34 Disease and Death of Trees — Generalities 



keeping trees in \igorous 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 indinduals 

 of the same species are adapted to the special features of 

 their nearer surroundings of local chmate as well as of soil, 

 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 Pacific 

 Coast conifers, grown from seed derived from the mild, moist 

 chmate 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 faU foUows 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. 



IMechanical injuries, by which the truly li\ing parts are 

 exposed to the air, are perhaps the most prohfic cause of 

 trouble and disease. 



