32 , INDIAN FOREST MEMOIRS. 



one it has replaced. Yet even in agriculture the impossibility of adopting effective direct 

 remedial measures is leading more and more to the adoption of such indirect methods as 

 the production of new and resistant varieties. Measures such as these, however, are 

 obviously out of place in practical forestry ; the forester, as a rule, must take his species as 

 he finds them in nature and if he wants to favour their healthy growth and development he 

 must keep as closely as possible to those conditions under which they grow best in nature 

 and under the influence of which the species have been gradually evolved. 



Moreover to carefully study the requirements and patiently elaborate the economic 

 treatment of our indigenous species, which we know to be suited to the local conditions of 

 environment, is surely, as a rule, a more rational policy for practical forestry than to try 

 haphazard experiments with exotics on which money has frequently been lavished in the 

 past with little practical result. Such experiments indeed as a general rule merely 

 emphasize the fact that exotics are usually more liable to diseases than are the local species. 

 It is a well-known fact that the most injurious insect and fungal-attacks tend to occur 

 where unnatural conditions of culture have been adopted, such as massing in pure woods 

 species naturally occurring chiefly dn mixed woods, and the adoption of mixed crops (i.e. a 

 return to normal conditions of existence) is one of the most practical preventive measures 

 recommended alike by mycologists and entomologists. There is moreover good reason to 

 believe that the expert mycologist, or entomologist, with his ideas concentrated on his special 

 branch of study, frequently fails to realise the dominant importance of the primary factors 

 of plant physiology. He may thus be led to believe that a particular fungus, or insect, is 

 the primary cause of a diseased state for which in reality the unfavourable condition of 

 some primary factor, such as available soil-moisture, is really responsible, the fungus or 

 insect being merely a secondary factor and the natural consequence of a sickly condition. 

 In such a case the real remedy should consist in attacking the dominant factor and not the 

 fungus or insect. 



In the treatment and prevention of diseases generally the great importance of main- 

 taining the general health and resistant-power of the organism is now usually admitted 

 and this can best be done by studying the effects of those primary factors which we know 

 to be capable of directly causing disease and health. This study is capable of giving us 

 the knowledge necessary to manage our forests in such a way that our valuable species will 

 be exposed to the conditions most favourable for their development in nature. Considera- 

 tions, such as the above are gradually forcing practical Forest Officers to the conclusion that 

 physiology and cecology at present constitute the richest field for research work which aims 

 at improving the economic management of our forests. 



When the post of Forest Botanist was created at the Dehra Dun Forest Research 

 Institute the principal duty prescribed for the incumbent of that post was that of studying 

 the diseases of our important forest species. With the object of attaining the most valu- 

 able results in this direction, for the reasons briefly outlined above, the Botanist undertook 

 the systematic study of the physiology and cecology of forest plants and has commenced 



[ 32 ]. 



