46 A NATIONAL PLAN FOR AMERICAN FORESTRY 



PROTECTION AGAINST FOREST INSECTS 



Insects cause losses in forest stands and in forest products estimated 

 at over $100,000,000 annually. They lower timber yields and retard 

 the growth of young stands. Frequently they change the composi- 

 tion of the forest to such an extent as to necessitate complete reshaping 

 of management plans. They create serious forest-fire hazards. They 

 damage or destroy finished wood products. 



A well-organized detection and control system is essential to detect 

 outbreaks of native insects in their early stages. The failure of some 

 control projects has resulted from tardiness in recognizing an active 

 infestation or from lack of complete information as to its virulence 

 and extent. Costs in time and money are greatly increased unless 

 control is begun promptly. Regional forest-insect surveys on a 

 cooperative basis have been organized to meet needs but these have 

 not been carried to the point where forests can be zoned according to 

 susceptibility to insect infestation and the values that would be 

 endangered by insect attack. 



The cost to public agencies of a general detection and control 

 system and of special control operations is estimated at $2,750,000 

 annually. This does not include needed private expenditures. 

 Serious epidemics would require special provisions. 



PROTECTION AGAINST FOREST DISEASES 



Each of the many valuable tree species of the United States is 

 subject to attack by one or more species of parasitic plants. Some 

 of the great number are capable of killing trees, others merely injure 

 them or destroy the wood they produce, and others retard their 

 growth. Some attack the germinating seedling, others the mature 

 tree. To identify the many different diseases that attack trees, to 

 determine the cause of their spread or the conditions or management 

 practices that affect it, and to ascertain what strains or varieties are 

 resistant to them for even the 25 most important timber species, at 

 the rate possible to the present force of investigators, would require 

 not less than half a century. 



Except for research, the outstanding need of forest pathology is a 

 control service which will act in both a control and an advisory 

 capacity. 



The control campaigns now under way, particularly on the white 

 pine blister rust in the East, and on the white and sugar pine forests 

 of Idaho and California, should be carried to completion. 



Measures for the control of forest diseases are mainly but not all 

 indirect, consisting principally in modification of forest management. 

 Actual disease-control work on private land can largely be handled 

 by the owners of the land. Effective methods must, however, be 

 based on a comprehensive knowledge of the influence of soil, climatic, 

 and other factors on both the parasite and the host. 



The dissemination of the knowledge which is available in several 

 organizations including the Division of Blister Rust Control of the 

 Bureau of Plant Industry requires an organization of experts. It 

 would seem logical to expand the scope of this Division to include 

 other forest-tree diseases. 



Quarantines now established should be strengthened to prevent the 

 introduction of further diseases, and interstate shipments, particu- 



