and 
other trees in Connecticut. We shall attempt here to show also 
that these conditions were not confined to this state. In Decem- 
ber, 1902, following a very open fall, the temperature suddenly 
fell below zero, with the result that many trees, especially 
young fruit trees which had not properly matured their wood, 
were severely injured or killed outright. The following winter 
of 1903-04 was so unusually severe that thousands of fruit 
trees in Connecticut, especially those situated in the valleys 
and on the lower slopes, were killed, and others so severely 
injured as to develop physiological troubles for some time 
afterward. The injuries caused by these two winters were most 
noticeable in the region along the Sound, in the valleys or on 
the lower hill slopes, and along the river courses, regions in 
which the chestnut blight afterward first appeared, and in which 
it has caused the most damage. The winters of 1906-07 and 
1907-08 also caused considerable winter injury. 
Although we did not at the time directly study the effect on 
the forest trees of these winters, especially that of 1903-04, 
which was the most severe, we do know from subsequent 
observations that many trees were injured. In the summer of 
1904 we examined a young fruit orchard, at Stamford, whose 
wood had been largely killed by winter injury; and two or 
three years later in examining chestnuts from this region, 
where: the blight has been the most severe, we could see indi- 
cations of winter injury to the wood of the chestnut sprouts 
dating back to the winter of 1903-04. In the winter of 1910, 
in examining chestnut at Middlebury, where the blight was 
just coming into prominence, we found quite a- number of 
