34 Disease and Death of Trees — Generalities 
keeping trees in vigorous constitution and of avoiding physio- 
logical diseases. 
Not only are certain species adapted to certain climatic 
conditions and hence may not be transferred into a different 
locality with assurance of success, but even the individuals 
of the same species are adapted to the special features of 
their nearer surroundings of local climate as well as of soll, 
and resent change, or at least must re-adapt themselves if 
moved into new surroundings. To some extent, even the seed 
itself inherits this adaptation; hence the young plants of Pacufic 
Coast conifers, grown from seed derived from the mild, moist 
climate of their habitat, may suffer from frost and drouth in the 
Eastern States, while plants of the same species, derived from 
the rigorous, dry, alpine climate of Colorado, will be hardy. 
In transplanted trees this difference in derivation of the 
plants and the difficulty of adaptation may sometimes 
account for their ailing condition, and may result in their 
death. ' 
The seasons will naturally influence the condition and 
disposition to disease of the tree: a period of drouth, for 
instance, may kill feeding roots, leaves and branches, and 
at the same time open the door for fungi to enter; a period 
of wet, rainy and cloudy weather may have the same effect, 
by depriving roots and leaves of their respiration; a severe 
cold spell in the spring may kill foliage and twigs, and espe- 
cially “kill back”? immature young wood of the previous 
season, such as forms when a moist fall follows a dry sum- 
mer. Attacks of fungi may or may not be of moment accord- 
ing to the season and the condition in which the tree is 
found by these parasites. 
Mechanical injuries, by which the truly living parts are 
exposed to the air, are perhaps the most prolific cause of 
trouble and disease. 
