SUGAR PliSTE. 7 



Since slash from cuttings or natural damage, such as mndf all or 

 snowbreak, furnishes excellent breeding ground for destructive insects 

 and materially increases the fhe danger, such refuse should be dis- 

 posed of by fire whenever possible before the spring following the 

 cutting or other occurrence. 



These insects are normally kept in check by woodpeckers, certain 

 predaceous and parasitic insects, and certain fungi. When, however, 

 an infestation by the mountain-pine beetle commences to increase 

 rapidly it can be controlled only by peehng the infested portions of 

 the principal groups of affected trees during the fall or early spring 

 before the beetles emerge. It is usually necessary as a precaution 

 against fire to dispose of the resulting slash by burning at a safe time. 

 These control measures, as conducted by the Forest Service, have cost 

 from $2.50 to $5 per tree, according to conditions. For each tree cut 

 in control work it seems evident from statistics that one is saved. 

 Since an average sugar pine tree is worth at least $15 on the stump, 

 the saving is worth making.^ 



SILVICAL REQUIREMENTS. 



MOISTURE AND SOIL. 



The most essential requisite for the rapid development of sugar 

 pine throughout all stages of its life history, but particularly during 

 the seedling and sapling periods, is moisture in both soil and air. 

 Lacking this, it becomes stunted, maKormed, and useless as a tim- 

 ber tree. It is generally found on cool northerly slopes and in 

 ravines where the humidity is highest. 



Though sugar pine occurs on a variety of soils, from glacial drift 

 and volcanic ash to deep, loose sands and clays, its maximum devel- 

 opment is reached only on comparatively moist, loose, deep sandy 

 loam. Its presence is unusual on hot, dry slopes as well as on poorly 

 drained wet soils. The chemical composition of the soil apparently 

 has but little bearing on its distribution. 



TliG relative soil and moisture requirements of this species are 

 indicated by the following list, in which the more exacting species 

 precede the less exacting: 



Soil. Moisture. 



Dou^la« fir. Red fir. 



While fir. Suoau Pine. 



Rod fir. DouLda.s fir. 



SuoAK Pine. While, fir. 



Incense cedar. Incei)s<> cedar. 



Yellow pine. Yellow pine. 



Jeifrey pino. Jeffrey pine. 



> For farther details regarding control measures, see pag«w 87-S9 of Bureau of Entomology nulletin 83, 

 Part I. 



