420 SYLVICULTURE NOTES ON TIMBER TREES 



Average returns from pure crops in even-aged high forest 

 should be, in cubic feet, per acre : 



Thinnings . . . 1000 cub. ft. to 2 in. q. g. 

 Final yield (at 80 years) . 5000 6 

 Total production . . 6400 6 

 Average annual increment, 80 cub. ft. to 2 in. q. g. 



The rental equivalents will be about the same as those 

 given for Silver Fir. 



Of Fungi. Phytophthora omnivera often causes the 

 "damping off" of large quantities of seedlings. 



Pestalozzia Hartigii produces a kind of canker or blister 

 on the bark of the smooth stems of Spruce, and also of Silver 

 Fir and other trees in nurseries, and in young plantations. 

 The attack is generally near the ground level, and the trees 

 wilt and die. 



Septoria parasitica attacks the leading shoots of seedlings 

 and young trees of Norway Spruce and Sitka Spruce. The 

 base of the young shoots is generally affected in about June ; 

 they hang down, wither, and die. Later on, black fungous 

 specks can be seen on the bark and the needle cushions of 

 the attacked shoots. 



Agaricus melleus ( = the Honey Fungus) and Trametes 

 radiciperda (Fomes annosus) = the Red Rot Root Fungus, 

 attack the roots. 



Trametes pini attacks the boles of trees after about the 

 age of 35 years, affecting the heartwood and also the sap- 

 wood and causing the bole to become hollow. 



Lophodermium macrosporum (= the Spruce Leaf Scurf), 

 attacks the leaves of 2-year-old shoots of young trees, 

 generally from 10 to 30 years of age. It either merely pro- 

 duces a rust, or else causes actual leaf shedding. 



Botrytis cinerea attacks the foliage of young trees and 

 nursery stock. 



Nectria curcubitula produces cankerous patches on the 

 bark of small stems and branches. 



Chrysomyxa abietis (= the Spruce Needle Rust or 

 Blister), produces a rust on the current year's needles only. 



