A NATIONAL PLAN FOR AMERICAN FORESTRY 711 



another, by changes in methods of cultivation, or by expensive 

 methods of direct control, such as spraying the plants. None of 

 these procedures are possible in forests. The ultimate result in 

 agriculture has been more complicated methods of production and 

 increased cost to the consumer. In forests similar invasions of 

 virulent pests are likely to mean the loss of valuable tree species and 

 permanent reduction in forest values. 



As the result of the unfortunate experiences which we have already 

 had, the impression has developed in certain quarters that any for- 

 eign fungus will do more damage than a native fungus of the same 

 type. This impression is incorrect. Most foreign fungi when 

 transferred to a new habitat find that the climate or the lack of the 

 food materials to which they are accustomed makes it difficult for 

 them to exist in competition with the better adapted native organisms. 

 However, a foreign fungus which does find among our tree species 

 one which is a congenial host may do to it exactly what the blight 

 has done to our chestnut, or at least may injure it more than any 

 native fungus could possibly do, because to the foreign fungus the 

 tree lacks the specific resistance which in past ages it has acquired to 

 the native parasites. 



A foreign fungus may attack in a less conspicuous manner than 

 the Chestnut blight and develop more slowly but nevertheless to a 

 sufficient degree to ultimately take most of the profit from the man- 

 agement of the host species. It often happens that the introduced 

 disease is not at first recognized as such. A number of the diseases 

 that are now causing concern in the United States are under the 

 suspicion of having been introduced, but if they have been intro- 

 duced it was so long ago that their history cannot be determined 

 with certainty. Among those that are known or suspected to have 

 been originally introduced are enough different types to illustrate 

 most of the kinds of damage that we have to fear from diseases from 

 other countries. 



The one that first occurs to the minds of everyone familiar with 

 eastern forests is chestnut blight, an importation from Asia. In a 

 period of approximately 40 years since its probable time of entrance 

 is has destroyed one of our half dozen most important hardwood 

 species through the northern two thirds of its range. There is still 

 available a large volume of chestnut saw timber in the southern 

 Appalachians and more widespread utilization of this chestnut lum- 

 ber would assist in conserving our limited stands of other eastern 

 hardwoods. But this southern Appalachian chestnut region is now 

 infected with the blight, which is rapidly advancing and will in time 

 eliminate the American chestnut as a commercial tree. Chestnut, 

 because of its excellent growth even on the poorer soils, its ease of 

 management, the value of its nuts, the high durability of its wood, 

 and consequent usefulness for a number of purposes, was perhaps the 

 most valuable single species of all our hardwoods. It still furnishes 

 over half of our domestic tanning materials, and has the unique fea- 

 ture that the tannic acid is taken from wood which is not wasted 

 but can then be converted into paper. No satisfactory domestic 

 substitute for chestnut tannin has been found. Fortunately chest- 

 nut can be used for tannin production for 20 or more years after the 

 trees are dead. Other species have promptly replaced the chestnut 



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