426 



Yearbook, of Agriculture 1949 



To view the problem in perspective, 

 one might well review some of the fac- 

 tors that have brought about the pres- 

 ent condition of the spruce-fir forests. 



Because spruce is far more valuable 

 for lumber and pulp than balsam fir, it 

 has been cut more heavily in logging 

 and pulpwood operations and its pro- 

 portion in the forests has thus been re- 

 duced. Balsam is far more aggressive 

 than spruce in seeding-in after a cut- 

 ting operation, fire, or wind damage. 

 Foresters repeatedly have observed that 

 after a serious budworm outbreak the 

 succeeding stand invariably contains a 

 higher proportion of balsam. Man's ac- 

 tivity and the spruce budworm, there- 

 fore, have often contributed to a grad- 

 ual conversion from a forest containing 

 a high percentage of spruce to one in 

 which balsam predominates and which 

 is far more favorable for the budworm. 



In view of such points, then, what 

 can be done through silvicultural prac- 

 tices to increase the resistance of the 

 forest to spruce budworm attack? 



There appear to be three general 

 procedures: To clear cut mature and 

 over-mature balsam stands; to operate 

 balsam stands on a short rotation; to 

 try to increase the proportion of spruce 

 in the stand. 



The first and second would be aimed 

 at keeping existing stands of fir as 

 young and vigorous as possible. Mature 

 and overmature balsam fir trees suffer 

 most during an outbreak. It is not be- 

 cause their foliage is more palatable to 

 budworm caterpillars than the leaves 

 of more vigorous trees, but because 

 they are low in vigor and cannot sur- 

 vive severe defoliation. The clear cut- 

 ting of such stands should be given first 

 priority in a plan of action. 



In a long-range program to build up 

 the resistance to future budworm out- 

 breaks, consideration needs to be given 

 to two major types of stands, those that 

 are predominantly balsam fir and those 

 that contain an appreciable proportion 

 of spruce. 



In a stand that is mostly balsam, cut- 

 ting on a rotation of 30 or preferably 20 

 years will help to maintain the stand in 



a condition of high vigor. Such a stand 

 may harbor a heavy population of bud- 

 worms, but it will suffer much less than 

 a stand of low vigor. The operation of 

 such a stand on short rotation will at 

 the same time greatly increase the ulti- 

 mate yield. 



Where spruce occupies an appre- 

 ciable proportion of the stand, every 

 effort should be made through cutting 

 operations to increase the proportion of 

 spruce and at the same time save only 

 the balsam firs that are very vigorous. 



In order to demonstrate these cut- 

 ting methods, experimental areas are 

 being established jointly by the Forest 

 Service, the Bureau of Entomology and 

 Plant Quarantine, the States, and the 

 owners of timberland in the Northeast. 

 The areas are cruised and marked by 

 the Federal agencies and operated by 

 industry. They are located in several 

 parts of the region, so that the influ- 

 ences and different site and stand con- 

 ditions can be observed. 



In these silvicultural operations, the 

 latest findings from the biological stud- 

 ies are put into practice. We hope that 

 the experimental areas will become a 

 pattern for future commercial opera- 

 tions so that resistant forests eventu- 

 ally will be established all over the 

 Northeast. 



IN SUM, then, we know that each 

 new epidemic is far more disastrous 

 than the last, and that now the spruce- 

 fir resources of this country and Can- 

 ada are in jeopardy. 



Aerial applications of insecticides 

 offer new possibilities for controlling 

 defoliators like the spruce budworm; 

 further attempts to control the insect 

 over extensive areas by aerial spraying 

 are now in progress and will be con- 

 tinued during the present outbreak. 



But all studies and observations by 

 entomologists and foresters suggest that 

 the ultimate solution lies in managing 

 the forest so as to maintain high vigor 

 in balsam fir stands and, where con- 

 ditions permit, to increase the propor- 

 tion of spruce. Every effort should be 

 made to obtain the basic biological 



