SUGAR PINE. 5 



Since extremely low temperatures do not occur very often in the 

 sugar pine belt, frost injuries are infrequent. Sapling and pole 

 stands are occasionally injured by the wet snows of early winter, 

 but sugar pine suffers less than yellow pine. 



Breakage caused by lightning, winds, or wet snow is serious, not so 

 much in itself, as because it opens the way to attack b}^ insects. Not 

 infrequently such damage gives rise to epidemic insect infestations. 



STOCK, ROBENTS, AND BIRDS. 



Under regulated grazing the damage to young trees by cattle and 

 horses is almost negligible. Sheep and goats, particularly goats, how- 

 ever, do appreciable damage by tramping down and nipping the 

 leaders of young seedlings and saplings. Such stock should not be 

 close-herded on areas of promising young forest, and should be 

 moved frequently. They should be excluded from cut-over areas 

 until reproduction is well started. 



Each year the red or Douglas squirrel and the gray squirrel cut 

 large quantities of cones, often while still unripe, and consume or 

 store the edible seed. Other smaller rodents, as well as quail and 

 jays, rehsh it also. The gray squirrel is so destructive to the seed 

 of this species as to cast doubt upon the wisdom of according him 

 the protection of the game laws in heavily forested counties. Wood 

 rats and rabbits are destructive in young sugar pine plantations, 

 sometimes cutting back every tree to the surface of the ground. 



DISEASES. 1 



Sugar pine is without doubt one of the healthiest of our coniferous 

 trees. Even the younger parts, such as the twigs and needles, are 

 rarely attacked by the ordinary enemies of associated tree species, 

 such as mistletoe {RazovmofsJcya cryptoj)oda), which frequently causes 

 the formation of heavy witches' brooms and gnarls the branches of the 

 yellow, Jeffrey, and lodgepole pine. A small bluish witches' broom, 

 caused either by a parasitic fungus, or more probably, a mite, and 

 resembling a spiny ball from 1 inch to 20 inches in diameter, is fairly com- 

 mon throughout the Sierra Nevadas. An unidentified species of Perider- 

 mium, probably P. luir-knessii, is also occasionally found on sugar pine. 

 The damage caused by these diseases is, however, insignificant. The 

 wood-destroying fungi cause more damage, but the loss is rarely more 

 than 3 per cent of the gross board measure content of the stand. The 

 fungi almost invariably attack the heartwood of the older and more valu- 

 able trees; therefore, though the number of trees killed is small, the 

 monetary loss through their work is appreciable. Trarncics pini and 

 Foraes lands are by far the most destructive of the wood-destroying 

 fungi which attack sugar pine. Sporophores of Fomes pinicola have 



' In'iulrles regarding disoaaes of forest trees should be addressed to the iJuroau of Plant Industry, U. S. 

 Department of Agriculture. 



