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 



