PINACE.E 275 



as the fungus spreads rapidly upon sawmill refuse, all such 

 refuse in the vicinity of young woods should be destroyed in the 

 same manner. 



Armillaria mellea, Vahl. (Tree Root Rot or Honey Fungus), is 

 one of the commonest fungi injurious to young trees. It usually 

 attacks trees about the junction of the stem and roots, the my- 

 celium finding its way into the cambium and sapwood. It is 

 common on old forest land, where stumps and roots have been 

 left to decay. When only a few trees have been attacked they 

 should be dug up and burnt, and a trench 2 ft. deep should be 

 made round the affected area to check the spread of the black 

 bootlace-like rhizomorphs. The fructifications also should be 

 collected and burnt. 



Pumped or Punched Wood or Heart-rot are terms applied to 

 a condition of decay found in larch and other trees. A fungus 

 may be present in trees less than twenty years old, and trees 

 35-40 years of age are sometimes hollow or have the heartwood 

 reduced to touchwood. The reason for pumped wood is usually 

 assigned to unsuitable soil, but that cannot be the only cause, for 

 unsound trees may be found on almost all kinds of soil, and sound 

 and unsound trees may grow side by side. Reduced vitality due 

 to the long growing season, followed by a shorter resting period 

 than the trees are accustomed to in a natural state, may be a 

 contributory cause. Larix europcea is very susceptible to attack, 

 and large numbers of trees are injured by the disease. The 

 fungus responsible for the decay of the wood is a species of 

 Polyporus. 



Phomopsis pseudotsugcB, a fungus disease that has caused 

 injury to young Douglas fir trees during the last few years, has 

 also been observed on Japanese larch. ^ 



For other remarks on diseases, see W. E. Hiley, The Fungal 

 Diseases of the Coinmon Larch (1919). 



Key to Larix in Cultivation. 



Young shoots hairy, cones 3 or more in. long. — L. Griffithii. 

 Young shoots hairy, cones |-2 in. long. 



Leaves very long and slender up to 2 in. — L. sibirica. 

 Leaves shorter, usually not more than H in. 



Foliage glaucous, cone-bracts not exceeding scale. 



Leaves about 40 in bundle, cones ovoid, scales strongly 



reflexed. — L. leptolepis. 

 Leaves about 40 in bundle, cones oblong, scales sHghtly 



reflexed. — L. eurolepis. 

 Leaves 20-30 in bundle, cone-scales not reflexed. — 

 L. kurilensis. 



^ Trans. Roy. Scot. Arb. Soc. XXXV, p. 73 (1921). 



